The PCI PASID enabling interface guarantees that the address space used by each PASID is unique. This is achieved by checking that the PCI ACS path is enabled for the device. If the path is not enabled, then the PASID feature cannot be used. if (!pci_acs_path_enabled(pdev, NULL, PCI_ACS_RR | PCI_ACS_UF)) return -EINVAL; The PASID array is not an attribute of the IOMMU group. It is more natural to store the PASID array in the per-device IOMMU data. This makes the code clearer and easier to understand. Please help review and suggest. Change log: v2: - Add an explict check for single-device group in the domain attaching device pasid interface. (Jason) - Make assert_pasid_dma_ownership() returns true or false. Refactor the code in a way that does not change its exsiting behavior. (Kevin) v1: https://lore.kernel.org/linux-iommu/20230801063125.34995-1-baolu.lu@xxxxxxxxxxxxxxx/ Lu Baolu (3): iommu: Make single-device group for PASID explicit iommu: Consolidate pasid dma ownership check iommu: Move pasid array from group to device include/linux/iommu.h | 2 + drivers/iommu/iommu.c | 102 +++++++++++++++++++----------------------- 2 files changed, 49 insertions(+), 55 deletions(-) -- 2.34.1