PCI/ATS: Handle sharing of PF PASID Capability with all VFs

Per PCIe r5.0, sec 9.3.7.14, if a PF implements the PASID Capability, the
PF PASID configuration is shared by its VFs.  VFs must not implement their
own PASID Capability.  Since VFs don't have a PASID Capability,
pci_enable_pasid() always failed, which caused IOMMU setup to fail.

Update the PASID interfaces so for VFs they reflect the state of the PF
PASID.

[bhelgaas: rebase without pasid_cap caching, commit log]
Suggested-by: Ashok Raj <ashok.raj@intel.com>
Link: https://lore.kernel.org/r/8ba1ac192e4ac737508b6ac15002158e176bab91.1567029860.git.sathyanarayanan.kuppuswamy@linux.intel.com
Link: https://lore.kernel.org/r/20190905193146.90250-3-helgaas@kernel.org
Signed-off-by: Kuppuswamy Sathyanarayanan <sathyanarayanan.kuppuswamy@linux.intel.com>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
Cc: Ashok Raj <ashok.raj@intel.com>
Cc: Keith Busch <keith.busch@intel.com>

diff --git a/drivers/pci/ats.c b/drivers/pci/ats.c
index b0f68c0..fb5cfd2 100644 (file)
--- a/drivers/pci/ats.c
+++ b/drivers/pci/ats.c
@@ -346,6 +346,16 @@ int pci_enable_pasid(struct pci_dev *pdev, int features)
        u16 control, supported;
        int pos;
 
+       /*
+        * VFs must not implement the PASID Capability, but if a PF
+        * supports PASID, its VFs share the PF PASID configuration.
+        */
+       if (pdev->is_virtfn) {
+               if (pci_physfn(pdev)->pasid_enabled)
+                       return 0;
+               return -EINVAL;
+       }
+
        if (WARN_ON(pdev->pasid_enabled))
                return -EBUSY;
 
@@ -383,6 +393,10 @@ void pci_disable_pasid(struct pci_dev *pdev)
        u16 control = 0;
        int pos;
 
+       /* VFs share the PF PASID configuration */
+       if (pdev->is_virtfn)
+               return;
+
        if (WARN_ON(!pdev->pasid_enabled))
                return;
 
@@ -405,6 +419,9 @@ void pci_restore_pasid_state(struct pci_dev *pdev)
        u16 control;
        int pos;
 
+       if (pdev->is_virtfn)
+               return;
+
        if (!pdev->pasid_enabled)
                return;
 
@@ -432,6 +449,9 @@ int pci_pasid_features(struct pci_dev *pdev)
        u16 supported;
        int pos;
 
+       if (pdev->is_virtfn)
+               pdev = pci_physfn(pdev);
+
        pos = pci_find_ext_capability(pdev, PCI_EXT_CAP_ID_PASID);
        if (!pos)
                return -EINVAL;
@@ -458,6 +478,9 @@ int pci_max_pasids(struct pci_dev *pdev)
        u16 supported;
        int pos;
 
+       if (pdev->is_virtfn)
+               pdev = pci_physfn(pdev);
+
        pos = pci_find_ext_capability(pdev, PCI_EXT_CAP_ID_PASID);
        if (!pos)
                return -EINVAL;