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: Joerg Roedel <joerg.roedel@amd.com>

1 files changed, 41 insertions, 36 deletions

diff --git a/arch/x86/kernel/amd_iommu.c b/arch/x86/kernel/amd_iommu.c
index a15a1723190..2d914a49b19 100644
--- a/arch/x86/kernel/amd_iommu.c
+++ b/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;
 }