From c9e1a7c51ea3dcde1a0f75d7a1062b03fdc68d5c Mon Sep 17 00:00:00 2001 From: Nikunj A Dadhania Date: Tue, 19 Aug 2025 16:48:26 -0700 Subject: [PATCH 1/8] KVM: SEV: Drop GHCB_VERSION_DEFAULT and open code it Remove the GHCB_VERSION_DEFAULT macro and open code it with '2'. The macro is used conditionally and is not a true default. KVM ABI does not advertise/emumerates the default GHCB version. Any future change to this macro would silently alter the ABI and potentially break existing deployments that rely on the current behavior. Additionally, move the GHCB version assignment earlier in the code flow and update the comment to clarify that KVM_SEV_INIT2 defaults to version 2, while KVM_SEV_INIT forces version 1. No functional change intended. Cc: Thomas Lendacky Cc: Michael Roth Suggested-by: Sean Christopherson Signed-off-by: Nikunj A Dadhania Link: https://lore.kernel.org/r/20250819234833.3080255-2-seanjc@google.com Signed-off-by: Sean Christopherson --- arch/x86/kvm/svm/sev.c | 17 ++++++++--------- 1 file changed, 8 insertions(+), 9 deletions(-) diff --git a/arch/x86/kvm/svm/sev.c b/arch/x86/kvm/svm/sev.c index 4b5816754c3b20..cbbb22b5d19de4 100644 --- a/arch/x86/kvm/svm/sev.c +++ b/arch/x86/kvm/svm/sev.c @@ -38,7 +38,6 @@ #include "lapic.h" #define GHCB_VERSION_MAX 2ULL -#define GHCB_VERSION_DEFAULT 2ULL #define GHCB_VERSION_MIN 1ULL #define GHCB_HV_FT_SUPPORTED (GHCB_HV_FT_SNP | \ @@ -428,6 +427,14 @@ static int __sev_guest_init(struct kvm *kvm, struct kvm_sev_cmd *argp, if (data->ghcb_version > GHCB_VERSION_MAX || (!es_active && data->ghcb_version)) return -EINVAL; + /* + * KVM supports the full range of mandatory features defined by version + * 2 of the GHCB protocol, so default to that for SEV-ES guests created + * via KVM_SEV_INIT2 (KVM_SEV_INIT forces version 1). + */ + if (es_active && !data->ghcb_version) + data->ghcb_version = 2; + if (unlikely(sev->active)) return -EINVAL; @@ -436,14 +443,6 @@ static int __sev_guest_init(struct kvm *kvm, struct kvm_sev_cmd *argp, sev->vmsa_features = data->vmsa_features; sev->ghcb_version = data->ghcb_version; - /* - * Currently KVM supports the full range of mandatory features defined - * by version 2 of the GHCB protocol, so default to that for SEV-ES - * guests created via KVM_SEV_INIT2. - */ - if (sev->es_active && !sev->ghcb_version) - sev->ghcb_version = GHCB_VERSION_DEFAULT; - if (vm_type == KVM_X86_SNP_VM) sev->vmsa_features |= SVM_SEV_FEAT_SNP_ACTIVE; From 34e175e5f7442ad25ab9a47d6d0c513792b30c65 Mon Sep 17 00:00:00 2001 From: Nikunj A Dadhania Date: Tue, 19 Aug 2025 16:48:27 -0700 Subject: [PATCH 2/8] KVM: SEV: Enforce minimum GHCB version requirement for SEV-SNP guests Require a minimum GHCB version of 2 when starting SEV-SNP guests through KVM_SEV_INIT2. When a VMM attempts to start an SEV-SNP guest with an incompatible GHCB version (less than 2), reject the request early rather than allowing the guest kernel to start with an incorrect protocol version and fail later with GHCB_SNP_UNSUPPORTED guest termination. Not enforcing the minimum version typically causes the guest to request termination with GHCB_SNP_UNSUPPORTED error code: kvm_amd: SEV-ES guest requested termination: 0x0:0x2 Fixes: 4af663c2f64a ("KVM: SEV: Allow per-guest configuration of GHCB protocol version") Cc: Thomas Lendacky Cc: Sean Christopherson Cc: Michael Roth Signed-off-by: Nikunj A Dadhania Link: https://lore.kernel.org/r/20250819234833.3080255-3-seanjc@google.com Signed-off-by: Sean Christopherson --- arch/x86/kvm/svm/sev.c | 8 ++++++-- 1 file changed, 6 insertions(+), 2 deletions(-) diff --git a/arch/x86/kvm/svm/sev.c b/arch/x86/kvm/svm/sev.c index cbbb22b5d19de4..81d9e4054dd4f0 100644 --- a/arch/x86/kvm/svm/sev.c +++ b/arch/x86/kvm/svm/sev.c @@ -412,6 +412,7 @@ static int __sev_guest_init(struct kvm *kvm, struct kvm_sev_cmd *argp, struct kvm_sev_info *sev = to_kvm_sev_info(kvm); struct sev_platform_init_args init_args = {0}; bool es_active = vm_type != KVM_X86_SEV_VM; + bool snp_active = vm_type == KVM_X86_SNP_VM; u64 valid_vmsa_features = es_active ? sev_supported_vmsa_features : 0; int ret; @@ -435,6 +436,9 @@ static int __sev_guest_init(struct kvm *kvm, struct kvm_sev_cmd *argp, if (es_active && !data->ghcb_version) data->ghcb_version = 2; + if (snp_active && data->ghcb_version < 2) + return -EINVAL; + if (unlikely(sev->active)) return -EINVAL; @@ -443,7 +447,7 @@ static int __sev_guest_init(struct kvm *kvm, struct kvm_sev_cmd *argp, sev->vmsa_features = data->vmsa_features; sev->ghcb_version = data->ghcb_version; - if (vm_type == KVM_X86_SNP_VM) + if (snp_active) sev->vmsa_features |= SVM_SEV_FEAT_SNP_ACTIVE; ret = sev_asid_new(sev); @@ -461,7 +465,7 @@ static int __sev_guest_init(struct kvm *kvm, struct kvm_sev_cmd *argp, } /* This needs to happen after SEV/SNP firmware initialization. */ - if (vm_type == KVM_X86_SNP_VM) { + if (snp_active) { ret = snp_guest_req_init(kvm); if (ret) goto e_free; From 0ab11384875bc104d7ffc98520e6fc57fe297e75 Mon Sep 17 00:00:00 2001 From: Nikunj A Dadhania Date: Tue, 19 Aug 2025 16:48:28 -0700 Subject: [PATCH 3/8] 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 Link: https://lore.kernel.org/r/20250819234833.3080255-4-seanjc@google.com Signed-off-by: Sean Christopherson --- arch/x86/include/asm/cpufeatures.h | 1 + 1 file changed, 1 insertion(+) diff --git a/arch/x86/include/asm/cpufeatures.h b/arch/x86/include/asm/cpufeatures.h index 1ad1388b3e34f3..cd9db5701efd28 100644 --- a/arch/x86/include/asm/cpufeatures.h +++ b/arch/x86/include/asm/cpufeatures.h @@ -444,6 +444,7 @@ #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" 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) /* hardware-enforced cache coherency */ #define X86_FEATURE_RESTRICTED_INJECTION (19*32+12) /* AMD SEV Restricted Injection */ From bc389dbbb33b88807958a640420837eb78336a4c Mon Sep 17 00:00:00 2001 From: Sean Christopherson Date: Tue, 19 Aug 2025 16:48:29 -0700 Subject: [PATCH 4/8] KVM: SVM: Move SEV-ES VMSA allocation to a dedicated sev_vcpu_create() helper Add a dedicated sev_vcpu_create() helper to allocate the VMSA page for SEV-ES+ vCPUs, and to allow for consolidating a variety of related SEV+ code in the near future. No functional change intended. (vaishali: Resolve merge conflicts) Reviewed-by: Nikunj A Dadhania Link: https://lore.kernel.org/r/20250819234833.3080255-5-seanjc@google.com Signed-off-by: Sean Christopherson --- arch/x86/kvm/svm/sev.c | 20 ++++++++++++++++++++ arch/x86/kvm/svm/svm.c | 24 +++++++----------------- arch/x86/kvm/svm/svm.h | 2 ++ 3 files changed, 29 insertions(+), 17 deletions(-) diff --git a/arch/x86/kvm/svm/sev.c b/arch/x86/kvm/svm/sev.c index 81d9e4054dd4f0..cc1c917bb324be 100644 --- a/arch/x86/kvm/svm/sev.c +++ b/arch/x86/kvm/svm/sev.c @@ -4998,6 +4998,26 @@ void sev_init_vmcb(struct vcpu_svm *svm) sev_es_init_vmcb(svm); } +int sev_vcpu_create(struct kvm_vcpu *vcpu) +{ + struct vcpu_svm *svm = to_svm(vcpu); + struct page *vmsa_page; + + if (!sev_es_guest(vcpu->kvm)) + return 0; + + /* + * SEV-ES guests require a separate (from the VMCB) VMSA page used to + * contain the encrypted register state of the guest. + */ + vmsa_page = snp_safe_alloc_page(); + if (!vmsa_page) + return -ENOMEM; + + svm->sev_es.vmsa = page_address(vmsa_page); + return 0; +} + void sev_es_vcpu_reset(struct vcpu_svm *svm) { struct kvm_vcpu *vcpu = &svm->vcpu; diff --git a/arch/x86/kvm/svm/svm.c b/arch/x86/kvm/svm/svm.c index 5e789a33d3c851..e841ef3c36837f 100644 --- a/arch/x86/kvm/svm/svm.c +++ b/arch/x86/kvm/svm/svm.c @@ -1278,7 +1278,6 @@ static int svm_vcpu_create(struct kvm_vcpu *vcpu) { struct vcpu_svm *svm; struct page *vmcb01_page; - struct page *vmsa_page = NULL; int err; BUILD_BUG_ON(offsetof(struct vcpu_svm, vcpu) != 0); @@ -1292,26 +1291,21 @@ static int svm_vcpu_create(struct kvm_vcpu *vcpu) if (sev_es_guest(vcpu->kvm)) { struct kvm_sev_info *sev = to_kvm_sev_info(vcpu->kvm); - /* - * SEV-ES guests require a separate VMSA page used to contain - * the encrypted register state of the guest. - */ - vmsa_page = snp_safe_alloc_page(); - if (!vmsa_page) - goto error_free_vmcb_page; - /* Sync VM SEV_FEATURES to VCPU - Might be overwritten later */ svm->sev_es.vmsa_features = sev->vmsa_features; } + err = sev_vcpu_create(vcpu); + if(err) + goto error_free_vmcb_page; err = avic_init_vcpu(svm); if (err) - goto error_free_vmsa_page; + goto error_free_sev; svm->msrpm = svm_vcpu_alloc_msrpm(); if (!svm->msrpm) { err = -ENOMEM; - goto error_free_vmsa_page; + goto error_free_sev; } svm->x2avic_msrs_intercepted = true; @@ -1320,16 +1314,12 @@ static int svm_vcpu_create(struct kvm_vcpu *vcpu) svm->vmcb01.pa = __sme_set(page_to_pfn(vmcb01_page) << PAGE_SHIFT); svm_switch_vmcb(svm, &svm->vmcb01); - if (vmsa_page) - svm->sev_es.vmsa = page_address(vmsa_page); - svm->guest_state_loaded = false; return 0; -error_free_vmsa_page: - if (vmsa_page) - __free_page(vmsa_page); +error_free_sev: + sev_free_vcpu(vcpu); error_free_vmcb_page: __free_page(vmcb01_page); out: diff --git a/arch/x86/kvm/svm/svm.h b/arch/x86/kvm/svm/svm.h index 8856b4219e9845..43ebb6b1593789 100644 --- a/arch/x86/kvm/svm/svm.h +++ b/arch/x86/kvm/svm/svm.h @@ -868,6 +868,7 @@ static inline struct page *snp_safe_alloc_page(void) return snp_safe_alloc_page_node(numa_node_id(), GFP_KERNEL_ACCOUNT); } +int sev_vcpu_create(struct kvm_vcpu *vcpu); void sev_free_vcpu(struct kvm_vcpu *vcpu); void sev_vm_destroy(struct kvm *kvm); void __init sev_set_cpu_caps(void); @@ -906,6 +907,7 @@ static inline struct page *snp_safe_alloc_page(void) return snp_safe_alloc_page_node(numa_node_id(), GFP_KERNEL_ACCOUNT); } +static inline int sev_vcpu_create(struct kvm_vcpu *vcpu) { return 0; } static inline void sev_free_vcpu(struct kvm_vcpu *vcpu) {} static inline void sev_vm_destroy(struct kvm *kvm) {} static inline void __init sev_set_cpu_caps(void) {} From e0afa2f878a847a48a281e6ad09ceef07528f576 Mon Sep 17 00:00:00 2001 From: Sean Christopherson Date: Tue, 19 Aug 2025 16:48:30 -0700 Subject: [PATCH 5/8] KVM: SEV: Move init of SNP guest state into sev_init_vmcb() Move the initialization of SNP guest state from svm_vcpu_reset() into sev_init_vmcb() to reduce the number of paths that deal with INIT/RESET for SEV+ vCPUs from 4+ to 1. Plumb in @init_event as necessary. Opportunistically check for an SNP guest outside of sev_snp_init_protected_guest_state() so that sev_init_vmcb() is consistent with respect to checking for SEV-ES+ and SNP+ guests. No functional change intended. Reviewed-by: Nikunj A Dadhania Link: https://lore.kernel.org/r/20250819234833.3080255-6-seanjc@google.com Signed-off-by: Sean Christopherson --- arch/x86/kvm/svm/sev.c | 16 +++++++++------- arch/x86/kvm/svm/svm.c | 9 +++------ arch/x86/kvm/svm/svm.h | 4 +--- 3 files changed, 13 insertions(+), 16 deletions(-) diff --git a/arch/x86/kvm/svm/sev.c b/arch/x86/kvm/svm/sev.c index cc1c917bb324be..5ac6c98f1559ce 100644 --- a/arch/x86/kvm/svm/sev.c +++ b/arch/x86/kvm/svm/sev.c @@ -1977,7 +1977,7 @@ static void sev_migrate_from(struct kvm *dst_kvm, struct kvm *src_kvm) kvm_for_each_vcpu(i, dst_vcpu, dst_kvm) { dst_svm = to_svm(dst_vcpu); - sev_init_vmcb(dst_svm); + sev_init_vmcb(dst_svm, false); if (!dst->es_active) continue; @@ -3951,7 +3951,7 @@ static int snp_begin_psc(struct vcpu_svm *svm, struct psc_buffer *psc) /* * Invoked as part of svm_vcpu_reset() processing of an init event. */ -void sev_snp_init_protected_guest_state(struct kvm_vcpu *vcpu) +static void sev_snp_init_protected_guest_state(struct kvm_vcpu *vcpu) { struct vcpu_svm *svm = to_svm(vcpu); struct kvm_memory_slot *slot; @@ -3959,9 +3959,6 @@ void sev_snp_init_protected_guest_state(struct kvm_vcpu *vcpu) kvm_pfn_t pfn; gfn_t gfn; - if (!sev_snp_guest(vcpu->kvm)) - return; - guard(mutex)(&svm->sev_es.snp_vmsa_mutex); if (!svm->sev_es.snp_ap_waiting_for_reset) @@ -4983,8 +4980,10 @@ static void sev_es_init_vmcb(struct vcpu_svm *svm) sev_snp_init_vmcb(svm); } -void sev_init_vmcb(struct vcpu_svm *svm) +void sev_init_vmcb(struct vcpu_svm *svm, bool init_event) { + struct kvm_vcpu *vcpu = &svm->vcpu; + svm->vmcb->control.nested_ctl |= SVM_NESTED_CTL_SEV_ENABLE; clr_exception_intercept(svm, UD_VECTOR); @@ -4994,7 +4993,10 @@ void sev_init_vmcb(struct vcpu_svm *svm) */ clr_exception_intercept(svm, GP_VECTOR); - if (sev_es_guest(svm->vcpu.kvm)) + if (init_event && sev_snp_guest(vcpu->kvm)) + sev_snp_init_protected_guest_state(vcpu); + + if (sev_es_guest(vcpu->kvm)) sev_es_init_vmcb(svm); } diff --git a/arch/x86/kvm/svm/svm.c b/arch/x86/kvm/svm/svm.c index e841ef3c36837f..b8c995de729ccb 100644 --- a/arch/x86/kvm/svm/svm.c +++ b/arch/x86/kvm/svm/svm.c @@ -1086,7 +1086,7 @@ static void svm_recalc_intercepts_after_set_cpuid(struct kvm_vcpu *vcpu) svm_recalc_msr_intercepts(vcpu); } -static void init_vmcb(struct kvm_vcpu *vcpu) +static void init_vmcb(struct kvm_vcpu *vcpu, bool init_event) { struct vcpu_svm *svm = to_svm(vcpu); struct vmcb *vmcb = svm->vmcb01.ptr; @@ -1224,7 +1224,7 @@ static void init_vmcb(struct kvm_vcpu *vcpu) svm_set_intercept(svm, INTERCEPT_BUSLOCK); if (sev_guest(vcpu->kvm)) - sev_init_vmcb(svm); + sev_init_vmcb(svm, init_event); svm_hv_init_vmcb(vmcb); @@ -1259,10 +1259,7 @@ static void svm_vcpu_reset(struct kvm_vcpu *vcpu, bool init_event) svm->spec_ctrl = 0; svm->virt_spec_ctrl = 0; - if (init_event) - sev_snp_init_protected_guest_state(vcpu); - - init_vmcb(vcpu); + init_vmcb(vcpu, init_event); if (!init_event) __svm_vcpu_reset(vcpu); diff --git a/arch/x86/kvm/svm/svm.h b/arch/x86/kvm/svm/svm.h index 43ebb6b1593789..8bbd7ea2a44244 100644 --- a/arch/x86/kvm/svm/svm.h +++ b/arch/x86/kvm/svm/svm.h @@ -840,7 +840,7 @@ void avic_refresh_virtual_apic_mode(struct kvm_vcpu *vcpu); /* sev.c */ int pre_sev_run(struct vcpu_svm *svm, int cpu); -void sev_init_vmcb(struct vcpu_svm *svm); +void sev_init_vmcb(struct vcpu_svm *svm, bool init_event); void sev_vcpu_after_set_cpuid(struct vcpu_svm *svm); int sev_es_string_io(struct vcpu_svm *svm, int size, unsigned int port, int in); void sev_es_vcpu_reset(struct vcpu_svm *svm); @@ -878,7 +878,6 @@ int sev_cpu_init(struct svm_cpu_data *sd); int sev_dev_get_attr(u32 group, u64 attr, u64 *val); extern unsigned int max_sev_asid; void sev_handle_rmp_fault(struct kvm_vcpu *vcpu, gpa_t gpa, u64 error_code); -void sev_snp_init_protected_guest_state(struct kvm_vcpu *vcpu); int sev_gmem_prepare(struct kvm *kvm, kvm_pfn_t pfn, gfn_t gfn, int max_order); void sev_gmem_invalidate(kvm_pfn_t start, kvm_pfn_t end); int sev_private_max_mapping_level(struct kvm *kvm, kvm_pfn_t pfn); @@ -917,7 +916,6 @@ static inline int sev_cpu_init(struct svm_cpu_data *sd) { return 0; } static inline int sev_dev_get_attr(u32 group, u64 attr, u64 *val) { return -ENXIO; } #define max_sev_asid 0 static inline void sev_handle_rmp_fault(struct kvm_vcpu *vcpu, gpa_t gpa, u64 error_code) {} -static inline void sev_snp_init_protected_guest_state(struct kvm_vcpu *vcpu) {} static inline int sev_gmem_prepare(struct kvm *kvm, kvm_pfn_t pfn, gfn_t gfn, int max_order) { return 0; From 4f74cdf86f9cb71c7420c92e587f8a9bef3ee733 Mon Sep 17 00:00:00 2001 From: Sean Christopherson Date: Tue, 19 Aug 2025 16:48:31 -0700 Subject: [PATCH 6/8] KVM: SEV: Set RESET GHCB MSR value during sev_es_init_vmcb() Set the RESET value for the GHCB "MSR" during sev_es_init_vmcb() instead of sev_es_vcpu_reset() to allow for dropping sev_es_vcpu_reset() entirely. Note, the call to sev_init_vmcb() from sev_migrate_from() also kinda sorta emulates a RESET, but sev_migrate_from() immediately overwrites ghcb_gpa with the source's current value, so whether or not stuffing the GHCB version is correct/desirable is moot. No functional change intended. (vaishali: Bring back 'sev' variable which was removed as part of the commit e07c01e1ec7cf) Reviewed-by: Nikunj A Dadhania Link: https://lore.kernel.org/r/20250819234833.3080255-7-seanjc@google.com Signed-off-by: Sean Christopherson --- arch/x86/kvm/svm/sev.c | 25 ++++++++++++------------- 1 file changed, 12 insertions(+), 13 deletions(-) diff --git a/arch/x86/kvm/svm/sev.c b/arch/x86/kvm/svm/sev.c index 5ac6c98f1559ce..195800b1f54a0a 100644 --- a/arch/x86/kvm/svm/sev.c +++ b/arch/x86/kvm/svm/sev.c @@ -4915,8 +4915,9 @@ static void sev_snp_init_vmcb(struct vcpu_svm *svm) svm->vmcb->control.int_ctl &= ~V_NMI_ENABLE_MASK; } -static void sev_es_init_vmcb(struct vcpu_svm *svm) +static void sev_es_init_vmcb(struct vcpu_svm *svm, bool init_event) { + struct kvm_sev_info *sev = to_kvm_sev_info(svm->vcpu.kvm); struct vmcb *vmcb = svm->vmcb01.ptr; svm->vmcb->control.nested_ctl |= SVM_NESTED_CTL_SEV_ES_ENABLE; @@ -4978,6 +4979,15 @@ static void sev_es_init_vmcb(struct vcpu_svm *svm) if (sev_snp_guest(svm->vcpu.kvm)) sev_snp_init_vmcb(svm); + + /* + * Set the GHCB MSR value as per the GHCB specification when emulating + * vCPU RESET for an SEV-ES guest. + */ + if (!init_event) + set_ghcb_msr(svm, GHCB_MSR_SEV_INFO((__u64)sev->ghcb_version, + GHCB_VERSION_MIN, + sev_enc_bit)); } void sev_init_vmcb(struct vcpu_svm *svm, bool init_event) @@ -4997,7 +5007,7 @@ void sev_init_vmcb(struct vcpu_svm *svm, bool init_event) sev_snp_init_protected_guest_state(vcpu); if (sev_es_guest(vcpu->kvm)) - sev_es_init_vmcb(svm); + sev_es_init_vmcb(svm, init_event); } int sev_vcpu_create(struct kvm_vcpu *vcpu) @@ -5022,17 +5032,6 @@ int sev_vcpu_create(struct kvm_vcpu *vcpu) void sev_es_vcpu_reset(struct vcpu_svm *svm) { - struct kvm_vcpu *vcpu = &svm->vcpu; - struct kvm_sev_info *sev = to_kvm_sev_info(vcpu->kvm); - - /* - * Set the GHCB MSR value as per the GHCB specification when emulating - * vCPU RESET for an SEV-ES guest. - */ - set_ghcb_msr(svm, GHCB_MSR_SEV_INFO((__u64)sev->ghcb_version, - GHCB_VERSION_MIN, - sev_enc_bit)); - mutex_init(&svm->sev_es.snp_vmsa_mutex); svm->sev_es.hvdb_gpa = INVALID_PAGE; } From 4be51f811d738ac966e99b37854e6cd1cd17b2be Mon Sep 17 00:00:00 2001 From: Sean Christopherson Date: Tue, 19 Aug 2025 16:48:32 -0700 Subject: [PATCH 7/8] KVM: SEV: Fold sev_es_vcpu_reset() into sev_vcpu_create() Fold the remaining line of sev_es_vcpu_reset() into sev_vcpu_create() as there's no need for a dedicated RESET hook just to init a mutex, and the mutex should be initialized as early as possible anyways. No functional change intended. Reviewed-by: Nikunj A Dadhania Link: https://lore.kernel.org/r/20250819234833.3080255-8-seanjc@google.com Signed-off-by: Sean Christopherson --- arch/x86/kvm/svm/sev.c | 8 ++------ arch/x86/kvm/svm/svm.c | 3 --- arch/x86/kvm/svm/svm.h | 1 - 3 files changed, 2 insertions(+), 10 deletions(-) diff --git a/arch/x86/kvm/svm/sev.c b/arch/x86/kvm/svm/sev.c index 195800b1f54a0a..3f6bc1ffbd4820 100644 --- a/arch/x86/kvm/svm/sev.c +++ b/arch/x86/kvm/svm/sev.c @@ -5015,6 +5015,8 @@ int sev_vcpu_create(struct kvm_vcpu *vcpu) struct vcpu_svm *svm = to_svm(vcpu); struct page *vmsa_page; + mutex_init(&svm->sev_es.snp_vmsa_mutex); + if (!sev_es_guest(vcpu->kvm)) return 0; @@ -5030,12 +5032,6 @@ int sev_vcpu_create(struct kvm_vcpu *vcpu) return 0; } -void sev_es_vcpu_reset(struct vcpu_svm *svm) -{ - mutex_init(&svm->sev_es.snp_vmsa_mutex); - svm->sev_es.hvdb_gpa = INVALID_PAGE; -} - void sev_es_prepare_switch_to_guest(struct vcpu_svm *svm, struct sev_es_save_area *hostsa) { struct kvm *kvm = svm->vcpu.kvm; diff --git a/arch/x86/kvm/svm/svm.c b/arch/x86/kvm/svm/svm.c index b8c995de729ccb..8ded3016b1115f 100644 --- a/arch/x86/kvm/svm/svm.c +++ b/arch/x86/kvm/svm/svm.c @@ -1247,9 +1247,6 @@ static void __svm_vcpu_reset(struct kvm_vcpu *vcpu) svm->nmi_masked = false; svm->awaiting_iret_completion = false; - - if (sev_es_guest(vcpu->kvm)) - sev_es_vcpu_reset(svm); } static void svm_vcpu_reset(struct kvm_vcpu *vcpu, bool init_event) diff --git a/arch/x86/kvm/svm/svm.h b/arch/x86/kvm/svm/svm.h index 8bbd7ea2a44244..27f166a3d2fb85 100644 --- a/arch/x86/kvm/svm/svm.h +++ b/arch/x86/kvm/svm/svm.h @@ -843,7 +843,6 @@ int pre_sev_run(struct vcpu_svm *svm, int cpu); void sev_init_vmcb(struct vcpu_svm *svm, bool init_event); void sev_vcpu_after_set_cpuid(struct vcpu_svm *svm); int sev_es_string_io(struct vcpu_svm *svm, int size, unsigned int port, int in); -void sev_es_vcpu_reset(struct vcpu_svm *svm); void sev_es_recalc_msr_intercepts(struct kvm_vcpu *vcpu); void sev_vcpu_deliver_sipi_vector(struct kvm_vcpu *vcpu, u8 vector); void sev_es_prepare_switch_to_guest(struct vcpu_svm *svm, struct sev_es_save_area *hostsa); From 8867c83e2313bdf5ee5159b085fb533e066c9f29 Mon Sep 17 00:00:00 2001 From: Nikunj A Dadhania Date: Tue, 19 Aug 2025 16:48:33 -0700 Subject: [PATCH 8/8] 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. Always use kvm->arch.arch.default_tsc_khz as the TSC frequency that is passed to SNP guests in the SNP_LAUNCH_START command. The default value is the host TSC frequency. The userspace can optionally change the TSC frequency via the KVM_SET_TSC_KHZ ioctl before calling the SNP_LAUNCH_START ioctl. 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. Co-developed-by: Ketan Chaturvedi Signed-off-by: Ketan Chaturvedi Reviewed-by: Kai Huang Reviewed-by: Tom Lendacky Signed-off-by: Nikunj A Dadhania [sean: contain Secure TSC to sev.c] Link: https://lore.kernel.org/r/20250819234833.3080255-9-seanjc@google.com [sean: return -EINVAL if TSC frequency is '0'] Signed-off-by: Sean Christopherson --- arch/x86/include/asm/svm.h | 1 + arch/x86/kvm/svm/sev.c | 28 ++++++++++++++++++++++++++++ 2 files changed, 29 insertions(+) diff --git a/arch/x86/include/asm/svm.h b/arch/x86/include/asm/svm.h index 04e1ba35fad22f..f2f14e8e9051c3 100644 --- a/arch/x86/include/asm/svm.h +++ b/arch/x86/include/asm/svm.h @@ -332,6 +332,7 @@ 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 VMCB_ALLOWED_SEV_FEATURES_VALID BIT_ULL(63) diff --git a/arch/x86/kvm/svm/sev.c b/arch/x86/kvm/svm/sev.c index 3f6bc1ffbd4820..87182194bfac53 100644 --- a/arch/x86/kvm/svm/sev.c +++ b/arch/x86/kvm/svm/sev.c @@ -153,6 +153,14 @@ static bool sev_vcpu_has_debug_swap(struct vcpu_svm *svm) return svm->sev_es.vmsa_features & SVM_SEV_FEAT_DEBUG_SWAP; } +static bool snp_is_secure_tsc_enabled(struct kvm *kvm) +{ + struct kvm_sev_info *sev = to_kvm_sev_info(kvm); + + return (sev->vmsa_features & SVM_SEV_FEAT_SECURE_TSC) && + !WARN_ON_ONCE(!sev_snp_guest(kvm)); +} + /* Must be called with the sev_bitmap_lock held */ static bool __sev_recycle_asids(unsigned int min_asid, unsigned int max_asid) { @@ -422,6 +430,9 @@ static int __sev_guest_init(struct kvm *kvm, struct kvm_sev_cmd *argp, if (data->flags) return -EINVAL; + if (!snp_active) + valid_vmsa_features &= ~SVM_SEV_FEAT_SECURE_TSC; + if (data->vmsa_features & ~valid_vmsa_features) return -EINVAL; @@ -2189,6 +2200,13 @@ static int snp_launch_start(struct kvm *kvm, struct kvm_sev_cmd *argp) if (!(params.policy & SNP_POLICY_MASK_RSVD_MBO)) return -EINVAL; + if (snp_is_secure_tsc_enabled(kvm)) { + if (WARN_ON_ONCE(!kvm->arch.default_tsc_khz)) + return -EINVAL; + + start.desired_tsc_khz = kvm->arch.default_tsc_khz; + } + sev->policy = params.policy; sev->snp_context = snp_context_create(kvm, argp); @@ -2197,6 +2215,7 @@ 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; + 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) { @@ -3127,6 +3146,9 @@ void __init sev_hardware_setup(void) if (sev_snp_restricted_injection_enabled) sev_supported_vmsa_features |= SVM_SEV_FEAT_RESTRICTED_INJECTION; + + if (sev_snp_enabled && tsc_khz && cpu_feature_enabled(X86_FEATURE_SNP_SECURE_TSC)) + sev_supported_vmsa_features |= SVM_SEV_FEAT_SECURE_TSC; } void sev_hardware_unsetup(void) @@ -4878,6 +4900,9 @@ void sev_es_recalc_msr_intercepts(struct kvm_vcpu *vcpu) !guest_cpu_cap_has(vcpu, X86_FEATURE_RDTSCP) && !guest_cpu_cap_has(vcpu, X86_FEATURE_RDPID)); + svm_set_intercept_for_msr(vcpu, MSR_AMD64_GUEST_TSC_FREQ, MSR_TYPE_R, + !snp_is_secure_tsc_enabled(vcpu->kvm)); + /* * For SEV-ES, accesses to MSR_IA32_XSS should not be intercepted if * the host/guest supports its use. @@ -5029,6 +5054,9 @@ int sev_vcpu_create(struct kvm_vcpu *vcpu) return -ENOMEM; svm->sev_es.vmsa = page_address(vmsa_page); + + vcpu->arch.guest_tsc_protected = snp_is_secure_tsc_enabled(vcpu->kvm); + return 0; }