Re: Enabling RO on a VF
From: Jason Gunthorpe <jgg@ziepe.ca>
Date: 2021-10-01 11:55:00
Also in:
linux-pci, lkml
On Fri, Oct 01, 2021 at 11:05:15AM +0000, Haakon Bugge wrote:
Hey,
Commit 1477d44ce47d ("RDMA/mlx5: Enable Relaxed Ordering by default
for kernel ULPs") uses pcie_relaxed_ordering_enabled() to check if
RO can be enabled. This function checks if the Enable Relaxed
Ordering bit in the Device Control register is set. However, on a
VF, this bit is RsvdP (Reserved for future RW
implementations. Register bits are read-only and must return zero
when read. Software must preserve the value read for writes to
bits.).
Hence, AFAICT, RO will not be enabled when using a VF.
How can that be fixed?When qemu takes a VF and turns it into a PF in a VM it must emulate the RO bit and return one Jason