On Tue, 2015-10-13 at 22:34 +0100, David Woodhouse wrote:
> If the device itself reports ATS in its PCIe capabilities, but the BIOS
> neglects to provide an ATSR structure to indicate that the root port can
> also cope, then assume the latter is lying.

Except, of course, that integrated devices aren't behind a root port. I
think this should fix it the correct way?

diff --git a/drivers/iommu/intel-iommu.c b/drivers/iommu/intel-iommu.c
index 4f2eab6..70a031d 100644
--- a/drivers/iommu/intel-iommu.c
+++ b/drivers/iommu/intel-iommu.c
@@ -4280,14 +4280,17 @@ int dmar_find_matched_atsr_unit(struct pci_dev *dev)
        dev = pci_physfn(dev);
        for (bus = dev->bus; bus; bus = bus->parent) {
                bridge = bus->self;
-               if (!bridge || !pci_is_pcie(bridge) ||
+               /* If it's an integrated device, allow ATS */
+               if (!bridge)
+                       return 1;
+               /* Connected via non-PCIe: no ATS */
+               if (!pci_is_pcie(bridge) ||
                    pci_pcie_type(bridge) == PCI_EXP_TYPE_PCI_BRIDGE)
                        return 0;
+               /* If we found the root port, look it up in the ATSR */
                if (pci_pcie_type(bridge) == PCI_EXP_TYPE_ROOT_PORT)
                        break;
        }
-       if (!bridge)
-               return 0;
 
        rcu_read_lock();
        list_for_each_entry_rcu(atsru, &dmar_atsr_units, list) {

-- 
David Woodhouse                            Open Source Technology Centre
david.woodho...@intel.com                              Intel Corporation

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