[PATCH v2 2/5] drm/virtio: Add a helper to map and note the dma addrs and lengths

[Dmitry Osipenko]

On 10/29/24 09:18, Kasireddy, Vivek wrote:
>>>> BTW, is any DG2 GPU suitable for testing of this patchset? Will I be
>>>> able to test it using a regular consumer A750 card?
>>> Yes, you can test with any DG2 dGPU as long as you can passthrough it to
>> the
>>> Guest VM. And, if there is an iGPU available on the Host, you can use
>> GTK/SDL UI
>>> for local display or Spice UI for remote display if there is no iGPU on the
>> Host.
>>> This is exactly how I started testing this patch series but I am now
>> predominantly
>>> testing this series with SRIOV enabled iGPUs and dGPUs.
>> Was hoping to try out SR-IOV on A750 if it's even possible at all.
> AFAIK, SRIOV is not supported on any versions of DG2 including A750.

I'm having trouble with getting it to work.

My testing setup:

1. Passthroughed A750 that uses XE driver
2. RaptorLake iGPU on host used for virtio-gpu, uses i915 driver
3. QEMU latest master branch + your QEMU vfio_dmabuf_2 patches applied
on top
4. Latest linux-next kernel on host
5. Latest linux-next kernel on guest + this v2 applied

In guest I'm running this:

  seatd-launch -- weston --drm-device=card1 --additional-devices=card0

where card1 is A750 and card0 is virtio-gpu.

I added printk's and see that virtio-gpu imports A750 dma-buf and gets
XE's SGT, but nothing shows on the QEMU display. I tried both GTK and
SPICE displays. If I connect HDMI display to passthroughed A750 while
running weston command above, then I get weston working on the A750 HDMI
display and still nothing is shown on virtio-gpu display.

I also had to force virtio-gpu driver to always probe before XE,
otherwise virtio-gpu gets PCI read errors and fails to probe because it
fails to detect virtio features.

Am I doing anything wrong? Suggestions are welcome.

-- 
Best regards,
Dmitry