The PCI subsystem uses PCI_NO_PASID for requests-without-PASID, but VT-d
emulation uses IOMMU_NO_PASID internally (ecap.RPS==0). This leads to
conversion and checking code between PCI_NO_PASID and IOMMU_NO_PASID
throughout the implementation.
Refactor to use IOMMU PASID consistently within Intel IOMMU by storing
IOMMU PASID value in vtd_as->pasid. After this change, PCI_NO_PASID is
only used at three boundary points:
1. PCI_NO_PASID -> IOMMU_NO_PASID: Convert PCI PASID to IOMMU PASID in
vtd_find_add_as() and cache in vtd_as->pasid.
2. IOMMU_NO_PASID -> PCI_NO_PASID: Convert when notifying UNMAP events
via memory_region_notify_iommu() and returning IOMMUTLBEntry in
vtd_iommu_translate().
This eliminates conversion/checks in PASID table lookups, simplifies
invalidation logic with consistent PASID values, and improves code
readability. The PCI subsystem interface remains unchanged to maintain
compatibility with other IOMMU implementations that may not use PASID 0
for requests-without-PASID.
Suggested-by: Clement Mathieu--Drif <clement.mathieu--drif@bull.com>
Signed-off-by: Zhenzhong Duan <zhenzhong.duan@intel.com>
Reviewed-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
Message-Id: <20260527054658.1021096-11-zhenzhong.duan@intel.com>
c579197d6b