PCI: Restore PRI and PASID state after Function-Level Reset

After a Function-Level Reset, PCI states need to be restored.  Save PASID
features and PRI reqs cached.

[bhelgaas: search for capability only if PRI/PASID were enabled]
Signed-off-by: CQ Tang <cq.tang@intel.com>
Signed-off-by: Ashok Raj <ashok.raj@intel.com>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
Cc: Joerg Roedel <joro@8bytes.org>
Cc: Jean-Phillipe Brucker <jean-philippe.brucker@arm.com>
Cc: David Woodhouse <dwmw2@infradead.org>

drivers/pci/ats.c

@@ -160,17 +160,16 @@ int pci_enable_pri(struct pci_dev *pdev, u32 reqs)
 	if (!pos)
 		return -EINVAL;
 
-	pci_read_config_word(pdev, pos + PCI_PRI_CTRL, &control);
 	pci_read_config_word(pdev, pos + PCI_PRI_STATUS, &status);
-	if ((control & PCI_PRI_CTRL_ENABLE) ||
-	    !(status & PCI_PRI_STATUS_STOPPED))
+	if (!(status & PCI_PRI_STATUS_STOPPED))
 		return -EBUSY;
 
 	pci_read_config_dword(pdev, pos + PCI_PRI_MAX_REQ, &max_requests);
 	reqs = min(max_requests, reqs);
+	pdev->pri_reqs_alloc = reqs;
 	pci_write_config_dword(pdev, pos + PCI_PRI_ALLOC_REQ, reqs);
 
-	control |= PCI_PRI_CTRL_ENABLE;
+	control = PCI_PRI_CTRL_ENABLE;
 	pci_write_config_word(pdev, pos + PCI_PRI_CTRL, control);
 
 	pdev->pri_enabled = 1;
@@ -205,6 +204,28 @@ void pci_disable_pri(struct pci_dev *pdev)
 }
 EXPORT_SYMBOL_GPL(pci_disable_pri);
 
+/**
+ * pci_restore_pri_state - Restore PRI
+ * @pdev: PCI device structure
+ */
+void pci_restore_pri_state(struct pci_dev *pdev)
+{
+	u16 control = PCI_PRI_CTRL_ENABLE;
+	u32 reqs = pdev->pri_reqs_alloc;
+	int pos;
+
+	if (!pdev->pri_enabled)
+		return;
+
+	pos = pci_find_ext_capability(pdev, PCI_EXT_CAP_ID_PRI);
+	if (!pos)
+		return;
+
+	pci_write_config_dword(pdev, pos + PCI_PRI_ALLOC_REQ, reqs);
+	pci_write_config_word(pdev, pos + PCI_PRI_CTRL, control);
+}
+EXPORT_SYMBOL_GPL(pci_restore_pri_state);
+
 /**
  * pci_reset_pri - Resets device's PRI state
  * @pdev: PCI device structure
@@ -224,12 +245,7 @@ int pci_reset_pri(struct pci_dev *pdev)
 	if (!pos)
 		return -EINVAL;
 
-	pci_read_config_word(pdev, pos + PCI_PRI_CTRL, &control);
-	if (control & PCI_PRI_CTRL_ENABLE)
-		return -EBUSY;
-
-	control |= PCI_PRI_CTRL_RESET;
-
+	control = PCI_PRI_CTRL_RESET;
 	pci_write_config_word(pdev, pos + PCI_PRI_CTRL, control);
 
 	return 0;
@@ -259,12 +275,7 @@ int pci_enable_pasid(struct pci_dev *pdev, int features)
 	if (!pos)
 		return -EINVAL;
 
-	pci_read_config_word(pdev, pos + PCI_PASID_CTRL, &control);
 	pci_read_config_word(pdev, pos + PCI_PASID_CAP, &supported);
-
-	if (control & PCI_PASID_CTRL_ENABLE)
-		return -EINVAL;
-
 	supported &= PCI_PASID_CAP_EXEC | PCI_PASID_CAP_PRIV;
 
 	/* User wants to enable anything unsupported? */
@@ -272,6 +283,7 @@ int pci_enable_pasid(struct pci_dev *pdev, int features)
 		return -EINVAL;
 
 	control = PCI_PASID_CTRL_ENABLE | features;
+	pdev->pasid_features = features;
 
 	pci_write_config_word(pdev, pos + PCI_PASID_CTRL, control);
 
@@ -284,7 +296,6 @@ EXPORT_SYMBOL_GPL(pci_enable_pasid);
 /**
  * pci_disable_pasid - Disable the PASID capability
  * @pdev: PCI device structure
- *
  */
 void pci_disable_pasid(struct pci_dev *pdev)
 {
@@ -304,6 +315,27 @@ void pci_disable_pasid(struct pci_dev *pdev)
 }
 EXPORT_SYMBOL_GPL(pci_disable_pasid);
 
+/**
+ * pci_restore_pasid_state - Restore PASID capabilities
+ * @pdev: PCI device structure
+ */
+void pci_restore_pasid_state(struct pci_dev *pdev)
+{
+	u16 control;
+	int pos;
+
+	if (!pdev->pasid_enabled)
+		return;
+
+	pos = pci_find_ext_capability(pdev, PCI_EXT_CAP_ID_PASID);
+	if (!pos)
+		return;
+
+	control = PCI_PASID_CTRL_ENABLE | pdev->pasid_features;
+	pci_write_config_word(pdev, pos + PCI_PASID_CTRL, control);
+}
+EXPORT_SYMBOL_GPL(pci_restore_pasid_state);
+
 /**
  * pci_pasid_features - Check which PASID features are supported
  * @pdev: PCI device structure

drivers/pci/pci.c

@@ -28,6 +28,7 @@
 #include <linux/pm_runtime.h>
 #include <linux/pci_hotplug.h>
 #include <linux/vmalloc.h>
+#include <linux/pci-ats.h>
 #include <asm/setup.h>
 #include <asm/dma.h>
 #include <linux/aer.h>
@@ -1173,6 +1174,8 @@ void pci_restore_state(struct pci_dev *dev)
 
 	/* PCI Express register must be restored first */
 	pci_restore_pcie_state(dev);
+	pci_restore_pasid_state(dev);
+	pci_restore_pri_state(dev);
 	pci_restore_ats_state(dev);
 	pci_restore_vc_state(dev);
 

include/linux/pci-ats.h

@@ -7,6 +7,7 @@
 
 int pci_enable_pri(struct pci_dev *pdev, u32 reqs);
 void pci_disable_pri(struct pci_dev *pdev);
+void pci_restore_pri_state(struct pci_dev *pdev);
 int pci_reset_pri(struct pci_dev *pdev);
 
 #else /* CONFIG_PCI_PRI */
@@ -20,6 +21,10 @@ static inline void pci_disable_pri(struct pci_dev *pdev)
 {
 }
 
+static inline void pci_restore_pri_state(struct pci_dev *pdev)
+{
+}
+
 static inline int pci_reset_pri(struct pci_dev *pdev)
 {
 	return -ENODEV;
@@ -31,6 +36,7 @@ static inline int pci_reset_pri(struct pci_dev *pdev)
 
 int pci_enable_pasid(struct pci_dev *pdev, int features);
 void pci_disable_pasid(struct pci_dev *pdev);
+void pci_restore_pasid_state(struct pci_dev *pdev);
 int pci_pasid_features(struct pci_dev *pdev);
 int pci_max_pasids(struct pci_dev *pdev);
 
@@ -45,6 +51,10 @@ static inline void pci_disable_pasid(struct pci_dev *pdev)
 {
 }
 
+static inline void pci_restore_pasid_state(struct pci_dev *pdev)
+{
+}
+
 static inline int pci_pasid_features(struct pci_dev *pdev)
 {
 	return -EINVAL;

include/linux/pci.h

@@ -400,6 +400,12 @@ struct pci_dev {
 	u16		ats_cap;	/* ATS Capability offset */
 	u8		ats_stu;	/* ATS Smallest Translation Unit */
 	atomic_t	ats_ref_cnt;	/* number of VFs with ATS enabled */
+#endif
+#ifdef CONFIG_PCI_PRI
+	u32		pri_reqs_alloc; /* Number of PRI requests allocated */
+#endif
+#ifdef CONFIG_PCI_PASID
+	u16		pasid_features;
 #endif
 	phys_addr_t rom; /* Physical address of ROM if it's not from the BAR */
 	size_t romlen; /* Length of ROM if it's not from the BAR */