[Bug 88671] Radeon driver fails to reset hardware properly after kvm guest reboot

[bugzilla-daemon@bugzilla.kernel.org]

https://bugzilla.kernel.org/show_bug.cgi?id=88671

--- Comment #7 from Alex Williamson <alex.williamson@redhat.com> ---
(In reply to Tom Stellard from comment #6)
> I've been playing with this a little more and it seems to be working
> correctly,
> but radeon dynamic power management (dpm) always fails to initialize on the
> second guest boot.  My questions are:
> 
> 1. What methods are being used by kvm/qemu/libvirt to reset the GPU on guest
> shutdown?

Secondary PCI bus reset from the parent bridge.

> 2. Is the problem only cuased by the fact that GPU reset is not implemented
> correctly in the radeon driver of are there improvements that are needed in
> kvm/qemu/libvirt in order to get this working?

Without a device specific reset, we're doing to most thorough standard reset
available to us.  I've also tried to use some of the reset mechanisms
implemented in the radeon FOSS driver but they offered no improvement over the
bus reset.  There seems to be some state retained in the device that is not
cleared via bus reset.

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