GPU passthrough support for Stoney [Radeon R2/R3/R4/R5 Graphics]?

[Micah Morton]

On Wed, May 15, 2019 at 7:19 PM Alex Deucher <alexdeucher at gmail.com> wrote:
>
> On Wed, May 15, 2019 at 2:26 PM Micah Morton <mortonm at chromium.org> wrote:
> >
> > Hi folks,
> >
> > I'm interested in running a VM on a system with an integrated Stoney
> > [Radeon R2/R3/R4/R5 Graphics] card and passing through the graphics
> > card to the VM using the IOMMU. I'm wondering whether this is feasible
> > and supposed to be doable with the right setup (as opposed to passing
> > a discrete GPU to the VM, which I think is definitely doable?).
> >
> > So far, I can do all the qemu/kvm/vfio/iommu stuff to run the VM and
> > pass the integrated GPU to it, but the drm driver in the VM fails
> > during amdgpu_device_init(). Specifically, the logs show the SMU being
> > unresponsive, which leads to a 'SMU firmware load failed' error
> > message and kernel panic. I can share VM logs and the invocation of
> > qemu and such if helpful, but first wanted to know at a high level if
> > this should be feasible?
> >
> > P.S.: I'm not initializing the GPU in the host bios or host kernel at
> > all, so I should be passing a fresh GPU to the VM. Also, I'm pretty
> > sure I'm running the correct VGA bios for this GPU in the guest VM
> > bios before guest boot.
> >
> > Any comments/suggestions would be appreciated!
>
> It should work in at least once as long as your vm is properly set up.

Is there any reason running coreboot vs UEFI at host boot would make a
difference? I was running a modified version of coreboot that avoids
doing any GPU initialization in firmware -- so the first POST happens
inside the guest.

> Note that the driver needs access to the vbios image in the guest to
> get device specific configuration details (clocks, display connector
> configuration, etc.).

Is there anything I need to do to ensure this besides passing '-device
vfio-pci,...,romfile=/path/to/vgarom' to qemu?

>
> Alex