[PATCH v1 3/5] PCI/ATS: Fix PASID PF/VF dependency issues

[sathyanarayanan.kuppuswamy@linux.intel.com]

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

As per PCIe spec r4.0, sec 9.3.7.14 ("PASID"), all VFs associated
with PF can only use the PASID of the PF and not implement it.
So for any PASID capability related queries on a VF device use
associated PF device capabilities. Also disable PASID support on
a PF device only when all related VFs disable PASID.

Cc: Ashok Raj <ashok.raj@intel.com>
Cc: Keith Busch <keith.busch@intel.com>
Suggested-by: Ashok Raj <ashok.raj@intel.com>
Signed-off-by: Kuppuswamy Sathyanarayanan <sathyanarayanan.kuppuswamy@linux.intel.com>
---
 drivers/pci/ats.c   | 62 +++++++++++++++++++++++++++++++++++++++++++++
 include/linux/pci.h |  1 +
 2 files changed, 63 insertions(+)

diff --git a/drivers/pci/ats.c b/drivers/pci/ats.c
index 3fcef4544c4c..28bbf7dad425 100644
--- a/drivers/pci/ats.c
+++ b/drivers/pci/ats.c
@@ -314,6 +314,7 @@ int pci_enable_pasid(struct pci_dev *pdev, int features)
 {
 	u16 control, supported;
 	int pos;
+	struct pci_dev *pf;
 
 	if (WARN_ON(pdev->pasid_enabled))
 		return -EBUSY;
@@ -321,6 +322,29 @@ int pci_enable_pasid(struct pci_dev *pdev, int features)
 	if (!pdev->eetlp_prefix_path)
 		return -EINVAL;
 
+	/* If PASID capability is invalid, return error */
+	if (pdev->is_virtfn || pdev->is_physfn) {
+		if (pdev->invalid_cap & PCI_IOV_INVALID_PASID)
+			return -EINVAL;
+	}
+
+	if (pdev->is_virtfn) {
+		/* Since VF shares PASID with PF, use PF config */
+		pf = pci_physfn(pdev);
+
+		/* If VF config does not match with PF, return error */
+		if (!pf->pasid_enabled || pf->pasid_features != features)
+			return -EINVAL;
+
+		pdev->pasid_features = features;
+		pdev->pasid_enabled = 1;
+
+		/* Increment PF PASID refcount */
+		atomic_inc(&pf->pasid_ref_cnt);
+
+		return 0;
+	}
+
 	pos = pci_find_ext_capability(pdev, PCI_EXT_CAP_ID_PASID);
 	if (!pos)
 		return -EINVAL;
@@ -351,10 +375,27 @@ void pci_disable_pasid(struct pci_dev *pdev)
 {
 	u16 control = 0;
 	int pos;
+	struct pci_dev *pf;
 
 	if (WARN_ON(!pdev->pasid_enabled))
 		return;
 
+	/* All VFs PASID should be disabled before disabling PF PASID*/
+	if (atomic_read(&pdev->pasid_ref_cnt))
+		return;
+
+	if (pdev->is_virtfn) {
+		/* Since VF shares PASID with PF, use PF config. */
+		pf = pci_physfn(pdev);
+
+		/* Decrement PF PASID refcount */
+		atomic_dec(&pf->pasid_ref_cnt);
+
+		pdev->pasid_enabled = 0;
+
+		return;
+	}
+
 	pos = pci_find_ext_capability(pdev, PCI_EXT_CAP_ID_PASID);
 	if (!pos)
 		return;
@@ -377,6 +418,9 @@ void pci_restore_pasid_state(struct pci_dev *pdev)
 	if (!pdev->pasid_enabled)
 		return;
 
+	if (pdev->is_virtfn)
+		return;
+
 	pos = pci_find_ext_capability(pdev, PCI_EXT_CAP_ID_PASID);
 	if (!pos)
 		return;
@@ -401,6 +445,15 @@ int pci_pasid_features(struct pci_dev *pdev)
 	u16 supported;
 	int pos;
 
+	/* If PASID Cap is invalid then return error */
+	if (pdev->is_virtfn || pdev->is_physfn) {
+		if (pdev->invalid_cap & PCI_IOV_INVALID_PASID)
+			return -EINVAL;
+	}
+
+	if (pdev->is_virtfn)
+		pdev = pci_physfn(pdev);
+
 	pos = pci_find_ext_capability(pdev, PCI_EXT_CAP_ID_PASID);
 	if (!pos)
 		return -EINVAL;
@@ -427,6 +480,15 @@ int pci_max_pasids(struct pci_dev *pdev)
 	u16 supported;
 	int pos;
 
+	/* If PASID Cap is invalid then return error */
+	if (pdev->is_virtfn || pdev->is_physfn) {
+		if (pdev->invalid_cap & PCI_IOV_INVALID_PASID)
+			return -EINVAL;
+	}
+
+	if (pdev->is_virtfn)
+		pdev = pci_physfn(pdev);
+
 	pos = pci_find_ext_capability(pdev, PCI_EXT_CAP_ID_PASID);
 	if (!pos)
 		return -EINVAL;
diff --git a/include/linux/pci.h b/include/linux/pci.h
index d5df80ab2645..c6c413c52403 100644
--- a/include/linux/pci.h
+++ b/include/linux/pci.h
@@ -452,6 +452,7 @@ struct pci_dev {
 #endif
 #ifdef CONFIG_PCI_PASID
 	u16		pasid_features;
+	atomic_t	pasid_ref_cnt;	/* Number of VFs with PASID enabled */
 #endif
 #ifdef CONFIG_PCI_P2PDMA
 	struct pci_p2pdma *p2pdma;
-- 
2.20.1