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Subject[PATCH 2/5] PCI/ATS: Handle sharing of PF PASID Capability with all VFs
Date
From: Kuppuswamy Sathyanarayanan <sathyanarayanan.kuppuswamy@linux.intel.com>

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
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>
---
drivers/pci/ats.c | 23 +++++++++++++++++++++++
1 file changed, 23 insertions(+)

diff --git a/drivers/pci/ats.c b/drivers/pci/ats.c
index 3b1c9a2305c1..ab928f8267cf 100644
--- a/drivers/pci/ats.c
+++ b/drivers/pci/ats.c
@@ -318,6 +318,16 @@ 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;

@@ -355,6 +365,10 @@ 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;

@@ -377,6 +391,9 @@ void pci_restore_pasid_state(struct pci_dev *pdev)
u16 control;
int pos;

+ if (pdev->is_virtfn)
+ return;
+
if (!pdev->pasid_enabled)
return;

@@ -404,6 +421,9 @@ 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;
@@ -463,6 +483,9 @@ 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;
--
2.23.0.187.g17f5b7556c-goog
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