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Subject[PATCH v2 5/7] amd_iommu: Make use of DMA quirks and ACS checks in IOMMU groups
Date
Work around broken devices and adhere to ACS support when determining
IOMMU grouping.

Signed-off-by: Alex Williamson <alex.williamson@redhat.com>
---
drivers/iommu/amd_iommu.c | 25 +++++++++++++++++++++++++
1 file changed, 25 insertions(+)
diff --git a/drivers/iommu/amd_iommu.c b/drivers/iommu/amd_iommu.c
index e072bd1..0e78d3c 100644
--- a/drivers/iommu/amd_iommu.c
+++ b/drivers/iommu/amd_iommu.c
@@ -254,6 +254,14 @@ static bool check_device(struct device *dev)
return true;
}

+static void swap_pci_ref(struct pci_dev **from, struct pci_dev *to)
+{
+ pci_dev_put(*from);
+ *from = to;
+}
+
+#define REQ_ACS_FLAGS (PCI_ACS_SV | PCI_ACS_RR | PCI_ACS_CR | PCI_ACS_UF)
+
static int iommu_init_device(struct device *dev)
{
struct pci_dev *dma_pdev, *pdev = to_pci_dev(dev);
@@ -286,6 +294,23 @@ static int iommu_init_device(struct device *dev)
} else
dma_pdev = pci_dev_get(pdev);

+ swap_pci_ref(&dma_pdev, pci_get_dma_source(dma_pdev));
+
+ if (dma_pdev->multifunction &&
+ !pci_acs_enabled(dma_pdev, REQ_ACS_FLAGS))
+ swap_pci_ref(&dma_pdev,
+ pci_get_slot(dma_pdev->bus,
+ PCI_DEVFN(PCI_SLOT(dma_pdev->devfn),
+ 0)));
+
+ while (!pci_is_root_bus(dma_pdev->bus)) {
+ if (pci_acs_path_enabled(dma_pdev->bus->self,
+ NULL, REQ_ACS_FLAGS))
+ break;
+
+ swap_pci_ref(&dma_pdev, pci_dev_get(dma_pdev->bus->self));
+ }
+
group = iommu_group_get(&dma_pdev->dev);
pci_dev_put(dma_pdev);
if (!group) {


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