[PATCH 1/5] PCI/ATS: Handle sharing of PF PRI Capability with all VFs

[Bjorn Helgaas <helgaas@kernel.org>]

From: Kuppuswamy Sathyanarayanan <sathyanarayanan.kuppuswamy@linux.intel.com>

Per PCIe r5.0, sec 9.3.7.11, VFs must not implement the PRI Capability.  If
the PF implements PRI, it is shared by the VFs.  Since VFs don't have a PRI
Capability, pci_enable_pri() always failed, which caused IOMMU setup to
fail.

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

[bhelgaas: rebase without pri_cap caching, commit log]
Suggested-by: Ashok Raj <ashok.raj@intel.com>
Link: https://lore.kernel.org/r/b971e31f8695980da8e4a7f93e3b6a3edba3edaa.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 | 24 ++++++++++++++++++++++++
 1 file changed, 24 insertions(+)

diff --git a/drivers/pci/ats.c b/drivers/pci/ats.c
index e18499243f84..3b1c9a2305c1 100644
--- a/drivers/pci/ats.c
+++ b/drivers/pci/ats.c
@@ -182,6 +182,17 @@ int pci_enable_pri(struct pci_dev *pdev, u32 reqs)
 	u32 max_requests;
 	int pos;
 
+	/*
+	 * VFs must not implement the PRI Capability.  If their PF
+	 * implements PRI, it is shared by the VFs, so if the PF PRI is
+	 * enabled, it is also enabled for the VF.
+	 */
+	if (pdev->is_virtfn) {
+		if (pci_physfn(pdev)->pri_enabled)
+			return 0;
+		return -EINVAL;
+	}
+
 	if (WARN_ON(pdev->pri_enabled))
 		return -EBUSY;
 
@@ -218,6 +229,10 @@ void pci_disable_pri(struct pci_dev *pdev)
 	u16 control;
 	int pos;
 
+	/* VFs share the PF PRI */
+	if (pdev->is_virtfn)
+		return;
+
 	if (WARN_ON(!pdev->pri_enabled))
 		return;
 
@@ -243,6 +258,9 @@ void pci_restore_pri_state(struct pci_dev *pdev)
 	u32 reqs = pdev->pri_reqs_alloc;
 	int pos;
 
+	if (pdev->is_virtfn)
+		return;
+
 	if (!pdev->pri_enabled)
 		return;
 
@@ -267,6 +285,9 @@ int pci_reset_pri(struct pci_dev *pdev)
 	u16 control;
 	int pos;
 
+	if (pdev->is_virtfn)
+		return 0;
+
 	if (WARN_ON(pdev->pri_enabled))
 		return -EBUSY;
 
@@ -412,6 +433,9 @@ int pci_prg_resp_pasid_required(struct pci_dev *pdev)
 	u16 status;
 	int pos;
 
+	if (pdev->is_virtfn)
+		pdev = pci_physfn(pdev);
+
 	pos = pci_find_ext_capability(pdev, PCI_EXT_CAP_ID_PRI);
 	if (!pos)
 		return 0;
-- 
2.23.0.187.g17f5b7556c-goog