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

[Alex Williamson]

On Fri, 11 Nov 2016 20:24:56 +0000
Paul Handy <paul.d.handy at gmail.com> wrote:

> 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.

/proc/iomem reports zeros now unless you're root, use sudo.  It's a
security measure.  Thanks,

Alex

> 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
> >