Re: [PATCH v12 02/13] virtio-gpu: Handle virtio_gpu_virgl_init() failure

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

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

> virtio_gpu_virgl_init() may fail, leading to a further Qemu crash
> because Qemu assumes it never fails. Check virtio_gpu_virgl_init()
> return code and don't execute virtio commands on error. Failed
> virtio_gpu_virgl_init() will result in a timed out virtio commands
> for a guest OS.
>
> Signed-off-by: Dmitry Osipenko <dmitry.osipenko@collabora.com>
> ---
>  hw/display/virtio-gpu-gl.c     | 15 +++++++++++++--
>  hw/display/virtio-gpu-virgl.c  |  3 +++
>  include/hw/virtio/virtio-gpu.h |  1 +
>  3 files changed, 17 insertions(+), 2 deletions(-)
>
> diff --git a/hw/display/virtio-gpu-gl.c b/hw/display/virtio-gpu-gl.c
> index 0c0a8d136954..b353c3193afa 100644
> --- a/hw/display/virtio-gpu-gl.c
> +++ b/hw/display/virtio-gpu-gl.c
> @@ -29,9 +29,14 @@ static void virtio_gpu_gl_update_cursor_data(VirtIOGPU *g,
>                                               struct virtio_gpu_scanout *s,
>                                               uint32_t resource_id)
>  {
> +    VirtIOGPUGL *gl = VIRTIO_GPU_GL(g);
>      uint32_t width, height;
>      uint32_t pixels, *data;
>  
> +    if (!gl->renderer_inited) {
> +        return;
> +    }
> +
>      data = virgl_renderer_get_cursor_data(resource_id, &width, &height);
>      if (!data) {
>          return;
> @@ -60,13 +65,18 @@ static void virtio_gpu_gl_handle_ctrl(VirtIODevice *vdev, VirtQueue *vq)
>      VirtIOGPU *g = VIRTIO_GPU(vdev);
>      VirtIOGPUGL *gl = VIRTIO_GPU_GL(vdev);
>      struct virtio_gpu_ctrl_command *cmd;
> +    int ret;
>  
> -    if (!virtio_queue_ready(vq)) {
> +    if (!virtio_queue_ready(vq) || gl->renderer_init_failed) {
>          return;
>      }
>  
>      if (!gl->renderer_inited) {
> -        virtio_gpu_virgl_init(g);
> +        ret = virtio_gpu_virgl_init(g);
> +        if (ret) {
> +            gl->renderer_init_failed = true;
> +            return;
> +        }
>          gl->renderer_inited = true;
>      }
>      if (gl->renderer_reset) {
> @@ -101,6 +111,7 @@ static void virtio_gpu_gl_reset(VirtIODevice *vdev)
>      if (gl->renderer_inited && !gl->renderer_reset) {
>          virtio_gpu_virgl_reset_scanout(g);
>          gl->renderer_reset = true;
> +        gl->renderer_init_failed = false;
>      }
>  }
>  
> diff --git a/hw/display/virtio-gpu-virgl.c b/hw/display/virtio-gpu-virgl.c
> index 6ba4c24fda1d..bfbc6553e879 100644
> --- a/hw/display/virtio-gpu-virgl.c
> +++ b/hw/display/virtio-gpu-virgl.c
> @@ -668,6 +668,9 @@ int virtio_gpu_virgl_get_num_capsets(VirtIOGPU *g)
>  
>  void virtio_gpu_virgl_deinit(VirtIOGPU *g)
>  {
> +    if (virtio_gpu_stats_enabled(g->parent_obj.conf)) {
> +        timer_free(g->print_stats);
> +    }
>      timer_free(g->fence_poll);
>      virgl_renderer_cleanup(NULL);
>  }
> diff --git a/include/hw/virtio/virtio-gpu.h b/include/hw/virtio/virtio-gpu.h
> index 8ece1ec2e98b..236daba24dd2 100644
> --- a/include/hw/virtio/virtio-gpu.h
> +++ b/include/hw/virtio/virtio-gpu.h
> @@ -230,6 +230,7 @@ struct VirtIOGPUGL {
>  
>      bool renderer_inited;
>      bool renderer_reset;
> +    bool renderer_init_failed;

Do we really want 3 bools to represent a bunch of mutually incompatible
state? How about:

  typedef enum {
    /** starting state */
    RS_START = 0,
    /** renderer initialised */
    RS_INITED,
    /** renderer reset */
    RS_RESET,
    /** failed initialisation */
    RS_INIT_FAILED
  } RenderState;

then for example you could flow virtio_gpu_gl_handle_ctrl() as:

  switch (gl->render_state) {
  case RS_START:
  {
        gl->render_state = virtio_gpu_virgl_init(g) ? RS_INIT_FAILED : RS_INITED;  
  }
  case RS_RESET:
  {
        virtio_gpu_virgl_reset(g);
        gl->render_state = RS_INITED;
        break;
  }
  case RS_INIT_FAILED:
       /* nothing to do, return early and maybe log */
       return;
  case RS_INITED:
         /* just continue */
         break;
  }



>  };
>  
>  struct VhostUserGPU {

-- 
Alex Bennée
Virtualisation Tech Lead @ Linaro