[PATCH v3 3/7] PCI/ATS: Initialize PASID in pci_ats_init()

[sathyanarayanan.kuppuswamy@linux.intel.com]

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

Currently, PASID Capability checks are repeated across all PASID API's.
Instead, cache the capability check result in pci_pasid_init() and use
it in other PASID API's. Also, since PASID is a shared resource between
PF/VF, initialize PASID features with default values in pci_pasid_init().

Signed-off-by: Kuppuswamy Sathyanarayanan <sathyanarayanan.kuppuswamy@linux.intel.com>
---
 drivers/pci/ats.c   | 76 ++++++++++++++++++++++++++++++++-------------
 include/linux/pci.h |  1 +
 2 files changed, 56 insertions(+), 21 deletions(-)

diff --git a/drivers/pci/ats.c b/drivers/pci/ats.c
index a14ab20f1c28..b5ce40c54e0b 100644
--- a/drivers/pci/ats.c
+++ b/drivers/pci/ats.c
@@ -50,6 +50,41 @@ static void pci_pri_init(struct pci_dev *pdev)
 }
 #endif
 
+#ifdef CONFIG_PCI_PASID
+static void pci_pasid_init(struct pci_dev *pdev)
+{
+	u16 supported;
+	int pos;
+
+	/*
+	 * As per PCIe r4.0, sec 9.3.7.14, only PF is permitted to
+	 * implement PASID Capability and all associated VFs can
+	 * only use it. Since PF already initialized the PASID
+	 * parameters there is no need to proceed further.
+	 */
+	if (pdev->is_virtfn)
+		return;
+
+	pos = pci_find_ext_capability(pdev, PCI_EXT_CAP_ID_PASID);
+	if (!pos)
+		return;
+
+	pci_read_config_word(pdev, pos + PCI_PASID_CAP, &supported);
+
+	supported &= PCI_PASID_CAP_EXEC | PCI_PASID_CAP_PRIV;
+
+	/*
+	 * Enable all supported features. Since PASID is a shared
+	 * resource between PF/VF, we must not set this feature as
+	 * a per device property in pci_enable_pasid().
+	 */
+	pci_write_config_word(pdev, pos + PCI_PASID_CTRL, supported);
+
+	pdev->pasid_features = supported;
+	pdev->pasid_cap = pos;
+}
+#endif
+
 void pci_ats_init(struct pci_dev *dev)
 {
 	int pos;
@@ -66,6 +101,9 @@ void pci_ats_init(struct pci_dev *dev)
 #ifdef CONFIG_PCI_PRI
 	pci_pri_init(dev);
 #endif
+#ifdef CONFIG_PCI_PASID
+	pci_pasid_init(dev);
+#endif
 }
 
 /**
@@ -326,11 +364,13 @@ EXPORT_SYMBOL_GPL(pci_reset_pri);
  * Returns 0 on success, negative value on error. This function checks
  * whether the features are actually supported by the device and returns
  * an error if not.
+ *
+ * TODO: Since PASID is a shared resource between PF/VF, don't update
+ * PASID features in the same API as a per device feature.
  */
 int pci_enable_pasid(struct pci_dev *pdev, int features)
 {
 	u16 control, supported;
-	int pos;
 
 	if (WARN_ON(pdev->pasid_enabled))
 		return -EBUSY;
@@ -338,11 +378,11 @@ int pci_enable_pasid(struct pci_dev *pdev, int features)
 	if (!pdev->eetlp_prefix_path)
 		return -EINVAL;
 
-	pos = pci_find_ext_capability(pdev, PCI_EXT_CAP_ID_PASID);
-	if (!pos)
+	if (!pdev->pasid_cap)
 		return -EINVAL;
 
-	pci_read_config_word(pdev, pos + PCI_PASID_CAP, &supported);
+	pci_read_config_word(pdev, pdev->pasid_cap + PCI_PASID_CAP,
+			     &supported);
 	supported &= PCI_PASID_CAP_EXEC | PCI_PASID_CAP_PRIV;
 
 	/* User wants to enable anything unsupported? */
@@ -352,7 +392,7 @@ int pci_enable_pasid(struct pci_dev *pdev, int features)
 	control = PCI_PASID_CTRL_ENABLE | features;
 	pdev->pasid_features = features;
 
-	pci_write_config_word(pdev, pos + PCI_PASID_CTRL, control);
+	pci_write_config_word(pdev, pdev->pasid_cap + PCI_PASID_CTRL, control);
 
 	pdev->pasid_enabled = 1;
 
@@ -367,16 +407,14 @@ EXPORT_SYMBOL_GPL(pci_enable_pasid);
 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)
+	if (!pdev->pasid_cap)
 		return;
 
-	pci_write_config_word(pdev, pos + PCI_PASID_CTRL, control);
+	pci_write_config_word(pdev, pdev->pasid_cap + PCI_PASID_CTRL, control);
 
 	pdev->pasid_enabled = 0;
 }
@@ -389,17 +427,15 @@ EXPORT_SYMBOL_GPL(pci_disable_pasid);
 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)
+	if (!pdev->pasid_cap)
 		return;
 
 	control = PCI_PASID_CTRL_ENABLE | pdev->pasid_features;
-	pci_write_config_word(pdev, pos + PCI_PASID_CTRL, control);
+	pci_write_config_word(pdev, pdev->pasid_cap + PCI_PASID_CTRL, control);
 }
 EXPORT_SYMBOL_GPL(pci_restore_pasid_state);
 
@@ -416,13 +452,12 @@ EXPORT_SYMBOL_GPL(pci_restore_pasid_state);
 int pci_pasid_features(struct pci_dev *pdev)
 {
 	u16 supported;
-	int pos;
 
-	pos = pci_find_ext_capability(pdev, PCI_EXT_CAP_ID_PASID);
-	if (!pos)
+	if (!pdev->pasid_cap)
 		return -EINVAL;
 
-	pci_read_config_word(pdev, pos + PCI_PASID_CAP, &supported);
+	pci_read_config_word(pdev, pdev->pasid_cap + PCI_PASID_CAP,
+			     &supported);
 
 	supported &= PCI_PASID_CAP_EXEC | PCI_PASID_CAP_PRIV;
 
@@ -472,13 +507,12 @@ EXPORT_SYMBOL_GPL(pci_prg_resp_pasid_required);
 int pci_max_pasids(struct pci_dev *pdev)
 {
 	u16 supported;
-	int pos;
 
-	pos = pci_find_ext_capability(pdev, PCI_EXT_CAP_ID_PASID);
-	if (!pos)
+	if (!pdev->pasid_cap)
 		return -EINVAL;
 
-	pci_read_config_word(pdev, pos + PCI_PASID_CAP, &supported);
+	pci_read_config_word(pdev, pdev->pasid_cap + PCI_PASID_CAP,
+			     &supported);
 
 	supported = (supported & PASID_NUMBER_MASK) >> PASID_NUMBER_SHIFT;
 
diff --git a/include/linux/pci.h b/include/linux/pci.h
index f3fe625bc8bb..b4010276dff6 100644
--- a/include/linux/pci.h
+++ b/include/linux/pci.h
@@ -456,6 +456,7 @@ struct pci_dev {
 	u32		pri_reqs_alloc; /* Number of PRI requests allocated */
 #endif
 #ifdef CONFIG_PCI_PASID
+	u16		pasid_cap;	/* PASID Capability offset */
 	u16		pasid_features;
 #endif
 #ifdef CONFIG_PCI_P2PDMA
-- 
2.21.0