vfio/pci: Fix issues with qword access

[PATCH v2 0/2] vfio/pci: Fix issues with qword access

Posted by Kevin Tian 1 month, 3 weeks ago

Certain devices (e.g. Intel X710) don't support qword access to the
rom bar, otherwise PCI aer errors are observed. Fix it by disabling
the qword access to the rom bar.

While at it, also restrict accesses to the legacy VGA resource to
dword. More for paranoia so stable kernel is not CC-ed.

v2:
- Rebase to 6.19-rc1
- Use enum to avoid adding another bool arg (Alex)
- Elaborate the commit msg (Alex)
- New patch to disallow qword access to legacy VGA (Alex)

v1:
https://lore.kernel.org/all/20251212020941.338355-1-kevin.tian@intel.com/

Kevin Tian (2):
  vfio/pci: Disable qword access to the PCI ROM bar
  vfio/pci: Disable qword access to the VGA region

 drivers/vfio/pci/nvgrace-gpu/main.c |  4 ++--
 drivers/vfio/pci/vfio_pci_rdwr.c    | 25 ++++++++++++++++++-------
 include/linux/vfio_pci_core.h       | 10 +++++++++-
 3 files changed, 29 insertions(+), 10 deletions(-)

-- 
2.43.0

Re: [PATCH v2 0/2] vfio/pci: Fix issues with qword access

Posted by Alex Williamson 1 month, 2 weeks ago

On Thu, 18 Dec 2025 08:16:48 +0000
Kevin Tian <kevin.tian@intel.com> wrote:

> Certain devices (e.g. Intel X710) don't support qword access to the
> rom bar, otherwise PCI aer errors are observed. Fix it by disabling
> the qword access to the rom bar.
> 
> While at it, also restrict accesses to the legacy VGA resource to
> dword. More for paranoia so stable kernel is not CC-ed.
> 
> v2:
> - Rebase to 6.19-rc1
> - Use enum to avoid adding another bool arg (Alex)
> - Elaborate the commit msg (Alex)
> - New patch to disallow qword access to legacy VGA (Alex)
> 
> v1:
> https://lore.kernel.org/all/20251212020941.338355-1-kevin.tian@intel.com/
> 
> Kevin Tian (2):
>   vfio/pci: Disable qword access to the PCI ROM bar
>   vfio/pci: Disable qword access to the VGA region
> 
>  drivers/vfio/pci/nvgrace-gpu/main.c |  4 ++--
>  drivers/vfio/pci/vfio_pci_rdwr.c    | 25 ++++++++++++++++++-------
>  include/linux/vfio_pci_core.h       | 10 +++++++++-
>  3 files changed, 29 insertions(+), 10 deletions(-)
> 

Applied to vfio for-linus branch for v6.19.  Thanks,

Alex