Re: [PATCH v5 0/8] Support virtio-gpu DRM native context

["Alex Bennée" <alex.bennee@linaro.org>]

Dmitry Osipenko <dmitry.osipenko@collabora.com> writes:

> This patchset adds DRM native context support to VirtIO-GPU on Qemu.
>
> Contarary to Virgl and Venus contexts that mediates high level GFX APIs,
> DRM native context [1] mediates lower level kernel driver UAPI, which
> reflects in a less CPU overhead and less/simpler code needed to support it.
> DRM context consists of a host and guest parts that have to be implemented
> for each GPU driver. On a guest side, DRM context presents a virtual GPU as
> a real/native host GPU device for GL/VK applications.
>
> [1] https://www.youtube.com/watch?v=9sFP_yddLLQ
>
> Today there are four known DRM native context drivers existing in a wild:
>
>   - Freedreno (Qualcomm SoC GPUs), completely upstreamed
>   - AMDGPU, mostly merged into upstreams

I tried my AMD system today with:

Host:
  Aarch64 AVA system
  Trixie
  virglrenderer @ v1.1.0/99557f5aa130930d11f04ffeb07f3a9aa5963182
  -display sdl,gl=on (gtk,gl=on also came up but handled window resizing
  poorly)
  
KVM Guest

  Aarch64
  Trixie
  mesa @ main/d27748a76f7dd9236bfcf9ef172dc13b8c0e170f
  -Dvulkan-drivers=virtio,amd -Dgallium-drivers=virgl,radeonsi -Damdgpu-virtio=true

However when I ran vulkan-info --summary KVM faulted with:

  debian-trixie login: error: kvm run failed Bad address
   PC=0000ffffb9aa1eb0 X00=0000ffffba0450a4 X01=0000aaaaf7f32400
  X02=000000000000013c X03=0000ffffba045098 X04=0000aaaaf7f3253c
  X05=0000ffffba0451d4 X06=00000000c0016900 X07=000000000000000e
  X08=0000000000000014 X09=00000000000000ff X10=0000aaaaf7f32500
  X11=0000aaaaf7e4d028 X12=0000aaaaf7edbcb0 X13=0000000000000001
  X14=000000000000000c X15=0000000000007718 X16=0000ffffb93601f0
  X17=0000ffffb9aa1dc0 X18=00000000000076f0 X19=0000aaaaf7f31330
  X20=0000aaaaf7f323f0 X21=0000aaaaf7f235e0 X22=000000000000004c
  X23=0000aaaaf7f2b5e0 X24=0000aaaaf7ee0cb0 X25=00000000000000ff
  X26=0000000000000076 X27=0000ffffcd2b18a8 X28=0000aaaaf7ee0cb0
  X29=0000ffffcd2b0bd0 X30=0000ffffb86c8b98  SP=0000ffffcd2b0bd0
  PSTATE=20001000 --C- EL0t
  QEMU 9.2.50 monitor - type 'help' for more information
  (qemu) quit

Which looks very much like the PFN locking failure. However booting up
with venus=on instead works. Could there be any differences in the way
device memory is mapped in the two cases?

>   - Intel (i915), merge requests are opened
>   - Asahi (Apple SoC GPUs), WIP status
>
<snip>

-- 
Alex Bennée
Virtualisation Tech Lead @ Linaro