iommu/vt-d: Introduce is_downstream_to_pci_bridge helper

Several call sites are about to check whether a device belongs
to the PCI sub-hierarchy of a candidate PCI-PCI bridge.
Introduce an helper to perform that check.

Signed-off-by: Eric Auger <eric.auger@redhat.com>
Reviewed-by: Lu Baolu <baolu.lu@linux.intel.com>
Signed-off-by: Joerg Roedel <jroedel@suse.de>

1 files changed, 29 insertions, 8 deletions

diff --git a/drivers/iommu/intel-iommu.c b/drivers/iommu/intel-iommu.c
index 082fbb1bdeaf..6747fec46cfb 100644
--- a/drivers/iommu/intel-iommu.c
+++ b/drivers/iommu/intel-iommu.c
@@ -729,12 +729,39 @@ static int iommu_dummy(struct device *dev)
         return dev->archdata.iommu == DUMMY_DEVICE_DOMAIN_INFO;
 }
 
+/**
+ * is_downstream_to_pci_bridge - test if a device belongs to the PCI
+ *                               sub-hierarchy of a candidate PCI-PCI bridge
+ * @dev: candidate PCI device belonging to @bridge PCI sub-hierarchy
+ * @bridge: the candidate PCI-PCI bridge
+ *
+ * Return: true if @dev belongs to @bridge PCI sub-hierarchy, else false.
+ */
+static bool
+is_downstream_to_pci_bridge(struct device *dev, struct device *bridge)
+{
+        struct pci_dev *pdev, *pbridge;
+
+        if (!dev_is_pci(dev) || !dev_is_pci(bridge))
+                return false;
+
+        pdev = to_pci_dev(dev);
+        pbridge = to_pci_dev(bridge);
+
+        if (pbridge->subordinate &&
+            pbridge->subordinate->number <= pdev->bus->number &&
+            pbridge->subordinate->busn_res.end >= pdev->bus->number)
+                return true;
+
+        return false;
+}
+
 static struct intel_iommu *device_to_iommu(struct device *dev, u8 *bus, u8 *devfn)
 {
         struct dmar_drhd_unit *drhd = NULL;
         struct intel_iommu *iommu;
         struct device *tmp;
-        struct pci_dev *ptmp, *pdev = NULL;
+        struct pci_dev *pdev = NULL;
         u16 segment = 0;
         int i;
 
@@ -780,13 +807,7 @@ static struct intel_iommu *device_to_iommu(struct device *dev, u8 *bus, u8 *devf
                                 goto out;
                         }
 
-                        if (!pdev || !dev_is_pci(tmp))
-                                continue;
-
-                        ptmp = to_pci_dev(tmp);
-                        if (ptmp->subordinate &&
-                            ptmp->subordinate->number <= pdev->bus->number &&
-                            ptmp->subordinate->busn_res.end >= pdev->bus->number)
+                        if (is_downstream_to_pci_bridge(dev, tmp))
                                 goto got_pdev;
                 }