diff options
| author |  Rajat Jain <rajatja@google.com>
| 2020-10-28 16:15:45 -0700 |
|---|---|---|
| committer |  Bjorn Helgaas <bhelgaas@google.com>
| 2020-10-30 16:26:51 -0500 |
| commit | 462b58fb033996e999cc213ed0b430d4f22a28fe (patch) | |
| tree | 9876a4987bf047d6ae97fdfd49212d5e533b8197 /drivers/pci/pci.c | |
| parent | Linux 5.10-rc1 (diff) | |
| download | linux-462b58fb033996e999cc213ed0b430d4f22a28fe.tar.gz linux-462b58fb033996e999cc213ed0b430d4f22a28fe.tar.bz2 linux-462b58fb033996e999cc213ed0b430d4f22a28fe.zip | |
PCI: Always enable ACS even if no ACS Capability
Some devices support ACS functionality even though they don't have a
spec-compliant ACS Capability; pci_enable_acs() has a quirk mechanism to
handle them.
We want to enable ACS whenever possible, but 52fbf5bdeeef ("PCI: Cache ACS
capability offset in device") inadvertently broke this by calling
pci_enable_acs() only if we find an ACS Capability.
This resulted in ACS not being enabled for these non-compliant devices,
which means devices can't be separated into different IOMMU groups, which
in turn means we may not be able to pass those devices through to VMs, as
reported by Boris V:
https://lore.kernel.org/r/74aeea93-8a46-5f5a-343c-790d4c655da3@bstnet.org
Fixes: 52fbf5bdeeef ("PCI: Cache ACS capability offset in device")
Link: https://lore.kernel.org/r/20201028231545.4116866-1-rajatja@google.com
Reported-by: Boris V <borisvk@bstnet.org>
Signed-off-by: Rajat Jain <rajatja@google.com>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
Reviewed-by: Alex Williamson <alex.williamson@redhat.com>
Diffstat (limited to 'drivers/pci/pci.c')
| -rw-r--r-- | drivers/pci/pci.c | 9 |
1 files changed, 7 insertions, 2 deletions
diff --git a/drivers/pci/pci.c b/drivers/pci/pci.c index 6d4d5a2f923d..e578d34095e9 100644 --- a/drivers/pci/pci.c +++ b/drivers/pci/pci.c @@ -3516,8 +3516,13 @@ void pci_acs_init(struct pci_dev *dev) { dev->acs_cap = pci_find_ext_capability(dev, PCI_EXT_CAP_ID_ACS); - if (dev->acs_cap) - pci_enable_acs(dev); + /* + * Attempt to enable ACS regardless of capability because some Root + * Ports (e.g. those quirked with *_intel_pch_acs_*) do not have + * the standard ACS capability but still support ACS via those + * quirks. + */ + pci_enable_acs(dev); } /** |