Re: [Qemu-devel] [PATCH] virtio-gpu: fix crashes upon warm reboot with vga mode

[Peter Maydell]

On 3 August 2018 at 16:32, Marc-André Lureau
<address@hidden> wrote:
> With vga=775 on the Linux command line a first boot of the VM running
> Linux works fine. After a warm reboot it crashes during Linux boot.
>
> Before that, valgrind points out bad memory write to console
> surface. The VGA code is not aware that virtio-gpu got a message
> surface scanout when the display is disabled. Let's reset VGA graphic
> mode when it is the case, so that a new display surface is created
> when doing further VGA operations.
>
> https://bugs.launchpad.net/qemu/+bug/1784900/
>
> Reported-by: Stefan Berger <address@hidden>
> Signed-off-by: Marc-André Lureau <address@hidden>
> ---
>  include/hw/virtio/virtio-gpu.h |  1 +
>  hw/display/virtio-gpu.c        |  5 +++++
>  hw/display/virtio-vga.c        | 11 +++++++++++
>  3 files changed, 17 insertions(+)
>
> diff --git a/include/hw/virtio/virtio-gpu.h b/include/hw/virtio/virtio-gpu.h
> index 9780f755ef..d0321672f4 100644
> --- a/include/hw/virtio/virtio-gpu.h
> +++ b/include/hw/virtio/virtio-gpu.h
> @@ -125,6 +125,7 @@ typedef struct VirtIOGPU {
>          uint32_t bytes_3d;
>      } stats;
>
> +    void (*disable_scanout)(struct VirtIOGPU *g, int scanout_id);
>      Error *migration_blocker;
>  } VirtIOGPU;

I guess for a last-minute 3.0 fix this is ok, but it looks
a bit weird to have a function pointer in a device instance
struct, which the user of the device has reached in and
set in order to modify the behaviour of the object...

thanks
-- PMM