PCI: Cache PRI and PASID bits in pci_dev

Device drivers need to check if an IOMMU enabled ATS, PRI and PASID in
order to know when they can use the SVM API.  Cache PRI and PASID bits in
the pci_dev structure, similarly to what is currently done for ATS.

Signed-off-by: Jean-Philippe Brucker <jean-philippe.brucker@arm.com>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>

drivers/pci/ats.c

@@ -153,6 +153,9 @@ int pci_enable_pri(struct pci_dev *pdev, u32 reqs)
 	u32 max_requests;
 	int pos;
 
+	if (WARN_ON(pdev->pri_enabled))
+		return -EBUSY;
+
 	pos = pci_find_ext_capability(pdev, PCI_EXT_CAP_ID_PRI);
 	if (!pos)
 		return -EINVAL;
@@ -170,6 +173,8 @@ int pci_enable_pri(struct pci_dev *pdev, u32 reqs)
 	control |= PCI_PRI_CTRL_ENABLE;
 	pci_write_config_word(pdev, pos + PCI_PRI_CTRL, control);
 
+	pdev->pri_enabled = 1;
+
 	return 0;
 }
 EXPORT_SYMBOL_GPL(pci_enable_pri);
@@ -185,13 +190,18 @@ void pci_disable_pri(struct pci_dev *pdev)
 	u16 control;
 	int pos;
 
+	if (WARN_ON(!pdev->pri_enabled))
+		return;
+
 	pos = pci_find_ext_capability(pdev, PCI_EXT_CAP_ID_PRI);
 	if (!pos)
 		return;
 
 	pci_read_config_word(pdev, pos + PCI_PRI_CTRL, &control);
 	control &= ~PCI_PRI_CTRL_ENABLE;
 	pci_write_config_word(pdev, pos + PCI_PRI_CTRL, control);
+
+	pdev->pri_enabled = 0;
 }
 EXPORT_SYMBOL_GPL(pci_disable_pri);
 
@@ -207,6 +217,9 @@ int pci_reset_pri(struct pci_dev *pdev)
 	u16 control;
 	int pos;
 
+	if (WARN_ON(pdev->pri_enabled))
+		return -EBUSY;
+
 	pos = pci_find_ext_capability(pdev, PCI_EXT_CAP_ID_PRI);
 	if (!pos)
 		return -EINVAL;
@@ -239,6 +252,9 @@ int pci_enable_pasid(struct pci_dev *pdev, int features)
 	u16 control, supported;
 	int pos;
 
+	if (WARN_ON(pdev->pasid_enabled))
+		return -EBUSY;
+
 	pos = pci_find_ext_capability(pdev, PCI_EXT_CAP_ID_PASID);
 	if (!pos)
 		return -EINVAL;
@@ -259,6 +275,8 @@ int pci_enable_pasid(struct pci_dev *pdev, int features)
 
 	pci_write_config_word(pdev, pos + PCI_PASID_CTRL, control);
 
+	pdev->pasid_enabled = 1;
+
 	return 0;
 }
 EXPORT_SYMBOL_GPL(pci_enable_pasid);
@@ -273,11 +291,16 @@ void pci_disable_pasid(struct pci_dev *pdev)
 	u16 control = 0;
 	int pos;
 
+	if (WARN_ON(!pdev->pasid_enabled))
+		return;
+
 	pos = pci_find_ext_capability(pdev, PCI_EXT_CAP_ID_PASID);
 	if (!pos)
 		return;
 
 	pci_write_config_word(pdev, pos + PCI_PASID_CTRL, control);
+
+	pdev->pasid_enabled = 0;
 }
 EXPORT_SYMBOL_GPL(pci_disable_pasid);
 

include/linux/pci.h

@@ -356,6 +356,8 @@ struct pci_dev {
 	unsigned int	msix_enabled:1;
 	unsigned int	ari_enabled:1;	/* ARI forwarding */
 	unsigned int	ats_enabled:1;	/* Address Translation Service */
+	unsigned int	pasid_enabled:1;	/* Process Address Space ID */
+	unsigned int	pri_enabled:1;		/* Page Request Interface */
 	unsigned int	is_managed:1;
 	unsigned int    needs_freset:1; /* Dev requires fundamental reset */
 	unsigned int	state_saved:1;