tree 90d4a57e6d63b5a55509a2ec417917568557acee
parent de5a4c816d312b137db36fe2e74b8fd486ca04df
author Alex Williamson <alex.williamson@redhat.com> 1506969549 -0600
committer Greg Kroah-Hartman <gregkh@linuxfoundation.org> 1514208225 +0100

vfio/pci: Virtualize Maximum Payload Size


[ Upstream commit 523184972b282cd9ca17a76f6ca4742394856818 ]

With virtual PCI-Express chipsets, we now see userspace/guest drivers
trying to match the physical MPS setting to a virtual downstream port.
Of course a lone physical device surrounded by virtual interconnects
cannot make a correct decision for a proper MPS setting.  Instead,
let's virtualize the MPS control register so that writes through to
hardware are disallowed.  Userspace drivers like QEMU assume they can
write anything to the device and we'll filter out anything dangerous.
Since mismatched MPS can lead to AER and other faults, let's add it
to the kernel side rather than relying on userspace virtualization to
handle it.

Signed-off-by: Alex Williamson <alex.williamson@redhat.com>
Reviewed-by: Eric Auger <eric.auger@redhat.com>
Signed-off-by: Sasha Levin <alexander.levin@verizon.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>