[PATCH v2 3/7] iommu/vt-d: Introduce is_downstream_to_pci_bridge helper

[Eric Auger]

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.au...@redhat.com>
---
 drivers/iommu/intel-iommu.c | 37 +++++++++++++++++++++++++++++--------
 1 file changed, 29 insertions(+), 8 deletions(-)

diff --git a/drivers/iommu/intel-iommu.c b/drivers/iommu/intel-iommu.c
index 590a0e78d11d..15c2f9677491 100644
--- a/drivers/iommu/intel-iommu.c
+++ b/drivers/iommu/intel-iommu.c
@@ -736,12 +736,39 @@ 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
+ */
+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;
 
@@ -787,13 +814,7 @@ 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;
                }
 
-- 
2.20.1