iommu/amd: Split IOMMU group allocation and attach

Add a WARN_ON to make it clear why we don't add dma_pdev->dev to the
group we're allocating.

Signed-off-by: Alex Williamson <alex.williamson@redhat.com>
Signed-off-by: Joerg Roedel <joerg.roedel@amd.com>

1 files changed, 19 insertions, 11 deletions

diff --git a/drivers/iommu/amd_iommu.c b/drivers/iommu/amd_iommu.c
index 3a00b5ce73ab..7fa97a5e3eaf 100644
--- a/drivers/iommu/amd_iommu.c
+++ b/drivers/iommu/amd_iommu.c
@@ -325,6 +325,24 @@ static struct pci_dev *get_isolation_root(struct pci_dev *pdev)
         return dma_pdev;
 }
 
+static int use_pdev_iommu_group(struct pci_dev *pdev, struct device *dev)
+{
+        struct iommu_group *group = iommu_group_get(&pdev->dev);
+        int ret;
+
+        if (!group) {
+                group = iommu_group_alloc();
+                if (IS_ERR(group))
+                        return PTR_ERR(group);
+
+                WARN_ON(&pdev->dev != dev);
+        }
+
+        ret = iommu_group_add_device(group, dev);
+        iommu_group_put(group);
+        return ret;
+}
+
 static int init_iommu_group(struct device *dev)
 {
         struct iommu_dev_data *dev_data;
@@ -353,18 +371,8 @@ static int init_iommu_group(struct device *dev)
                 dma_pdev = pci_dev_get(to_pci_dev(dev));
 
         dma_pdev = get_isolation_root(dma_pdev);
-        group = iommu_group_get(&dma_pdev->dev);
+        ret = use_pdev_iommu_group(dma_pdev, dev);
         pci_dev_put(dma_pdev);
-        if (!group) {
-                group = iommu_group_alloc();
-                if (IS_ERR(group))
-                        return PTR_ERR(group);
-        }
-
-        ret = iommu_group_add_device(group, dev);
-
-        iommu_group_put(group);
-
         return ret;
 }