iommu/amd: Split upstream bus device lookup

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

1 files changed, 15 insertions, 9 deletions

diff --git a/drivers/iommu/amd_iommu.c b/drivers/iommu/amd_iommu.c
index 6edbd0edcae7..3a00b5ce73ab 100644
--- a/drivers/iommu/amd_iommu.c
+++ b/drivers/iommu/amd_iommu.c
@@ -274,6 +274,18 @@ static void swap_pci_ref(struct pci_dev **from, struct pci_dev *to)
         *from = to;
 }
 
+static struct pci_bus *find_hosted_bus(struct pci_bus *bus)
+{
+        while (!bus->self) {
+                if (!pci_is_root_bus(bus))
+                        bus = bus->parent;
+                else
+                        return ERR_PTR(-ENODEV);
+        }
+
+        return bus;
+}
+
 #define REQ_ACS_FLAGS   (PCI_ACS_SV | PCI_ACS_RR | PCI_ACS_CR | PCI_ACS_UF)
 
 static struct pci_dev *get_isolation_root(struct pci_dev *pdev)
@@ -300,14 +312,9 @@ static struct pci_dev *get_isolation_root(struct pci_dev *pdev)
          * Finding the next device may require skipping virtual buses.
          */
         while (!pci_is_root_bus(dma_pdev->bus)) {
-                struct pci_bus *bus = dma_pdev->bus;
-
-                while (!bus->self) {
-                        if (!pci_is_root_bus(bus))
-                                bus = bus->parent;
-                        else
-                                goto root_bus;
-                }
+                struct pci_bus *bus = find_hosted_bus(dma_pdev->bus);
+                if (IS_ERR(bus))
+                        break;
 
                 if (pci_acs_path_enabled(bus->self, NULL, REQ_ACS_FLAGS))
                         break;
@@ -315,7 +322,6 @@ static struct pci_dev *get_isolation_root(struct pci_dev *pdev)
                 swap_pci_ref(&dma_pdev, pci_dev_get(bus->self));
         }
 
-root_bus:
         return dma_pdev;
 }