On Sat, Jan 14, 2023 at 03:34:20PM +0800, Lu Baolu wrote:
> The PCIe fabric routes Memory Requests based on the TLP address, ignoring
> the PASID. In order to ensure system integrity, commit 201007ef707a ("PCI:
> Enable PASID only when ACS RR & UF enabled on upstream path") requires
> some ACS features being supported on device's upstream path when enabling
> PCI/PASID.
>
> One alternative is ATS/PRI which lets the device resolve the PASID + addr
> pair before a memory request is made into a routeable TLB address through
> the translation agent. Those resolved addresses are then cached on the
> device instead of in the IOMMU TLB and the device always sets translated
> bit for PASID. One example of those devices are AMD graphic devices that
> always have ACS or ATS/PRI enabled together with PASID.
>
> This adds a flag parameter in the pci_enable_pasid() helper, with which
> the device driver could opt-in the fact that device always sets the
> translated bit for PASID.
>
> It also applies this opt-in for AMD graphic devices. Without this change,
> kernel boots to black screen on a system with below AMD graphic device:
>
> 00:01.0 VGA compatible controller: Advanced Micro Devices, Inc.
> [AMD/ATI] Wani [Radeon R5/R6/R7 Graphics] (rev ca)
> (prog-if 00 [VGA controller])
> DeviceName: ATI EG BROADWAY
> Subsystem: Hewlett-Packard Company Device 8332
>
> At present, it is a common practice to enable/disable PCI PASID in the
> iommu drivers. Considering that the device driver knows more about the
> specific device, we will follow up by moving pci_enable_pasid() into
> the specific device drivers.
>
> Fixes: 201007ef707a ("PCI: Enable PASID only when ACS RR & UF enabled on upstream path")
> Reported-and-tested-by: Matt Fagnani <matt.fagnani@xxxxxxxx>
> Link: https://bugzilla.kernel.org/show_bug.cgi?id=216865
> Link: https://lore.kernel.org/r/15d0f9ff-2a56-b3e9-5b45-e6b23300ae3b@xxxxxxxxxxxxx/
> Suggested-by: Jason Gunthorpe <jgg@xxxxxxxxxx>
> Suggested-by: Christian König <christian.koenig@xxxxxxx>
> Reviewed-by: Kevin Tian <kevin.tian@xxxxxxxxx>
> Signed-off-by: Lu Baolu <baolu.lu@xxxxxxxxxxxxxxx>
> ---
> include/linux/pci-ats.h | 6 ++++--
> drivers/iommu/amd/iommu.c | 2 +-
> drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c | 2 +-
> drivers/iommu/intel/iommu.c | 3 ++-
> drivers/pci/ats.c | 8 ++++++--
> 5 files changed, 14 insertions(+), 7 deletions(-)
Reviewed-by: Jason Gunthorpe <jgg@xxxxxxxxxx>
Jason
