x86/amd-iommu: Allow dev_data->alias to be NULL

Let dev_data->alias be just NULL if the device has no alias.
Signed-off-by: NJoerg Roedel <joerg.roedel@amd.com>

arch/x86/kernel/amd_iommu.c

@@ -183,12 +183,14 @@ static int iommu_init_device(struct device *dev)
 		return -ENOMEM;
 
 	alias = amd_iommu_alias_table[dev_data->devid];
-	pdev = pci_get_bus_and_slot(PCI_BUS(alias), alias & 0xff);
-	if (pdev)
-		dev_data->alias = &pdev->dev;
-	else {
-		free_dev_data(dev_data);
-		return -ENOTSUPP;
+	if (alias != dev_data->devid) {
+		pdev = pci_get_bus_and_slot(PCI_BUS(alias), alias & 0xff);
+		if (pdev)
+			dev_data->alias = &pdev->dev;
+		else {
+			free_dev_data(dev_data);
+			return -ENOTSUPP;
+		}
 	}
 
 	dev->archdata.iommu = dev_data;
@@ -1604,29 +1606,31 @@ static void do_detach(struct iommu_dev_data *dev_data)
 static int __attach_device(struct iommu_dev_data *dev_data,
 			   struct protection_domain *domain)
 {
-	struct iommu_dev_data *alias_data;
 	int ret;
 
-	alias_data = get_dev_data(dev_data->alias);
-
-	if (!alias_data)
-		return -EINVAL;
-
 	/* lock domain */
 	spin_lock(&domain->lock);
 
-	/* Some sanity checks */
-	ret = -EBUSY;
-	if (alias_data->domain != NULL &&
-	    alias_data->domain != domain)
-		goto out_unlock;
+	if (dev_data->alias != NULL) {
+		struct iommu_dev_data *alias_data;
+
+		alias_data = get_dev_data(dev_data->alias);
+
+		ret = -EINVAL;
+		if (!alias_data)
+			goto out_unlock;
 
-	if (dev_data->domain != NULL &&
-	    dev_data->domain != domain)
-		goto out_unlock;
+		/* Some sanity checks */
+		ret = -EBUSY;
+		if (alias_data->domain != NULL &&
+				alias_data->domain != domain)
+			goto out_unlock;
 
-	/* Do real assignment */
-	if (dev_data->devid != alias_data->devid) {
+		if (dev_data->domain != NULL &&
+				dev_data->domain != domain)
+			goto out_unlock;
+
+		/* Do real assignment */
 		if (alias_data->domain == NULL)
 			do_attach(alias_data, domain);
 
@@ -1696,8 +1700,8 @@ static void __detach_device(struct iommu_dev_data *dev_data)
 
 	spin_lock_irqsave(&domain->lock, flags);
 
-	alias_data = get_dev_data(dev_data->alias);
-	if (dev_data->devid != alias_data->devid) {
+	if (dev_data->alias) {
+		alias_data = get_dev_data(dev_data->alias);
 		if (atomic_dec_and_test(&alias_data->bind))
 			do_detach(alias_data);
 	}
@@ -1744,24 +1748,25 @@ static void detach_device(struct device *dev)
  */
 static struct protection_domain *domain_for_device(struct device *dev)
 {
-	struct protection_domain *dom;
 	struct iommu_dev_data *dev_data, *alias_data;
+	struct protection_domain *dom = NULL;
 	unsigned long flags;
 
 	dev_data   = get_dev_data(dev);
-	alias_data = get_dev_data(dev_data->alias);
-	if (!alias_data)
-		return NULL;
 
-	read_lock_irqsave(&amd_iommu_devtable_lock, flags);
-	dom = dev_data->domain;
-	if (dom == NULL &&
-	    alias_data->domain != NULL) {
-		__attach_device(dev_data, alias_data->domain);
-		dom = alias_data->domain;
-	}
+	if (dev_data->domain)
+		return dev_data->domain;
 
-	read_unlock_irqrestore(&amd_iommu_devtable_lock, flags);
+	if (dev_data->alias != NULL) {
+		alias_data = get_dev_data(dev_data->alias);
+
+		read_lock_irqsave(&amd_iommu_devtable_lock, flags);
+		if (alias_data->domain != NULL) {
+			__attach_device(dev_data, alias_data->domain);
+			dom = alias_data->domain;
+		}
+		read_unlock_irqrestore(&amd_iommu_devtable_lock, flags);
+	}
 
 	return dom;
 }