libvirt: resolve passthrough BDFs from visible devices

[vyadavmsft]

Improve libvirt PCI passthrough handling by resolving requested BDFs to visible nested devices before building IOMMU-backed pools.

This commit also tolerates non-PCI management NICs when determining the primary NIC exclusion set and reuses the same BDF resolution path in device passthrough functional validation for BDF-only pools so host sysfs lookup follows the resolved passthrough device.

Description

Related Issue

Type of Change

• Bug fix
• New feature
• Breaking change
• Refactoring
• Documentation update

Checklist

• Description is filled in above
• No credentials, secrets, or internal details are included
• Peer review requested (if not, add required peer reviewers after raising PR)
• Tests executed and results posted below

Test Validation

Key Test Cases:

verify_device_passthrough_on_guest

Impacted LISA Features:

NIC Passthrough

Tested Azure Marketplace Images:

-Local HyperV VHD

Test Results

verify_device_passthrough_on_guest

Image	VM Size	Result
		PASSED

[Copilot]

Pull request overview

Improves libvirt PCI passthrough robustness in nested scenarios by resolving runbook-requested BDFs to PCI devices actually visible on the libvirt host before building IOMMU-backed pools, and aligns functional validation to read sysfs from the resolved device.

Changes:

• Add BDF resolution logic for PCI BDF-based pools, including candidate discovery via host-visible passthrough devices.
• Tolerate non-PCI-backed management NICs when computing the “primary NIC” IOMMU exclusion set.
• Update device passthrough functional validation to use the same BDF resolution path before reading vendor/device IDs from sysfs.

Reviewed changes

Copilot reviewed 2 out of 2 changed files in this pull request and generated 1 comment.

File	Description
lisa/sut_orchestrator/libvirt/libvirt_device_pool.py	Resolve requested BDFs to host-visible devices; cache IOMMU device paths; improve IOMMU-group lookup error reporting; tolerate non-PCI management NICs.
lisa/microsoft/testsuites/device_passthrough/functional_tests.py	Resolve BDFs before sysfs vendor/device reads for BDF-only pools to match libvirt host-visible devices.

[Copilot]

Pull request overview

Copilot reviewed 2 out of 2 changed files in this pull request and generated 2 comments.

[Copilot]

Pull request overview

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

Comments suppressed due to low confidence (1)

lisa/sut_orchestrator/util/device_pool.py:10

• DeviceLocationPathIdentifier is imported from lisa.sut_orchestrator.util.schema, but that symbol doesn't exist in that module (schema.py currently defines only VendorDeviceIdIdentifier/PciAddressIdentifier/etc.). This will raise an ImportError at runtime and prevent any platform from loading BaseDevicePool. Either add/restore DeviceLocationPathIdentifier to util/schema.py (and update HostDevicePoolSchema.devices accordingly), or remove this import/type check and rely on the dict location_path handling that already exists in _configure_dict_identifier_pool.

from lisa.sut_orchestrator.util.schema import (
    DeviceLocationPathIdentifier,
    HostDevicePoolSchema,
    HostDevicePoolType,
    PciAddressIdentifier,
    VendorDeviceIdIdentifier,
)

[Copilot]

Pull request overview

Copilot reviewed 2 out of 2 changed files in this pull request and generated 1 comment.

[vyadavmsft]

@anirudhrb Fixed some lint issues. please approve again.