iommu/ipmmu-vmsa: Fix IOMMU lookup when multiple IOMMUs are registered

When adding a new device the driver loops over all registered IOMMUs and
calls the ipmmu_find_utlbs() function to parse the DT iommus attribute.
The function returns an error when the IOMMU referenced in DT doesn't
match the current IOMMU. The caller incorrectly breaks from the loop
immediately when the error is reported, resulting in only the first
IOMMU being considered.

Fix this, and while at it move code that isn't specific to an IOMMU
instance out of the loop.
Signed-off-by: Laurent Pinchart <laurent.pinchart+renesas@ideasonboard.com>
Signed-off-by: Joerg Roedel <jroedel@suse.de>

drivers/iommu/ipmmu-vmsa.c

@@ -573,45 +573,28 @@ static phys_addr_t ipmmu_iova_to_phys(struct iommu_domain *io_domain,
 }
 
 static int ipmmu_find_utlbs(struct ipmmu_vmsa_device *mmu, struct device *dev,
-			    unsigned int **_utlbs)
+			    unsigned int *utlbs, unsigned int num_utlbs)
 {
-	unsigned int *utlbs;
 	unsigned int i;
-	int count;
-
-	count = of_count_phandle_with_args(dev->of_node, "iommus",
-					   "#iommu-cells");
-	if (count < 0)
-		return -EINVAL;
-
-	utlbs = kcalloc(count, sizeof(*utlbs), GFP_KERNEL);
-	if (!utlbs)
-		return -ENOMEM;
 
-	for (i = 0; i < count; ++i) {
+	for (i = 0; i < num_utlbs; ++i) {
 		struct of_phandle_args args;
 		int ret;
 
 		ret = of_parse_phandle_with_args(dev->of_node, "iommus",
 						 "#iommu-cells", i, &args);
 		if (ret < 0)
-			goto error;
+			return ret;
 
 		of_node_put(args.np);
 
 		if (args.np != mmu->dev->of_node || args.args_count != 1)
-			goto error;
+			return -EINVAL;
 
 		utlbs[i] = args.args[0];
 	}
 
-	*_utlbs = utlbs;
-
-	return count;
-
-error:
-	kfree(utlbs);
-	return -EINVAL;
+	return 0;
 }
 
 static int ipmmu_add_device(struct device *dev)
@@ -619,10 +602,10 @@ static int ipmmu_add_device(struct device *dev)
 	struct ipmmu_vmsa_archdata *archdata;
 	struct ipmmu_vmsa_device *mmu;
 	struct iommu_group *group = NULL;
-	unsigned int *utlbs = NULL;
+	unsigned int *utlbs;
 	unsigned int i;
-	int num_utlbs = 0;
-	int ret;
+	int num_utlbs;
+	int ret = -ENODEV;
 
 	if (dev->archdata.iommu) {
 		dev_warn(dev, "IOMMU driver already assigned to device %s\n",
@@ -631,11 +614,21 @@ static int ipmmu_add_device(struct device *dev)
 	}
 
 	/* Find the master corresponding to the device. */
+
+	num_utlbs = of_count_phandle_with_args(dev->of_node, "iommus",
+					       "#iommu-cells");
+	if (num_utlbs < 0)
+		return -ENODEV;
+
+	utlbs = kcalloc(num_utlbs, sizeof(*utlbs), GFP_KERNEL);
+	if (!utlbs)
+		return -ENOMEM;
+
 	spin_lock(&ipmmu_devices_lock);
 
 	list_for_each_entry(mmu, &ipmmu_devices, list) {
-		num_utlbs = ipmmu_find_utlbs(mmu, dev, &utlbs);
-		if (num_utlbs) {
+		ret = ipmmu_find_utlbs(mmu, dev, utlbs, num_utlbs);
+		if (!ret) {
 			/*
 			 * TODO Take a reference to the MMU to protect
 			 * against device removal.
@@ -646,7 +639,7 @@ static int ipmmu_add_device(struct device *dev)
 
 	spin_unlock(&ipmmu_devices_lock);
 
-	if (num_utlbs <= 0)
+	if (ret < 0)
 		return -ENODEV;
 
 	for (i = 0; i < num_utlbs; ++i) {