virt_mshv: Wire up SignalMsi implementation

[sprt]

The MSHV backend did not override as_signal_msi(), so the default returned None and left PCIe MSI connections wired to a disconnected target that silently dropped all interrupts. This caused PCIe devices to hang after probe (see below). Fixed this by implementing SignalMsi for MshvPartitionInner, delegating to the existing request_msi().

virtio_blk virtio0: 1/0/0 default/read/poll queues
virtio_blk virtio0: [vda] 368640 512-byte logical blocks (189 MB/180 MiB)
WARN pci_core::msi:  dropped MSI interrupt to disconnected target
WARN pci_core::msi:  dropped MSI interrupt to disconnected target

Co-authored-by: GitHub Copilot

[github-actions]

⚠️ Unsafe Code Detected

This PR modifies files containing unsafe Rust code. Extra scrutiny is required during review.

For more on why we check whole files, instead of just diffs, check out the Rustonomicon

[Copilot]

Pull request overview

This PR fixes MSI interrupt delivery for the MSHV backend by wiring up the SignalMsi interface, so PCIe devices no longer connect to a disconnected MSI target that drops interrupts.

Changes:

• Implement virt::Partition::as_signal_msi() for MshvPartition to return an MSI signaling target.
• Implement pci_core::msi::SignalMsi for MshvPartitionInner, delegating to the existing request_msi() path.
• Add the pci_core workspace dependency to virt_mshv.

Reviewed changes

Copilot reviewed 2 out of 3 changed files in this pull request and generated no comments.

File	Description
vmm_core/virt_mshv/src/lib.rs	Exposes an MSI signaling target for MSHV and implements SignalMsi by forwarding to request_msi().
vmm_core/virt_mshv/Cargo.toml	Adds pci_core dependency needed for the SignalMsi trait.
Cargo.lock	Lockfile update reflecting the new pci_core dependency.

---

You can also share your feedback on Copilot code review. Take the survey.

[github-actions]

At least one Petri test failed.