iommu/vt-d: Add a helper to get svm and sdev for pasid

There are several places in the code that need to get the pointers of
svm and sdev according to a pasid and device. Add a helper to achieve
this for code consolidation and readability.

Signed-off-by: Lu Baolu <baolu.lu@linux.intel.com>
Reviewed-by: Kevin Tian <kevin.tian@intel.com>
Link: https://lore.kernel.org/r/20200724014925.15523-10-baolu.lu@linux.intel.com
Signed-off-by: Joerg Roedel <jroedel@suse.de>

drivers/iommu/intel/svm.c

@@ -228,13 +228,57 @@ static LIST_HEAD(global_svm_list);
 	list_for_each_entry((sdev), &(svm)->devs, list)	\
 		if ((d) != (sdev)->dev) {} else
 
+static int pasid_to_svm_sdev(struct device *dev, unsigned int pasid,
+			     struct intel_svm **rsvm,
+			     struct intel_svm_dev **rsdev)
+{
+	struct intel_svm_dev *d, *sdev = NULL;
+	struct intel_svm *svm;
+
+	/* The caller should hold the pasid_mutex lock */
+	if (WARN_ON(!mutex_is_locked(&pasid_mutex)))
+		return -EINVAL;
+
+	if (pasid == INVALID_IOASID || pasid >= PASID_MAX)
+		return -EINVAL;
+
+	svm = ioasid_find(NULL, pasid, NULL);
+	if (IS_ERR(svm))
+		return PTR_ERR(svm);
+
+	if (!svm)
+		goto out;
+
+	/*
+	 * If we found svm for the PASID, there must be at least one device
+	 * bond.
+	 */
+	if (WARN_ON(list_empty(&svm->devs)))
+		return -EINVAL;
+
+	rcu_read_lock();
+	list_for_each_entry_rcu(d, &svm->devs, list) {
+		if (d->dev == dev) {
+			sdev = d;
+			break;
+		}
+	}
+	rcu_read_unlock();
+
+out:
+	*rsvm = svm;
+	*rsdev = sdev;
+
+	return 0;
+}
+
 int intel_svm_bind_gpasid(struct iommu_domain *domain, struct device *dev,
 			  struct iommu_gpasid_bind_data *data)
 {
 	struct intel_iommu *iommu = device_to_iommu(dev, NULL, NULL);
+	struct intel_svm_dev *sdev = NULL;
 	struct dmar_domain *dmar_domain;
-	struct intel_svm_dev *sdev;
-	struct intel_svm *svm;
+	struct intel_svm *svm = NULL;
 	int ret = 0;
 
 	if (WARN_ON(!iommu) || !data)
@@ -261,35 +305,23 @@ int intel_svm_bind_gpasid(struct iommu_domain *domain, struct device *dev,
 	dmar_domain = to_dmar_domain(domain);
 
 	mutex_lock(&pasid_mutex);
-	svm = ioasid_find(NULL, data->hpasid, NULL);
-	if (IS_ERR(svm)) {
-		ret = PTR_ERR(svm);
+	ret = pasid_to_svm_sdev(dev, data->hpasid, &svm, &sdev);
+	if (ret)
 		goto out;
-	}
-
-	if (svm) {
-		/*
-		 * If we found svm for the PASID, there must be at
-		 * least one device bond, otherwise svm should be freed.
-		 */
-		if (WARN_ON(list_empty(&svm->devs))) {
-			ret = -EINVAL;
-			goto out;
-		}
 
+	if (sdev) {
 		/*
 		 * Do not allow multiple bindings of the same device-PASID since
 		 * there is only one SL page tables per PASID. We may revisit
 		 * once sharing PGD across domains are supported.
 		 */
-		for_each_svm_dev(sdev, svm, dev) {
-			dev_warn_ratelimited(dev,
-					     "Already bound with PASID %u\n",
-					     svm->pasid);
-			ret = -EBUSY;
-			goto out;
-		}
-	} else {
+		dev_warn_ratelimited(dev, "Already bound with PASID %u\n",
+				     svm->pasid);
+		ret = -EBUSY;
+		goto out;
+	}
+
+	if (!svm) {
 		/* We come here when PASID has never been bond to a device. */
 		svm = kzalloc(sizeof(*svm), GFP_KERNEL);
 		if (!svm) {
@@ -372,25 +404,17 @@ int intel_svm_unbind_gpasid(struct device *dev, int pasid)
 	struct intel_iommu *iommu = device_to_iommu(dev, NULL, NULL);
 	struct intel_svm_dev *sdev;
 	struct intel_svm *svm;
-	int ret = -EINVAL;
+	int ret;
 
 	if (WARN_ON(!iommu))
 		return -EINVAL;
 
 	mutex_lock(&pasid_mutex);
-	svm = ioasid_find(NULL, pasid, NULL);
-	if (!svm) {
-		ret = -EINVAL;
-		goto out;
-	}
-
-	if (IS_ERR(svm)) {
-		ret = PTR_ERR(svm);
+	ret = pasid_to_svm_sdev(dev, pasid, &svm, &sdev);
+	if (ret)
 		goto out;
-	}
 
-	for_each_svm_dev(sdev, svm, dev) {
-		ret = 0;
+	if (sdev) {
 		if (iommu_dev_feature_enabled(dev, IOMMU_DEV_FEAT_AUX))
 			sdev->users--;
 		if (!sdev->users) {
@@ -414,7 +438,6 @@ int intel_svm_unbind_gpasid(struct device *dev, int pasid)
 				kfree(svm);
 			}
 		}
-		break;
 	}
 out:
 	mutex_unlock(&pasid_mutex);
@@ -592,7 +615,7 @@ intel_svm_bind_mm(struct device *dev, int flags, struct svm_dev_ops *ops,
 	if (sd)
 		*sd = sdev;
 	ret = 0;
- out:
+out:
 	return ret;
 }
 
@@ -608,17 +631,11 @@ static int intel_svm_unbind_mm(struct device *dev, int pasid)
 	if (!iommu)
 		goto out;
 
-	svm = ioasid_find(NULL, pasid, NULL);
-	if (!svm)
-		goto out;
-
-	if (IS_ERR(svm)) {
-		ret = PTR_ERR(svm);
+	ret = pasid_to_svm_sdev(dev, pasid, &svm, &sdev);
+	if (ret)
 		goto out;
-	}
 
-	for_each_svm_dev(sdev, svm, dev) {
-		ret = 0;
+	if (sdev) {
 		sdev->users--;
 		if (!sdev->users) {
 			list_del_rcu(&sdev->list);
@@ -647,10 +664,8 @@ static int intel_svm_unbind_mm(struct device *dev, int pasid)
 				kfree(svm);
 			}
 		}
-		break;
 	}
- out:
-
+out:
 	return ret;
 }