[PATCH] drm/virtio: Support drm_panic with non-vmapped shmem BO

[Ryosuke Yasuoka]

On Wed, Apr 16, 2025 at 4:29 PM Dmitry Osipenko
<dmitry.osipenko at collabora.com> wrote:
>
> On 4/12/25 16:20, Ryosuke Yasuoka wrote:
> > Pass array of pages of the scanout buffer [1] to shmem BO, allowing
> > drm_panic to work even if the BO is not vmapped.
> >
> > [1] https://lore.kernel.org/all/20250407140138.162383-3-jfalempe@redhat.com/
> >
> > Signed-off-by: Jocelyn Falempe <jfalempe at redhat.com>
> > Signed-off-by: Ryosuke Yasuoka <ryasuoka at redhat.com>
> > ---
> >  drivers/gpu/drm/virtio/virtgpu_plane.c | 14 +++++++++++---
> >  1 file changed, 11 insertions(+), 3 deletions(-)
> >
> > diff --git a/drivers/gpu/drm/virtio/virtgpu_plane.c b/drivers/gpu/drm/virtio/virtgpu_plane.c
> > index a6f5a78f436a..2ff57d559c86 100644
> > --- a/drivers/gpu/drm/virtio/virtgpu_plane.c
> > +++ b/drivers/gpu/drm/virtio/virtgpu_plane.c
> > @@ -500,11 +500,19 @@ static int virtio_drm_get_scanout_buffer(struct drm_plane *plane,
> >
> >       bo = gem_to_virtio_gpu_obj(plane->state->fb->obj[0]);
> >
> > -     /* Only support mapped shmem bo */
> > -     if (virtio_gpu_is_vram(bo) || bo->base.base.import_attach || !bo->base.vaddr)
> > +     if (virtio_gpu_is_vram(bo) || bo->base.base.import_attach)
> >               return -ENODEV;
> >
> > -     iosys_map_set_vaddr(&sb->map[0], bo->base.vaddr);
> > +     if (bo->base.vaddr)
> > +             iosys_map_set_vaddr(&sb->map[0], bo->base.vaddr);
> > +     else {
> > +             struct drm_gem_shmem_object *shmem = &bo->base;
> > +
> > +             if (!shmem->pages)
> > +                     return -ENODEV;
> > +             /* map scanout buffer later */
> > +             sb->pages = shmem->pages;
> > +     }
> >
> >       sb->format = plane->state->fb->format;
> >       sb->height = plane->state->fb->height;
> >
> > base-commit: e7bb7d44c3b97aea1f0e354c6499900154ac67f2
>
> Rebased on top of [1], fixed checkpatch warning about braces and applied
> to misc-next. Thanks!
>
> [1] https://lore.kernel.org/all/20250414131507.566072-1-tzimmermann@suse.de/

Thomas,
Thank you for your comment.

Dmitry,
Thank you for fixing it and applying my patch.

> --
> Best regards,
> Dmitry
>

Best regards,
Ryosuke