[vfio-users] IGD primary pci passthrough troubles - can anyone help?

[Paul Handy]

Thanks! I don't have to blacklist i915 now, and it behaves mostly the same
(with windows guest freaking out). One odd thing to note, all of the
addresses in my /proc/iomem are 000000000000-00000000000. I accidentally
had them load as actual values just a little while ago, but now I'm back to
all zeros. I think the forcefully-remove-bootfb module in my last message
may be the key I need in this case.

Paul

On Fri, Nov 11, 2016, 10:49 AM Alex Williamson <alex.williamson at redhat.com>
wrote:

> On Fri, 11 Nov 2016 10:34:48 -0700
> Alex Williamson <alex.williamson at redhat.com> wrote:
>
> > On Fri, 11 Nov 2016 10:06:58 -0700
> > Alex Williamson <alex.williamson at redhat.com> wrote:
> >
> > > On Fri, 11 Nov 2016 09:52:49 -0700
> > > Paul Handy <paul.d.handy at gmail.com> wrote:
> > > >
> > > > As others have reported, I've gotten this message despite best
> efforts:
> > > > Failed to mmap 0000:00:02.0 BAR 2. Performance may be slow
> > >
> > > Are there any clues in /proc/iomem as to what might be consuming
> > > resources on the device?
> >
> > D'oh, you provided that, BOOTFB... whatever that is.
>
> Ok, this is simplefb and that driver apparently doesn't care that
> you're trying to disable it with simplefb:off.  The approach I'd take
> would be to let i915 take the IGD device on boot, it's easier to deal
> with removing i915 and keeping it off the device than all these
> miscellaneous other driver grabbing it.  So remove the i915 blacklist,
> remove the IGD device from the vfio-pci ids list, then create an rc
> script (or even @reboot crontab entry) that does:
>
> echo "vfio-pci" > /sys/bus/pci/devices/0000:00:02.0/driver_override
>
> Your libvirt <hostdev> entry should also set managed='yes', which is
> the default.  The effect will be that the host boots with i915 claiming
> the device, when the VM is started libvirt will move it to vfio-pci,
> and when the VM is stopped, the driver_override will prevent i915 from
> reattaching to the device, which avoids the i915 driver issues on the
> host.  So it's basically a one-way path from i915 to vfio-pci.  The
> benefit is that unbinding i915 from the IGD should be clean and random
> other FB drivers won't be clinging to resources.  Thanks,
>
> Alex
>
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