From 873ee1c9a08ffa8cfdcf8df1eb6e6ceb9cef826c Mon Sep 17 00:00:00 2001 From: Nikunj A Dadhania Date: Wed, 31 Jul 2024 20:37:52 +0530 Subject: [PATCH 01/29] virt: sev-guest: Replace dev_dbg() with pr_debug() In preparation for moving code to arch/x86/coco/sev/core.c, replace dev_dbg with pr_debug. No functional change. Signed-off-by: Nikunj A Dadhania Signed-off-by: Borislav Petkov (AMD) Reviewed-by: Tom Lendacky Reviewed-by: Borislav Petkov (AMD) Tested-by: Peter Gonda Link: https://lore.kernel.org/r/20240731150811.156771-2-nikunj@amd.com --- drivers/virt/coco/sev-guest/sev-guest.c | 9 +++++---- 1 file changed, 5 insertions(+), 4 deletions(-) diff --git a/drivers/virt/coco/sev-guest/sev-guest.c b/drivers/virt/coco/sev-guest/sev-guest.c index 6fc7884ea0a11d..7d343f2c6ef8c0 100644 --- a/drivers/virt/coco/sev-guest/sev-guest.c +++ b/drivers/virt/coco/sev-guest/sev-guest.c @@ -296,8 +296,9 @@ static int verify_and_dec_payload(struct snp_guest_dev *snp_dev, void *payload, struct snp_guest_msg_hdr *req_hdr = &req->hdr; struct snp_guest_msg_hdr *resp_hdr = &resp->hdr; - dev_dbg(snp_dev->dev, "response [seqno %lld type %d version %d sz %d]\n", - resp_hdr->msg_seqno, resp_hdr->msg_type, resp_hdr->msg_version, resp_hdr->msg_sz); + pr_debug("response [seqno %lld type %d version %d sz %d]\n", + resp_hdr->msg_seqno, resp_hdr->msg_type, resp_hdr->msg_version, + resp_hdr->msg_sz); /* Copy response from shared memory to encrypted memory. */ memcpy(resp, snp_dev->response, sizeof(*resp)); @@ -343,8 +344,8 @@ static int enc_payload(struct snp_guest_dev *snp_dev, u64 seqno, int version, u8 if (!hdr->msg_seqno) return -ENOSR; - dev_dbg(snp_dev->dev, "request [seqno %lld type %d version %d sz %d]\n", - hdr->msg_seqno, hdr->msg_type, hdr->msg_version, hdr->msg_sz); + pr_debug("request [seqno %lld type %d version %d sz %d]\n", + hdr->msg_seqno, hdr->msg_type, hdr->msg_version, hdr->msg_sz); return __enc_payload(snp_dev, req, payload, sz); } From 1a7d6bd8cdbc5f40c39dcfb219992ad80ebb67b8 Mon Sep 17 00:00:00 2001 From: Nikunj A Dadhania Date: Wed, 31 Jul 2024 20:37:53 +0530 Subject: [PATCH 02/29] virt: sev-guest: Rename local guest message variables Rename local guest message variables for more clarity. No functional change. Signed-off-by: Nikunj A Dadhania Signed-off-by: Borislav Petkov (AMD) Link: https://lore.kernel.org/r/20240731150811.156771-3-nikunj@amd.com --- drivers/virt/coco/sev-guest/sev-guest.c | 117 ++++++++++++------------ 1 file changed, 59 insertions(+), 58 deletions(-) diff --git a/drivers/virt/coco/sev-guest/sev-guest.c b/drivers/virt/coco/sev-guest/sev-guest.c index 7d343f2c6ef8c0..a72fe1e959c2a7 100644 --- a/drivers/virt/coco/sev-guest/sev-guest.c +++ b/drivers/virt/coco/sev-guest/sev-guest.c @@ -291,45 +291,45 @@ static int dec_payload(struct snp_guest_dev *snp_dev, struct snp_guest_msg *msg, static int verify_and_dec_payload(struct snp_guest_dev *snp_dev, void *payload, u32 sz) { struct snp_guest_crypto *crypto = snp_dev->crypto; - struct snp_guest_msg *resp = &snp_dev->secret_response; - struct snp_guest_msg *req = &snp_dev->secret_request; - struct snp_guest_msg_hdr *req_hdr = &req->hdr; - struct snp_guest_msg_hdr *resp_hdr = &resp->hdr; + struct snp_guest_msg *resp_msg = &snp_dev->secret_response; + struct snp_guest_msg *req_msg = &snp_dev->secret_request; + struct snp_guest_msg_hdr *req_msg_hdr = &req_msg->hdr; + struct snp_guest_msg_hdr *resp_msg_hdr = &resp_msg->hdr; pr_debug("response [seqno %lld type %d version %d sz %d]\n", - resp_hdr->msg_seqno, resp_hdr->msg_type, resp_hdr->msg_version, - resp_hdr->msg_sz); + resp_msg_hdr->msg_seqno, resp_msg_hdr->msg_type, resp_msg_hdr->msg_version, + resp_msg_hdr->msg_sz); /* Copy response from shared memory to encrypted memory. */ - memcpy(resp, snp_dev->response, sizeof(*resp)); + memcpy(resp_msg, snp_dev->response, sizeof(*resp_msg)); /* Verify that the sequence counter is incremented by 1 */ - if (unlikely(resp_hdr->msg_seqno != (req_hdr->msg_seqno + 1))) + if (unlikely(resp_msg_hdr->msg_seqno != (req_msg_hdr->msg_seqno + 1))) return -EBADMSG; /* Verify response message type and version number. */ - if (resp_hdr->msg_type != (req_hdr->msg_type + 1) || - resp_hdr->msg_version != req_hdr->msg_version) + if (resp_msg_hdr->msg_type != (req_msg_hdr->msg_type + 1) || + resp_msg_hdr->msg_version != req_msg_hdr->msg_version) return -EBADMSG; /* * If the message size is greater than our buffer length then return * an error. */ - if (unlikely((resp_hdr->msg_sz + crypto->a_len) > sz)) + if (unlikely((resp_msg_hdr->msg_sz + crypto->a_len) > sz)) return -EBADMSG; /* Decrypt the payload */ - return dec_payload(snp_dev, resp, payload, resp_hdr->msg_sz + crypto->a_len); + return dec_payload(snp_dev, resp_msg, payload, resp_msg_hdr->msg_sz + crypto->a_len); } static int enc_payload(struct snp_guest_dev *snp_dev, u64 seqno, int version, u8 type, void *payload, size_t sz) { - struct snp_guest_msg *req = &snp_dev->secret_request; - struct snp_guest_msg_hdr *hdr = &req->hdr; + struct snp_guest_msg *msg = &snp_dev->secret_request; + struct snp_guest_msg_hdr *hdr = &msg->hdr; - memset(req, 0, sizeof(*req)); + memset(msg, 0, sizeof(*msg)); hdr->algo = SNP_AEAD_AES_256_GCM; hdr->hdr_version = MSG_HDR_VER; @@ -347,7 +347,7 @@ static int enc_payload(struct snp_guest_dev *snp_dev, u64 seqno, int version, u8 pr_debug("request [seqno %lld type %d version %d sz %d]\n", hdr->msg_seqno, hdr->msg_type, hdr->msg_version, hdr->msg_sz); - return __enc_payload(snp_dev, req, payload, sz); + return __enc_payload(snp_dev, msg, payload, sz); } static int __handle_guest_request(struct snp_guest_dev *snp_dev, u64 exit_code, @@ -496,8 +496,8 @@ struct snp_req_resp { static int get_report(struct snp_guest_dev *snp_dev, struct snp_guest_request_ioctl *arg) { struct snp_guest_crypto *crypto = snp_dev->crypto; - struct snp_report_req *req = &snp_dev->req.report; - struct snp_report_resp *resp; + struct snp_report_req *report_req = &snp_dev->req.report; + struct snp_report_resp *report_resp; int rc, resp_len; lockdep_assert_held(&snp_cmd_mutex); @@ -505,7 +505,7 @@ static int get_report(struct snp_guest_dev *snp_dev, struct snp_guest_request_io if (!arg->req_data || !arg->resp_data) return -EINVAL; - if (copy_from_user(req, (void __user *)arg->req_data, sizeof(*req))) + if (copy_from_user(report_req, (void __user *)arg->req_data, sizeof(*report_req))) return -EFAULT; /* @@ -513,30 +513,29 @@ static int get_report(struct snp_guest_dev *snp_dev, struct snp_guest_request_io * response payload. Make sure that it has enough space to cover the * authtag. */ - resp_len = sizeof(resp->data) + crypto->a_len; - resp = kzalloc(resp_len, GFP_KERNEL_ACCOUNT); - if (!resp) + resp_len = sizeof(report_resp->data) + crypto->a_len; + report_resp = kzalloc(resp_len, GFP_KERNEL_ACCOUNT); + if (!report_resp) return -ENOMEM; - rc = handle_guest_request(snp_dev, SVM_VMGEXIT_GUEST_REQUEST, arg, - SNP_MSG_REPORT_REQ, req, sizeof(*req), resp->data, - resp_len); + rc = handle_guest_request(snp_dev, SVM_VMGEXIT_GUEST_REQUEST, arg, SNP_MSG_REPORT_REQ, + report_req, sizeof(*report_req), report_resp->data, resp_len); if (rc) goto e_free; - if (copy_to_user((void __user *)arg->resp_data, resp, sizeof(*resp))) + if (copy_to_user((void __user *)arg->resp_data, report_resp, sizeof(*report_resp))) rc = -EFAULT; e_free: - kfree(resp); + kfree(report_resp); return rc; } static int get_derived_key(struct snp_guest_dev *snp_dev, struct snp_guest_request_ioctl *arg) { - struct snp_derived_key_req *req = &snp_dev->req.derived_key; + struct snp_derived_key_req *derived_key_req = &snp_dev->req.derived_key; struct snp_guest_crypto *crypto = snp_dev->crypto; - struct snp_derived_key_resp resp = {0}; + struct snp_derived_key_resp derived_key_resp = {0}; int rc, resp_len; /* Response data is 64 bytes and max authsize for GCM is 16 bytes. */ u8 buf[64 + 16]; @@ -551,25 +550,27 @@ static int get_derived_key(struct snp_guest_dev *snp_dev, struct snp_guest_reque * response payload. Make sure that it has enough space to cover the * authtag. */ - resp_len = sizeof(resp.data) + crypto->a_len; + resp_len = sizeof(derived_key_resp.data) + crypto->a_len; if (sizeof(buf) < resp_len) return -ENOMEM; - if (copy_from_user(req, (void __user *)arg->req_data, sizeof(*req))) + if (copy_from_user(derived_key_req, (void __user *)arg->req_data, + sizeof(*derived_key_req))) return -EFAULT; - rc = handle_guest_request(snp_dev, SVM_VMGEXIT_GUEST_REQUEST, arg, - SNP_MSG_KEY_REQ, req, sizeof(*req), buf, resp_len); + rc = handle_guest_request(snp_dev, SVM_VMGEXIT_GUEST_REQUEST, arg, SNP_MSG_KEY_REQ, + derived_key_req, sizeof(*derived_key_req), buf, resp_len); if (rc) return rc; - memcpy(resp.data, buf, sizeof(resp.data)); - if (copy_to_user((void __user *)arg->resp_data, &resp, sizeof(resp))) + memcpy(derived_key_resp.data, buf, sizeof(derived_key_resp.data)); + if (copy_to_user((void __user *)arg->resp_data, &derived_key_resp, + sizeof(derived_key_resp))) rc = -EFAULT; /* The response buffer contains the sensitive data, explicitly clear it. */ memzero_explicit(buf, sizeof(buf)); - memzero_explicit(&resp, sizeof(resp)); + memzero_explicit(&derived_key_resp, sizeof(derived_key_resp)); return rc; } @@ -577,9 +578,9 @@ static int get_ext_report(struct snp_guest_dev *snp_dev, struct snp_guest_reques struct snp_req_resp *io) { - struct snp_ext_report_req *req = &snp_dev->req.ext_report; + struct snp_ext_report_req *report_req = &snp_dev->req.ext_report; struct snp_guest_crypto *crypto = snp_dev->crypto; - struct snp_report_resp *resp; + struct snp_report_resp *report_resp; int ret, npages = 0, resp_len; sockptr_t certs_address; @@ -588,22 +589,22 @@ static int get_ext_report(struct snp_guest_dev *snp_dev, struct snp_guest_reques if (sockptr_is_null(io->req_data) || sockptr_is_null(io->resp_data)) return -EINVAL; - if (copy_from_sockptr(req, io->req_data, sizeof(*req))) + if (copy_from_sockptr(report_req, io->req_data, sizeof(*report_req))) return -EFAULT; /* caller does not want certificate data */ - if (!req->certs_len || !req->certs_address) + if (!report_req->certs_len || !report_req->certs_address) goto cmd; - if (req->certs_len > SEV_FW_BLOB_MAX_SIZE || - !IS_ALIGNED(req->certs_len, PAGE_SIZE)) + if (report_req->certs_len > SEV_FW_BLOB_MAX_SIZE || + !IS_ALIGNED(report_req->certs_len, PAGE_SIZE)) return -EINVAL; if (sockptr_is_kernel(io->resp_data)) { - certs_address = KERNEL_SOCKPTR((void *)req->certs_address); + certs_address = KERNEL_SOCKPTR((void *)report_req->certs_address); } else { - certs_address = USER_SOCKPTR((void __user *)req->certs_address); - if (!access_ok(certs_address.user, req->certs_len)) + certs_address = USER_SOCKPTR((void __user *)report_req->certs_address); + if (!access_ok(certs_address.user, report_req->certs_len)) return -EFAULT; } @@ -613,45 +614,45 @@ static int get_ext_report(struct snp_guest_dev *snp_dev, struct snp_guest_reques * the host. If host does not supply any certs in it, then copy * zeros to indicate that certificate data was not provided. */ - memset(snp_dev->certs_data, 0, req->certs_len); - npages = req->certs_len >> PAGE_SHIFT; + memset(snp_dev->certs_data, 0, report_req->certs_len); + npages = report_req->certs_len >> PAGE_SHIFT; cmd: /* * The intermediate response buffer is used while decrypting the * response payload. Make sure that it has enough space to cover the * authtag. */ - resp_len = sizeof(resp->data) + crypto->a_len; - resp = kzalloc(resp_len, GFP_KERNEL_ACCOUNT); - if (!resp) + resp_len = sizeof(report_resp->data) + crypto->a_len; + report_resp = kzalloc(resp_len, GFP_KERNEL_ACCOUNT); + if (!report_resp) return -ENOMEM; snp_dev->input.data_npages = npages; - ret = handle_guest_request(snp_dev, SVM_VMGEXIT_EXT_GUEST_REQUEST, arg, - SNP_MSG_REPORT_REQ, &req->data, - sizeof(req->data), resp->data, resp_len); + ret = handle_guest_request(snp_dev, SVM_VMGEXIT_EXT_GUEST_REQUEST, arg, SNP_MSG_REPORT_REQ, + &report_req->data, sizeof(report_req->data), + report_resp->data, resp_len); /* If certs length is invalid then copy the returned length */ if (arg->vmm_error == SNP_GUEST_VMM_ERR_INVALID_LEN) { - req->certs_len = snp_dev->input.data_npages << PAGE_SHIFT; + report_req->certs_len = snp_dev->input.data_npages << PAGE_SHIFT; - if (copy_to_sockptr(io->req_data, req, sizeof(*req))) + if (copy_to_sockptr(io->req_data, report_req, sizeof(*report_req))) ret = -EFAULT; } if (ret) goto e_free; - if (npages && copy_to_sockptr(certs_address, snp_dev->certs_data, req->certs_len)) { + if (npages && copy_to_sockptr(certs_address, snp_dev->certs_data, report_req->certs_len)) { ret = -EFAULT; goto e_free; } - if (copy_to_sockptr(io->resp_data, resp, sizeof(*resp))) + if (copy_to_sockptr(io->resp_data, report_resp, sizeof(*report_resp))) ret = -EFAULT; e_free: - kfree(resp); + kfree(report_resp); return ret; } From 9e8162c1e68a035f83c1e9f4ecbf32f03a510c48 Mon Sep 17 00:00:00 2001 From: Nikunj A Dadhania Date: Wed, 31 Jul 2024 20:37:54 +0530 Subject: [PATCH 03/29] virt: sev-guest: Fix user-visible strings User-visible abbreviations should be in capitals, ensure messages are readable and clear. No functional change. Signed-off-by: Nikunj A Dadhania Signed-off-by: Borislav Petkov (AMD) Link: https://lore.kernel.org/r/20240731150811.156771-4-nikunj@amd.com --- drivers/virt/coco/sev-guest/sev-guest.c | 8 ++++---- 1 file changed, 4 insertions(+), 4 deletions(-) diff --git a/drivers/virt/coco/sev-guest/sev-guest.c b/drivers/virt/coco/sev-guest/sev-guest.c index a72fe1e959c2a7..3b76cbf78f41fd 100644 --- a/drivers/virt/coco/sev-guest/sev-guest.c +++ b/drivers/virt/coco/sev-guest/sev-guest.c @@ -114,7 +114,7 @@ static bool is_vmpck_empty(struct snp_guest_dev *snp_dev) */ static void snp_disable_vmpck(struct snp_guest_dev *snp_dev) { - dev_alert(snp_dev->dev, "Disabling vmpck_id %d to prevent IV reuse.\n", + dev_alert(snp_dev->dev, "Disabling VMPCK%d communication key to prevent IV reuse.\n", vmpck_id); memzero_explicit(snp_dev->vmpck, VMPCK_KEY_LEN); snp_dev->vmpck = NULL; @@ -1117,13 +1117,13 @@ static int __init sev_guest_probe(struct platform_device *pdev) ret = -EINVAL; snp_dev->vmpck = get_vmpck(vmpck_id, secrets, &snp_dev->os_area_msg_seqno); if (!snp_dev->vmpck) { - dev_err(dev, "invalid vmpck id %d\n", vmpck_id); + dev_err(dev, "Invalid VMPCK%d communication key\n", vmpck_id); goto e_unmap; } /* Verify that VMPCK is not zero. */ if (is_vmpck_empty(snp_dev)) { - dev_err(dev, "vmpck id %d is null\n", vmpck_id); + dev_err(dev, "Empty VMPCK%d communication key\n", vmpck_id); goto e_unmap; } @@ -1174,7 +1174,7 @@ static int __init sev_guest_probe(struct platform_device *pdev) if (ret) goto e_free_cert_data; - dev_info(dev, "Initialized SEV guest driver (using vmpck_id %d)\n", vmpck_id); + dev_info(dev, "Initialized SEV guest driver (using VMPCK%d communication key)\n", vmpck_id); return 0; e_free_cert_data: From 80ee22099d4be721108206f50ccb7991e4d8423f Mon Sep 17 00:00:00 2001 From: Nikunj A Dadhania Date: Wed, 31 Jul 2024 20:37:55 +0530 Subject: [PATCH 04/29] virt: sev-guest: Ensure the SNP guest messages do not exceed a page Currently, struct snp_guest_msg includes a message header (96 bytes) and a payload (4000 bytes). There is an implicit assumption here that the SNP message header will always be 96 bytes, and with that assumption the payload array size has been set to 4000 bytes - a magic number. If any new member is added to the SNP message header, the SNP guest message will span more than a page. Instead of using a magic number for the payload, declare struct snp_guest_msg in a way that payload plus the message header do not exceed a page. [ bp: Massage. ] Suggested-by: Tom Lendacky Signed-off-by: Nikunj A Dadhania Signed-off-by: Borislav Petkov (AMD) Acked-by: Borislav Petkov (AMD) Link: https://lore.kernel.org/r/20240731150811.156771-5-nikunj@amd.com --- arch/x86/include/asm/sev.h | 2 +- drivers/virt/coco/sev-guest/sev-guest.c | 2 ++ 2 files changed, 3 insertions(+), 1 deletion(-) diff --git a/arch/x86/include/asm/sev.h b/arch/x86/include/asm/sev.h index 79bbe2be900eb7..ee34ab00a8d6d9 100644 --- a/arch/x86/include/asm/sev.h +++ b/arch/x86/include/asm/sev.h @@ -164,7 +164,7 @@ struct snp_guest_msg_hdr { struct snp_guest_msg { struct snp_guest_msg_hdr hdr; - u8 payload[4000]; + u8 payload[PAGE_SIZE - sizeof(struct snp_guest_msg_hdr)]; } __packed; struct sev_guest_platform_data { diff --git a/drivers/virt/coco/sev-guest/sev-guest.c b/drivers/virt/coco/sev-guest/sev-guest.c index 3b76cbf78f41fd..89754b019be2ba 100644 --- a/drivers/virt/coco/sev-guest/sev-guest.c +++ b/drivers/virt/coco/sev-guest/sev-guest.c @@ -1092,6 +1092,8 @@ static int __init sev_guest_probe(struct platform_device *pdev) void __iomem *mapping; int ret; + BUILD_BUG_ON(sizeof(struct snp_guest_msg) > PAGE_SIZE); + if (!cc_platform_has(CC_ATTR_GUEST_SEV_SNP)) return -ENODEV; From b7a1ca95c4a3f229f539b72e35eeef928819fc92 Mon Sep 17 00:00:00 2001 From: Nikunj A Dadhania Date: Wed, 9 Oct 2024 14:58:32 +0530 Subject: [PATCH 05/29] virt: sev-guest: Use AES GCM crypto library The sev-guest driver encryption code uses the crypto API for SNP guest messaging with the AMD Security processor. In order to enable secure TSC, SEV-SNP guests need to send such a TSC_INFO message before the APs are booted. Details from the TSC_INFO response will then be used to program the VMSA before the APs are brought up. However, the crypto API is not available this early in the boot process. In preparation for moving the encryption code out of sev-guest to support secure TSC and to ease review, switch to using the AES GCM library implementation instead. Drop __enc_payload() and dec_payload() helpers as both are small and can be moved to the respective callers. Signed-off-by: Nikunj A Dadhania Signed-off-by: Borislav Petkov (AMD) Reviewed-by: Tom Lendacky Acked-by: Borislav Petkov (AMD) Tested-by: Peter Gonda Link: https://lore.kernel.org/r/20241009092850.197575-2-nikunj@amd.com --- arch/x86/include/asm/sev.h | 3 + drivers/virt/coco/sev-guest/Kconfig | 4 +- drivers/virt/coco/sev-guest/sev-guest.c | 175 ++++++------------------ 3 files changed, 43 insertions(+), 139 deletions(-) diff --git a/arch/x86/include/asm/sev.h b/arch/x86/include/asm/sev.h index ee34ab00a8d6d9..e7977f76d77e0b 100644 --- a/arch/x86/include/asm/sev.h +++ b/arch/x86/include/asm/sev.h @@ -120,6 +120,9 @@ struct snp_req_data { }; #define MAX_AUTHTAG_LEN 32 +#define AUTHTAG_LEN 16 +#define AAD_LEN 48 +#define MSG_HDR_VER 1 /* See SNP spec SNP_GUEST_REQUEST section for the structure */ enum msg_type { diff --git a/drivers/virt/coco/sev-guest/Kconfig b/drivers/virt/coco/sev-guest/Kconfig index 1cffc72c41cb14..0b772bd921d818 100644 --- a/drivers/virt/coco/sev-guest/Kconfig +++ b/drivers/virt/coco/sev-guest/Kconfig @@ -2,9 +2,7 @@ config SEV_GUEST tristate "AMD SEV Guest driver" default m depends on AMD_MEM_ENCRYPT - select CRYPTO - select CRYPTO_AEAD2 - select CRYPTO_GCM + select CRYPTO_LIB_AESGCM select TSM_REPORTS help SEV-SNP firmware provides the guest a mechanism to communicate with diff --git a/drivers/virt/coco/sev-guest/sev-guest.c b/drivers/virt/coco/sev-guest/sev-guest.c index 89754b019be2ba..a33daff516ed92 100644 --- a/drivers/virt/coco/sev-guest/sev-guest.c +++ b/drivers/virt/coco/sev-guest/sev-guest.c @@ -17,8 +17,7 @@ #include #include #include -#include -#include +#include #include #include #include @@ -31,26 +30,18 @@ #include #define DEVICE_NAME "sev-guest" -#define AAD_LEN 48 -#define MSG_HDR_VER 1 #define SNP_REQ_MAX_RETRY_DURATION (60*HZ) #define SNP_REQ_RETRY_DELAY (2*HZ) #define SVSM_MAX_RETRIES 3 -struct snp_guest_crypto { - struct crypto_aead *tfm; - u8 *iv, *authtag; - int iv_len, a_len; -}; - struct snp_guest_dev { struct device *dev; struct miscdevice misc; void *certs_data; - struct snp_guest_crypto *crypto; + struct aesgcm_ctx *ctx; /* request and response are in unencrypted memory */ struct snp_guest_msg *request, *response; @@ -169,132 +160,31 @@ static inline struct snp_guest_dev *to_snp_dev(struct file *file) return container_of(dev, struct snp_guest_dev, misc); } -static struct snp_guest_crypto *init_crypto(struct snp_guest_dev *snp_dev, u8 *key, size_t keylen) +static struct aesgcm_ctx *snp_init_crypto(u8 *key, size_t keylen) { - struct snp_guest_crypto *crypto; + struct aesgcm_ctx *ctx; - crypto = kzalloc(sizeof(*crypto), GFP_KERNEL_ACCOUNT); - if (!crypto) + ctx = kzalloc(sizeof(*ctx), GFP_KERNEL_ACCOUNT); + if (!ctx) return NULL; - crypto->tfm = crypto_alloc_aead("gcm(aes)", 0, 0); - if (IS_ERR(crypto->tfm)) - goto e_free; - - if (crypto_aead_setkey(crypto->tfm, key, keylen)) - goto e_free_crypto; - - crypto->iv_len = crypto_aead_ivsize(crypto->tfm); - crypto->iv = kmalloc(crypto->iv_len, GFP_KERNEL_ACCOUNT); - if (!crypto->iv) - goto e_free_crypto; - - if (crypto_aead_authsize(crypto->tfm) > MAX_AUTHTAG_LEN) { - if (crypto_aead_setauthsize(crypto->tfm, MAX_AUTHTAG_LEN)) { - dev_err(snp_dev->dev, "failed to set authsize to %d\n", MAX_AUTHTAG_LEN); - goto e_free_iv; - } + if (aesgcm_expandkey(ctx, key, keylen, AUTHTAG_LEN)) { + pr_err("Crypto context initialization failed\n"); + kfree(ctx); + return NULL; } - crypto->a_len = crypto_aead_authsize(crypto->tfm); - crypto->authtag = kmalloc(crypto->a_len, GFP_KERNEL_ACCOUNT); - if (!crypto->authtag) - goto e_free_iv; - - return crypto; - -e_free_iv: - kfree(crypto->iv); -e_free_crypto: - crypto_free_aead(crypto->tfm); -e_free: - kfree(crypto); - - return NULL; -} - -static void deinit_crypto(struct snp_guest_crypto *crypto) -{ - crypto_free_aead(crypto->tfm); - kfree(crypto->iv); - kfree(crypto->authtag); - kfree(crypto); -} - -static int enc_dec_message(struct snp_guest_crypto *crypto, struct snp_guest_msg *msg, - u8 *src_buf, u8 *dst_buf, size_t len, bool enc) -{ - struct snp_guest_msg_hdr *hdr = &msg->hdr; - struct scatterlist src[3], dst[3]; - DECLARE_CRYPTO_WAIT(wait); - struct aead_request *req; - int ret; - - req = aead_request_alloc(crypto->tfm, GFP_KERNEL); - if (!req) - return -ENOMEM; - - /* - * AEAD memory operations: - * +------ AAD -------+------- DATA -----+---- AUTHTAG----+ - * | msg header | plaintext | hdr->authtag | - * | bytes 30h - 5Fh | or | | - * | | cipher | | - * +------------------+------------------+----------------+ - */ - sg_init_table(src, 3); - sg_set_buf(&src[0], &hdr->algo, AAD_LEN); - sg_set_buf(&src[1], src_buf, hdr->msg_sz); - sg_set_buf(&src[2], hdr->authtag, crypto->a_len); - - sg_init_table(dst, 3); - sg_set_buf(&dst[0], &hdr->algo, AAD_LEN); - sg_set_buf(&dst[1], dst_buf, hdr->msg_sz); - sg_set_buf(&dst[2], hdr->authtag, crypto->a_len); - - aead_request_set_ad(req, AAD_LEN); - aead_request_set_tfm(req, crypto->tfm); - aead_request_set_callback(req, 0, crypto_req_done, &wait); - - aead_request_set_crypt(req, src, dst, len, crypto->iv); - ret = crypto_wait_req(enc ? crypto_aead_encrypt(req) : crypto_aead_decrypt(req), &wait); - - aead_request_free(req); - return ret; -} - -static int __enc_payload(struct snp_guest_dev *snp_dev, struct snp_guest_msg *msg, - void *plaintext, size_t len) -{ - struct snp_guest_crypto *crypto = snp_dev->crypto; - struct snp_guest_msg_hdr *hdr = &msg->hdr; - - memset(crypto->iv, 0, crypto->iv_len); - memcpy(crypto->iv, &hdr->msg_seqno, sizeof(hdr->msg_seqno)); - - return enc_dec_message(crypto, msg, plaintext, msg->payload, len, true); -} - -static int dec_payload(struct snp_guest_dev *snp_dev, struct snp_guest_msg *msg, - void *plaintext, size_t len) -{ - struct snp_guest_crypto *crypto = snp_dev->crypto; - struct snp_guest_msg_hdr *hdr = &msg->hdr; - - /* Build IV with response buffer sequence number */ - memset(crypto->iv, 0, crypto->iv_len); - memcpy(crypto->iv, &hdr->msg_seqno, sizeof(hdr->msg_seqno)); - - return enc_dec_message(crypto, msg, msg->payload, plaintext, len, false); + return ctx; } static int verify_and_dec_payload(struct snp_guest_dev *snp_dev, void *payload, u32 sz) { - struct snp_guest_crypto *crypto = snp_dev->crypto; struct snp_guest_msg *resp_msg = &snp_dev->secret_response; struct snp_guest_msg *req_msg = &snp_dev->secret_request; struct snp_guest_msg_hdr *req_msg_hdr = &req_msg->hdr; struct snp_guest_msg_hdr *resp_msg_hdr = &resp_msg->hdr; + struct aesgcm_ctx *ctx = snp_dev->ctx; + u8 iv[GCM_AES_IV_SIZE] = {}; pr_debug("response [seqno %lld type %d version %d sz %d]\n", resp_msg_hdr->msg_seqno, resp_msg_hdr->msg_type, resp_msg_hdr->msg_version, @@ -316,11 +206,16 @@ static int verify_and_dec_payload(struct snp_guest_dev *snp_dev, void *payload, * If the message size is greater than our buffer length then return * an error. */ - if (unlikely((resp_msg_hdr->msg_sz + crypto->a_len) > sz)) + if (unlikely((resp_msg_hdr->msg_sz + ctx->authsize) > sz)) return -EBADMSG; /* Decrypt the payload */ - return dec_payload(snp_dev, resp_msg, payload, resp_msg_hdr->msg_sz + crypto->a_len); + memcpy(iv, &resp_msg_hdr->msg_seqno, min(sizeof(iv), sizeof(resp_msg_hdr->msg_seqno))); + if (!aesgcm_decrypt(ctx, payload, resp_msg->payload, resp_msg_hdr->msg_sz, + &resp_msg_hdr->algo, AAD_LEN, iv, resp_msg_hdr->authtag)) + return -EBADMSG; + + return 0; } static int enc_payload(struct snp_guest_dev *snp_dev, u64 seqno, int version, u8 type, @@ -328,6 +223,8 @@ static int enc_payload(struct snp_guest_dev *snp_dev, u64 seqno, int version, u8 { struct snp_guest_msg *msg = &snp_dev->secret_request; struct snp_guest_msg_hdr *hdr = &msg->hdr; + struct aesgcm_ctx *ctx = snp_dev->ctx; + u8 iv[GCM_AES_IV_SIZE] = {}; memset(msg, 0, sizeof(*msg)); @@ -347,7 +244,14 @@ static int enc_payload(struct snp_guest_dev *snp_dev, u64 seqno, int version, u8 pr_debug("request [seqno %lld type %d version %d sz %d]\n", hdr->msg_seqno, hdr->msg_type, hdr->msg_version, hdr->msg_sz); - return __enc_payload(snp_dev, msg, payload, sz); + if (WARN_ON((sz + ctx->authsize) > sizeof(msg->payload))) + return -EBADMSG; + + memcpy(iv, &hdr->msg_seqno, min(sizeof(iv), sizeof(hdr->msg_seqno))); + aesgcm_encrypt(ctx, msg->payload, payload, sz, &hdr->algo, AAD_LEN, + iv, hdr->authtag); + + return 0; } static int __handle_guest_request(struct snp_guest_dev *snp_dev, u64 exit_code, @@ -495,7 +399,6 @@ struct snp_req_resp { static int get_report(struct snp_guest_dev *snp_dev, struct snp_guest_request_ioctl *arg) { - struct snp_guest_crypto *crypto = snp_dev->crypto; struct snp_report_req *report_req = &snp_dev->req.report; struct snp_report_resp *report_resp; int rc, resp_len; @@ -513,7 +416,7 @@ static int get_report(struct snp_guest_dev *snp_dev, struct snp_guest_request_io * response payload. Make sure that it has enough space to cover the * authtag. */ - resp_len = sizeof(report_resp->data) + crypto->a_len; + resp_len = sizeof(report_resp->data) + snp_dev->ctx->authsize; report_resp = kzalloc(resp_len, GFP_KERNEL_ACCOUNT); if (!report_resp) return -ENOMEM; @@ -534,7 +437,6 @@ static int get_report(struct snp_guest_dev *snp_dev, struct snp_guest_request_io static int get_derived_key(struct snp_guest_dev *snp_dev, struct snp_guest_request_ioctl *arg) { struct snp_derived_key_req *derived_key_req = &snp_dev->req.derived_key; - struct snp_guest_crypto *crypto = snp_dev->crypto; struct snp_derived_key_resp derived_key_resp = {0}; int rc, resp_len; /* Response data is 64 bytes and max authsize for GCM is 16 bytes. */ @@ -550,7 +452,7 @@ static int get_derived_key(struct snp_guest_dev *snp_dev, struct snp_guest_reque * response payload. Make sure that it has enough space to cover the * authtag. */ - resp_len = sizeof(derived_key_resp.data) + crypto->a_len; + resp_len = sizeof(derived_key_resp.data) + snp_dev->ctx->authsize; if (sizeof(buf) < resp_len) return -ENOMEM; @@ -579,7 +481,6 @@ static int get_ext_report(struct snp_guest_dev *snp_dev, struct snp_guest_reques { struct snp_ext_report_req *report_req = &snp_dev->req.ext_report; - struct snp_guest_crypto *crypto = snp_dev->crypto; struct snp_report_resp *report_resp; int ret, npages = 0, resp_len; sockptr_t certs_address; @@ -622,7 +523,7 @@ static int get_ext_report(struct snp_guest_dev *snp_dev, struct snp_guest_reques * response payload. Make sure that it has enough space to cover the * authtag. */ - resp_len = sizeof(report_resp->data) + crypto->a_len; + resp_len = sizeof(report_resp->data) + snp_dev->ctx->authsize; report_resp = kzalloc(resp_len, GFP_KERNEL_ACCOUNT); if (!report_resp) return -ENOMEM; @@ -1147,8 +1048,8 @@ static int __init sev_guest_probe(struct platform_device *pdev) goto e_free_response; ret = -EIO; - snp_dev->crypto = init_crypto(snp_dev, snp_dev->vmpck, VMPCK_KEY_LEN); - if (!snp_dev->crypto) + snp_dev->ctx = snp_init_crypto(snp_dev->vmpck, VMPCK_KEY_LEN); + if (!snp_dev->ctx) goto e_free_cert_data; misc = &snp_dev->misc; @@ -1174,11 +1075,13 @@ static int __init sev_guest_probe(struct platform_device *pdev) ret = misc_register(misc); if (ret) - goto e_free_cert_data; + goto e_free_ctx; dev_info(dev, "Initialized SEV guest driver (using VMPCK%d communication key)\n", vmpck_id); return 0; +e_free_ctx: + kfree(snp_dev->ctx); e_free_cert_data: free_shared_pages(snp_dev->certs_data, SEV_FW_BLOB_MAX_SIZE); e_free_response: @@ -1197,7 +1100,7 @@ static void __exit sev_guest_remove(struct platform_device *pdev) free_shared_pages(snp_dev->certs_data, SEV_FW_BLOB_MAX_SIZE); free_shared_pages(snp_dev->response, sizeof(struct snp_guest_msg)); free_shared_pages(snp_dev->request, sizeof(struct snp_guest_msg)); - deinit_crypto(snp_dev->crypto); + kfree(snp_dev->ctx); misc_deregister(&snp_dev->misc); } From 9e6b9cf18a84e3e0c1fc18bceeb9eff9ff982087 Mon Sep 17 00:00:00 2001 From: Nikunj A Dadhania Date: Wed, 9 Oct 2024 14:58:33 +0530 Subject: [PATCH 06/29] x86/sev: Handle failures from snp_init() Address the ignored failures from snp_init() in sme_enable(). Add error handling for scenarios where snp_init() fails to retrieve the SEV-SNP CC blob or encounters issues while parsing the CC blob. Ensure that SNP guests will error out early, preventing delayed error reporting or undefined behavior. Signed-off-by: Nikunj A Dadhania Signed-off-by: Borislav Petkov (AMD) Reviewed-by: Tom Lendacky Link: https://lore.kernel.org/r/20241009092850.197575-3-nikunj@amd.com --- arch/x86/mm/mem_encrypt_identity.c | 11 +++++++---- 1 file changed, 7 insertions(+), 4 deletions(-) diff --git a/arch/x86/mm/mem_encrypt_identity.c b/arch/x86/mm/mem_encrypt_identity.c index ac33b2263a434d..e6c7686f443a06 100644 --- a/arch/x86/mm/mem_encrypt_identity.c +++ b/arch/x86/mm/mem_encrypt_identity.c @@ -495,10 +495,10 @@ void __head sme_enable(struct boot_params *bp) unsigned int eax, ebx, ecx, edx; unsigned long feature_mask; unsigned long me_mask; - bool snp; + bool snp_en; u64 msr; - snp = snp_init(bp); + snp_en = snp_init(bp); /* Check for the SME/SEV support leaf */ eax = 0x80000000; @@ -531,8 +531,11 @@ void __head sme_enable(struct boot_params *bp) RIP_REL_REF(sev_status) = msr = __rdmsr(MSR_AMD64_SEV); feature_mask = (msr & MSR_AMD64_SEV_ENABLED) ? AMD_SEV_BIT : AMD_SME_BIT; - /* The SEV-SNP CC blob should never be present unless SEV-SNP is enabled. */ - if (snp && !(msr & MSR_AMD64_SEV_SNP_ENABLED)) + /* + * Any discrepancies between the presence of a CC blob and SNP + * enablement abort the guest. + */ + if (snp_en ^ !!(msr & MSR_AMD64_SEV_SNP_ENABLED)) snp_abort(); /* Check if memory encryption is enabled */ From 72b7eaa4c8883341bde63f315fcb6794ca5e4630 Mon Sep 17 00:00:00 2001 From: Nikunj A Dadhania Date: Wed, 9 Oct 2024 14:58:34 +0530 Subject: [PATCH 07/29] x86/sev: Cache the secrets page address Instead of calling get_secrets_page(), which parses the CC blob every time to get the secrets page physical address (secrets_pa), save the secrets page physical address during snp_init() from the CC blob. Since get_secrets_page() is no longer used, remove the function. Signed-off-by: Nikunj A Dadhania Signed-off-by: Borislav Petkov (AMD) Reviewed-by: Tom Lendacky Link: https://lore.kernel.org/r/20241009092850.197575-4-nikunj@amd.com --- arch/x86/coco/sev/core.c | 51 +++++++++------------------------------- 1 file changed, 11 insertions(+), 40 deletions(-) diff --git a/arch/x86/coco/sev/core.c b/arch/x86/coco/sev/core.c index 3069feb91409d6..5c832c9f9a1beb 100644 --- a/arch/x86/coco/sev/core.c +++ b/arch/x86/coco/sev/core.c @@ -93,6 +93,9 @@ static struct ghcb *boot_ghcb __section(".data"); /* Bitmap of SEV features supported by the hypervisor */ static u64 sev_hv_features __ro_after_init; +/* Secrets page physical address from the CC blob */ +static u64 secrets_pa __ro_after_init; + /* #VC handler runtime per-CPU data */ struct sev_es_runtime_data { struct ghcb ghcb_page; @@ -723,45 +726,13 @@ void noinstr __sev_es_nmi_complete(void) __sev_put_ghcb(&state); } -static u64 __init get_secrets_page(void) -{ - u64 pa_data = boot_params.cc_blob_address; - struct cc_blob_sev_info info; - void *map; - - /* - * The CC blob contains the address of the secrets page, check if the - * blob is present. - */ - if (!pa_data) - return 0; - - map = early_memremap(pa_data, sizeof(info)); - if (!map) { - pr_err("Unable to locate SNP secrets page: failed to map the Confidential Computing blob.\n"); - return 0; - } - memcpy(&info, map, sizeof(info)); - early_memunmap(map, sizeof(info)); - - /* smoke-test the secrets page passed */ - if (!info.secrets_phys || info.secrets_len != PAGE_SIZE) - return 0; - - return info.secrets_phys; -} - static u64 __init get_snp_jump_table_addr(void) { struct snp_secrets_page *secrets; void __iomem *mem; - u64 pa, addr; - - pa = get_secrets_page(); - if (!pa) - return 0; + u64 addr; - mem = ioremap_encrypted(pa, PAGE_SIZE); + mem = ioremap_encrypted(secrets_pa, PAGE_SIZE); if (!mem) { pr_err("Unable to locate AP jump table address: failed to map the SNP secrets page.\n"); return 0; @@ -2301,6 +2272,11 @@ bool __head snp_init(struct boot_params *bp) if (!cc_info) return false; + if (cc_info->secrets_phys && cc_info->secrets_len == PAGE_SIZE) + secrets_pa = cc_info->secrets_phys; + else + return false; + setup_cpuid_table(cc_info); svsm_setup(cc_info); @@ -2558,16 +2534,11 @@ static bool is_svsm_vtpm_send_command_supported(void) static int __init snp_init_platform_device(void) { struct sev_guest_platform_data data; - u64 gpa; if (!cc_platform_has(CC_ATTR_GUEST_SEV_SNP)) return -ENODEV; - gpa = get_secrets_page(); - if (!gpa) - return -ENODEV; - - data.secrets_gpa = gpa; + data.secrets_gpa = secrets_pa; if (platform_device_add_data(&sev_guest_device, &data, sizeof(data))) return -ENODEV; From 6c36baf8fccc5e8e278e58763fb8beaf0bad0973 Mon Sep 17 00:00:00 2001 From: Nikunj A Dadhania Date: Wed, 9 Oct 2024 14:58:35 +0530 Subject: [PATCH 08/29] virt: sev-guest: Consolidate SNP guest messaging parameters to a struct Add a snp_guest_req structure to eliminate the need to pass a long list of parameters. This structure will be used to call the SNP Guest message request API, simplifying the function arguments. Update the snp_issue_guest_request() prototype to include the new guest request structure. Signed-off-by: Nikunj A Dadhania Signed-off-by: Borislav Petkov (AMD) Reviewed-by: Tom Lendacky Link: https://lore.kernel.org/r/20241009092850.197575-5-nikunj@amd.com --- arch/x86/coco/sev/core.c | 9 +-- arch/x86/include/asm/sev.h | 19 +++++- drivers/virt/coco/sev-guest/sev-guest.c | 84 ++++++++++++++++--------- 3 files changed, 76 insertions(+), 36 deletions(-) diff --git a/arch/x86/coco/sev/core.c b/arch/x86/coco/sev/core.c index 5c832c9f9a1beb..2f182d0a65d27f 100644 --- a/arch/x86/coco/sev/core.c +++ b/arch/x86/coco/sev/core.c @@ -2418,7 +2418,8 @@ int snp_issue_svsm_attest_req(u64 call_id, struct svsm_call *call, } EXPORT_SYMBOL_GPL(snp_issue_svsm_attest_req); -int snp_issue_guest_request(u64 exit_code, struct snp_req_data *input, struct snp_guest_request_ioctl *rio) +int snp_issue_guest_request(struct snp_guest_req *req, struct snp_req_data *input, + struct snp_guest_request_ioctl *rio) { struct ghcb_state state; struct es_em_ctxt ctxt; @@ -2442,12 +2443,12 @@ int snp_issue_guest_request(u64 exit_code, struct snp_req_data *input, struct sn vc_ghcb_invalidate(ghcb); - if (exit_code == SVM_VMGEXIT_EXT_GUEST_REQUEST) { + if (req->exit_code == SVM_VMGEXIT_EXT_GUEST_REQUEST) { ghcb_set_rax(ghcb, input->data_gpa); ghcb_set_rbx(ghcb, input->data_npages); } - ret = sev_es_ghcb_hv_call(ghcb, &ctxt, exit_code, input->req_gpa, input->resp_gpa); + ret = sev_es_ghcb_hv_call(ghcb, &ctxt, req->exit_code, input->req_gpa, input->resp_gpa); if (ret) goto e_put; @@ -2462,7 +2463,7 @@ int snp_issue_guest_request(u64 exit_code, struct snp_req_data *input, struct sn case SNP_GUEST_VMM_ERR(SNP_GUEST_VMM_ERR_INVALID_LEN): /* Number of expected pages are returned in RBX */ - if (exit_code == SVM_VMGEXIT_EXT_GUEST_REQUEST) { + if (req->exit_code == SVM_VMGEXIT_EXT_GUEST_REQUEST) { input->data_npages = ghcb_get_rbx(ghcb); ret = -ENOSPC; break; diff --git a/arch/x86/include/asm/sev.h b/arch/x86/include/asm/sev.h index e7977f76d77e0b..27fa1c9c3465b9 100644 --- a/arch/x86/include/asm/sev.h +++ b/arch/x86/include/asm/sev.h @@ -174,6 +174,19 @@ struct sev_guest_platform_data { u64 secrets_gpa; }; +struct snp_guest_req { + void *req_buf; + size_t req_sz; + + void *resp_buf; + size_t resp_sz; + + u64 exit_code; + unsigned int vmpck_id; + u8 msg_version; + u8 msg_type; +}; + /* * The secrets page contains 96-bytes of reserved field that can be used by * the guest OS. The guest OS uses the area to save the message sequence @@ -395,7 +408,8 @@ void snp_set_wakeup_secondary_cpu(void); bool snp_init(struct boot_params *bp); void __noreturn snp_abort(void); void snp_dmi_setup(void); -int snp_issue_guest_request(u64 exit_code, struct snp_req_data *input, struct snp_guest_request_ioctl *rio); +int snp_issue_guest_request(struct snp_guest_req *req, struct snp_req_data *input, + struct snp_guest_request_ioctl *rio); int snp_issue_svsm_attest_req(u64 call_id, struct svsm_call *call, struct svsm_attest_call *input); void snp_accept_memory(phys_addr_t start, phys_addr_t end); u64 snp_get_unsupported_features(u64 status); @@ -425,7 +439,8 @@ static inline void snp_set_wakeup_secondary_cpu(void) { } static inline bool snp_init(struct boot_params *bp) { return false; } static inline void snp_abort(void) { } static inline void snp_dmi_setup(void) { } -static inline int snp_issue_guest_request(u64 exit_code, struct snp_req_data *input, struct snp_guest_request_ioctl *rio) +static inline int snp_issue_guest_request(struct snp_guest_req *req, struct snp_req_data *input, + struct snp_guest_request_ioctl *rio) { return -ENOTTY; } diff --git a/drivers/virt/coco/sev-guest/sev-guest.c b/drivers/virt/coco/sev-guest/sev-guest.c index a33daff516ed92..2a1b542168b12d 100644 --- a/drivers/virt/coco/sev-guest/sev-guest.c +++ b/drivers/virt/coco/sev-guest/sev-guest.c @@ -177,7 +177,7 @@ static struct aesgcm_ctx *snp_init_crypto(u8 *key, size_t keylen) return ctx; } -static int verify_and_dec_payload(struct snp_guest_dev *snp_dev, void *payload, u32 sz) +static int verify_and_dec_payload(struct snp_guest_dev *snp_dev, struct snp_guest_req *req) { struct snp_guest_msg *resp_msg = &snp_dev->secret_response; struct snp_guest_msg *req_msg = &snp_dev->secret_request; @@ -206,20 +206,19 @@ static int verify_and_dec_payload(struct snp_guest_dev *snp_dev, void *payload, * If the message size is greater than our buffer length then return * an error. */ - if (unlikely((resp_msg_hdr->msg_sz + ctx->authsize) > sz)) + if (unlikely((resp_msg_hdr->msg_sz + ctx->authsize) > req->resp_sz)) return -EBADMSG; /* Decrypt the payload */ memcpy(iv, &resp_msg_hdr->msg_seqno, min(sizeof(iv), sizeof(resp_msg_hdr->msg_seqno))); - if (!aesgcm_decrypt(ctx, payload, resp_msg->payload, resp_msg_hdr->msg_sz, + if (!aesgcm_decrypt(ctx, req->resp_buf, resp_msg->payload, resp_msg_hdr->msg_sz, &resp_msg_hdr->algo, AAD_LEN, iv, resp_msg_hdr->authtag)) return -EBADMSG; return 0; } -static int enc_payload(struct snp_guest_dev *snp_dev, u64 seqno, int version, u8 type, - void *payload, size_t sz) +static int enc_payload(struct snp_guest_dev *snp_dev, u64 seqno, struct snp_guest_req *req) { struct snp_guest_msg *msg = &snp_dev->secret_request; struct snp_guest_msg_hdr *hdr = &msg->hdr; @@ -231,11 +230,11 @@ static int enc_payload(struct snp_guest_dev *snp_dev, u64 seqno, int version, u8 hdr->algo = SNP_AEAD_AES_256_GCM; hdr->hdr_version = MSG_HDR_VER; hdr->hdr_sz = sizeof(*hdr); - hdr->msg_type = type; - hdr->msg_version = version; + hdr->msg_type = req->msg_type; + hdr->msg_version = req->msg_version; hdr->msg_seqno = seqno; - hdr->msg_vmpck = vmpck_id; - hdr->msg_sz = sz; + hdr->msg_vmpck = req->vmpck_id; + hdr->msg_sz = req->req_sz; /* Verify the sequence number is non-zero */ if (!hdr->msg_seqno) @@ -244,17 +243,17 @@ static int enc_payload(struct snp_guest_dev *snp_dev, u64 seqno, int version, u8 pr_debug("request [seqno %lld type %d version %d sz %d]\n", hdr->msg_seqno, hdr->msg_type, hdr->msg_version, hdr->msg_sz); - if (WARN_ON((sz + ctx->authsize) > sizeof(msg->payload))) + if (WARN_ON((req->req_sz + ctx->authsize) > sizeof(msg->payload))) return -EBADMSG; memcpy(iv, &hdr->msg_seqno, min(sizeof(iv), sizeof(hdr->msg_seqno))); - aesgcm_encrypt(ctx, msg->payload, payload, sz, &hdr->algo, AAD_LEN, - iv, hdr->authtag); + aesgcm_encrypt(ctx, msg->payload, req->req_buf, req->req_sz, &hdr->algo, + AAD_LEN, iv, hdr->authtag); return 0; } -static int __handle_guest_request(struct snp_guest_dev *snp_dev, u64 exit_code, +static int __handle_guest_request(struct snp_guest_dev *snp_dev, struct snp_guest_req *req, struct snp_guest_request_ioctl *rio) { unsigned long req_start = jiffies; @@ -269,7 +268,7 @@ static int __handle_guest_request(struct snp_guest_dev *snp_dev, u64 exit_code, * sequence number must be incremented or the VMPCK must be deleted to * prevent reuse of the IV. */ - rc = snp_issue_guest_request(exit_code, &snp_dev->input, rio); + rc = snp_issue_guest_request(req, &snp_dev->input, rio); switch (rc) { case -ENOSPC: /* @@ -280,7 +279,7 @@ static int __handle_guest_request(struct snp_guest_dev *snp_dev, u64 exit_code, * IV reuse. */ override_npages = snp_dev->input.data_npages; - exit_code = SVM_VMGEXIT_GUEST_REQUEST; + req->exit_code = SVM_VMGEXIT_GUEST_REQUEST; /* * Override the error to inform callers the given extended @@ -340,10 +339,8 @@ static int __handle_guest_request(struct snp_guest_dev *snp_dev, u64 exit_code, return rc; } -static int handle_guest_request(struct snp_guest_dev *snp_dev, u64 exit_code, - struct snp_guest_request_ioctl *rio, u8 type, - void *req_buf, size_t req_sz, void *resp_buf, - u32 resp_sz) +static int snp_send_guest_request(struct snp_guest_dev *snp_dev, struct snp_guest_req *req, + struct snp_guest_request_ioctl *rio) { u64 seqno; int rc; @@ -357,7 +354,7 @@ static int handle_guest_request(struct snp_guest_dev *snp_dev, u64 exit_code, memset(snp_dev->response, 0, sizeof(struct snp_guest_msg)); /* Encrypt the userspace provided payload in snp_dev->secret_request. */ - rc = enc_payload(snp_dev, seqno, rio->msg_version, type, req_buf, req_sz); + rc = enc_payload(snp_dev, seqno, req); if (rc) return rc; @@ -368,7 +365,7 @@ static int handle_guest_request(struct snp_guest_dev *snp_dev, u64 exit_code, memcpy(snp_dev->request, &snp_dev->secret_request, sizeof(snp_dev->secret_request)); - rc = __handle_guest_request(snp_dev, exit_code, rio); + rc = __handle_guest_request(snp_dev, req, rio); if (rc) { if (rc == -EIO && rio->exitinfo2 == SNP_GUEST_VMM_ERR(SNP_GUEST_VMM_ERR_INVALID_LEN)) @@ -382,7 +379,7 @@ static int handle_guest_request(struct snp_guest_dev *snp_dev, u64 exit_code, return rc; } - rc = verify_and_dec_payload(snp_dev, resp_buf, resp_sz); + rc = verify_and_dec_payload(snp_dev, req); if (rc) { dev_alert(snp_dev->dev, "Detected unexpected decode failure from ASP. rc: %d\n", rc); snp_disable_vmpck(snp_dev); @@ -401,6 +398,7 @@ static int get_report(struct snp_guest_dev *snp_dev, struct snp_guest_request_io { struct snp_report_req *report_req = &snp_dev->req.report; struct snp_report_resp *report_resp; + struct snp_guest_req req = {}; int rc, resp_len; lockdep_assert_held(&snp_cmd_mutex); @@ -421,8 +419,16 @@ static int get_report(struct snp_guest_dev *snp_dev, struct snp_guest_request_io if (!report_resp) return -ENOMEM; - rc = handle_guest_request(snp_dev, SVM_VMGEXIT_GUEST_REQUEST, arg, SNP_MSG_REPORT_REQ, - report_req, sizeof(*report_req), report_resp->data, resp_len); + req.msg_version = arg->msg_version; + req.msg_type = SNP_MSG_REPORT_REQ; + req.vmpck_id = vmpck_id; + req.req_buf = report_req; + req.req_sz = sizeof(*report_req); + req.resp_buf = report_resp->data; + req.resp_sz = resp_len; + req.exit_code = SVM_VMGEXIT_GUEST_REQUEST; + + rc = snp_send_guest_request(snp_dev, &req, arg); if (rc) goto e_free; @@ -438,6 +444,7 @@ static int get_derived_key(struct snp_guest_dev *snp_dev, struct snp_guest_reque { struct snp_derived_key_req *derived_key_req = &snp_dev->req.derived_key; struct snp_derived_key_resp derived_key_resp = {0}; + struct snp_guest_req req = {}; int rc, resp_len; /* Response data is 64 bytes and max authsize for GCM is 16 bytes. */ u8 buf[64 + 16]; @@ -460,8 +467,16 @@ static int get_derived_key(struct snp_guest_dev *snp_dev, struct snp_guest_reque sizeof(*derived_key_req))) return -EFAULT; - rc = handle_guest_request(snp_dev, SVM_VMGEXIT_GUEST_REQUEST, arg, SNP_MSG_KEY_REQ, - derived_key_req, sizeof(*derived_key_req), buf, resp_len); + req.msg_version = arg->msg_version; + req.msg_type = SNP_MSG_KEY_REQ; + req.vmpck_id = vmpck_id; + req.req_buf = derived_key_req; + req.req_sz = sizeof(*derived_key_req); + req.resp_buf = buf; + req.resp_sz = resp_len; + req.exit_code = SVM_VMGEXIT_GUEST_REQUEST; + + rc = snp_send_guest_request(snp_dev, &req, arg); if (rc) return rc; @@ -482,6 +497,7 @@ static int get_ext_report(struct snp_guest_dev *snp_dev, struct snp_guest_reques { struct snp_ext_report_req *report_req = &snp_dev->req.ext_report; struct snp_report_resp *report_resp; + struct snp_guest_req req = {}; int ret, npages = 0, resp_len; sockptr_t certs_address; @@ -529,9 +545,17 @@ static int get_ext_report(struct snp_guest_dev *snp_dev, struct snp_guest_reques return -ENOMEM; snp_dev->input.data_npages = npages; - ret = handle_guest_request(snp_dev, SVM_VMGEXIT_EXT_GUEST_REQUEST, arg, SNP_MSG_REPORT_REQ, - &report_req->data, sizeof(report_req->data), - report_resp->data, resp_len); + + req.msg_version = arg->msg_version; + req.msg_type = SNP_MSG_REPORT_REQ; + req.vmpck_id = vmpck_id; + req.req_buf = &report_req->data; + req.req_sz = sizeof(report_req->data); + req.resp_buf = report_resp->data; + req.resp_sz = resp_len; + req.exit_code = SVM_VMGEXIT_EXT_GUEST_REQUEST; + + ret = snp_send_guest_request(snp_dev, &req, arg); /* If certs length is invalid then copy the returned length */ if (arg->vmm_error == SNP_GUEST_VMM_ERR_INVALID_LEN) { @@ -1057,7 +1081,7 @@ static int __init sev_guest_probe(struct platform_device *pdev) misc->name = DEVICE_NAME; misc->fops = &snp_guest_fops; - /* initial the input address for guest request */ + /* Initialize the input addresses for guest request */ snp_dev->input.req_gpa = __pa(snp_dev->request); snp_dev->input.resp_gpa = __pa(snp_dev->response); snp_dev->input.data_gpa = __pa(snp_dev->certs_data); From 11917238e2dfdc79fc8124b91d07a960d7ce2396 Mon Sep 17 00:00:00 2001 From: Nikunj A Dadhania Date: Wed, 9 Oct 2024 14:58:36 +0530 Subject: [PATCH 09/29] virt: sev-guest: Reduce the scope of SNP command mutex The SNP command mutex is used to serialize access to the shared buffer, command handling, and message sequence number. All shared buffer, command handling, and message sequence updates are done within snp_send_guest_request(), so moving the mutex to this function is appropriate and maintains the critical section. Since the mutex is now taken at a later point in time, remove the lockdep checks that occur before taking the mutex. Signed-off-by: Nikunj A Dadhania Signed-off-by: Borislav Petkov (AMD) Reviewed-by: Tom Lendacky Link: https://lore.kernel.org/r/20241009092850.197575-6-nikunj@amd.com --- drivers/virt/coco/sev-guest/sev-guest.c | 35 ++++++------------------- 1 file changed, 8 insertions(+), 27 deletions(-) diff --git a/drivers/virt/coco/sev-guest/sev-guest.c b/drivers/virt/coco/sev-guest/sev-guest.c index 2a1b542168b12d..1bddef82244651 100644 --- a/drivers/virt/coco/sev-guest/sev-guest.c +++ b/drivers/virt/coco/sev-guest/sev-guest.c @@ -345,6 +345,14 @@ static int snp_send_guest_request(struct snp_guest_dev *snp_dev, struct snp_gues u64 seqno; int rc; + guard(mutex)(&snp_cmd_mutex); + + /* Check if the VMPCK is not empty */ + if (is_vmpck_empty(snp_dev)) { + dev_err_ratelimited(snp_dev->dev, "VMPCK is disabled\n"); + return -ENOTTY; + } + /* Get message sequence and verify that its a non-zero */ seqno = snp_get_msg_seqno(snp_dev); if (!seqno) @@ -401,8 +409,6 @@ static int get_report(struct snp_guest_dev *snp_dev, struct snp_guest_request_io struct snp_guest_req req = {}; int rc, resp_len; - lockdep_assert_held(&snp_cmd_mutex); - if (!arg->req_data || !arg->resp_data) return -EINVAL; @@ -449,8 +455,6 @@ static int get_derived_key(struct snp_guest_dev *snp_dev, struct snp_guest_reque /* Response data is 64 bytes and max authsize for GCM is 16 bytes. */ u8 buf[64 + 16]; - lockdep_assert_held(&snp_cmd_mutex); - if (!arg->req_data || !arg->resp_data) return -EINVAL; @@ -501,8 +505,6 @@ static int get_ext_report(struct snp_guest_dev *snp_dev, struct snp_guest_reques int ret, npages = 0, resp_len; sockptr_t certs_address; - lockdep_assert_held(&snp_cmd_mutex); - if (sockptr_is_null(io->req_data) || sockptr_is_null(io->resp_data)) return -EINVAL; @@ -598,15 +600,6 @@ static long snp_guest_ioctl(struct file *file, unsigned int ioctl, unsigned long if (!input.msg_version) return -EINVAL; - mutex_lock(&snp_cmd_mutex); - - /* Check if the VMPCK is not empty */ - if (is_vmpck_empty(snp_dev)) { - dev_err_ratelimited(snp_dev->dev, "VMPCK is disabled\n"); - mutex_unlock(&snp_cmd_mutex); - return -ENOTTY; - } - switch (ioctl) { case SNP_GET_REPORT: ret = get_report(snp_dev, &input); @@ -628,8 +621,6 @@ static long snp_guest_ioctl(struct file *file, unsigned int ioctl, unsigned long break; } - mutex_unlock(&snp_cmd_mutex); - if (input.exitinfo2 && copy_to_user(argp, &input, sizeof(input))) return -EFAULT; @@ -744,8 +735,6 @@ static int sev_svsm_report_new(struct tsm_report *report, void *data) man_len = SZ_4K; certs_len = SEV_FW_BLOB_MAX_SIZE; - guard(mutex)(&snp_cmd_mutex); - if (guid_is_null(&desc->service_guid)) { call_id = SVSM_ATTEST_CALL(SVSM_ATTEST_SERVICES); } else { @@ -880,14 +869,6 @@ static int sev_report_new(struct tsm_report *report, void *data) if (!buf) return -ENOMEM; - guard(mutex)(&snp_cmd_mutex); - - /* Check if the VMPCK is not empty */ - if (is_vmpck_empty(snp_dev)) { - dev_err_ratelimited(snp_dev->dev, "VMPCK is disabled\n"); - return -ENOTTY; - } - cert_table = buf + report_size; struct snp_ext_report_req ext_req = { .data = { .vmpl = desc->privlevel }, From 9fd4bb1fb8f5a63075ec9115744fb76e7c689cef Mon Sep 17 00:00:00 2001 From: Nikunj A Dadhania Date: Wed, 9 Oct 2024 14:58:37 +0530 Subject: [PATCH 10/29] virt: sev-guest: Carve out SNP message context structure Currently, the sev-guest driver is the only user of SNP guest messaging. The snp_guest_dev structure holds all the allocated buffers, secrets page and VMPCK details. In preparation for adding messaging allocation and initialization APIs, decouple snp_guest_dev from messaging-related information by carving out the guest message context structure(snp_msg_desc). Incorporate this newly added context into snp_send_guest_request() and all related functions, replacing the use of the snp_guest_dev. No functional change. Signed-off-by: Nikunj A Dadhania Signed-off-by: Borislav Petkov (AMD) Reviewed-by: Tom Lendacky Link: https://lore.kernel.org/r/20241009092850.197575-7-nikunj@amd.com --- arch/x86/include/asm/sev.h | 21 +++ drivers/virt/coco/sev-guest/sev-guest.c | 178 ++++++++++++------------ 2 files changed, 108 insertions(+), 91 deletions(-) diff --git a/arch/x86/include/asm/sev.h b/arch/x86/include/asm/sev.h index 27fa1c9c3465b9..2e49c4a9e7fe7a 100644 --- a/arch/x86/include/asm/sev.h +++ b/arch/x86/include/asm/sev.h @@ -234,6 +234,27 @@ struct snp_secrets_page { u8 rsvd4[3744]; } __packed; +struct snp_msg_desc { + /* request and response are in unencrypted memory */ + struct snp_guest_msg *request, *response; + + /* + * Avoid information leakage by double-buffering shared messages + * in fields that are in regular encrypted memory. + */ + struct snp_guest_msg secret_request, secret_response; + + struct snp_secrets_page *secrets; + struct snp_req_data input; + + void *certs_data; + + struct aesgcm_ctx *ctx; + + u32 *os_area_msg_seqno; + u8 *vmpck; +}; + /* * The SVSM Calling Area (CA) related structures. */ diff --git a/drivers/virt/coco/sev-guest/sev-guest.c b/drivers/virt/coco/sev-guest/sev-guest.c index 1bddef82244651..fca5c45ed5cd9d 100644 --- a/drivers/virt/coco/sev-guest/sev-guest.c +++ b/drivers/virt/coco/sev-guest/sev-guest.c @@ -40,26 +40,13 @@ struct snp_guest_dev { struct device *dev; struct miscdevice misc; - void *certs_data; - struct aesgcm_ctx *ctx; - /* request and response are in unencrypted memory */ - struct snp_guest_msg *request, *response; - - /* - * Avoid information leakage by double-buffering shared messages - * in fields that are in regular encrypted memory. - */ - struct snp_guest_msg secret_request, secret_response; + struct snp_msg_desc *msg_desc; - struct snp_secrets_page *secrets; - struct snp_req_data input; union { struct snp_report_req report; struct snp_derived_key_req derived_key; struct snp_ext_report_req ext_report; } req; - u32 *os_area_msg_seqno; - u8 *vmpck; }; /* @@ -76,12 +63,12 @@ MODULE_PARM_DESC(vmpck_id, "The VMPCK ID to use when communicating with the PSP. /* Mutex to serialize the shared buffer access and command handling. */ static DEFINE_MUTEX(snp_cmd_mutex); -static bool is_vmpck_empty(struct snp_guest_dev *snp_dev) +static bool is_vmpck_empty(struct snp_msg_desc *mdesc) { char zero_key[VMPCK_KEY_LEN] = {0}; - if (snp_dev->vmpck) - return !memcmp(snp_dev->vmpck, zero_key, VMPCK_KEY_LEN); + if (mdesc->vmpck) + return !memcmp(mdesc->vmpck, zero_key, VMPCK_KEY_LEN); return true; } @@ -103,30 +90,30 @@ static bool is_vmpck_empty(struct snp_guest_dev *snp_dev) * vulnerable. If the sequence number were incremented for a fresh IV the ASP * will reject the request. */ -static void snp_disable_vmpck(struct snp_guest_dev *snp_dev) +static void snp_disable_vmpck(struct snp_msg_desc *mdesc) { - dev_alert(snp_dev->dev, "Disabling VMPCK%d communication key to prevent IV reuse.\n", + pr_alert("Disabling VMPCK%d communication key to prevent IV reuse.\n", vmpck_id); - memzero_explicit(snp_dev->vmpck, VMPCK_KEY_LEN); - snp_dev->vmpck = NULL; + memzero_explicit(mdesc->vmpck, VMPCK_KEY_LEN); + mdesc->vmpck = NULL; } -static inline u64 __snp_get_msg_seqno(struct snp_guest_dev *snp_dev) +static inline u64 __snp_get_msg_seqno(struct snp_msg_desc *mdesc) { u64 count; lockdep_assert_held(&snp_cmd_mutex); /* Read the current message sequence counter from secrets pages */ - count = *snp_dev->os_area_msg_seqno; + count = *mdesc->os_area_msg_seqno; return count + 1; } /* Return a non-zero on success */ -static u64 snp_get_msg_seqno(struct snp_guest_dev *snp_dev) +static u64 snp_get_msg_seqno(struct snp_msg_desc *mdesc) { - u64 count = __snp_get_msg_seqno(snp_dev); + u64 count = __snp_get_msg_seqno(mdesc); /* * The message sequence counter for the SNP guest request is a 64-bit @@ -137,20 +124,20 @@ static u64 snp_get_msg_seqno(struct snp_guest_dev *snp_dev) * invalid number and will fail the message request. */ if (count >= UINT_MAX) { - dev_err(snp_dev->dev, "request message sequence counter overflow\n"); + pr_err("request message sequence counter overflow\n"); return 0; } return count; } -static void snp_inc_msg_seqno(struct snp_guest_dev *snp_dev) +static void snp_inc_msg_seqno(struct snp_msg_desc *mdesc) { /* * The counter is also incremented by the PSP, so increment it by 2 * and save in secrets page. */ - *snp_dev->os_area_msg_seqno += 2; + *mdesc->os_area_msg_seqno += 2; } static inline struct snp_guest_dev *to_snp_dev(struct file *file) @@ -177,13 +164,13 @@ static struct aesgcm_ctx *snp_init_crypto(u8 *key, size_t keylen) return ctx; } -static int verify_and_dec_payload(struct snp_guest_dev *snp_dev, struct snp_guest_req *req) +static int verify_and_dec_payload(struct snp_msg_desc *mdesc, struct snp_guest_req *req) { - struct snp_guest_msg *resp_msg = &snp_dev->secret_response; - struct snp_guest_msg *req_msg = &snp_dev->secret_request; + struct snp_guest_msg *resp_msg = &mdesc->secret_response; + struct snp_guest_msg *req_msg = &mdesc->secret_request; struct snp_guest_msg_hdr *req_msg_hdr = &req_msg->hdr; struct snp_guest_msg_hdr *resp_msg_hdr = &resp_msg->hdr; - struct aesgcm_ctx *ctx = snp_dev->ctx; + struct aesgcm_ctx *ctx = mdesc->ctx; u8 iv[GCM_AES_IV_SIZE] = {}; pr_debug("response [seqno %lld type %d version %d sz %d]\n", @@ -191,7 +178,7 @@ static int verify_and_dec_payload(struct snp_guest_dev *snp_dev, struct snp_gues resp_msg_hdr->msg_sz); /* Copy response from shared memory to encrypted memory. */ - memcpy(resp_msg, snp_dev->response, sizeof(*resp_msg)); + memcpy(resp_msg, mdesc->response, sizeof(*resp_msg)); /* Verify that the sequence counter is incremented by 1 */ if (unlikely(resp_msg_hdr->msg_seqno != (req_msg_hdr->msg_seqno + 1))) @@ -218,11 +205,11 @@ static int verify_and_dec_payload(struct snp_guest_dev *snp_dev, struct snp_gues return 0; } -static int enc_payload(struct snp_guest_dev *snp_dev, u64 seqno, struct snp_guest_req *req) +static int enc_payload(struct snp_msg_desc *mdesc, u64 seqno, struct snp_guest_req *req) { - struct snp_guest_msg *msg = &snp_dev->secret_request; + struct snp_guest_msg *msg = &mdesc->secret_request; struct snp_guest_msg_hdr *hdr = &msg->hdr; - struct aesgcm_ctx *ctx = snp_dev->ctx; + struct aesgcm_ctx *ctx = mdesc->ctx; u8 iv[GCM_AES_IV_SIZE] = {}; memset(msg, 0, sizeof(*msg)); @@ -253,7 +240,7 @@ static int enc_payload(struct snp_guest_dev *snp_dev, u64 seqno, struct snp_gues return 0; } -static int __handle_guest_request(struct snp_guest_dev *snp_dev, struct snp_guest_req *req, +static int __handle_guest_request(struct snp_msg_desc *mdesc, struct snp_guest_req *req, struct snp_guest_request_ioctl *rio) { unsigned long req_start = jiffies; @@ -268,7 +255,7 @@ static int __handle_guest_request(struct snp_guest_dev *snp_dev, struct snp_gues * sequence number must be incremented or the VMPCK must be deleted to * prevent reuse of the IV. */ - rc = snp_issue_guest_request(req, &snp_dev->input, rio); + rc = snp_issue_guest_request(req, &mdesc->input, rio); switch (rc) { case -ENOSPC: /* @@ -278,7 +265,7 @@ static int __handle_guest_request(struct snp_guest_dev *snp_dev, struct snp_gues * order to increment the sequence number and thus avoid * IV reuse. */ - override_npages = snp_dev->input.data_npages; + override_npages = mdesc->input.data_npages; req->exit_code = SVM_VMGEXIT_GUEST_REQUEST; /* @@ -318,7 +305,7 @@ static int __handle_guest_request(struct snp_guest_dev *snp_dev, struct snp_gues * structure and any failure will wipe the VMPCK, preventing further * use anyway. */ - snp_inc_msg_seqno(snp_dev); + snp_inc_msg_seqno(mdesc); if (override_err) { rio->exitinfo2 = override_err; @@ -334,12 +321,12 @@ static int __handle_guest_request(struct snp_guest_dev *snp_dev, struct snp_gues } if (override_npages) - snp_dev->input.data_npages = override_npages; + mdesc->input.data_npages = override_npages; return rc; } -static int snp_send_guest_request(struct snp_guest_dev *snp_dev, struct snp_guest_req *req, +static int snp_send_guest_request(struct snp_msg_desc *mdesc, struct snp_guest_req *req, struct snp_guest_request_ioctl *rio) { u64 seqno; @@ -348,21 +335,21 @@ static int snp_send_guest_request(struct snp_guest_dev *snp_dev, struct snp_gues guard(mutex)(&snp_cmd_mutex); /* Check if the VMPCK is not empty */ - if (is_vmpck_empty(snp_dev)) { - dev_err_ratelimited(snp_dev->dev, "VMPCK is disabled\n"); + if (is_vmpck_empty(mdesc)) { + pr_err_ratelimited("VMPCK is disabled\n"); return -ENOTTY; } /* Get message sequence and verify that its a non-zero */ - seqno = snp_get_msg_seqno(snp_dev); + seqno = snp_get_msg_seqno(mdesc); if (!seqno) return -EIO; /* Clear shared memory's response for the host to populate. */ - memset(snp_dev->response, 0, sizeof(struct snp_guest_msg)); + memset(mdesc->response, 0, sizeof(struct snp_guest_msg)); - /* Encrypt the userspace provided payload in snp_dev->secret_request. */ - rc = enc_payload(snp_dev, seqno, req); + /* Encrypt the userspace provided payload in mdesc->secret_request. */ + rc = enc_payload(mdesc, seqno, req); if (rc) return rc; @@ -370,27 +357,26 @@ static int snp_send_guest_request(struct snp_guest_dev *snp_dev, struct snp_gues * Write the fully encrypted request to the shared unencrypted * request page. */ - memcpy(snp_dev->request, &snp_dev->secret_request, - sizeof(snp_dev->secret_request)); + memcpy(mdesc->request, &mdesc->secret_request, + sizeof(mdesc->secret_request)); - rc = __handle_guest_request(snp_dev, req, rio); + rc = __handle_guest_request(mdesc, req, rio); if (rc) { if (rc == -EIO && rio->exitinfo2 == SNP_GUEST_VMM_ERR(SNP_GUEST_VMM_ERR_INVALID_LEN)) return rc; - dev_alert(snp_dev->dev, - "Detected error from ASP request. rc: %d, exitinfo2: 0x%llx\n", - rc, rio->exitinfo2); + pr_alert("Detected error from ASP request. rc: %d, exitinfo2: 0x%llx\n", + rc, rio->exitinfo2); - snp_disable_vmpck(snp_dev); + snp_disable_vmpck(mdesc); return rc; } - rc = verify_and_dec_payload(snp_dev, req); + rc = verify_and_dec_payload(mdesc, req); if (rc) { - dev_alert(snp_dev->dev, "Detected unexpected decode failure from ASP. rc: %d\n", rc); - snp_disable_vmpck(snp_dev); + pr_alert("Detected unexpected decode failure from ASP. rc: %d\n", rc); + snp_disable_vmpck(mdesc); return rc; } @@ -405,6 +391,7 @@ struct snp_req_resp { static int get_report(struct snp_guest_dev *snp_dev, struct snp_guest_request_ioctl *arg) { struct snp_report_req *report_req = &snp_dev->req.report; + struct snp_msg_desc *mdesc = snp_dev->msg_desc; struct snp_report_resp *report_resp; struct snp_guest_req req = {}; int rc, resp_len; @@ -420,7 +407,7 @@ static int get_report(struct snp_guest_dev *snp_dev, struct snp_guest_request_io * response payload. Make sure that it has enough space to cover the * authtag. */ - resp_len = sizeof(report_resp->data) + snp_dev->ctx->authsize; + resp_len = sizeof(report_resp->data) + mdesc->ctx->authsize; report_resp = kzalloc(resp_len, GFP_KERNEL_ACCOUNT); if (!report_resp) return -ENOMEM; @@ -434,7 +421,7 @@ static int get_report(struct snp_guest_dev *snp_dev, struct snp_guest_request_io req.resp_sz = resp_len; req.exit_code = SVM_VMGEXIT_GUEST_REQUEST; - rc = snp_send_guest_request(snp_dev, &req, arg); + rc = snp_send_guest_request(mdesc, &req, arg); if (rc) goto e_free; @@ -450,6 +437,7 @@ static int get_derived_key(struct snp_guest_dev *snp_dev, struct snp_guest_reque { struct snp_derived_key_req *derived_key_req = &snp_dev->req.derived_key; struct snp_derived_key_resp derived_key_resp = {0}; + struct snp_msg_desc *mdesc = snp_dev->msg_desc; struct snp_guest_req req = {}; int rc, resp_len; /* Response data is 64 bytes and max authsize for GCM is 16 bytes. */ @@ -463,7 +451,7 @@ static int get_derived_key(struct snp_guest_dev *snp_dev, struct snp_guest_reque * response payload. Make sure that it has enough space to cover the * authtag. */ - resp_len = sizeof(derived_key_resp.data) + snp_dev->ctx->authsize; + resp_len = sizeof(derived_key_resp.data) + mdesc->ctx->authsize; if (sizeof(buf) < resp_len) return -ENOMEM; @@ -480,7 +468,7 @@ static int get_derived_key(struct snp_guest_dev *snp_dev, struct snp_guest_reque req.resp_sz = resp_len; req.exit_code = SVM_VMGEXIT_GUEST_REQUEST; - rc = snp_send_guest_request(snp_dev, &req, arg); + rc = snp_send_guest_request(mdesc, &req, arg); if (rc) return rc; @@ -500,6 +488,7 @@ static int get_ext_report(struct snp_guest_dev *snp_dev, struct snp_guest_reques { struct snp_ext_report_req *report_req = &snp_dev->req.ext_report; + struct snp_msg_desc *mdesc = snp_dev->msg_desc; struct snp_report_resp *report_resp; struct snp_guest_req req = {}; int ret, npages = 0, resp_len; @@ -533,7 +522,7 @@ static int get_ext_report(struct snp_guest_dev *snp_dev, struct snp_guest_reques * the host. If host does not supply any certs in it, then copy * zeros to indicate that certificate data was not provided. */ - memset(snp_dev->certs_data, 0, report_req->certs_len); + memset(mdesc->certs_data, 0, report_req->certs_len); npages = report_req->certs_len >> PAGE_SHIFT; cmd: /* @@ -541,12 +530,12 @@ static int get_ext_report(struct snp_guest_dev *snp_dev, struct snp_guest_reques * response payload. Make sure that it has enough space to cover the * authtag. */ - resp_len = sizeof(report_resp->data) + snp_dev->ctx->authsize; + resp_len = sizeof(report_resp->data) + mdesc->ctx->authsize; report_resp = kzalloc(resp_len, GFP_KERNEL_ACCOUNT); if (!report_resp) return -ENOMEM; - snp_dev->input.data_npages = npages; + mdesc->input.data_npages = npages; req.msg_version = arg->msg_version; req.msg_type = SNP_MSG_REPORT_REQ; @@ -557,11 +546,11 @@ static int get_ext_report(struct snp_guest_dev *snp_dev, struct snp_guest_reques req.resp_sz = resp_len; req.exit_code = SVM_VMGEXIT_EXT_GUEST_REQUEST; - ret = snp_send_guest_request(snp_dev, &req, arg); + ret = snp_send_guest_request(mdesc, &req, arg); /* If certs length is invalid then copy the returned length */ if (arg->vmm_error == SNP_GUEST_VMM_ERR_INVALID_LEN) { - report_req->certs_len = snp_dev->input.data_npages << PAGE_SHIFT; + report_req->certs_len = mdesc->input.data_npages << PAGE_SHIFT; if (copy_to_sockptr(io->req_data, report_req, sizeof(*report_req))) ret = -EFAULT; @@ -570,7 +559,7 @@ static int get_ext_report(struct snp_guest_dev *snp_dev, struct snp_guest_reques if (ret) goto e_free; - if (npages && copy_to_sockptr(certs_address, snp_dev->certs_data, report_req->certs_len)) { + if (npages && copy_to_sockptr(certs_address, mdesc->certs_data, report_req->certs_len)) { ret = -EFAULT; goto e_free; } @@ -994,6 +983,7 @@ static int __init sev_guest_probe(struct platform_device *pdev) struct snp_secrets_page *secrets; struct device *dev = &pdev->dev; struct snp_guest_dev *snp_dev; + struct snp_msg_desc *mdesc; struct miscdevice *misc; void __iomem *mapping; int ret; @@ -1018,43 +1008,47 @@ static int __init sev_guest_probe(struct platform_device *pdev) if (!snp_dev) goto e_unmap; + mdesc = devm_kzalloc(&pdev->dev, sizeof(struct snp_msg_desc), GFP_KERNEL); + if (!mdesc) + goto e_unmap; + /* Adjust the default VMPCK key based on the executing VMPL level */ if (vmpck_id == -1) vmpck_id = snp_vmpl; ret = -EINVAL; - snp_dev->vmpck = get_vmpck(vmpck_id, secrets, &snp_dev->os_area_msg_seqno); - if (!snp_dev->vmpck) { + mdesc->vmpck = get_vmpck(vmpck_id, secrets, &mdesc->os_area_msg_seqno); + if (!mdesc->vmpck) { dev_err(dev, "Invalid VMPCK%d communication key\n", vmpck_id); goto e_unmap; } /* Verify that VMPCK is not zero. */ - if (is_vmpck_empty(snp_dev)) { + if (is_vmpck_empty(mdesc)) { dev_err(dev, "Empty VMPCK%d communication key\n", vmpck_id); goto e_unmap; } platform_set_drvdata(pdev, snp_dev); snp_dev->dev = dev; - snp_dev->secrets = secrets; + mdesc->secrets = secrets; /* Allocate the shared page used for the request and response message. */ - snp_dev->request = alloc_shared_pages(dev, sizeof(struct snp_guest_msg)); - if (!snp_dev->request) + mdesc->request = alloc_shared_pages(dev, sizeof(struct snp_guest_msg)); + if (!mdesc->request) goto e_unmap; - snp_dev->response = alloc_shared_pages(dev, sizeof(struct snp_guest_msg)); - if (!snp_dev->response) + mdesc->response = alloc_shared_pages(dev, sizeof(struct snp_guest_msg)); + if (!mdesc->response) goto e_free_request; - snp_dev->certs_data = alloc_shared_pages(dev, SEV_FW_BLOB_MAX_SIZE); - if (!snp_dev->certs_data) + mdesc->certs_data = alloc_shared_pages(dev, SEV_FW_BLOB_MAX_SIZE); + if (!mdesc->certs_data) goto e_free_response; ret = -EIO; - snp_dev->ctx = snp_init_crypto(snp_dev->vmpck, VMPCK_KEY_LEN); - if (!snp_dev->ctx) + mdesc->ctx = snp_init_crypto(mdesc->vmpck, VMPCK_KEY_LEN); + if (!mdesc->ctx) goto e_free_cert_data; misc = &snp_dev->misc; @@ -1063,9 +1057,9 @@ static int __init sev_guest_probe(struct platform_device *pdev) misc->fops = &snp_guest_fops; /* Initialize the input addresses for guest request */ - snp_dev->input.req_gpa = __pa(snp_dev->request); - snp_dev->input.resp_gpa = __pa(snp_dev->response); - snp_dev->input.data_gpa = __pa(snp_dev->certs_data); + mdesc->input.req_gpa = __pa(mdesc->request); + mdesc->input.resp_gpa = __pa(mdesc->response); + mdesc->input.data_gpa = __pa(mdesc->certs_data); /* Set the privlevel_floor attribute based on the vmpck_id */ sev_tsm_ops.privlevel_floor = vmpck_id; @@ -1082,17 +1076,18 @@ static int __init sev_guest_probe(struct platform_device *pdev) if (ret) goto e_free_ctx; + snp_dev->msg_desc = mdesc; dev_info(dev, "Initialized SEV guest driver (using VMPCK%d communication key)\n", vmpck_id); return 0; e_free_ctx: - kfree(snp_dev->ctx); + kfree(mdesc->ctx); e_free_cert_data: - free_shared_pages(snp_dev->certs_data, SEV_FW_BLOB_MAX_SIZE); + free_shared_pages(mdesc->certs_data, SEV_FW_BLOB_MAX_SIZE); e_free_response: - free_shared_pages(snp_dev->response, sizeof(struct snp_guest_msg)); + free_shared_pages(mdesc->response, sizeof(struct snp_guest_msg)); e_free_request: - free_shared_pages(snp_dev->request, sizeof(struct snp_guest_msg)); + free_shared_pages(mdesc->request, sizeof(struct snp_guest_msg)); e_unmap: iounmap(mapping); return ret; @@ -1101,11 +1096,12 @@ static int __init sev_guest_probe(struct platform_device *pdev) static void __exit sev_guest_remove(struct platform_device *pdev) { struct snp_guest_dev *snp_dev = platform_get_drvdata(pdev); + struct snp_msg_desc *mdesc = snp_dev->msg_desc; - free_shared_pages(snp_dev->certs_data, SEV_FW_BLOB_MAX_SIZE); - free_shared_pages(snp_dev->response, sizeof(struct snp_guest_msg)); - free_shared_pages(snp_dev->request, sizeof(struct snp_guest_msg)); - kfree(snp_dev->ctx); + free_shared_pages(mdesc->certs_data, SEV_FW_BLOB_MAX_SIZE); + free_shared_pages(mdesc->response, sizeof(struct snp_guest_msg)); + free_shared_pages(mdesc->request, sizeof(struct snp_guest_msg)); + kfree(mdesc->ctx); misc_deregister(&snp_dev->misc); } From 2e6bfc9a693e9b6270f5167c1715aec26a478e3c Mon Sep 17 00:00:00 2001 From: Nikunj A Dadhania Date: Mon, 6 Jan 2025 18:16:21 +0530 Subject: [PATCH 11/29] virt: sev-guest: Remove is_vmpck_empty() helper Remove is_vmpck_empty() which uses a local array allocation to check if the VMPCK is empty and replace it with memchr_inv() to directly determine if the VMPCK is empty without additional memory allocation. [ bp: Massage commit message. ] Suggested-by: Borislav Petkov Signed-off-by: Nikunj A Dadhania Signed-off-by: Borislav Petkov (AMD) Link: https://lore.kernel.org/r/20250106124633.1418972-2-nikunj@amd.com --- drivers/virt/coco/sev-guest/sev-guest.c | 14 ++------------ 1 file changed, 2 insertions(+), 12 deletions(-) diff --git a/drivers/virt/coco/sev-guest/sev-guest.c b/drivers/virt/coco/sev-guest/sev-guest.c index fca5c45ed5cd9d..b09a04e64501ad 100644 --- a/drivers/virt/coco/sev-guest/sev-guest.c +++ b/drivers/virt/coco/sev-guest/sev-guest.c @@ -63,16 +63,6 @@ MODULE_PARM_DESC(vmpck_id, "The VMPCK ID to use when communicating with the PSP. /* Mutex to serialize the shared buffer access and command handling. */ static DEFINE_MUTEX(snp_cmd_mutex); -static bool is_vmpck_empty(struct snp_msg_desc *mdesc) -{ - char zero_key[VMPCK_KEY_LEN] = {0}; - - if (mdesc->vmpck) - return !memcmp(mdesc->vmpck, zero_key, VMPCK_KEY_LEN); - - return true; -} - /* * If an error is received from the host or AMD Secure Processor (ASP) there * are two options. Either retry the exact same encrypted request or discontinue @@ -335,7 +325,7 @@ static int snp_send_guest_request(struct snp_msg_desc *mdesc, struct snp_guest_r guard(mutex)(&snp_cmd_mutex); /* Check if the VMPCK is not empty */ - if (is_vmpck_empty(mdesc)) { + if (!mdesc->vmpck || !memchr_inv(mdesc->vmpck, 0, VMPCK_KEY_LEN)) { pr_err_ratelimited("VMPCK is disabled\n"); return -ENOTTY; } @@ -1024,7 +1014,7 @@ static int __init sev_guest_probe(struct platform_device *pdev) } /* Verify that VMPCK is not zero. */ - if (is_vmpck_empty(mdesc)) { + if (!memchr_inv(mdesc->vmpck, 0, VMPCK_KEY_LEN)) { dev_err(dev, "Empty VMPCK%d communication key\n", vmpck_id); goto e_unmap; } From 3ce8779c2cfd3bb0d92eaee5fbff1086d286fe82 Mon Sep 17 00:00:00 2001 From: Nikunj A Dadhania Date: Mon, 6 Jan 2025 18:16:22 +0530 Subject: [PATCH 12/29] virt: sev-guest: Replace GFP_KERNEL_ACCOUNT with GFP_KERNEL Replace GFP_KERNEL_ACCOUNT with GFP_KERNEL in the sev-guest driver code. GFP_KERNEL_ACCOUNT is typically used for accounting untrusted userspace allocations. After auditing the sev-guest code, the following changes are necessary: * snp_init_crypto(): Use GFP_KERNEL as this is a trusted device probe path. Retain GFP_KERNEL_ACCOUNT in the following cases for robustness and specific path requirements: * alloc_shared_pages(): Although all allocations are limited, retain GFP_KERNEL_ACCOUNT for future robustness. * get_report() and get_ext_report(): These functions are on the unlocked ioctl path and should continue using GFP_KERNEL_ACCOUNT. Suggested-by: Borislav Petkov Signed-off-by: Nikunj A Dadhania Signed-off-by: Borislav Petkov (AMD) Link: https://lore.kernel.org/r/20250106124633.1418972-3-nikunj@amd.com --- drivers/virt/coco/sev-guest/sev-guest.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/drivers/virt/coco/sev-guest/sev-guest.c b/drivers/virt/coco/sev-guest/sev-guest.c index b09a04e64501ad..12f1fc81b422fc 100644 --- a/drivers/virt/coco/sev-guest/sev-guest.c +++ b/drivers/virt/coco/sev-guest/sev-guest.c @@ -141,7 +141,7 @@ static struct aesgcm_ctx *snp_init_crypto(u8 *key, size_t keylen) { struct aesgcm_ctx *ctx; - ctx = kzalloc(sizeof(*ctx), GFP_KERNEL_ACCOUNT); + ctx = kzalloc(sizeof(*ctx), GFP_KERNEL); if (!ctx) return NULL; From 3d3fd96eda0d6fdc4e5bfb990de7821c6666faae Mon Sep 17 00:00:00 2001 From: Nikunj A Dadhania Date: Mon, 6 Jan 2025 18:16:23 +0530 Subject: [PATCH 13/29] x86/sev: Carve out and export SNP guest messaging init routines Currently, the sev-guest driver is the only user of SNP guest messaging. All routines for initializing SNP guest messaging are implemented within the sev-guest driver and are not available during early boot. In preparation for adding Secure TSC guest support, carve out APIs to allocate and initialize the guest messaging descriptor context and make it part of coco/sev/core.c. As there is no user of sev_guest_platform_data anymore, remove the structure. Signed-off-by: Nikunj A Dadhania Signed-off-by: Borislav Petkov (AMD) Reviewed-by: Tom Lendacky Link: https://lore.kernel.org/r/20250106124633.1418972-4-nikunj@amd.com --- arch/x86/Kconfig | 1 + arch/x86/coco/sev/core.c | 183 ++++++++++++++++++++++- arch/x86/include/asm/sev.h | 13 +- drivers/virt/coco/sev-guest/Kconfig | 1 - drivers/virt/coco/sev-guest/sev-guest.c | 185 +++--------------------- 5 files changed, 208 insertions(+), 175 deletions(-) diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig index 007bab9f2a0e39..45060e7cea4859 100644 --- a/arch/x86/Kconfig +++ b/arch/x86/Kconfig @@ -1552,6 +1552,7 @@ config AMD_MEM_ENCRYPT select ARCH_HAS_CC_PLATFORM select X86_MEM_ENCRYPT select UNACCEPTED_MEMORY + select CRYPTO_LIB_AESGCM help Say yes to enable support for the encryption of system memory. This requires an AMD processor that supports Secure Memory diff --git a/arch/x86/coco/sev/core.c b/arch/x86/coco/sev/core.c index 2f182d0a65d27f..feb1b32b34263a 100644 --- a/arch/x86/coco/sev/core.c +++ b/arch/x86/coco/sev/core.c @@ -26,6 +26,7 @@ #include #include #include +#include #include #include @@ -2534,15 +2535,9 @@ static bool is_svsm_vtpm_send_command_supported(void) static int __init snp_init_platform_device(void) { - struct sev_guest_platform_data data; - if (!cc_platform_has(CC_ATTR_GUEST_SEV_SNP)) return -ENODEV; - data.secrets_gpa = secrets_pa; - if (platform_device_add_data(&sev_guest_device, &data, sizeof(data))) - return -ENODEV; - if (platform_device_register(&sev_guest_device)) return -ENODEV; @@ -2639,3 +2634,179 @@ static int __init sev_sysfs_init(void) } arch_initcall(sev_sysfs_init); #endif // CONFIG_SYSFS + +static void free_shared_pages(void *buf, size_t sz) +{ + unsigned int npages = PAGE_ALIGN(sz) >> PAGE_SHIFT; + int ret; + + if (!buf) + return; + + ret = set_memory_encrypted((unsigned long)buf, npages); + if (ret) { + WARN_ONCE(ret, "failed to restore encryption mask (leak it)\n"); + return; + } + + __free_pages(virt_to_page(buf), get_order(sz)); +} + +static void *alloc_shared_pages(size_t sz) +{ + unsigned int npages = PAGE_ALIGN(sz) >> PAGE_SHIFT; + struct page *page; + int ret; + + page = alloc_pages(GFP_KERNEL_ACCOUNT, get_order(sz)); + if (!page) + return NULL; + + ret = set_memory_decrypted((unsigned long)page_address(page), npages); + if (ret) { + pr_err("failed to mark page shared, ret=%d\n", ret); + __free_pages(page, get_order(sz)); + return NULL; + } + + return page_address(page); +} + +static u8 *get_vmpck(int id, struct snp_secrets_page *secrets, u32 **seqno) +{ + u8 *key = NULL; + + switch (id) { + case 0: + *seqno = &secrets->os_area.msg_seqno_0; + key = secrets->vmpck0; + break; + case 1: + *seqno = &secrets->os_area.msg_seqno_1; + key = secrets->vmpck1; + break; + case 2: + *seqno = &secrets->os_area.msg_seqno_2; + key = secrets->vmpck2; + break; + case 3: + *seqno = &secrets->os_area.msg_seqno_3; + key = secrets->vmpck3; + break; + default: + break; + } + + return key; +} + +static struct aesgcm_ctx *snp_init_crypto(u8 *key, size_t keylen) +{ + struct aesgcm_ctx *ctx; + + ctx = kzalloc(sizeof(*ctx), GFP_KERNEL); + if (!ctx) + return NULL; + + if (aesgcm_expandkey(ctx, key, keylen, AUTHTAG_LEN)) { + pr_err("Crypto context initialization failed\n"); + kfree(ctx); + return NULL; + } + + return ctx; +} + +int snp_msg_init(struct snp_msg_desc *mdesc, int vmpck_id) +{ + /* Adjust the default VMPCK key based on the executing VMPL level */ + if (vmpck_id == -1) + vmpck_id = snp_vmpl; + + mdesc->vmpck = get_vmpck(vmpck_id, mdesc->secrets, &mdesc->os_area_msg_seqno); + if (!mdesc->vmpck) { + pr_err("Invalid VMPCK%d communication key\n", vmpck_id); + return -EINVAL; + } + + /* Verify that VMPCK is not zero. */ + if (!memchr_inv(mdesc->vmpck, 0, VMPCK_KEY_LEN)) { + pr_err("Empty VMPCK%d communication key\n", vmpck_id); + return -EINVAL; + } + + mdesc->vmpck_id = vmpck_id; + + mdesc->ctx = snp_init_crypto(mdesc->vmpck, VMPCK_KEY_LEN); + if (!mdesc->ctx) + return -ENOMEM; + + return 0; +} +EXPORT_SYMBOL_GPL(snp_msg_init); + +struct snp_msg_desc *snp_msg_alloc(void) +{ + struct snp_msg_desc *mdesc; + void __iomem *mem; + + BUILD_BUG_ON(sizeof(struct snp_guest_msg) > PAGE_SIZE); + + mdesc = kzalloc(sizeof(struct snp_msg_desc), GFP_KERNEL); + if (!mdesc) + return ERR_PTR(-ENOMEM); + + mem = ioremap_encrypted(secrets_pa, PAGE_SIZE); + if (!mem) + goto e_free_mdesc; + + mdesc->secrets = (__force struct snp_secrets_page *)mem; + + /* Allocate the shared page used for the request and response message. */ + mdesc->request = alloc_shared_pages(sizeof(struct snp_guest_msg)); + if (!mdesc->request) + goto e_unmap; + + mdesc->response = alloc_shared_pages(sizeof(struct snp_guest_msg)); + if (!mdesc->response) + goto e_free_request; + + mdesc->certs_data = alloc_shared_pages(SEV_FW_BLOB_MAX_SIZE); + if (!mdesc->certs_data) + goto e_free_response; + + /* initial the input address for guest request */ + mdesc->input.req_gpa = __pa(mdesc->request); + mdesc->input.resp_gpa = __pa(mdesc->response); + mdesc->input.data_gpa = __pa(mdesc->certs_data); + + return mdesc; + +e_free_response: + free_shared_pages(mdesc->response, sizeof(struct snp_guest_msg)); +e_free_request: + free_shared_pages(mdesc->request, sizeof(struct snp_guest_msg)); +e_unmap: + iounmap(mem); +e_free_mdesc: + kfree(mdesc); + + return ERR_PTR(-ENOMEM); +} +EXPORT_SYMBOL_GPL(snp_msg_alloc); + +void snp_msg_free(struct snp_msg_desc *mdesc) +{ + if (!mdesc) + return; + + kfree(mdesc->ctx); + free_shared_pages(mdesc->response, sizeof(struct snp_guest_msg)); + free_shared_pages(mdesc->request, sizeof(struct snp_guest_msg)); + free_shared_pages(mdesc->certs_data, SEV_FW_BLOB_MAX_SIZE); + iounmap((__force void __iomem *)mdesc->secrets); + + memset(mdesc, 0, sizeof(*mdesc)); + kfree(mdesc); +} +EXPORT_SYMBOL_GPL(snp_msg_free); diff --git a/arch/x86/include/asm/sev.h b/arch/x86/include/asm/sev.h index 2e49c4a9e7fe7a..14759400454c25 100644 --- a/arch/x86/include/asm/sev.h +++ b/arch/x86/include/asm/sev.h @@ -14,6 +14,7 @@ #include #include #include +#include #define GHCB_PROTOCOL_MIN 1ULL #define GHCB_PROTOCOL_MAX 2ULL @@ -170,10 +171,6 @@ struct snp_guest_msg { u8 payload[PAGE_SIZE - sizeof(struct snp_guest_msg_hdr)]; } __packed; -struct sev_guest_platform_data { - u64 secrets_gpa; -}; - struct snp_guest_req { void *req_buf; size_t req_sz; @@ -253,6 +250,7 @@ struct snp_msg_desc { u32 *os_area_msg_seqno; u8 *vmpck; + int vmpck_id; }; /* @@ -438,6 +436,10 @@ u64 sev_get_status(void); void sev_show_status(void); void snp_update_svsm_ca(void); +int snp_msg_init(struct snp_msg_desc *mdesc, int vmpck_id); +struct snp_msg_desc *snp_msg_alloc(void); +void snp_msg_free(struct snp_msg_desc *mdesc); + #else /* !CONFIG_AMD_MEM_ENCRYPT */ #define snp_vmpl 0 @@ -474,6 +476,9 @@ static inline u64 snp_get_unsupported_features(u64 status) { return 0; } static inline u64 sev_get_status(void) { return 0; } static inline void sev_show_status(void) { } static inline void snp_update_svsm_ca(void) { } +static inline int snp_msg_init(struct snp_msg_desc *mdesc, int vmpck_id) { return -1; } +static inline struct snp_msg_desc *snp_msg_alloc(void) { return NULL; } +static inline void snp_msg_free(struct snp_msg_desc *mdesc) { } #endif /* CONFIG_AMD_MEM_ENCRYPT */ diff --git a/drivers/virt/coco/sev-guest/Kconfig b/drivers/virt/coco/sev-guest/Kconfig index 0b772bd921d818..a6405ab6c2c37c 100644 --- a/drivers/virt/coco/sev-guest/Kconfig +++ b/drivers/virt/coco/sev-guest/Kconfig @@ -2,7 +2,6 @@ config SEV_GUEST tristate "AMD SEV Guest driver" default m depends on AMD_MEM_ENCRYPT - select CRYPTO_LIB_AESGCM select TSM_REPORTS help SEV-SNP firmware provides the guest a mechanism to communicate with diff --git a/drivers/virt/coco/sev-guest/sev-guest.c b/drivers/virt/coco/sev-guest/sev-guest.c index 12f1fc81b422fc..54cb30c0687d61 100644 --- a/drivers/virt/coco/sev-guest/sev-guest.c +++ b/drivers/virt/coco/sev-guest/sev-guest.c @@ -83,7 +83,7 @@ static DEFINE_MUTEX(snp_cmd_mutex); static void snp_disable_vmpck(struct snp_msg_desc *mdesc) { pr_alert("Disabling VMPCK%d communication key to prevent IV reuse.\n", - vmpck_id); + mdesc->vmpck_id); memzero_explicit(mdesc->vmpck, VMPCK_KEY_LEN); mdesc->vmpck = NULL; } @@ -137,23 +137,6 @@ static inline struct snp_guest_dev *to_snp_dev(struct file *file) return container_of(dev, struct snp_guest_dev, misc); } -static struct aesgcm_ctx *snp_init_crypto(u8 *key, size_t keylen) -{ - struct aesgcm_ctx *ctx; - - ctx = kzalloc(sizeof(*ctx), GFP_KERNEL); - if (!ctx) - return NULL; - - if (aesgcm_expandkey(ctx, key, keylen, AUTHTAG_LEN)) { - pr_err("Crypto context initialization failed\n"); - kfree(ctx); - return NULL; - } - - return ctx; -} - static int verify_and_dec_payload(struct snp_msg_desc *mdesc, struct snp_guest_req *req) { struct snp_guest_msg *resp_msg = &mdesc->secret_response; @@ -404,7 +387,7 @@ static int get_report(struct snp_guest_dev *snp_dev, struct snp_guest_request_io req.msg_version = arg->msg_version; req.msg_type = SNP_MSG_REPORT_REQ; - req.vmpck_id = vmpck_id; + req.vmpck_id = mdesc->vmpck_id; req.req_buf = report_req; req.req_sz = sizeof(*report_req); req.resp_buf = report_resp->data; @@ -451,7 +434,7 @@ static int get_derived_key(struct snp_guest_dev *snp_dev, struct snp_guest_reque req.msg_version = arg->msg_version; req.msg_type = SNP_MSG_KEY_REQ; - req.vmpck_id = vmpck_id; + req.vmpck_id = mdesc->vmpck_id; req.req_buf = derived_key_req; req.req_sz = sizeof(*derived_key_req); req.resp_buf = buf; @@ -529,7 +512,7 @@ static int get_ext_report(struct snp_guest_dev *snp_dev, struct snp_guest_reques req.msg_version = arg->msg_version; req.msg_type = SNP_MSG_REPORT_REQ; - req.vmpck_id = vmpck_id; + req.vmpck_id = mdesc->vmpck_id; req.req_buf = &report_req->data; req.req_sz = sizeof(report_req->data); req.resp_buf = report_resp->data; @@ -606,76 +589,11 @@ static long snp_guest_ioctl(struct file *file, unsigned int ioctl, unsigned long return ret; } -static void free_shared_pages(void *buf, size_t sz) -{ - unsigned int npages = PAGE_ALIGN(sz) >> PAGE_SHIFT; - int ret; - - if (!buf) - return; - - ret = set_memory_encrypted((unsigned long)buf, npages); - if (ret) { - WARN_ONCE(ret, "failed to restore encryption mask (leak it)\n"); - return; - } - - __free_pages(virt_to_page(buf), get_order(sz)); -} - -static void *alloc_shared_pages(struct device *dev, size_t sz) -{ - unsigned int npages = PAGE_ALIGN(sz) >> PAGE_SHIFT; - struct page *page; - int ret; - - page = alloc_pages(GFP_KERNEL_ACCOUNT, get_order(sz)); - if (!page) - return NULL; - - ret = set_memory_decrypted((unsigned long)page_address(page), npages); - if (ret) { - dev_err(dev, "failed to mark page shared, ret=%d\n", ret); - __free_pages(page, get_order(sz)); - return NULL; - } - - return page_address(page); -} - static const struct file_operations snp_guest_fops = { .owner = THIS_MODULE, .unlocked_ioctl = snp_guest_ioctl, }; -static u8 *get_vmpck(int id, struct snp_secrets_page *secrets, u32 **seqno) -{ - u8 *key = NULL; - - switch (id) { - case 0: - *seqno = &secrets->os_area.msg_seqno_0; - key = secrets->vmpck0; - break; - case 1: - *seqno = &secrets->os_area.msg_seqno_1; - key = secrets->vmpck1; - break; - case 2: - *seqno = &secrets->os_area.msg_seqno_2; - key = secrets->vmpck2; - break; - case 3: - *seqno = &secrets->os_area.msg_seqno_3; - key = secrets->vmpck3; - break; - default: - break; - } - - return key; -} - struct snp_msg_report_resp_hdr { u32 status; u32 report_size; @@ -969,13 +887,10 @@ static void unregister_sev_tsm(void *data) static int __init sev_guest_probe(struct platform_device *pdev) { - struct sev_guest_platform_data *data; - struct snp_secrets_page *secrets; struct device *dev = &pdev->dev; struct snp_guest_dev *snp_dev; struct snp_msg_desc *mdesc; struct miscdevice *misc; - void __iomem *mapping; int ret; BUILD_BUG_ON(sizeof(struct snp_guest_msg) > PAGE_SIZE); @@ -983,115 +898,57 @@ static int __init sev_guest_probe(struct platform_device *pdev) if (!cc_platform_has(CC_ATTR_GUEST_SEV_SNP)) return -ENODEV; - if (!dev->platform_data) - return -ENODEV; - - data = (struct sev_guest_platform_data *)dev->platform_data; - mapping = ioremap_encrypted(data->secrets_gpa, PAGE_SIZE); - if (!mapping) - return -ENODEV; - - secrets = (__force void *)mapping; - - ret = -ENOMEM; snp_dev = devm_kzalloc(&pdev->dev, sizeof(struct snp_guest_dev), GFP_KERNEL); if (!snp_dev) - goto e_unmap; - - mdesc = devm_kzalloc(&pdev->dev, sizeof(struct snp_msg_desc), GFP_KERNEL); - if (!mdesc) - goto e_unmap; - - /* Adjust the default VMPCK key based on the executing VMPL level */ - if (vmpck_id == -1) - vmpck_id = snp_vmpl; + return -ENOMEM; - ret = -EINVAL; - mdesc->vmpck = get_vmpck(vmpck_id, secrets, &mdesc->os_area_msg_seqno); - if (!mdesc->vmpck) { - dev_err(dev, "Invalid VMPCK%d communication key\n", vmpck_id); - goto e_unmap; - } + mdesc = snp_msg_alloc(); + if (IS_ERR_OR_NULL(mdesc)) + return -ENOMEM; - /* Verify that VMPCK is not zero. */ - if (!memchr_inv(mdesc->vmpck, 0, VMPCK_KEY_LEN)) { - dev_err(dev, "Empty VMPCK%d communication key\n", vmpck_id); - goto e_unmap; - } + ret = snp_msg_init(mdesc, vmpck_id); + if (ret) + goto e_msg_init; platform_set_drvdata(pdev, snp_dev); snp_dev->dev = dev; - mdesc->secrets = secrets; - - /* Allocate the shared page used for the request and response message. */ - mdesc->request = alloc_shared_pages(dev, sizeof(struct snp_guest_msg)); - if (!mdesc->request) - goto e_unmap; - - mdesc->response = alloc_shared_pages(dev, sizeof(struct snp_guest_msg)); - if (!mdesc->response) - goto e_free_request; - - mdesc->certs_data = alloc_shared_pages(dev, SEV_FW_BLOB_MAX_SIZE); - if (!mdesc->certs_data) - goto e_free_response; - - ret = -EIO; - mdesc->ctx = snp_init_crypto(mdesc->vmpck, VMPCK_KEY_LEN); - if (!mdesc->ctx) - goto e_free_cert_data; misc = &snp_dev->misc; misc->minor = MISC_DYNAMIC_MINOR; misc->name = DEVICE_NAME; misc->fops = &snp_guest_fops; - /* Initialize the input addresses for guest request */ - mdesc->input.req_gpa = __pa(mdesc->request); - mdesc->input.resp_gpa = __pa(mdesc->response); - mdesc->input.data_gpa = __pa(mdesc->certs_data); - /* Set the privlevel_floor attribute based on the vmpck_id */ - sev_tsm_ops.privlevel_floor = vmpck_id; + sev_tsm_ops.privlevel_floor = mdesc->vmpck_id; ret = tsm_register(&sev_tsm_ops, snp_dev); if (ret) - goto e_free_cert_data; + goto e_msg_init; ret = devm_add_action_or_reset(&pdev->dev, unregister_sev_tsm, NULL); if (ret) - goto e_free_cert_data; + goto e_msg_init; ret = misc_register(misc); if (ret) - goto e_free_ctx; + goto e_msg_init; snp_dev->msg_desc = mdesc; - dev_info(dev, "Initialized SEV guest driver (using VMPCK%d communication key)\n", vmpck_id); + dev_info(dev, "Initialized SEV guest driver (using VMPCK%d communication key)\n", + mdesc->vmpck_id); return 0; -e_free_ctx: - kfree(mdesc->ctx); -e_free_cert_data: - free_shared_pages(mdesc->certs_data, SEV_FW_BLOB_MAX_SIZE); -e_free_response: - free_shared_pages(mdesc->response, sizeof(struct snp_guest_msg)); -e_free_request: - free_shared_pages(mdesc->request, sizeof(struct snp_guest_msg)); -e_unmap: - iounmap(mapping); +e_msg_init: + snp_msg_free(mdesc); + return ret; } static void __exit sev_guest_remove(struct platform_device *pdev) { struct snp_guest_dev *snp_dev = platform_get_drvdata(pdev); - struct snp_msg_desc *mdesc = snp_dev->msg_desc; - free_shared_pages(mdesc->certs_data, SEV_FW_BLOB_MAX_SIZE); - free_shared_pages(mdesc->response, sizeof(struct snp_guest_msg)); - free_shared_pages(mdesc->request, sizeof(struct snp_guest_msg)); - kfree(mdesc->ctx); + snp_msg_free(snp_dev->msg_desc); misc_deregister(&snp_dev->misc); } From 45c07811083a07a761b3988f38ae50a39055dfec Mon Sep 17 00:00:00 2001 From: Nikunj A Dadhania Date: Mon, 6 Jan 2025 18:16:24 +0530 Subject: [PATCH 14/29] x86/sev: Relocate SNP guest messaging routines to common code At present, the SEV guest driver exclusively handles SNP guest messaging. All routines for sending guest messages are embedded within it. To support Secure TSC, SEV-SNP guests must communicate with the AMD Security Processor during early boot. However, these guest messaging functions are not accessible during early boot since they are currently part of the guest driver. Hence, relocate the core SNP guest messaging functions to SEV common code and provide an API for sending SNP guest messages. No functional change, but just an export symbol added for snp_send_guest_request() and dropped the export symbol on snp_issue_guest_request() and made it static. Signed-off-by: Nikunj A Dadhania Signed-off-by: Borislav Petkov (AMD) Reviewed-by: Tom Lendacky Link: https://lore.kernel.org/r/20250106124633.1418972-5-nikunj@amd.com --- arch/x86/coco/sev/core.c | 294 +++++++++++++++++++++++- arch/x86/include/asm/sev.h | 14 +- drivers/virt/coco/sev-guest/sev-guest.c | 292 ----------------------- 3 files changed, 298 insertions(+), 302 deletions(-) diff --git a/arch/x86/coco/sev/core.c b/arch/x86/coco/sev/core.c index feb1b32b34263a..dedc087270876a 100644 --- a/arch/x86/coco/sev/core.c +++ b/arch/x86/coco/sev/core.c @@ -2419,8 +2419,8 @@ int snp_issue_svsm_attest_req(u64 call_id, struct svsm_call *call, } EXPORT_SYMBOL_GPL(snp_issue_svsm_attest_req); -int snp_issue_guest_request(struct snp_guest_req *req, struct snp_req_data *input, - struct snp_guest_request_ioctl *rio) +static int snp_issue_guest_request(struct snp_guest_req *req, struct snp_req_data *input, + struct snp_guest_request_ioctl *rio) { struct ghcb_state state; struct es_em_ctxt ctxt; @@ -2482,7 +2482,6 @@ int snp_issue_guest_request(struct snp_guest_req *req, struct snp_req_data *inpu return ret; } -EXPORT_SYMBOL_GPL(snp_issue_guest_request); static struct platform_device sev_guest_device = { .name = "sev-guest", @@ -2810,3 +2809,292 @@ void snp_msg_free(struct snp_msg_desc *mdesc) kfree(mdesc); } EXPORT_SYMBOL_GPL(snp_msg_free); + +/* Mutex to serialize the shared buffer access and command handling. */ +static DEFINE_MUTEX(snp_cmd_mutex); + +/* + * If an error is received from the host or AMD Secure Processor (ASP) there + * are two options. Either retry the exact same encrypted request or discontinue + * using the VMPCK. + * + * This is because in the current encryption scheme GHCB v2 uses AES-GCM to + * encrypt the requests. The IV for this scheme is the sequence number. GCM + * cannot tolerate IV reuse. + * + * The ASP FW v1.51 only increments the sequence numbers on a successful + * guest<->ASP back and forth and only accepts messages at its exact sequence + * number. + * + * So if the sequence number were to be reused the encryption scheme is + * vulnerable. If the sequence number were incremented for a fresh IV the ASP + * will reject the request. + */ +static void snp_disable_vmpck(struct snp_msg_desc *mdesc) +{ + pr_alert("Disabling VMPCK%d communication key to prevent IV reuse.\n", + mdesc->vmpck_id); + memzero_explicit(mdesc->vmpck, VMPCK_KEY_LEN); + mdesc->vmpck = NULL; +} + +static inline u64 __snp_get_msg_seqno(struct snp_msg_desc *mdesc) +{ + u64 count; + + lockdep_assert_held(&snp_cmd_mutex); + + /* Read the current message sequence counter from secrets pages */ + count = *mdesc->os_area_msg_seqno; + + return count + 1; +} + +/* Return a non-zero on success */ +static u64 snp_get_msg_seqno(struct snp_msg_desc *mdesc) +{ + u64 count = __snp_get_msg_seqno(mdesc); + + /* + * The message sequence counter for the SNP guest request is a 64-bit + * value but the version 2 of GHCB specification defines a 32-bit storage + * for it. If the counter exceeds the 32-bit value then return zero. + * The caller should check the return value, but if the caller happens to + * not check the value and use it, then the firmware treats zero as an + * invalid number and will fail the message request. + */ + if (count >= UINT_MAX) { + pr_err("request message sequence counter overflow\n"); + return 0; + } + + return count; +} + +static void snp_inc_msg_seqno(struct snp_msg_desc *mdesc) +{ + /* + * The counter is also incremented by the PSP, so increment it by 2 + * and save in secrets page. + */ + *mdesc->os_area_msg_seqno += 2; +} + +static int verify_and_dec_payload(struct snp_msg_desc *mdesc, struct snp_guest_req *req) +{ + struct snp_guest_msg *resp_msg = &mdesc->secret_response; + struct snp_guest_msg *req_msg = &mdesc->secret_request; + struct snp_guest_msg_hdr *req_msg_hdr = &req_msg->hdr; + struct snp_guest_msg_hdr *resp_msg_hdr = &resp_msg->hdr; + struct aesgcm_ctx *ctx = mdesc->ctx; + u8 iv[GCM_AES_IV_SIZE] = {}; + + pr_debug("response [seqno %lld type %d version %d sz %d]\n", + resp_msg_hdr->msg_seqno, resp_msg_hdr->msg_type, resp_msg_hdr->msg_version, + resp_msg_hdr->msg_sz); + + /* Copy response from shared memory to encrypted memory. */ + memcpy(resp_msg, mdesc->response, sizeof(*resp_msg)); + + /* Verify that the sequence counter is incremented by 1 */ + if (unlikely(resp_msg_hdr->msg_seqno != (req_msg_hdr->msg_seqno + 1))) + return -EBADMSG; + + /* Verify response message type and version number. */ + if (resp_msg_hdr->msg_type != (req_msg_hdr->msg_type + 1) || + resp_msg_hdr->msg_version != req_msg_hdr->msg_version) + return -EBADMSG; + + /* + * If the message size is greater than our buffer length then return + * an error. + */ + if (unlikely((resp_msg_hdr->msg_sz + ctx->authsize) > req->resp_sz)) + return -EBADMSG; + + /* Decrypt the payload */ + memcpy(iv, &resp_msg_hdr->msg_seqno, min(sizeof(iv), sizeof(resp_msg_hdr->msg_seqno))); + if (!aesgcm_decrypt(ctx, req->resp_buf, resp_msg->payload, resp_msg_hdr->msg_sz, + &resp_msg_hdr->algo, AAD_LEN, iv, resp_msg_hdr->authtag)) + return -EBADMSG; + + return 0; +} + +static int enc_payload(struct snp_msg_desc *mdesc, u64 seqno, struct snp_guest_req *req) +{ + struct snp_guest_msg *msg = &mdesc->secret_request; + struct snp_guest_msg_hdr *hdr = &msg->hdr; + struct aesgcm_ctx *ctx = mdesc->ctx; + u8 iv[GCM_AES_IV_SIZE] = {}; + + memset(msg, 0, sizeof(*msg)); + + hdr->algo = SNP_AEAD_AES_256_GCM; + hdr->hdr_version = MSG_HDR_VER; + hdr->hdr_sz = sizeof(*hdr); + hdr->msg_type = req->msg_type; + hdr->msg_version = req->msg_version; + hdr->msg_seqno = seqno; + hdr->msg_vmpck = req->vmpck_id; + hdr->msg_sz = req->req_sz; + + /* Verify the sequence number is non-zero */ + if (!hdr->msg_seqno) + return -ENOSR; + + pr_debug("request [seqno %lld type %d version %d sz %d]\n", + hdr->msg_seqno, hdr->msg_type, hdr->msg_version, hdr->msg_sz); + + if (WARN_ON((req->req_sz + ctx->authsize) > sizeof(msg->payload))) + return -EBADMSG; + + memcpy(iv, &hdr->msg_seqno, min(sizeof(iv), sizeof(hdr->msg_seqno))); + aesgcm_encrypt(ctx, msg->payload, req->req_buf, req->req_sz, &hdr->algo, + AAD_LEN, iv, hdr->authtag); + + return 0; +} + +static int __handle_guest_request(struct snp_msg_desc *mdesc, struct snp_guest_req *req, + struct snp_guest_request_ioctl *rio) +{ + unsigned long req_start = jiffies; + unsigned int override_npages = 0; + u64 override_err = 0; + int rc; + +retry_request: + /* + * Call firmware to process the request. In this function the encrypted + * message enters shared memory with the host. So after this call the + * sequence number must be incremented or the VMPCK must be deleted to + * prevent reuse of the IV. + */ + rc = snp_issue_guest_request(req, &mdesc->input, rio); + switch (rc) { + case -ENOSPC: + /* + * If the extended guest request fails due to having too + * small of a certificate data buffer, retry the same + * guest request without the extended data request in + * order to increment the sequence number and thus avoid + * IV reuse. + */ + override_npages = mdesc->input.data_npages; + req->exit_code = SVM_VMGEXIT_GUEST_REQUEST; + + /* + * Override the error to inform callers the given extended + * request buffer size was too small and give the caller the + * required buffer size. + */ + override_err = SNP_GUEST_VMM_ERR(SNP_GUEST_VMM_ERR_INVALID_LEN); + + /* + * If this call to the firmware succeeds, the sequence number can + * be incremented allowing for continued use of the VMPCK. If + * there is an error reflected in the return value, this value + * is checked further down and the result will be the deletion + * of the VMPCK and the error code being propagated back to the + * user as an ioctl() return code. + */ + goto retry_request; + + /* + * The host may return SNP_GUEST_VMM_ERR_BUSY if the request has been + * throttled. Retry in the driver to avoid returning and reusing the + * message sequence number on a different message. + */ + case -EAGAIN: + if (jiffies - req_start > SNP_REQ_MAX_RETRY_DURATION) { + rc = -ETIMEDOUT; + break; + } + schedule_timeout_killable(SNP_REQ_RETRY_DELAY); + goto retry_request; + } + + /* + * Increment the message sequence number. There is no harm in doing + * this now because decryption uses the value stored in the response + * structure and any failure will wipe the VMPCK, preventing further + * use anyway. + */ + snp_inc_msg_seqno(mdesc); + + if (override_err) { + rio->exitinfo2 = override_err; + + /* + * If an extended guest request was issued and the supplied certificate + * buffer was not large enough, a standard guest request was issued to + * prevent IV reuse. If the standard request was successful, return -EIO + * back to the caller as would have originally been returned. + */ + if (!rc && override_err == SNP_GUEST_VMM_ERR(SNP_GUEST_VMM_ERR_INVALID_LEN)) + rc = -EIO; + } + + if (override_npages) + mdesc->input.data_npages = override_npages; + + return rc; +} + +int snp_send_guest_request(struct snp_msg_desc *mdesc, struct snp_guest_req *req, + struct snp_guest_request_ioctl *rio) +{ + u64 seqno; + int rc; + + guard(mutex)(&snp_cmd_mutex); + + /* Check if the VMPCK is not empty */ + if (!mdesc->vmpck || !memchr_inv(mdesc->vmpck, 0, VMPCK_KEY_LEN)) { + pr_err_ratelimited("VMPCK is disabled\n"); + return -ENOTTY; + } + + /* Get message sequence and verify that its a non-zero */ + seqno = snp_get_msg_seqno(mdesc); + if (!seqno) + return -EIO; + + /* Clear shared memory's response for the host to populate. */ + memset(mdesc->response, 0, sizeof(struct snp_guest_msg)); + + /* Encrypt the userspace provided payload in mdesc->secret_request. */ + rc = enc_payload(mdesc, seqno, req); + if (rc) + return rc; + + /* + * Write the fully encrypted request to the shared unencrypted + * request page. + */ + memcpy(mdesc->request, &mdesc->secret_request, sizeof(mdesc->secret_request)); + + rc = __handle_guest_request(mdesc, req, rio); + if (rc) { + if (rc == -EIO && + rio->exitinfo2 == SNP_GUEST_VMM_ERR(SNP_GUEST_VMM_ERR_INVALID_LEN)) + return rc; + + pr_alert("Detected error from ASP request. rc: %d, exitinfo2: 0x%llx\n", + rc, rio->exitinfo2); + + snp_disable_vmpck(mdesc); + return rc; + } + + rc = verify_and_dec_payload(mdesc, req); + if (rc) { + pr_alert("Detected unexpected decode failure from ASP. rc: %d\n", rc); + snp_disable_vmpck(mdesc); + return rc; + } + + return 0; +} +EXPORT_SYMBOL_GPL(snp_send_guest_request); diff --git a/arch/x86/include/asm/sev.h b/arch/x86/include/asm/sev.h index 14759400454c25..3527318a856ec6 100644 --- a/arch/x86/include/asm/sev.h +++ b/arch/x86/include/asm/sev.h @@ -125,6 +125,9 @@ struct snp_req_data { #define AAD_LEN 48 #define MSG_HDR_VER 1 +#define SNP_REQ_MAX_RETRY_DURATION (60*HZ) +#define SNP_REQ_RETRY_DELAY (2*HZ) + /* See SNP spec SNP_GUEST_REQUEST section for the structure */ enum msg_type { SNP_MSG_TYPE_INVALID = 0, @@ -427,8 +430,6 @@ void snp_set_wakeup_secondary_cpu(void); bool snp_init(struct boot_params *bp); void __noreturn snp_abort(void); void snp_dmi_setup(void); -int snp_issue_guest_request(struct snp_guest_req *req, struct snp_req_data *input, - struct snp_guest_request_ioctl *rio); int snp_issue_svsm_attest_req(u64 call_id, struct svsm_call *call, struct svsm_attest_call *input); void snp_accept_memory(phys_addr_t start, phys_addr_t end); u64 snp_get_unsupported_features(u64 status); @@ -439,6 +440,8 @@ void snp_update_svsm_ca(void); int snp_msg_init(struct snp_msg_desc *mdesc, int vmpck_id); struct snp_msg_desc *snp_msg_alloc(void); void snp_msg_free(struct snp_msg_desc *mdesc); +int snp_send_guest_request(struct snp_msg_desc *mdesc, struct snp_guest_req *req, + struct snp_guest_request_ioctl *rio); #else /* !CONFIG_AMD_MEM_ENCRYPT */ @@ -462,11 +465,6 @@ static inline void snp_set_wakeup_secondary_cpu(void) { } static inline bool snp_init(struct boot_params *bp) { return false; } static inline void snp_abort(void) { } static inline void snp_dmi_setup(void) { } -static inline int snp_issue_guest_request(struct snp_guest_req *req, struct snp_req_data *input, - struct snp_guest_request_ioctl *rio) -{ - return -ENOTTY; -} static inline int snp_issue_svsm_attest_req(u64 call_id, struct svsm_call *call, struct svsm_attest_call *input) { return -ENOTTY; @@ -479,6 +477,8 @@ static inline void snp_update_svsm_ca(void) { } static inline int snp_msg_init(struct snp_msg_desc *mdesc, int vmpck_id) { return -1; } static inline struct snp_msg_desc *snp_msg_alloc(void) { return NULL; } static inline void snp_msg_free(struct snp_msg_desc *mdesc) { } +static inline int snp_send_guest_request(struct snp_msg_desc *mdesc, struct snp_guest_req *req, + struct snp_guest_request_ioctl *rio) { return -ENODEV; } #endif /* CONFIG_AMD_MEM_ENCRYPT */ diff --git a/drivers/virt/coco/sev-guest/sev-guest.c b/drivers/virt/coco/sev-guest/sev-guest.c index 54cb30c0687d61..82e4242495227c 100644 --- a/drivers/virt/coco/sev-guest/sev-guest.c +++ b/drivers/virt/coco/sev-guest/sev-guest.c @@ -31,9 +31,6 @@ #define DEVICE_NAME "sev-guest" -#define SNP_REQ_MAX_RETRY_DURATION (60*HZ) -#define SNP_REQ_RETRY_DELAY (2*HZ) - #define SVSM_MAX_RETRIES 3 struct snp_guest_dev { @@ -60,76 +57,6 @@ static int vmpck_id = -1; module_param(vmpck_id, int, 0444); MODULE_PARM_DESC(vmpck_id, "The VMPCK ID to use when communicating with the PSP."); -/* Mutex to serialize the shared buffer access and command handling. */ -static DEFINE_MUTEX(snp_cmd_mutex); - -/* - * If an error is received from the host or AMD Secure Processor (ASP) there - * are two options. Either retry the exact same encrypted request or discontinue - * using the VMPCK. - * - * This is because in the current encryption scheme GHCB v2 uses AES-GCM to - * encrypt the requests. The IV for this scheme is the sequence number. GCM - * cannot tolerate IV reuse. - * - * The ASP FW v1.51 only increments the sequence numbers on a successful - * guest<->ASP back and forth and only accepts messages at its exact sequence - * number. - * - * So if the sequence number were to be reused the encryption scheme is - * vulnerable. If the sequence number were incremented for a fresh IV the ASP - * will reject the request. - */ -static void snp_disable_vmpck(struct snp_msg_desc *mdesc) -{ - pr_alert("Disabling VMPCK%d communication key to prevent IV reuse.\n", - mdesc->vmpck_id); - memzero_explicit(mdesc->vmpck, VMPCK_KEY_LEN); - mdesc->vmpck = NULL; -} - -static inline u64 __snp_get_msg_seqno(struct snp_msg_desc *mdesc) -{ - u64 count; - - lockdep_assert_held(&snp_cmd_mutex); - - /* Read the current message sequence counter from secrets pages */ - count = *mdesc->os_area_msg_seqno; - - return count + 1; -} - -/* Return a non-zero on success */ -static u64 snp_get_msg_seqno(struct snp_msg_desc *mdesc) -{ - u64 count = __snp_get_msg_seqno(mdesc); - - /* - * The message sequence counter for the SNP guest request is a 64-bit - * value but the version 2 of GHCB specification defines a 32-bit storage - * for it. If the counter exceeds the 32-bit value then return zero. - * The caller should check the return value, but if the caller happens to - * not check the value and use it, then the firmware treats zero as an - * invalid number and will fail the message request. - */ - if (count >= UINT_MAX) { - pr_err("request message sequence counter overflow\n"); - return 0; - } - - return count; -} - -static void snp_inc_msg_seqno(struct snp_msg_desc *mdesc) -{ - /* - * The counter is also incremented by the PSP, so increment it by 2 - * and save in secrets page. - */ - *mdesc->os_area_msg_seqno += 2; -} - static inline struct snp_guest_dev *to_snp_dev(struct file *file) { struct miscdevice *dev = file->private_data; @@ -137,225 +64,6 @@ static inline struct snp_guest_dev *to_snp_dev(struct file *file) return container_of(dev, struct snp_guest_dev, misc); } -static int verify_and_dec_payload(struct snp_msg_desc *mdesc, struct snp_guest_req *req) -{ - struct snp_guest_msg *resp_msg = &mdesc->secret_response; - struct snp_guest_msg *req_msg = &mdesc->secret_request; - struct snp_guest_msg_hdr *req_msg_hdr = &req_msg->hdr; - struct snp_guest_msg_hdr *resp_msg_hdr = &resp_msg->hdr; - struct aesgcm_ctx *ctx = mdesc->ctx; - u8 iv[GCM_AES_IV_SIZE] = {}; - - pr_debug("response [seqno %lld type %d version %d sz %d]\n", - resp_msg_hdr->msg_seqno, resp_msg_hdr->msg_type, resp_msg_hdr->msg_version, - resp_msg_hdr->msg_sz); - - /* Copy response from shared memory to encrypted memory. */ - memcpy(resp_msg, mdesc->response, sizeof(*resp_msg)); - - /* Verify that the sequence counter is incremented by 1 */ - if (unlikely(resp_msg_hdr->msg_seqno != (req_msg_hdr->msg_seqno + 1))) - return -EBADMSG; - - /* Verify response message type and version number. */ - if (resp_msg_hdr->msg_type != (req_msg_hdr->msg_type + 1) || - resp_msg_hdr->msg_version != req_msg_hdr->msg_version) - return -EBADMSG; - - /* - * If the message size is greater than our buffer length then return - * an error. - */ - if (unlikely((resp_msg_hdr->msg_sz + ctx->authsize) > req->resp_sz)) - return -EBADMSG; - - /* Decrypt the payload */ - memcpy(iv, &resp_msg_hdr->msg_seqno, min(sizeof(iv), sizeof(resp_msg_hdr->msg_seqno))); - if (!aesgcm_decrypt(ctx, req->resp_buf, resp_msg->payload, resp_msg_hdr->msg_sz, - &resp_msg_hdr->algo, AAD_LEN, iv, resp_msg_hdr->authtag)) - return -EBADMSG; - - return 0; -} - -static int enc_payload(struct snp_msg_desc *mdesc, u64 seqno, struct snp_guest_req *req) -{ - struct snp_guest_msg *msg = &mdesc->secret_request; - struct snp_guest_msg_hdr *hdr = &msg->hdr; - struct aesgcm_ctx *ctx = mdesc->ctx; - u8 iv[GCM_AES_IV_SIZE] = {}; - - memset(msg, 0, sizeof(*msg)); - - hdr->algo = SNP_AEAD_AES_256_GCM; - hdr->hdr_version = MSG_HDR_VER; - hdr->hdr_sz = sizeof(*hdr); - hdr->msg_type = req->msg_type; - hdr->msg_version = req->msg_version; - hdr->msg_seqno = seqno; - hdr->msg_vmpck = req->vmpck_id; - hdr->msg_sz = req->req_sz; - - /* Verify the sequence number is non-zero */ - if (!hdr->msg_seqno) - return -ENOSR; - - pr_debug("request [seqno %lld type %d version %d sz %d]\n", - hdr->msg_seqno, hdr->msg_type, hdr->msg_version, hdr->msg_sz); - - if (WARN_ON((req->req_sz + ctx->authsize) > sizeof(msg->payload))) - return -EBADMSG; - - memcpy(iv, &hdr->msg_seqno, min(sizeof(iv), sizeof(hdr->msg_seqno))); - aesgcm_encrypt(ctx, msg->payload, req->req_buf, req->req_sz, &hdr->algo, - AAD_LEN, iv, hdr->authtag); - - return 0; -} - -static int __handle_guest_request(struct snp_msg_desc *mdesc, struct snp_guest_req *req, - struct snp_guest_request_ioctl *rio) -{ - unsigned long req_start = jiffies; - unsigned int override_npages = 0; - u64 override_err = 0; - int rc; - -retry_request: - /* - * Call firmware to process the request. In this function the encrypted - * message enters shared memory with the host. So after this call the - * sequence number must be incremented or the VMPCK must be deleted to - * prevent reuse of the IV. - */ - rc = snp_issue_guest_request(req, &mdesc->input, rio); - switch (rc) { - case -ENOSPC: - /* - * If the extended guest request fails due to having too - * small of a certificate data buffer, retry the same - * guest request without the extended data request in - * order to increment the sequence number and thus avoid - * IV reuse. - */ - override_npages = mdesc->input.data_npages; - req->exit_code = SVM_VMGEXIT_GUEST_REQUEST; - - /* - * Override the error to inform callers the given extended - * request buffer size was too small and give the caller the - * required buffer size. - */ - override_err = SNP_GUEST_VMM_ERR(SNP_GUEST_VMM_ERR_INVALID_LEN); - - /* - * If this call to the firmware succeeds, the sequence number can - * be incremented allowing for continued use of the VMPCK. If - * there is an error reflected in the return value, this value - * is checked further down and the result will be the deletion - * of the VMPCK and the error code being propagated back to the - * user as an ioctl() return code. - */ - goto retry_request; - - /* - * The host may return SNP_GUEST_VMM_ERR_BUSY if the request has been - * throttled. Retry in the driver to avoid returning and reusing the - * message sequence number on a different message. - */ - case -EAGAIN: - if (jiffies - req_start > SNP_REQ_MAX_RETRY_DURATION) { - rc = -ETIMEDOUT; - break; - } - schedule_timeout_killable(SNP_REQ_RETRY_DELAY); - goto retry_request; - } - - /* - * Increment the message sequence number. There is no harm in doing - * this now because decryption uses the value stored in the response - * structure and any failure will wipe the VMPCK, preventing further - * use anyway. - */ - snp_inc_msg_seqno(mdesc); - - if (override_err) { - rio->exitinfo2 = override_err; - - /* - * If an extended guest request was issued and the supplied certificate - * buffer was not large enough, a standard guest request was issued to - * prevent IV reuse. If the standard request was successful, return -EIO - * back to the caller as would have originally been returned. - */ - if (!rc && override_err == SNP_GUEST_VMM_ERR(SNP_GUEST_VMM_ERR_INVALID_LEN)) - rc = -EIO; - } - - if (override_npages) - mdesc->input.data_npages = override_npages; - - return rc; -} - -static int snp_send_guest_request(struct snp_msg_desc *mdesc, struct snp_guest_req *req, - struct snp_guest_request_ioctl *rio) -{ - u64 seqno; - int rc; - - guard(mutex)(&snp_cmd_mutex); - - /* Check if the VMPCK is not empty */ - if (!mdesc->vmpck || !memchr_inv(mdesc->vmpck, 0, VMPCK_KEY_LEN)) { - pr_err_ratelimited("VMPCK is disabled\n"); - return -ENOTTY; - } - - /* Get message sequence and verify that its a non-zero */ - seqno = snp_get_msg_seqno(mdesc); - if (!seqno) - return -EIO; - - /* Clear shared memory's response for the host to populate. */ - memset(mdesc->response, 0, sizeof(struct snp_guest_msg)); - - /* Encrypt the userspace provided payload in mdesc->secret_request. */ - rc = enc_payload(mdesc, seqno, req); - if (rc) - return rc; - - /* - * Write the fully encrypted request to the shared unencrypted - * request page. - */ - memcpy(mdesc->request, &mdesc->secret_request, - sizeof(mdesc->secret_request)); - - rc = __handle_guest_request(mdesc, req, rio); - if (rc) { - if (rc == -EIO && - rio->exitinfo2 == SNP_GUEST_VMM_ERR(SNP_GUEST_VMM_ERR_INVALID_LEN)) - return rc; - - pr_alert("Detected error from ASP request. rc: %d, exitinfo2: 0x%llx\n", - rc, rio->exitinfo2); - - snp_disable_vmpck(mdesc); - return rc; - } - - rc = verify_and_dec_payload(mdesc, req); - if (rc) { - pr_alert("Detected unexpected decode failure from ASP. rc: %d\n", rc); - snp_disable_vmpck(mdesc); - return rc; - } - - return 0; -} - struct snp_req_resp { sockptr_t req_data; sockptr_t resp_data; From ae3684beb88cf47e2dec80bc97794fbbb5b14cf5 Mon Sep 17 00:00:00 2001 From: Nikunj A Dadhania Date: Mon, 6 Jan 2025 18:16:25 +0530 Subject: [PATCH 15/29] x86/sev: Add Secure TSC support for SNP guests Add support for Secure TSC in SNP-enabled guests. Secure TSC allows guests to securely use RDTSC/RDTSCP instructions, ensuring that the parameters used cannot be altered by the hypervisor once the guest is launched. Secure TSC-enabled guests need to query TSC information from the AMD Security Processor. This communication channel is encrypted between the AMD Security Processor and the guest, with the hypervisor acting merely as a conduit to deliver the guest messages to the AMD Security Processor. Each message is protected with AEAD (AES-256 GCM). [ bp: Zap a stray newline over amd_cc_platform_has() while at it, simplify CC_ATTR_GUEST_SNP_SECURE_TSC check ] Signed-off-by: Nikunj A Dadhania Signed-off-by: Borislav Petkov (AMD) Link: https://lore.kernel.org/r/20250106124633.1418972-6-nikunj@amd.com --- arch/x86/coco/core.c | 4 +- arch/x86/coco/sev/core.c | 107 ++++++++++++++++++++++++++++++ arch/x86/include/asm/sev-common.h | 1 + arch/x86/include/asm/sev.h | 21 ++++++ arch/x86/include/asm/svm.h | 6 +- arch/x86/mm/mem_encrypt.c | 2 + include/linux/cc_platform.h | 8 +++ 7 files changed, 146 insertions(+), 3 deletions(-) diff --git a/arch/x86/coco/core.c b/arch/x86/coco/core.c index 0f81f70aca822e..9a0ddda3aa6976 100644 --- a/arch/x86/coco/core.c +++ b/arch/x86/coco/core.c @@ -65,7 +65,6 @@ static __maybe_unused __always_inline bool amd_cc_platform_vtom(enum cc_attr att * up under SME the trampoline area cannot be encrypted, whereas under SEV * the trampoline area must be encrypted. */ - static bool noinstr amd_cc_platform_has(enum cc_attr attr) { #ifdef CONFIG_AMD_MEM_ENCRYPT @@ -97,6 +96,9 @@ static bool noinstr amd_cc_platform_has(enum cc_attr attr) case CC_ATTR_GUEST_SEV_SNP: return sev_status & MSR_AMD64_SEV_SNP_ENABLED; + case CC_ATTR_GUEST_SNP_SECURE_TSC: + return sev_status & MSR_AMD64_SNP_SECURE_TSC; + case CC_ATTR_HOST_SEV_SNP: return cc_flags.host_sev_snp; diff --git a/arch/x86/coco/sev/core.c b/arch/x86/coco/sev/core.c index dedc087270876a..18e26d5298fb28 100644 --- a/arch/x86/coco/sev/core.c +++ b/arch/x86/coco/sev/core.c @@ -97,6 +97,14 @@ static u64 sev_hv_features __ro_after_init; /* Secrets page physical address from the CC blob */ static u64 secrets_pa __ro_after_init; +/* + * For Secure TSC guests, the BSP fetches TSC_INFO using SNP guest messaging and + * initializes snp_tsc_scale and snp_tsc_offset. These values are replicated + * across the APs VMSA fields (TSC_SCALE and TSC_OFFSET). + */ +static u64 snp_tsc_scale __ro_after_init; +static u64 snp_tsc_offset __ro_after_init; + /* #VC handler runtime per-CPU data */ struct sev_es_runtime_data { struct ghcb ghcb_page; @@ -1174,6 +1182,12 @@ static int wakeup_cpu_via_vmgexit(u32 apic_id, unsigned long start_ip) vmsa->vmpl = snp_vmpl; vmsa->sev_features = sev_status >> 2; + /* Populate AP's TSC scale/offset to get accurate TSC values. */ + if (cc_platform_has(CC_ATTR_GUEST_SNP_SECURE_TSC)) { + vmsa->tsc_scale = snp_tsc_scale; + vmsa->tsc_offset = snp_tsc_offset; + } + /* Switch the page over to a VMSA page now that it is initialized */ ret = snp_set_vmsa(vmsa, caa, apic_id, true); if (ret) { @@ -3098,3 +3112,96 @@ int snp_send_guest_request(struct snp_msg_desc *mdesc, struct snp_guest_req *req return 0; } EXPORT_SYMBOL_GPL(snp_send_guest_request); + +static int __init snp_get_tsc_info(void) +{ + struct snp_guest_request_ioctl *rio; + struct snp_tsc_info_resp *tsc_resp; + struct snp_tsc_info_req *tsc_req; + struct snp_msg_desc *mdesc; + struct snp_guest_req *req; + int rc = -ENOMEM; + + tsc_req = kzalloc(sizeof(*tsc_req), GFP_KERNEL); + if (!tsc_req) + return rc; + + /* + * The intermediate response buffer is used while decrypting the + * response payload. Make sure that it has enough space to cover + * the authtag. + */ + tsc_resp = kzalloc(sizeof(*tsc_resp) + AUTHTAG_LEN, GFP_KERNEL); + if (!tsc_resp) + goto e_free_tsc_req; + + req = kzalloc(sizeof(*req), GFP_KERNEL); + if (!req) + goto e_free_tsc_resp; + + rio = kzalloc(sizeof(*rio), GFP_KERNEL); + if (!rio) + goto e_free_req; + + mdesc = snp_msg_alloc(); + if (IS_ERR_OR_NULL(mdesc)) + goto e_free_rio; + + rc = snp_msg_init(mdesc, snp_vmpl); + if (rc) + goto e_free_mdesc; + + req->msg_version = MSG_HDR_VER; + req->msg_type = SNP_MSG_TSC_INFO_REQ; + req->vmpck_id = snp_vmpl; + req->req_buf = tsc_req; + req->req_sz = sizeof(*tsc_req); + req->resp_buf = (void *)tsc_resp; + req->resp_sz = sizeof(*tsc_resp) + AUTHTAG_LEN; + req->exit_code = SVM_VMGEXIT_GUEST_REQUEST; + + rc = snp_send_guest_request(mdesc, req, rio); + if (rc) + goto e_request; + + pr_debug("%s: response status 0x%x scale 0x%llx offset 0x%llx factor 0x%x\n", + __func__, tsc_resp->status, tsc_resp->tsc_scale, tsc_resp->tsc_offset, + tsc_resp->tsc_factor); + + if (!tsc_resp->status) { + snp_tsc_scale = tsc_resp->tsc_scale; + snp_tsc_offset = tsc_resp->tsc_offset; + } else { + pr_err("Failed to get TSC info, response status 0x%x\n", tsc_resp->status); + rc = -EIO; + } + +e_request: + /* The response buffer contains sensitive data, explicitly clear it. */ + memzero_explicit(tsc_resp, sizeof(*tsc_resp) + AUTHTAG_LEN); +e_free_mdesc: + snp_msg_free(mdesc); +e_free_rio: + kfree(rio); +e_free_req: + kfree(req); + e_free_tsc_resp: + kfree(tsc_resp); +e_free_tsc_req: + kfree(tsc_req); + + return rc; +} + +void __init snp_secure_tsc_prepare(void) +{ + if (!cc_platform_has(CC_ATTR_GUEST_SNP_SECURE_TSC)) + return; + + if (snp_get_tsc_info()) { + pr_alert("Unable to retrieve Secure TSC info from ASP\n"); + sev_es_terminate(SEV_TERM_SET_LINUX, GHCB_TERM_SECURE_TSC); + } + + pr_debug("SecureTSC enabled"); +} diff --git a/arch/x86/include/asm/sev-common.h b/arch/x86/include/asm/sev-common.h index fbf86829714a7a..9a4026604ba4f9 100644 --- a/arch/x86/include/asm/sev-common.h +++ b/arch/x86/include/asm/sev-common.h @@ -214,6 +214,7 @@ struct snp_psc_desc { #define GHCB_TERM_NO_SVSM 7 /* SVSM is not advertised in the secrets page */ #define GHCB_TERM_SVSM_VMPL0 8 /* SVSM is present but has set VMPL to 0 */ #define GHCB_TERM_SVSM_CAA 9 /* SVSM is present but CAA is not page aligned */ +#define GHCB_TERM_SECURE_TSC 10 /* Secure TSC initialization failed */ #define GHCB_RESP_CODE(v) ((v) & GHCB_MSR_INFO_MASK) diff --git a/arch/x86/include/asm/sev.h b/arch/x86/include/asm/sev.h index 3527318a856ec6..0f946514401ab7 100644 --- a/arch/x86/include/asm/sev.h +++ b/arch/x86/include/asm/sev.h @@ -146,6 +146,9 @@ enum msg_type { SNP_MSG_VMRK_REQ, SNP_MSG_VMRK_RSP, + SNP_MSG_TSC_INFO_REQ = 17, + SNP_MSG_TSC_INFO_RSP, + SNP_MSG_TYPE_MAX }; @@ -174,6 +177,21 @@ struct snp_guest_msg { u8 payload[PAGE_SIZE - sizeof(struct snp_guest_msg_hdr)]; } __packed; +#define SNP_TSC_INFO_REQ_SZ 128 + +struct snp_tsc_info_req { + u8 rsvd[SNP_TSC_INFO_REQ_SZ]; +} __packed; + +struct snp_tsc_info_resp { + u32 status; + u32 rsvd1; + u64 tsc_scale; + u64 tsc_offset; + u32 tsc_factor; + u8 rsvd2[100]; +} __packed; + struct snp_guest_req { void *req_buf; size_t req_sz; @@ -443,6 +461,8 @@ void snp_msg_free(struct snp_msg_desc *mdesc); int snp_send_guest_request(struct snp_msg_desc *mdesc, struct snp_guest_req *req, struct snp_guest_request_ioctl *rio); +void __init snp_secure_tsc_prepare(void); + #else /* !CONFIG_AMD_MEM_ENCRYPT */ #define snp_vmpl 0 @@ -479,6 +499,7 @@ static inline struct snp_msg_desc *snp_msg_alloc(void) { return NULL; } static inline void snp_msg_free(struct snp_msg_desc *mdesc) { } static inline int snp_send_guest_request(struct snp_msg_desc *mdesc, struct snp_guest_req *req, struct snp_guest_request_ioctl *rio) { return -ENODEV; } +static inline void __init snp_secure_tsc_prepare(void) { } #endif /* CONFIG_AMD_MEM_ENCRYPT */ diff --git a/arch/x86/include/asm/svm.h b/arch/x86/include/asm/svm.h index 7fa276bdd0e4eb..08caab15dfab31 100644 --- a/arch/x86/include/asm/svm.h +++ b/arch/x86/include/asm/svm.h @@ -426,7 +426,9 @@ struct sev_es_save_area { u8 reserved_0x298[80]; u32 pkru; u32 tsc_aux; - u8 reserved_0x2f0[24]; + u64 tsc_scale; + u64 tsc_offset; + u8 reserved_0x300[8]; u64 rcx; u64 rdx; u64 rbx; @@ -599,7 +601,7 @@ static inline void __unused_size_checks(void) BUILD_BUG_RESERVED_OFFSET(sev_es_save_area, 0x1c0); BUILD_BUG_RESERVED_OFFSET(sev_es_save_area, 0x248); BUILD_BUG_RESERVED_OFFSET(sev_es_save_area, 0x298); - BUILD_BUG_RESERVED_OFFSET(sev_es_save_area, 0x2f0); + BUILD_BUG_RESERVED_OFFSET(sev_es_save_area, 0x300); BUILD_BUG_RESERVED_OFFSET(sev_es_save_area, 0x320); BUILD_BUG_RESERVED_OFFSET(sev_es_save_area, 0x380); BUILD_BUG_RESERVED_OFFSET(sev_es_save_area, 0x3f0); diff --git a/arch/x86/mm/mem_encrypt.c b/arch/x86/mm/mem_encrypt.c index 0a120d85d7bba8..95bae74fdab233 100644 --- a/arch/x86/mm/mem_encrypt.c +++ b/arch/x86/mm/mem_encrypt.c @@ -94,6 +94,8 @@ void __init mem_encrypt_init(void) /* Call into SWIOTLB to update the SWIOTLB DMA buffers */ swiotlb_update_mem_attributes(); + snp_secure_tsc_prepare(); + print_mem_encrypt_feature_info(); } diff --git a/include/linux/cc_platform.h b/include/linux/cc_platform.h index caa4b443063469..0bf7d33a1048cf 100644 --- a/include/linux/cc_platform.h +++ b/include/linux/cc_platform.h @@ -81,6 +81,14 @@ enum cc_attr { */ CC_ATTR_GUEST_SEV_SNP, + /** + * @CC_ATTR_GUEST_SNP_SECURE_TSC: SNP Secure TSC is active. + * + * The platform/OS is running as a guest/virtual machine and actively + * using AMD SEV-SNP Secure TSC feature. + */ + CC_ATTR_GUEST_SNP_SECURE_TSC, + /** * @CC_ATTR_HOST_SEV_SNP: AMD SNP enabled on the host. * From a0d93592820d1c2e8f4f864efb5389cdd5f1da0a Mon Sep 17 00:00:00 2001 From: "Borislav Petkov (AMD)" Date: Wed, 6 Nov 2024 18:21:58 +0100 Subject: [PATCH 16/29] x86/sev: Cleanup vc_handle_msr() Carve out the MSR_SVSM_CAA into a helper with the suggestion that upcoming future users should do the same. Rename that silly exit_info_1 into what it actually means in this function - whether the MSR access is a read or a write. No functional changes. Signed-off-by: Borislav Petkov (AMD) Reviewed-by: Tom Lendacky Reviewed-by: Pankaj Gupta Link: https://lore.kernel.org/r/20241106172647.GAZyum1zngPDwyD2IJ@fat_crate.local --- arch/x86/coco/sev/core.c | 34 +++++++++++++++++++--------------- 1 file changed, 19 insertions(+), 15 deletions(-) diff --git a/arch/x86/coco/sev/core.c b/arch/x86/coco/sev/core.c index 18e26d5298fb28..c62df5cc9dfb7e 100644 --- a/arch/x86/coco/sev/core.c +++ b/arch/x86/coco/sev/core.c @@ -1318,35 +1318,39 @@ int __init sev_es_efi_map_ghcbs(pgd_t *pgd) return 0; } +/* Writes to the SVSM CAA MSR are ignored */ +static enum es_result __vc_handle_msr_caa(struct pt_regs *regs, bool write) +{ + if (write) + return ES_OK; + + regs->ax = lower_32_bits(this_cpu_read(svsm_caa_pa)); + regs->dx = upper_32_bits(this_cpu_read(svsm_caa_pa)); + + return ES_OK; +} + static enum es_result vc_handle_msr(struct ghcb *ghcb, struct es_em_ctxt *ctxt) { struct pt_regs *regs = ctxt->regs; enum es_result ret; - u64 exit_info_1; + bool write; /* Is it a WRMSR? */ - exit_info_1 = (ctxt->insn.opcode.bytes[1] == 0x30) ? 1 : 0; - - if (regs->cx == MSR_SVSM_CAA) { - /* Writes to the SVSM CAA msr are ignored */ - if (exit_info_1) - return ES_OK; - - regs->ax = lower_32_bits(this_cpu_read(svsm_caa_pa)); - regs->dx = upper_32_bits(this_cpu_read(svsm_caa_pa)); + write = ctxt->insn.opcode.bytes[1] == 0x30; - return ES_OK; - } + if (regs->cx == MSR_SVSM_CAA) + return __vc_handle_msr_caa(regs, write); ghcb_set_rcx(ghcb, regs->cx); - if (exit_info_1) { + if (write) { ghcb_set_rax(ghcb, regs->ax); ghcb_set_rdx(ghcb, regs->dx); } - ret = sev_es_ghcb_hv_call(ghcb, ctxt, SVM_EXIT_MSR, exit_info_1, 0); + ret = sev_es_ghcb_hv_call(ghcb, ctxt, SVM_EXIT_MSR, write, 0); - if ((ret == ES_OK) && (!exit_info_1)) { + if ((ret == ES_OK) && !write) { regs->ax = ghcb->save.rax; regs->dx = ghcb->save.rdx; } From b114ab9f73527caf269fed327fc14a4090b09d58 Mon Sep 17 00:00:00 2001 From: Nikunj A Dadhania Date: Mon, 6 Jan 2025 18:16:26 +0530 Subject: [PATCH 17/29] x86/sev: Change TSC MSR behavior for Secure TSC enabled guests Secure TSC enabled guests should not write to the MSR_IA32_TSC (0x10) register as the subsequent TSC value reads are undefined. On AMD, MSR_IA32_TSC is intercepted by the hypervisor by default. MSR_IA32_TSC read/write accesses should not exit to the hypervisor for such guests. Accesses to MSR_IA32_TSC need special handling in the #VC handler for the guests with Secure TSC enabled. Writes to MSR_IA32_TSC should be ignored and flagged once with a warning, and reads of MSR_IA32_TSC should return the result of the RDTSC instruction. [ bp: Massage commit message. ] Suggested-by: Borislav Petkov (AMD) Signed-off-by: Nikunj A Dadhania Signed-off-by: Borislav Petkov (AMD) Reviewed-by: Tom Lendacky Link: https://lore.kernel.org/r/20250106124633.1418972-7-nikunj@amd.com --- arch/x86/coco/sev/core.c | 39 ++++++++++++++++++++++++++++++++++++++- 1 file changed, 38 insertions(+), 1 deletion(-) diff --git a/arch/x86/coco/sev/core.c b/arch/x86/coco/sev/core.c index c62df5cc9dfb7e..fc620ce347f04c 100644 --- a/arch/x86/coco/sev/core.c +++ b/arch/x86/coco/sev/core.c @@ -1330,6 +1330,34 @@ static enum es_result __vc_handle_msr_caa(struct pt_regs *regs, bool write) return ES_OK; } +/* + * TSC related accesses should not exit to the hypervisor when a guest is + * executing with Secure TSC enabled, so special handling is required for + * accesses of MSR_IA32_TSC. + */ +static enum es_result __vc_handle_secure_tsc_msrs(struct pt_regs *regs, bool write) +{ + u64 tsc; + + /* + * Writes: Writing to MSR_IA32_TSC can cause subsequent reads of the TSC + * to return undefined values, so ignore all writes. + * + * Reads: Reads of MSR_IA32_TSC should return the current TSC value, use + * the value returned by rdtsc_ordered(). + */ + if (write) { + WARN_ONCE(1, "TSC MSR writes are verboten!\n"); + return ES_OK; + } + + tsc = rdtsc_ordered(); + regs->ax = lower_32_bits(tsc); + regs->dx = upper_32_bits(tsc); + + return ES_OK; +} + static enum es_result vc_handle_msr(struct ghcb *ghcb, struct es_em_ctxt *ctxt) { struct pt_regs *regs = ctxt->regs; @@ -1339,8 +1367,17 @@ static enum es_result vc_handle_msr(struct ghcb *ghcb, struct es_em_ctxt *ctxt) /* Is it a WRMSR? */ write = ctxt->insn.opcode.bytes[1] == 0x30; - if (regs->cx == MSR_SVSM_CAA) + switch (regs->cx) { + case MSR_SVSM_CAA: return __vc_handle_msr_caa(regs, write); + case MSR_IA32_TSC: + if (sev_status & MSR_AMD64_SNP_SECURE_TSC) + return __vc_handle_secure_tsc_msrs(regs, write); + else + break; + default: + break; + } ghcb_set_rcx(ghcb, regs->cx); if (write) { From 59ce59facada208ff231dc9a741aa46535698f94 Mon Sep 17 00:00:00 2001 From: Nikunj A Dadhania Date: Mon, 6 Jan 2025 18:16:27 +0530 Subject: [PATCH 18/29] x86/sev: Prevent GUEST_TSC_FREQ MSR interception for Secure TSC enabled guests The hypervisor should not be intercepting GUEST_TSC_FREQ MSR(0xcOO10134) when Secure TSC is enabled. A #VC exception will be generated otherwise. If this should occur and Secure TSC is enabled, terminate guest execution. Signed-off-by: Nikunj A Dadhania Signed-off-by: Borislav Petkov (AMD) Reviewed-by: Tom Lendacky Link: https://lore.kernel.org/r/20250106124633.1418972-8-nikunj@amd.com --- arch/x86/coco/sev/core.c | 10 +++++++++- arch/x86/include/asm/msr-index.h | 1 + 2 files changed, 10 insertions(+), 1 deletion(-) diff --git a/arch/x86/coco/sev/core.c b/arch/x86/coco/sev/core.c index fc620ce347f04c..b6bd2b223c44ad 100644 --- a/arch/x86/coco/sev/core.c +++ b/arch/x86/coco/sev/core.c @@ -1333,12 +1333,19 @@ static enum es_result __vc_handle_msr_caa(struct pt_regs *regs, bool write) /* * TSC related accesses should not exit to the hypervisor when a guest is * executing with Secure TSC enabled, so special handling is required for - * accesses of MSR_IA32_TSC. + * accesses of MSR_IA32_TSC and MSR_AMD64_GUEST_TSC_FREQ. */ static enum es_result __vc_handle_secure_tsc_msrs(struct pt_regs *regs, bool write) { u64 tsc; + /* + * GUEST_TSC_FREQ should not be intercepted when Secure TSC is enabled. + * Terminate the SNP guest when the interception is enabled. + */ + if (regs->cx == MSR_AMD64_GUEST_TSC_FREQ) + return ES_VMM_ERROR; + /* * Writes: Writing to MSR_IA32_TSC can cause subsequent reads of the TSC * to return undefined values, so ignore all writes. @@ -1371,6 +1378,7 @@ static enum es_result vc_handle_msr(struct ghcb *ghcb, struct es_em_ctxt *ctxt) case MSR_SVSM_CAA: return __vc_handle_msr_caa(regs, write); case MSR_IA32_TSC: + case MSR_AMD64_GUEST_TSC_FREQ: if (sev_status & MSR_AMD64_SNP_SECURE_TSC) return __vc_handle_secure_tsc_msrs(regs, write); else diff --git a/arch/x86/include/asm/msr-index.h b/arch/x86/include/asm/msr-index.h index 82c6a4d350e09e..b15635de129049 100644 --- a/arch/x86/include/asm/msr-index.h +++ b/arch/x86/include/asm/msr-index.h @@ -586,6 +586,7 @@ #define MSR_AMD_PERF_CTL 0xc0010062 #define MSR_AMD_PERF_STATUS 0xc0010063 #define MSR_AMD_PSTATE_DEF_BASE 0xc0010064 +#define MSR_AMD64_GUEST_TSC_FREQ 0xc0010134 #define MSR_AMD64_OSVW_ID_LENGTH 0xc0010140 #define MSR_AMD64_OSVW_STATUS 0xc0010141 #define MSR_AMD_PPIN_CTL 0xc00102f0 From 654859659c1d364f81545865d13bdf799ff5e93c Mon Sep 17 00:00:00 2001 From: Nikunj A Dadhania Date: Mon, 6 Jan 2025 18:16:28 +0530 Subject: [PATCH 19/29] x86/sev: Prevent RDTSC/RDTSCP interception for Secure TSC enabled guests The hypervisor should not be intercepting RDTSC/RDTSCP when Secure TSC is enabled. A #VC exception will be generated if the RDTSC/RDTSCP instructions are being intercepted. If this should occur and Secure TSC is enabled, guest execution should be terminated as the guest cannot rely on the TSC value provided by the hypervisor. Signed-off-by: Nikunj A Dadhania Signed-off-by: Borislav Petkov (AMD) Reviewed-by: Tom Lendacky Tested-by: Peter Gonda Link: https://lore.kernel.org/r/20250106124633.1418972-9-nikunj@amd.com --- arch/x86/coco/sev/shared.c | 10 ++++++++++ 1 file changed, 10 insertions(+) diff --git a/arch/x86/coco/sev/shared.c b/arch/x86/coco/sev/shared.c index 71de5319408910..4386f37bd31d54 100644 --- a/arch/x86/coco/sev/shared.c +++ b/arch/x86/coco/sev/shared.c @@ -1140,6 +1140,16 @@ static enum es_result vc_handle_rdtsc(struct ghcb *ghcb, bool rdtscp = (exit_code == SVM_EXIT_RDTSCP); enum es_result ret; + /* + * The hypervisor should not be intercepting RDTSC/RDTSCP when Secure + * TSC is enabled. A #VC exception will be generated if the RDTSC/RDTSCP + * instructions are being intercepted. If this should occur and Secure + * TSC is enabled, guest execution should be terminated as the guest + * cannot rely on the TSC value provided by the hypervisor. + */ + if (sev_status & MSR_AMD64_SNP_SECURE_TSC) + return ES_VMM_ERROR; + ret = sev_es_ghcb_hv_call(ghcb, ctxt, exit_code, 0, 0); if (ret != ES_OK) return ret; From 65f6f282f7e3263375086574bf6e63e4bb0a58c8 Mon Sep 17 00:00:00 2001 From: Nikunj A Dadhania Date: Mon, 6 Jan 2025 18:16:29 +0530 Subject: [PATCH 20/29] x86/sev: Mark the TSC in a secure TSC guest as reliable In SNP guest environment with Secure TSC enabled, unlike other clock sources (such as HPET, ACPI timer, APIC, etc), the RDTSC instruction is handled without causing a VM exit, resulting in minimal overhead and jitters. Even when the host CPU's TSC is tampered with, the Secure TSC enabled guest keeps on ticking forward. Hence, mark Secure TSC as the only reliable clock source, bypassing unstable calibration. [ bp: Massage. ] Signed-off-by: Nikunj A Dadhania Signed-off-by: Borislav Petkov (AMD) Reviewed-by: Tom Lendacky Tested-by: Peter Gonda Link: https://lore.kernel.org/r/20250106124633.1418972-10-nikunj@amd.com --- arch/x86/mm/mem_encrypt_amd.c | 3 +++ 1 file changed, 3 insertions(+) diff --git a/arch/x86/mm/mem_encrypt_amd.c b/arch/x86/mm/mem_encrypt_amd.c index 86a476a426c26d..24b84ebc5dc427 100644 --- a/arch/x86/mm/mem_encrypt_amd.c +++ b/arch/x86/mm/mem_encrypt_amd.c @@ -516,6 +516,9 @@ void __init sme_early_init(void) * kernel mapped. */ snp_update_svsm_ca(); + + if (sev_status & MSR_AMD64_SNP_SECURE_TSC) + setup_force_cpu_cap(X86_FEATURE_TSC_RELIABLE); } void __init mem_encrypt_free_decrypted_mem(void) From 282b07b18aa09cd9f5b7aabb0c28b6f5b9345e6e Mon Sep 17 00:00:00 2001 From: Nikunj A Dadhania Date: Mon, 6 Jan 2025 18:16:30 +0530 Subject: [PATCH 21/29] x86/tsc: Init the TSC for Secure TSC guests Use the GUEST_TSC_FREQ MSR to discover the TSC frequency instead of relying on kvm-clock based frequency calibration. Override both CPU and TSC frequency calibration callbacks with securetsc_get_tsc_khz(). Since the difference between CPU base and TSC frequency does not apply in this case, the same callback is being used. [ bp: Carve out from https://lore.kernel.org/r/20250106124633.1418972-11-nikunj@amd.com ] Signed-off-by: Nikunj A Dadhania Signed-off-by: Borislav Petkov (AMD) Link: https://lore.kernel.org/r/20250106124633.1418972-11-nikunj@amd.com --- arch/x86/coco/sev/core.c | 21 +++++++++++++++++++++ arch/x86/include/asm/sev.h | 2 ++ arch/x86/kernel/tsc.c | 4 ++++ 3 files changed, 27 insertions(+) diff --git a/arch/x86/coco/sev/core.c b/arch/x86/coco/sev/core.c index b6bd2b223c44ad..745a8911210f20 100644 --- a/arch/x86/coco/sev/core.c +++ b/arch/x86/coco/sev/core.c @@ -104,6 +104,7 @@ static u64 secrets_pa __ro_after_init; */ static u64 snp_tsc_scale __ro_after_init; static u64 snp_tsc_offset __ro_after_init; +static u64 snp_tsc_freq_khz __ro_after_init; /* #VC handler runtime per-CPU data */ struct sev_es_runtime_data { @@ -3254,3 +3255,23 @@ void __init snp_secure_tsc_prepare(void) pr_debug("SecureTSC enabled"); } + +static unsigned long securetsc_get_tsc_khz(void) +{ + return snp_tsc_freq_khz; +} + +void __init snp_secure_tsc_init(void) +{ + unsigned long long tsc_freq_mhz; + + if (!cc_platform_has(CC_ATTR_GUEST_SNP_SECURE_TSC)) + return; + + setup_force_cpu_cap(X86_FEATURE_TSC_KNOWN_FREQ); + rdmsrl(MSR_AMD64_GUEST_TSC_FREQ, tsc_freq_mhz); + snp_tsc_freq_khz = (unsigned long)(tsc_freq_mhz * 1000); + + x86_platform.calibrate_cpu = securetsc_get_tsc_khz; + x86_platform.calibrate_tsc = securetsc_get_tsc_khz; +} diff --git a/arch/x86/include/asm/sev.h b/arch/x86/include/asm/sev.h index 0f946514401ab7..706635df00a64e 100644 --- a/arch/x86/include/asm/sev.h +++ b/arch/x86/include/asm/sev.h @@ -462,6 +462,7 @@ int snp_send_guest_request(struct snp_msg_desc *mdesc, struct snp_guest_req *req struct snp_guest_request_ioctl *rio); void __init snp_secure_tsc_prepare(void); +void __init snp_secure_tsc_init(void); #else /* !CONFIG_AMD_MEM_ENCRYPT */ @@ -500,6 +501,7 @@ static inline void snp_msg_free(struct snp_msg_desc *mdesc) { } static inline int snp_send_guest_request(struct snp_msg_desc *mdesc, struct snp_guest_req *req, struct snp_guest_request_ioctl *rio) { return -ENODEV; } static inline void __init snp_secure_tsc_prepare(void) { } +static inline void __init snp_secure_tsc_init(void) { } #endif /* CONFIG_AMD_MEM_ENCRYPT */ diff --git a/arch/x86/kernel/tsc.c b/arch/x86/kernel/tsc.c index d4462fb2629969..ed2ad09c650399 100644 --- a/arch/x86/kernel/tsc.c +++ b/arch/x86/kernel/tsc.c @@ -29,6 +29,7 @@ #include #include #include +#include unsigned int __read_mostly cpu_khz; /* TSC clocks / usec, not used here */ EXPORT_SYMBOL(cpu_khz); @@ -1516,6 +1517,9 @@ void __init tsc_early_init(void) /* Don't change UV TSC multi-chassis synchronization */ if (is_early_uv_system()) return; + + snp_secure_tsc_init(); + if (!determine_cpu_tsc_frequencies(true)) return; tsc_enable_sched_clock(); From 0118f7f717dfb5016d40ac605e30e364955abcf7 Mon Sep 17 00:00:00 2001 From: Nikunj A Dadhania Date: Mon, 6 Jan 2025 18:16:33 +0530 Subject: [PATCH 22/29] x86/sev: Add the Secure TSC feature for SNP guests Now that all the required plumbing is done for enabling Secure TSC, add it to the SNP features present list. Signed-off-by: Nikunj A Dadhania Signed-off-by: Borislav Petkov (AMD) Reviewed-by: Tom Lendacky Tested-by: Peter Gonda Link: https://lore.kernel.org/r/20250106124633.1418972-14-nikunj@amd.com --- arch/x86/boot/compressed/sev.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) diff --git a/arch/x86/boot/compressed/sev.c b/arch/x86/boot/compressed/sev.c index cd44e120fe5377..bb55934c1cee70 100644 --- a/arch/x86/boot/compressed/sev.c +++ b/arch/x86/boot/compressed/sev.c @@ -401,7 +401,8 @@ void do_boot_stage2_vc(struct pt_regs *regs, unsigned long exit_code) * by the guest kernel. As and when a new feature is implemented in the * guest kernel, a corresponding bit should be added to the mask. */ -#define SNP_FEATURES_PRESENT MSR_AMD64_SNP_DEBUG_SWAP +#define SNP_FEATURES_PRESENT (MSR_AMD64_SNP_DEBUG_SWAP | \ + MSR_AMD64_SNP_SECURE_TSC) u64 snp_get_unsupported_features(u64 status) { From 81a08b96e18750f252504a0706d58e600ede8158 Mon Sep 17 00:00:00 2001 From: Sean Christopherson Date: Wed, 27 Nov 2024 15:46:59 -0800 Subject: [PATCH 23/29] KVM: SVM: Macrofy SEV=n versions of sev_xxx_guest() Define sev_{,es_,snp_}guest() as "false" when SEV is disabled via Kconfig, i.e. when CONFIG_KVM_AMD_SEV=n. Despite the helpers being __always_inline, gcc-12 is somehow incapable of realizing that the return value is a compile-time constant and generates sub-optimal code. Opportunistically clump the paths together to reduce the amount of ifdeffery. No functional change intended. Link: https://lore.kernel.org/r/20241127234659.4046347-1-seanjc@google.com Signed-off-by: Sean Christopherson --- arch/x86/kvm/svm/svm.h | 17 +++++------------ 1 file changed, 5 insertions(+), 12 deletions(-) diff --git a/arch/x86/kvm/svm/svm.h b/arch/x86/kvm/svm/svm.h index 8b40e4bd1c200c..0ed3270e20ce97 100644 --- a/arch/x86/kvm/svm/svm.h +++ b/arch/x86/kvm/svm/svm.h @@ -383,39 +383,32 @@ static __always_inline struct kvm_sev_info *to_kvm_sev_info(struct kvm *kvm) return &to_kvm_svm(kvm)->sev_info; } +#ifdef CONFIG_KVM_AMD_SEV static __always_inline bool sev_guest(struct kvm *kvm) { -#ifdef CONFIG_KVM_AMD_SEV struct kvm_sev_info *sev = &to_kvm_svm(kvm)->sev_info; return sev->active; -#else - return false; -#endif } - static __always_inline bool sev_es_guest(struct kvm *kvm) { -#ifdef CONFIG_KVM_AMD_SEV struct kvm_sev_info *sev = &to_kvm_svm(kvm)->sev_info; return sev->es_active && !WARN_ON_ONCE(!sev->active); -#else - return false; -#endif } static __always_inline bool sev_snp_guest(struct kvm *kvm) { -#ifdef CONFIG_KVM_AMD_SEV struct kvm_sev_info *sev = &to_kvm_svm(kvm)->sev_info; return (sev->vmsa_features[SVM_SEV_VMPL0] & SVM_SEV_FEAT_SNP_ACTIVE) && !WARN_ON_ONCE(!sev_es_guest(kvm)); +} #else - return false; +#define sev_guest(kvm) false +#define sev_es_guest(kvm) false +#define sev_snp_guest(kvm) false #endif -} static inline bool ghcb_gpa_is_registered(struct vcpu_svm *svm, u64 val) { From 4e7927c0eb1fa2969d4fa2964ffa9eabbd970674 Mon Sep 17 00:00:00 2001 From: Nikunj A Dadhania Date: Mon, 17 Mar 2025 10:53:05 +0530 Subject: [PATCH 24/29] x86/cpufeatures: Add SNP Secure TSC The Secure TSC feature for SEV-SNP allows guests to securely use the RDTSC and RDTSCP instructions, ensuring that the parameters used cannot be altered by the hypervisor once the guest is launched. For more details, refer to the AMD64 APM Vol 2, Section "Secure TSC". Acked-by: Borislav Petkov (AMD) Reviewed-by: Tom Lendacky Tested-by: Vaishali Thakkar Signed-off-by: Nikunj A Dadhania --- arch/x86/include/asm/cpufeatures.h | 5 +++-- 1 file changed, 3 insertions(+), 2 deletions(-) diff --git a/arch/x86/include/asm/cpufeatures.h b/arch/x86/include/asm/cpufeatures.h index ff846640540933..24ca5819281c8e 100644 --- a/arch/x86/include/asm/cpufeatures.h +++ b/arch/x86/include/asm/cpufeatures.h @@ -442,8 +442,9 @@ #define X86_FEATURE_SME (19*32+ 0) /* "sme" AMD Secure Memory Encryption */ #define X86_FEATURE_SEV (19*32+ 1) /* "sev" AMD Secure Encrypted Virtualization */ #define X86_FEATURE_VM_PAGE_FLUSH (19*32+ 2) /* VM Page Flush MSR is supported */ -#define X86_FEATURE_SEV_ES (19*32+ 3) /* "sev_es" AMD Secure Encrypted Virtualization - Encrypted State */ -#define X86_FEATURE_SEV_SNP (19*32+ 4) /* "sev_snp" AMD Secure Encrypted Virtualization - Secure Nested Paging */ +#define X86_FEATURE_SEV_ES (19*32+ 3) /* "sev_es" Secure Encrypted Virtualization - Encrypted State */ +#define X86_FEATURE_SEV_SNP (19*32+ 4) /* "sev_snp" Secure Encrypted Virtualization - Secure Nested Paging */ +#define X86_FEATURE_SNP_SECURE_TSC (19*32+ 8) /* SEV-SNP Secure TSC */ #define X86_FEATURE_V_TSC_AUX (19*32+ 9) /* Virtual TSC_AUX */ #define X86_FEATURE_SME_COHERENT (19*32+10) /* AMD hardware-enforced cache coherency */ #define X86_FEATURE_RESTRICTED_INJECTION (19*32+12) /* AMD SEV Restricted Injection */ From b19db683775729f66584a748bc7fa637ad0ed835 Mon Sep 17 00:00:00 2001 From: Nikunj A Dadhania Date: Mon, 17 Mar 2025 10:53:06 +0530 Subject: [PATCH 25/29] KVM: SVM: Add missing member in SNP_LAUNCH_START command structure The sev_data_snp_launch_start structure should include a 4-byte desired_tsc_khz field before the gosvw field, which was missed in the initial implementation. As a result, the structure is 4 bytes shorter than expected by the firmware, causing the gosvw field to start 4 bytes early. Fix this by adding the missing 4-byte member for the desired TSC frequency. Fixes: 3a45dc2b419e ("crypto: ccp: Define the SEV-SNP commands") Cc: stable@vger.kernel.org Suggested-by: Tom Lendacky Reviewed-by: Tom Lendacky Tested-by: Vaishali Thakkar Signed-off-by: Nikunj A Dadhania --- include/linux/psp-sev.h | 2 ++ 1 file changed, 2 insertions(+) diff --git a/include/linux/psp-sev.h b/include/linux/psp-sev.h index 903ddfea858505..613a8209bed275 100644 --- a/include/linux/psp-sev.h +++ b/include/linux/psp-sev.h @@ -594,6 +594,7 @@ struct sev_data_snp_addr { * @imi_en: launch flow is launching an IMI (Incoming Migration Image) for the * purpose of guest-assisted migration. * @rsvd: reserved + * @desired_tsc_khz: hypervisor desired mean TSC freq in kHz of the guest * @gosvw: guest OS-visible workarounds, as defined by hypervisor */ struct sev_data_snp_launch_start { @@ -603,6 +604,7 @@ struct sev_data_snp_launch_start { u32 ma_en:1; /* In */ u32 imi_en:1; /* In */ u32 rsvd:30; + u32 desired_tsc_khz; /* In */ u8 gosvw[16]; /* In */ } __packed; From 03f77e9edb1777c832d6c11bfc7a71edc0bae508 Mon Sep 17 00:00:00 2001 From: Nikunj A Dadhania Date: Mon, 17 Mar 2025 10:53:07 +0530 Subject: [PATCH 26/29] KVM: SVM: Add GUEST_TSC_FREQ MSR for Secure TSC enabled guests Introduce the read-only MSR GUEST_TSC_FREQ (0xc0010134) that returns guest's effective frequency in MHZ when Secure TSC is enabled for SNP guests. Disable interception of this MSR when Secure TSC is enabled. Note that GUEST_TSC_FREQ MSR is accessible only to the guest and not from the hypervisor context. (Vaishali: Adapt the value of MAX_DIRECT_ACCESS_MSRs to incorporate the change introduced by this commit, allow Secure TSC to be used at VMPL 0 level) Reviewed-by: Tom Lendacky Tested-by: Vaishali Thakkar Signed-off-by: Nikunj A Dadhania --- arch/x86/include/asm/svm.h | 1 + arch/x86/kvm/svm/sev.c | 3 +++ arch/x86/kvm/svm/svm.c | 1 + arch/x86/kvm/svm/svm.h | 11 ++++++++++- 4 files changed, 15 insertions(+), 1 deletion(-) diff --git a/arch/x86/include/asm/svm.h b/arch/x86/include/asm/svm.h index 08caab15dfab31..3e3da133545b96 100644 --- a/arch/x86/include/asm/svm.h +++ b/arch/x86/include/asm/svm.h @@ -289,6 +289,7 @@ static_assert((X2AVIC_MAX_PHYSICAL_ID & AVIC_PHYSICAL_MAX_INDEX_MASK) == X2AVIC_ #define SVM_SEV_FEAT_RESTRICTED_INJECTION BIT(3) #define SVM_SEV_FEAT_ALTERNATE_INJECTION BIT(4) #define SVM_SEV_FEAT_DEBUG_SWAP BIT(5) +#define SVM_SEV_FEAT_SECURE_TSC BIT(9) #define SVM_SEV_FEAT_INT_INJ_MODES \ (SVM_SEV_FEAT_RESTRICTED_INJECTION | \ diff --git a/arch/x86/kvm/svm/sev.c b/arch/x86/kvm/svm/sev.c index 55384e4e976b73..b3d1e538887a38 100644 --- a/arch/x86/kvm/svm/sev.c +++ b/arch/x86/kvm/svm/sev.c @@ -5023,6 +5023,9 @@ static void sev_es_init_vmcb(struct vcpu_svm *svm) if (sev_snp_guest(vcpu->kvm)) sev_snp_init_vmcb(svm); + + if (snp_secure_tsc_enabled(vcpu->kvm)) + set_msr_interception(vcpu, svm->msrpm, MSR_AMD64_GUEST_TSC_FREQ, 1, 1); } void sev_init_vmcb(struct vcpu_svm *svm) diff --git a/arch/x86/kvm/svm/svm.c b/arch/x86/kvm/svm/svm.c index cb172369c606d1..417d3f0aa58481 100644 --- a/arch/x86/kvm/svm/svm.c +++ b/arch/x86/kvm/svm/svm.c @@ -151,6 +151,7 @@ static const struct svm_direct_access_msrs { { .index = MSR_IA32_PL2_SSP, .always = false }, { .index = MSR_IA32_PL3_SSP, .always = false }, { .index = MSR_IA32_INT_SSP_TAB, .always = false }, + { .index = MSR_AMD64_GUEST_TSC_FREQ, .always = false }, { .index = MSR_INVALID, .always = false }, }; diff --git a/arch/x86/kvm/svm/svm.h b/arch/x86/kvm/svm/svm.h index 0ed3270e20ce97..efc3eaf20cdba6 100644 --- a/arch/x86/kvm/svm/svm.h +++ b/arch/x86/kvm/svm/svm.h @@ -30,7 +30,7 @@ #define IOPM_SIZE PAGE_SIZE * 3 #define MSRPM_SIZE PAGE_SIZE * 2 -#define MAX_DIRECT_ACCESS_MSRS 55 +#define MAX_DIRECT_ACCESS_MSRS 56 #define MSRPM_OFFSETS 32 extern u32 msrpm_offsets[MSRPM_OFFSETS] __read_mostly; extern bool npt_enabled; @@ -404,10 +404,19 @@ static __always_inline bool sev_snp_guest(struct kvm *kvm) return (sev->vmsa_features[SVM_SEV_VMPL0] & SVM_SEV_FEAT_SNP_ACTIVE) && !WARN_ON_ONCE(!sev_es_guest(kvm)); } + +static inline bool snp_secure_tsc_enabled(struct kvm *kvm) +{ + struct kvm_sev_info *sev = to_kvm_sev_info(kvm); + + return (sev->vmsa_features[SVM_SEV_VMPL0] & SVM_SEV_FEAT_SECURE_TSC) && + !WARN_ON_ONCE(!sev_snp_guest(kvm)); +} #else #define sev_guest(kvm) false #define sev_es_guest(kvm) false #define sev_snp_guest(kvm) false +#define snp_secure_tsc_enabled(kvm) false #endif static inline bool ghcb_gpa_is_registered(struct vcpu_svm *svm, u64 val) From 9839fe6990ed696b8a007aa543302ba51d505344 Mon Sep 17 00:00:00 2001 From: Ketan Chaturvedi Date: Tue, 30 Aug 2022 02:42:40 +0000 Subject: [PATCH 27/29] KVM: SVM: Enable Secure TSC for SNP guests Add support for Secure TSC, allowing userspace to configure the Secure TSC feature for SNP guests. Use the SNP specification's desired TSC frequency parameter during the SNP_LAUNCH_START command to set the mean TSC frequency in KHz for Secure TSC enabled guests. As the frequency needs to be set in the SNP_LAUNCH_START command, userspace should set the frequency using the KVM_CAP_SET_TSC_KHZ VM ioctl instead of the VCPU ioctl. The desired_tsc_khz defaults to kvm->arch.default_tsc_khz. Signed-off-by: Ketan Chaturvedi Co-developed-by: Nikunj A Dadhania Tested-by: Vaishali Thakkar Reviewed-by: Tom Lendacky Signed-off-by: Nikunj A Dadhania --- arch/x86/include/uapi/asm/kvm.h | 3 ++- arch/x86/kvm/svm/sev.c | 18 ++++++++++++++---- 2 files changed, 16 insertions(+), 5 deletions(-) diff --git a/arch/x86/include/uapi/asm/kvm.h b/arch/x86/include/uapi/asm/kvm.h index a24f3197e240f1..22ccaf55a40d56 100644 --- a/arch/x86/include/uapi/asm/kvm.h +++ b/arch/x86/include/uapi/asm/kvm.h @@ -838,7 +838,8 @@ struct kvm_sev_snp_launch_start { __u64 policy; __u8 gosvw[16]; __u16 flags; - __u8 pad0[6]; + __u8 pad0[2]; + __u32 desired_tsc_khz; __u64 pad1[4]; }; diff --git a/arch/x86/kvm/svm/sev.c b/arch/x86/kvm/svm/sev.c index b3d1e538887a38..16e2d5b7f38adb 100644 --- a/arch/x86/kvm/svm/sev.c +++ b/arch/x86/kvm/svm/sev.c @@ -2253,6 +2253,14 @@ static int snp_launch_start(struct kvm *kvm, struct kvm_sev_cmd *argp) start.gctx_paddr = __psp_pa(sev->snp_context); start.policy = params.policy; + + if (snp_secure_tsc_enabled(kvm)) { + if (!kvm->arch.default_tsc_khz) + return -EINVAL; + + start.desired_tsc_khz = kvm->arch.default_tsc_khz; + } + memcpy(start.gosvw, params.gosvw, sizeof(params.gosvw)); rc = __sev_issue_cmd(argp->sev_fd, SEV_CMD_SNP_LAUNCH_START, &start, &argp->error); if (rc) { @@ -2579,7 +2587,9 @@ static int snp_launch_update_vmsa(struct kvm *kvm, struct kvm_sev_cmd *argp) return ret; } - svm->vcpu.arch.guest_state_protected = true; + vcpu->arch.guest_state_protected = true; + vcpu->arch.guest_tsc_protected = snp_secure_tsc_enabled(kvm); + /* * SEV-ES (and thus SNP) guest mandates LBR Virtualization to * be _always_ ON. Enable it only after setting @@ -3202,11 +3212,11 @@ void __init sev_hardware_setup(void) if (sev_es_debug_swap_enabled) sev_supported_vmsa_features |= SVM_SEV_FEAT_DEBUG_SWAP; - if (!sev_snp_enabled || !cpu_feature_enabled(X86_FEATURE_RESTRICTED_INJECTION)) - sev_snp_restricted_injection_enabled = false; - if (sev_snp_restricted_injection_enabled) sev_supported_vmsa_features |= SVM_SEV_FEAT_RESTRICTED_INJECTION; + + if (sev_snp_enabled && cpu_feature_enabled(X86_FEATURE_SNP_SECURE_TSC)) + sev_supported_vmsa_features |= SVM_SEV_FEAT_SECURE_TSC; } void sev_hardware_unsetup(void) From de7b2882c4647cf8f442a9dc6cbdaea976729e37 Mon Sep 17 00:00:00 2001 From: Isaku Yamahata Date: Sat, 12 Oct 2024 00:55:55 -0700 Subject: [PATCH 28/29] KVM: x86: Push down setting vcpu.arch.user_set_tsc Push down setting vcpu.arch.user_set_tsc to true from kvm_synchronize_tsc() to __kvm_synchronize_tsc() so that the two callers don't have to modify user_set_tsc directly as preparation. Later, prohibit changing TSC synchronization for TDX guests to modify __kvm_synchornize_tsc() change. We don't want to touch caller sites not to change user_set_tsc. Signed-off-by: Isaku Yamahata Message-ID: <62b1a7a35d6961844786b6e47e8ecb774af7a228.1728719037.git.isaku.yamahata@intel.com> Signed-off-by: Paolo Bonzini --- arch/x86/kvm/x86.c | 12 ++++++------ 1 file changed, 6 insertions(+), 6 deletions(-) diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c index b78fb6806bd822..6ddac335398784 100644 --- a/arch/x86/kvm/x86.c +++ b/arch/x86/kvm/x86.c @@ -2644,12 +2644,15 @@ static inline bool kvm_check_tsc_unstable(void) * participates in. */ static void __kvm_synchronize_tsc(struct kvm_vcpu *vcpu, u64 offset, u64 tsc, - u64 ns, bool matched) + u64 ns, bool matched, bool user_set_tsc) { struct kvm *kvm = vcpu->kvm; lockdep_assert_held(&kvm->arch.tsc_write_lock); + if (user_set_tsc) + vcpu->kvm->arch.user_set_tsc = true; + /* * We also track th most recent recorded KHZ, write and time to * allow the matching interval to be extended at each write. @@ -2735,8 +2738,6 @@ static void kvm_synchronize_tsc(struct kvm_vcpu *vcpu, u64 *user_value) } } - if (user_value) - kvm->arch.user_set_tsc = true; /* * For a reliable TSC, we can match TSC offsets, and for an unstable @@ -2756,7 +2757,7 @@ static void kvm_synchronize_tsc(struct kvm_vcpu *vcpu, u64 *user_value) matched = true; } - __kvm_synchronize_tsc(vcpu, offset, data, ns, matched); + __kvm_synchronize_tsc(vcpu, offset, data, ns, matched, !!user_value); raw_spin_unlock_irqrestore(&kvm->arch.tsc_write_lock, flags); } @@ -5762,8 +5763,7 @@ static int kvm_arch_tsc_set_attr(struct kvm_vcpu *vcpu, tsc = kvm_scale_tsc(rdtsc(), vcpu->arch.l1_tsc_scaling_ratio) + offset; ns = get_kvmclock_base_ns(); - kvm->arch.user_set_tsc = true; - __kvm_synchronize_tsc(vcpu, offset, tsc, ns, matched); + __kvm_synchronize_tsc(vcpu, offset, tsc, ns, matched, true); raw_spin_unlock_irqrestore(&kvm->arch.tsc_write_lock, flags); r = 0; From 572ace0d793f5bb802a41012c41367633fbcd178 Mon Sep 17 00:00:00 2001 From: Isaku Yamahata Date: Sat, 12 Oct 2024 00:55:56 -0700 Subject: [PATCH 29/29] KVM: SVM: Don't allow tsc_offset, tsc_scaling_ratio to change Add guest_tsc_protected member to struct kvm_arch_vcpu and prohibit changing TSC offset/multiplier when guest_tsc_protected is true. X86 confidential computing technology defines protected guest TSC so that the VMM can't change the TSC offset/multiplier once vCPU is initialized. SEV-SNP defines Secure TSC as optional, whereas TDX mandates it. KVM has common logic on x86 that tries to guess or adjust TSC offset/multiplier for better guest TSC and TSC interrupt latency at KVM vCPU creation (kvm_arch_vcpu_postcreate()), vCPU migration over pCPU (kvm_arch_vcpu_load()), vCPU TSC device attributes (kvm_arch_tsc_set_attr()) and guest/host writing to TSC or TSC adjust MSR (kvm_set_msr_common()). The current x86 KVM implementation conflicts with protected TSC because the VMM can't change the TSC offset/multiplier. Because KVM emulates the TSC timer or the TSC deadline timer with the TSC offset/multiplier, the TSC timer interrupts is injected to the guest at the wrong time if the KVM TSC offset is different from what the TDX module determined. Originally this issue was found by cyclic test of rt-test [1] as the latency in TDX case is worse than VMX value + TDX SEAMCALL overhead. It turned out that the KVM TSC offset is different from what the TDX module determines. Disable or ignore the KVM logic to change/adjust the TSC offset/multiplier somehow, thus keeping the KVM TSC offset/multiplier the same as the value of the TDX module. Writes to MSR_IA32_TSC are also blocked as they amount to a change in the TSC offset. [1] https://git.kernel.org/pub/scm/utils/rt-tests/rt-tests.git (Vaishali: Skip cherry-picking arch/x86/kvm/vmx/tdx.c as part of this commit from upstream, adjust the subject line to adopt this change) Reported-by: Marcelo Tosatti Signed-off-by: Isaku Yamahata Message-ID: <3a7444aec08042fe205666864b6858910e86aa98.1728719037.git.isaku.yamahata@intel.com> Signed-off-by: Paolo Bonzini --- arch/x86/include/asm/kvm_host.h | 1 + arch/x86/kvm/x86.c | 11 +++++++++-- 2 files changed, 10 insertions(+), 2 deletions(-) diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h index f6250299e17a1d..20b9a4cf2b9b18 100644 --- a/arch/x86/include/asm/kvm_host.h +++ b/arch/x86/include/asm/kvm_host.h @@ -1032,6 +1032,7 @@ struct kvm_vcpu_arch { /* Protected Guests */ bool guest_state_protected; + bool guest_tsc_protected; /* * Set when PDPTS were loaded directly by the userspace without diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c index 6ddac335398784..bc295f5d994a34 100644 --- a/arch/x86/kvm/x86.c +++ b/arch/x86/kvm/x86.c @@ -2587,6 +2587,9 @@ EXPORT_SYMBOL_GPL(kvm_calc_nested_tsc_multiplier); static void kvm_vcpu_write_tsc_offset(struct kvm_vcpu *vcpu, u64 l1_offset) { + if (vcpu->arch.guest_tsc_protected) + return; + trace_kvm_write_tsc_offset(vcpu->vcpu_id, vcpu->arch.l1_tsc_offset, l1_offset); @@ -2650,6 +2653,9 @@ static void __kvm_synchronize_tsc(struct kvm_vcpu *vcpu, u64 offset, u64 tsc, lockdep_assert_held(&kvm->arch.tsc_write_lock); + if (vcpu->arch.guest_tsc_protected) + return; + if (user_set_tsc) vcpu->kvm->arch.user_set_tsc = true; @@ -3934,7 +3940,7 @@ int kvm_set_msr_common(struct kvm_vcpu *vcpu, struct msr_data *msr_info) case MSR_IA32_TSC: if (msr_info->host_initiated) { kvm_synchronize_tsc(vcpu, &data); - } else { + } else if (!vcpu->arch.guest_tsc_protected) { u64 adj = kvm_compute_l1_tsc_offset(vcpu, data) - vcpu->arch.l1_tsc_offset; adjust_tsc_offset_guest(vcpu, adj); vcpu->arch.ia32_tsc_adjust_msr += adj; @@ -5030,7 +5036,8 @@ void kvm_arch_vcpu_load(struct kvm_vcpu *vcpu, int cpu) u64 offset = kvm_compute_l1_tsc_offset(vcpu, vcpu->arch.last_guest_tsc); kvm_vcpu_write_tsc_offset(vcpu, offset); - vcpu->arch.tsc_catchup = 1; + if (!vcpu->arch.guest_tsc_protected) + vcpu->arch.tsc_catchup = 1; } if (kvm_lapic_hv_timer_in_use(vcpu))