[PATCH v4 01/12] dmaengine: idxd: Separate user and kernel pasid enabling

[Lu Baolu <baolu.lu@linux.intel.com>]

From: Dave Jiang <dave.jiang@intel.com>

The idxd driver always gated the pasid enabling under a single knob and
this assumption is incorrect. The pasid used for kernel operation can be
independently toggled and has no dependency on the user pasid (and vice
versa). Split the two so they are independent "enabled" flags.

Signed-off-by: Dave Jiang <dave.jiang@intel.com>
Signed-off-by: Jacob Pan <jacob.jun.pan@linux.intel.com>
Link: https://lore.kernel.org/linux-iommu/20220315050713.2000518-10-jacob.jun.pan@linux.intel.com/
Signed-off-by: Lu Baolu <baolu.lu@linux.intel.com>
---
 drivers/dma/idxd/idxd.h |  6 ++++++
 drivers/dma/idxd/cdev.c |  4 ++--
 drivers/dma/idxd/init.c | 30 ++++++++++++++++++------------
 3 files changed, 26 insertions(+), 14 deletions(-)

diff --git a/drivers/dma/idxd/idxd.h b/drivers/dma/idxd/idxd.h
index da72eb15f610..ccbefd0be617 100644
--- a/drivers/dma/idxd/idxd.h
+++ b/drivers/dma/idxd/idxd.h
@@ -239,6 +239,7 @@ enum idxd_device_flag {
 	IDXD_FLAG_CONFIGURABLE = 0,
 	IDXD_FLAG_CMD_RUNNING,
 	IDXD_FLAG_PASID_ENABLED,
+	IDXD_FLAG_USER_PASID_ENABLED,
 };
 
 struct idxd_dma_dev {
@@ -469,6 +470,11 @@ static inline bool device_pasid_enabled(struct idxd_device *idxd)
 	return test_bit(IDXD_FLAG_PASID_ENABLED, &idxd->flags);
 }
 
+static inline bool device_user_pasid_enabled(struct idxd_device *idxd)
+{
+	return test_bit(IDXD_FLAG_USER_PASID_ENABLED, &idxd->flags);
+}
+
 static inline bool device_swq_supported(struct idxd_device *idxd)
 {
 	return (support_enqcmd && device_pasid_enabled(idxd));
diff --git a/drivers/dma/idxd/cdev.c b/drivers/dma/idxd/cdev.c
index b9b2b4a4124e..7df996deffbe 100644
--- a/drivers/dma/idxd/cdev.c
+++ b/drivers/dma/idxd/cdev.c
@@ -99,7 +99,7 @@ static int idxd_cdev_open(struct inode *inode, struct file *filp)
 	ctx->wq = wq;
 	filp->private_data = ctx;
 
-	if (device_pasid_enabled(idxd)) {
+	if (device_user_pasid_enabled(idxd)) {
 		sva = iommu_sva_bind_device(dev, current->mm, NULL);
 		if (IS_ERR(sva)) {
 			rc = PTR_ERR(sva);
@@ -152,7 +152,7 @@ static int idxd_cdev_release(struct inode *node, struct file *filep)
 	if (wq_shared(wq)) {
 		idxd_device_drain_pasid(idxd, ctx->pasid);
 	} else {
-		if (device_pasid_enabled(idxd)) {
+		if (device_user_pasid_enabled(idxd)) {
 			/* The wq disable in the disable pasid function will drain the wq */
 			rc = idxd_wq_disable_pasid(wq);
 			if (rc < 0)
diff --git a/drivers/dma/idxd/init.c b/drivers/dma/idxd/init.c
index 993a5dcca24f..e1b5d1e4a949 100644
--- a/drivers/dma/idxd/init.c
+++ b/drivers/dma/idxd/init.c
@@ -513,16 +513,19 @@ static int idxd_probe(struct idxd_device *idxd)
 
 	if (IS_ENABLED(CONFIG_INTEL_IDXD_SVM) && sva) {
 		rc = iommu_dev_enable_feature(dev, IOMMU_DEV_FEAT_SVA);
-		if (rc == 0) {
-			rc = idxd_enable_system_pasid(idxd);
-			if (rc < 0) {
-				iommu_dev_disable_feature(dev, IOMMU_DEV_FEAT_SVA);
-				dev_warn(dev, "Failed to enable PASID. No SVA support: %d\n", rc);
-			} else {
-				set_bit(IDXD_FLAG_PASID_ENABLED, &idxd->flags);
-			}
-		} else {
+		if (rc) {
+			/*
+			 * Do not bail here since legacy DMA is still
+			 * supported, both user and in-kernel DMA with
+			 * PASID rely on SVA feature.
+			 */
 			dev_warn(dev, "Unable to turn on SVA feature.\n");
+		} else {
+			set_bit(IDXD_FLAG_USER_PASID_ENABLED, &idxd->flags);
+			if (idxd_enable_system_pasid(idxd))
+				dev_warn(dev, "No in-kernel DMA with PASID.\n");
+			else
+				set_bit(IDXD_FLAG_PASID_ENABLED, &idxd->flags);
 		}
 	} else if (!sva) {
 		dev_warn(dev, "User forced SVA off via module param.\n");
@@ -561,7 +564,8 @@ static int idxd_probe(struct idxd_device *idxd)
  err:
 	if (device_pasid_enabled(idxd))
 		idxd_disable_system_pasid(idxd);
-	iommu_dev_disable_feature(dev, IOMMU_DEV_FEAT_SVA);
+	if (device_user_pasid_enabled(idxd) || device_pasid_enabled(idxd))
+		iommu_dev_disable_feature(dev, IOMMU_DEV_FEAT_SVA);
 	return rc;
 }
 
@@ -574,7 +578,8 @@ static void idxd_cleanup(struct idxd_device *idxd)
 	idxd_cleanup_internals(idxd);
 	if (device_pasid_enabled(idxd))
 		idxd_disable_system_pasid(idxd);
-	iommu_dev_disable_feature(dev, IOMMU_DEV_FEAT_SVA);
+	if (device_user_pasid_enabled(idxd) || device_pasid_enabled(idxd))
+		iommu_dev_disable_feature(dev, IOMMU_DEV_FEAT_SVA);
 }
 
 static int idxd_pci_probe(struct pci_dev *pdev, const struct pci_device_id *id)
@@ -691,7 +696,8 @@ static void idxd_remove(struct pci_dev *pdev)
 	free_irq(irq_entry->vector, irq_entry);
 	pci_free_irq_vectors(pdev);
 	pci_iounmap(pdev, idxd->reg_base);
-	iommu_dev_disable_feature(&pdev->dev, IOMMU_DEV_FEAT_SVA);
+	if (device_user_pasid_enabled(idxd) || device_pasid_enabled(idxd))
+		iommu_dev_disable_feature(&pdev->dev, IOMMU_DEV_FEAT_SVA);
 	pci_disable_device(pdev);
 	destroy_workqueue(idxd->wq);
 	perfmon_pmu_remove(idxd);
-- 
2.25.1

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