vmm_tests: boot UEFI NVMe across multiple root complexes

[jstarks]

Extend pcie_nvme_boot to cover a richer PCIe topology: five root complexes split asymmetrically across two segments, booting from an NVMe controller that is not on the first root complex. This exercises UEFI's enumeration of multiple root complexes sharing segment numbers, which the prior single-RC topology never touched.

Supporting this, with_pcie_root_topology is now additive (successive calls append to fresh segments), and a new with_pcie_boot_port allows placing the boot NVMe controller on a port other than s0rc0rp0.

[jstarks]

This is in draft until microsoft/mu_msvm#87 is merged and we update our UEFI dependency.

[Copilot]

Pull request overview

Extends the existing PCIe/NVMe UEFI boot test to cover a more complex, asymmetric PCIe topology (multiple root complexes across two segments) and introduces supporting Petri configuration knobs to place the boot NVMe controller on a non-default root port.

Changes:

• Expanded pcie_nvme_boot to build a 5-root-complex, 2-segment topology and boot from an NVMe controller not on the first root complex.
• Made with_pcie_root_topology additive so it can be called multiple times to construct asymmetric topologies.
• Added PetriVmBuilder::with_pcie_boot_port to select which PCIe root port hosts the boot NVMe controller (default remains s0rc0rp0).

Reviewed changes

Copilot reviewed 3 out of 3 changed files in this pull request and generated 1 comment.

File	Description
vmm_tests/vmm_tests/tests/tests/multiarch/pcie.rs	Updates pcie_nvme_boot to use an asymmetric multi-segment topology and assert both NVMe controllers enumerate.
petri/src/vm/openvmm/modify.rs	Updates with_pcie_root_topology so successive calls append new segments/RCs rather than restarting numbering.
petri/src/vm/mod.rs	Adds a builder option/method to override the boot NVMe controller’s PCIe port for BootDeviceType::PcieNvme.