openkylin
/
linux
mirror of https://gitee.com/openkylin/linux.git
9
0
Fork 0
Code Issues Projects Releases Wiki Activity

iommu/vt-d: Fix ATSR handling for Root-Complex integrated endpoints 

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 <David.Woodhouse@intel.com>
This commit is contained in:
David Woodhouse 2015-10-15 09:28:06 +01:00
parent 50d3fb5625
commit d14053b3c7
1 changed files with 6 additions and 3 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

9
drivers/iommu/intel-iommu.c
View File

@ -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) {