From: Kuppuswamy Sathyanarayanan <sathyanarayanan.kuppuswamy@xxxxxxxxxxxxxxx> Intel IOMMU responds automatically when receiving page-requests from a PCIe endpoint and the page-request queue is full and it cannot accept any more page-requests. When it auto-responds to page-requests with a success to the endpoint, it automatically responds with the PASID if the page-request had a PASID in the incoming request. IOMMU doesn't actually have any place to check device capabilities (like whether the device expects PASID in PGR response or not) before sending the response message. Due to this restriction Intel IOMMU driver only enables PASID, if the endpoint is compliant to Intel IOMMU's. Kuppuswamy Sathyanarayanan (2): PCI: ATS: Add function to check PRG response PASID bit status. iommu/vt-d: Enable PASID only if device expects PASID in PRG response. drivers/iommu/intel-iommu.c | 3 ++- drivers/pci/ats.c | 27 +++++++++++++++++++++++++++ include/linux/pci-ats.h | 5 +++++ include/uapi/linux/pci_regs.h | 1 + 4 files changed, 35 insertions(+), 1 deletion(-) -- 2.20.1
