amd_iommu: Make use of DMA quirks and ACS checks in IOMMU groups

Work around broken devices and adhere to ACS support when determining
IOMMU grouping.

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

diff --git a/drivers/iommu/amd_iommu.c b/drivers/iommu/amd_iommu.c
index 60ea920..4917239 100644 (file)
--- 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) {