From d14053b3c714178525f22660e6aaf41263d00056 Mon Sep 17 00:00:00 2001 From: David Woodhouse Date: Thu, 15 Oct 2015 09:28:06 +0100 Subject: [PATCH] iommu/vt-d: Fix ATSR handling for Root-Complex integrated endpoints MIME-Version: 1.0 Content-Type: text/plain; charset=utf8 Content-Transfer-Encoding: 8bit The VT-d specification says that "Software must enable ATS on endpoint devices behind a Root Port only if the Root Port is reported as supporting ATS transactions." We walk up the tree to find a Root Port, but for integrated devices we don't find one — we get to the host bridge. In that case we *should* allow ATS. Currently we don't, which means that we are incorrectly failing to use ATS for the integrated graphics. Fix that. We should never break out of this loop "naturally" with bus==NULL, since we'll always find bridge==NULL in that case (and now return 1). So remove the check for (!bridge) after the loop, since it can never happen. If it did, it would be worthy of a BUG_ON(!bridge). But since it'll oops anyway in that case, that'll do just as well. Cc: stable@vger.kernel.org Signed-off-by: David Woodhouse --- drivers/iommu/intel-iommu.c | 9 ++++++--- 1 file changed, 6 insertions(+), 3 deletions(-) diff --git a/drivers/iommu/intel-iommu.c b/drivers/iommu/intel-iommu.c index df53855a5f3e..17b4744628ab 100644 --- a/drivers/iommu/intel-iommu.c +++ b/drivers/iommu/intel-iommu.c @@ -4193,14 +4193,17 @@ 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) { -- 2.39.5