[PATCH v2 06/13] iommu: Make use of DMA quirking and ACS enabledcheck for groups

[Alex Williamson]

Incorporate DMA quirking and ACS checking into amd_iommu and
intel-iommu.  Note that IOMMU groups are not yet used for
streaming DMA, so this doesn't immediately solve the problems
with broken Ricoh devices.  This a very strict implementation of
ACS checking, which will often result in multifunction devices
being grouped together.  This is actually a good thing as we
generally have no reason to trust isolation between functions,
but I won't be surprised if we later add a boot option to relax
this if a user wants to opt-in to a less secure grouping.

Signed-off-by: Alex Williamson <alex.williamson@xxxxxxxxxx>
---

 drivers/iommu/amd_iommu.c   |   18 ++++++++++++++++++
 drivers/iommu/intel-iommu.c |   18 ++++++++++++++++++
 2 files changed, 36 insertions(+), 0 deletions(-)

diff --git a/drivers/iommu/amd_iommu.c b/drivers/iommu/amd_iommu.c
index b7e5ddf..be72d6d 100644
--- a/drivers/iommu/amd_iommu.c
+++ b/drivers/iommu/amd_iommu.c
@@ -254,6 +254,8 @@ static bool check_device(struct device *dev)
 	return true;
 }
 
+#define PCI_ACS_ENABLED	(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);
@@ -291,6 +293,22 @@ static int iommu_init_device(struct device *dev)
 		dma_pdev = pci_get_slot(pdev->bus,
 					PCI_DEVFN(PCI_SLOT(pdev->devfn), 0));
 
+	dma_pdev = pci_dma_source(dma_pdev);
+
+	if (dma_pdev->multifunction &&
+	    !pci_acs_enabled(dma_pdev, PCI_ACS_ENABLED))
+		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, PCI_ACS_ENABLED))
+			break;
+
+		dma_pdev = dma_pdev->bus->self;
+	}
+
 	group = iommu_group_get(&dma_pdev->dev);
 	if (!group) {
 		group = iommu_group_alloc();
diff --git a/drivers/iommu/intel-iommu.c b/drivers/iommu/intel-iommu.c
index e63b33b..cf2a650 100644
--- a/drivers/iommu/intel-iommu.c
+++ b/drivers/iommu/intel-iommu.c
@@ -4087,6 +4087,8 @@ static int intel_iommu_domain_has_cap(struct iommu_domain *domain,
 	return 0;
 }
 
+#define PCI_ACS_ENABLED	(PCI_ACS_SV | PCI_ACS_RR | PCI_ACS_CR | PCI_ACS_UF)
+
 static int intel_iommu_add_device(struct device *dev)
 {
 	struct pci_dev *pdev = to_pci_dev(dev);
@@ -4113,6 +4115,22 @@ static int intel_iommu_add_device(struct device *dev)
 		dma_pdev = pci_get_slot(pdev->bus,
 					PCI_DEVFN(PCI_SLOT(pdev->devfn), 0));
 
+	dma_pdev = pci_dma_source(dma_pdev);
+
+	if (dma_pdev->multifunction &&
+	    !pci_acs_enabled(dma_pdev, PCI_ACS_ENABLED))
+		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, PCI_ACS_ENABLED))
+			break;
+
+		dma_pdev = dma_pdev->bus->self;
+	}
+
 	group = iommu_group_get(&dma_pdev->dev);
 	if (!group) {
 		group = iommu_group_alloc();

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