[vfio-users] GPU passthrough errors with linux 5.1 and newer

[José Ramón Muñoz Pekkarinen]

On Sun, 21 Jul 2019 at 21:59, Zoltán Kővágó <dirty.ice.hu at gmail.com> wrote:
>
> Hi,
>
> Recently my previously perfectly working GPU passthrough setup (with a
> win8.1 x64 guest with OVMF) started to malfunction in various ways:
> screen randomly turned off for a few seconds, BSOD with
> VIDEO_TDR_FAILURE, 3d apps randomly crashing, not drawing the windows'
> content, and graphical glitches (for example in furmark the OSD text
> flickers).
>
> After fiddling around with various qemu versions, nvidia driver versions
> on the guest, I figured out that with a linux 5.0 kernel it works fine,
> but with 5.1 it randomly fails. I bisected it and it looks like the
> culprit is the commit 4e103134b862 "KVM: x86/mmu: Zap only the relevant
> pages when removing a memslot"[1]. I tried to revert in on top of 5.2.1
> but too many things changed in the meantime. Anyway, if I replace the
> body of kvm_mmu_invalidate_zap_pages_in_memslot with
> kvm_mmu_zap_all(kvm); it works again (probably with horrible performance
> degradation).
>
> Did anyone experience anything like this? I'm using Alex's ACS override
> patch, maybe it violates some assumption that the new code has?

    Hi,

    I noticed some changes that made 5.0 not working well when
detecting screen speakers through hdmi, but this I didn't see anytime.
My problem flew away with 5.1.15(the one I currently use), and no
other spread. I never needed the ACS override patch in my setup,
what happen if you try without it, does your groups comes wrong in
any ways?

    Best regards.

    José.