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

[Ivan Volosyuk]

I encountered some acl problems as I cp'ed my system to a new disk, so I
re-compiled entire system, except for the kernel. After that I no longer
have the graphic glitches in win8.1 passthrough so far. So, sadly cannot
confirm or deny whether it had the same cause.

On Sun, Aug 4, 2019, 03:20 Zoltán Kővágó <dirty.ice.hu at gmail.com> wrote:

> I'm attaching the workaround I use with linux 5.2.1 and a w8.1 guest.
> I'm not saying you should use it, as it probably has a negative effect
> on performance (I never benchmarked it, but I didn't notice anything
> with older games) but at least you could confirm whether you have the
> same problem or not.
>
> Regards,
> Zoltan
>
> On 2019-08-03 13:35, Ivan Volosyuk wrote:
> > I just hit the problem on Windows 8.1 guest on kernel 5.2.5 (gentoo),
> tried
> > to upgrade from kernel 4.19.57.
> > It seems the problem doesn't happen if I use Windows 10 guest or kernel
> > 4.19.57.
> > There is graphics artifacts on my RTX-2080TI in W8.1 guest. I temporary
> > switched to older kernel. Any news about this? Any way to debug it?
> >
> >
> > On Thu, Aug 1, 2019 at 5:08 AM Zoltán Kővágó <dirty.ice.hu at gmail.com>
> wrote:
> >
> >> On 2019-07-31 15:41, José Ramón Muñoz Pekkarinen wrote:
> >>> 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.
> >>>
> >>
> >> Hi,
> >>
> >> Unfortunately without pcie_acs_override=downstream my iommu groups look
> >> like this (i.e. both video cards and their pci bridges are in one
> >> group), and I never had a problem with it in the last ~4.5 years.
> >>
> >> # ls /sys/kernel/iommu_groups/*/devices
> >> /sys/kernel/iommu_groups/0/devices:
> >> 0000:00:00.0
> >>
> >> /sys/kernel/iommu_groups/10/devices:
> >> 0000:00:1c.3
> >>
> >> /sys/kernel/iommu_groups/11/devices:
> >> 0000:00:1d.0
> >>
> >> /sys/kernel/iommu_groups/12/devices:
> >> 0000:00:1f.0  0000:00:1f.2  0000:00:1f.3
> >>
> >> /sys/kernel/iommu_groups/1/devices:
> >> 0000:00:01.0  0000:00:01.1  0000:01:00.0  0000:01:00.1  0000:02:00.0
> >> 0000:02:00.1
> >>
> >> /sys/kernel/iommu_groups/2/devices:
> >> 0000:00:02.0
> >>
> >> /sys/kernel/iommu_groups/3/devices:
> >> 0000:00:03.0
> >>
> >> /sys/kernel/iommu_groups/4/devices:
> >> 0000:00:14.0
> >>
> >> /sys/kernel/iommu_groups/5/devices:
> >> 0000:00:16.0
> >>
> >> /sys/kernel/iommu_groups/6/devices:
> >> 0000:00:19.0
> >>
> >> /sys/kernel/iommu_groups/7/devices:
> >> 0000:00:1a.0
> >>
> >> /sys/kernel/iommu_groups/8/devices:
> >> 0000:00:1b.0
> >>
> >> /sys/kernel/iommu_groups/9/devices:
> >> 0000:00:1c.0
> >>
> >> Regards,
> >> Zoltan
> >>
> >> _______________________________________________
> >> vfio-users mailing list
> >> vfio-users at redhat.com
> >> https://www.redhat.com/mailman/listinfo/vfio-users
> >>
> >
>
>
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