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UPSTREAM: PCI: Enable PASID only when ACS RR & UF enabled on upstream path

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The Requester ID/Process Address Space ID (PASID) combination
identifies an address space distinct from the PCI bus address space,
e.g., an address space defined by an IOMMU.

But the PCIe fabric routes Memory Requests based on the TLP address,
ignoring any PASID (PCIe r6.0, sec 2.2.10.4), so a TLP with PASID that
SHOULD go upstream to the IOMMU may instead be routed as a P2P
Request if its address falls in a bridge window.

To ensure that all Memory Requests with PASID are routed upstream,
only enable PASID if ACS P2P Request Redirect and Upstream Forwarding
are enabled for the path leading to the device.

Suggested-by: Jason Gunthorpe <jgg@nvidia.com>
Suggested-by: Kevin Tian <kevin.tian@intel.com>
Signed-off-by: Lu Baolu <baolu.lu@linux.intel.com>
Acked-by: Bjorn Helgaas <bhelgaas@google.com>
Reviewed-by: Jason Gunthorpe <jgg@nvidia.com>
Tested-by: Tony Zhu <tony.zhu@intel.com>
Link: https://lore.kernel.org/r/20221031005917.45690-5-baolu.lu@linux.intel.com
Signed-off-by: Joerg Roedel <jroedel@suse.de>

(cherry picked from commit 201007ef707a8bb5592cd07dd46fc9222c48e0b9)
Bug: 271394577
Change-Id: I302e3c26cd5d3a0122f4ef52a0191959aef574c0
Signed-off-by: Michael Shavit <mshavit@google.com>
This commit is contained in:
Lu Baolu 2022-10-31 08:59:08 +08:00 committed by Carlos Llamas
parent 36db10b1ad
commit db8a6a29f4
1 changed files with 3 additions and 0 deletions
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3
drivers/pci/ats.c
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@ -382,6 +382,9 @@ int pci_enable_pasid(struct pci_dev *pdev, int features)
if (!pasid)
return -EINVAL;
if (!pci_acs_path_enabled(pdev, NULL, PCI_ACS_RR | PCI_ACS_UF))
return -EINVAL;
pci_read_config_word(pdev, pasid + PCI_PASID_CAP, &supported);
supported &= PCI_PASID_CAP_EXEC | PCI_PASID_CAP_PRIV;