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

From: Eric Auger
Date: Thu May 16 2019 - 04:49:49 EST


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@xxxxxxxxxx>
---
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