[Bug] virtio-gpu broken with qemu/kvm on arm64 on kernel 5.5+

[Guillaume Gardet]

> -----Original Message-----
> From: Gurchetan Singh <gurchetansingh at chromium.org>
> Sent: 22 February 2020 01:47
> To: Guillaume Gardet <Guillaume.Gardet at arm.com>
> Cc: dri-devel at lists.freedesktop.org; Gerd Hoffmann <kraxel at redhat.com>;
> Daniel Vetter <daniel.vetter at ffwll.ch>; Catalin Marinas
> <Catalin.Marinas at arm.com>; nd <nd at arm.com>; Chia-I Wu
> <olvaffe at gmail.com>
> Subject: Re: [Bug] virtio-gpu broken with qemu/kvm on arm64 on kernel 5.5+
> 
> On Fri, Feb 21, 2020 at 10:41 AM Chia-I Wu <olvaffe at gmail.com> wrote:
> >
> > On Fri, Feb 21, 2020 at 2:06 AM Guillaume Gardet
> > <Guillaume.Gardet at arm.com> wrote:
> > >
> > > Hi,
> > >
> > > > -----Original Message-----
> > > > From: Chia-I Wu <olvaffe at gmail.com>
> > > > Sent: 20 February 2020 19:41
> > > > To: Guillaume Gardet <Guillaume.Gardet at arm.com>
> > > > Cc: dri-devel at lists.freedesktop.org; Gerd Hoffmann
> > > > <kraxel at redhat.com>; Daniel Vetter <daniel.vetter at ffwll.ch>;
> > > > Catalin Marinas <Catalin.Marinas at arm.com>; nd <nd at arm.com>
> > > > Subject: Re: [Bug] virtio-gpu broken with qemu/kvm on arm64 on
> > > > kernel 5.5+
> > > >
> > > > On Thu, Feb 20, 2020 at 4:44 AM Guillaume Gardet
> > > > <Guillaume.Gardet at arm.com>
> > > > wrote:
> > > > >
> > > > > Hi,
> > > > >
> > > > > With (guest) kernel 5.5+ with qemu/kvm on arm64, I get lots of
> > > > > display
> > > > corruptions leading to this kind of screen:
> > > > > https://openqa.opensuse.org/tests/1174521#step/yast2_i/24
> > > > Looking at the screenshot, it seems cacheline-related?
> > >
> > > It could be.
> > >
> > > >
> > > > There was a change of memory type
> > > >
> > > >
> > > > https://lists.freedesktop.org/archives/dri-devel/2019-August/23345
> > > > 6.html
> > > >
> > > > While the guest memory type is ignored on Intel, it is honored on ARM.
> > > > This attempt to fix it
> > > >
> > > >
> > > > https://lists.freedesktop.org/archives/dri-devel/2019-December/248
> > > > 271.html
> > > >
> > > > does not seem to land.
> > >
> > > I applied this patch on top of 5.5.4, but it does not fix the problem.
> > > Maybe more similar changes are required?
> > The patch looks legit.  Maybe the memory type is not the root cause?
> 
> Perhaps try the entire series?
> 
> https://patchwork.kernel.org/cover/11300619/

Applied entire series on top of 5.5.6, but still the same problem.

Guillaume