On Wed, Feb 03, 2021 at 11:34:21AM +0100, Thomas Zimmermann wrote:
> Hi
>
> Am 03.02.21 um 11:29 schrieb Daniel Vetter:
> > On Wed, Jan 27, 2021 at 03:05:03PM +0100, Thomas Zimmermann wrote:
> > > Functions in the atomic commit tail are not allowed to acquire the
> > > dmabuf's reservation lock. So we cannot legally call the GEM object's
> > > vmap functionality in atomic_update.
> > >
> > > Instead vmap the cursor BO in prepare_fb and vunmap it in cleanup_fb.
> > > The cursor plane state stores the mapping's address. The pinning of the
> > > BO is implicitly done by vmap.
> > >
> > > As an extra benefit, there's no source of runtime errors left in
> > > atomic_update.
> > >
> > > Signed-off-by: Thomas Zimmermann <tzimmermann@xxxxxxx>
> >
> > Did you test this with my dma_fence_signalling annotations patches?
>
> Not with vbox. I did test similar code in my recent ast patchset. But I
> think there's still a bug here, as there's no custom plane-reset function.
Do right, KASAN should complain when you load the driver because the first
state is a bit too small. But probably still within the kmalloc'ed block
by sheer luck. Worth confirming that KASAN can catch this.
> >
> > Reviewed-by: Daniel Vetter <daniel.vetter@xxxxxxxx>
>
> I'll certainly send out an updated patch.
I wonder whether it's worth to have a runtime check that when you
overwrite one, you have to overwrite all of them or it's clearly buggy?
-Daniel
>
> Best regards
> Thomas
>
> >
> > > ---
> > > drivers/gpu/drm/vboxvideo/vbox_mode.c | 102 +++++++++++++++++++++-----
> > > 1 file changed, 82 insertions(+), 20 deletions(-)
> > >
> > > diff --git a/drivers/gpu/drm/vboxvideo/vbox_mode.c b/drivers/gpu/drm/vboxvideo/vbox_mode.c
> > > index dbc0dd53c69e..b5625a7d6cef 100644
> > > --- a/drivers/gpu/drm/vboxvideo/vbox_mode.c
> > > +++ b/drivers/gpu/drm/vboxvideo/vbox_mode.c
> > > @@ -324,6 +324,19 @@ static void vbox_primary_atomic_disable(struct drm_plane *plane,
> > > old_state->src_y >> 16);
> > > }
> > > +struct vbox_cursor_plane_state {
> > > + struct drm_plane_state base;
> > > +
> > > + /* Transitional state - do not export or duplicate */
> > > +
> > > + struct dma_buf_map map;
> > > +};
> > > +
> > > +static struct vbox_cursor_plane_state *to_vbox_cursor_plane_state(struct drm_plane_state *state)
> > > +{
> > > + return container_of(state, struct vbox_cursor_plane_state, base);
> > > +}
> > > +
> > > static int vbox_cursor_atomic_check(struct drm_plane *plane,
> > > struct drm_plane_state *new_state)
> > > {
> > > @@ -381,14 +394,13 @@ static void vbox_cursor_atomic_update(struct drm_plane *plane,
> > > container_of(plane->dev, struct vbox_private, ddev);
> > > struct vbox_crtc *vbox_crtc = to_vbox_crtc(plane->state->crtc);
> > > struct drm_framebuffer *fb = plane->state->fb;
> > > - struct drm_gem_vram_object *gbo = drm_gem_vram_of_gem(fb->obj[0]);
> > > u32 width = plane->state->crtc_w;
> > > u32 height = plane->state->crtc_h;
> > > + struct vbox_cursor_plane_state *vbox_state = to_vbox_cursor_plane_state(plane->state);
> > > + struct dma_buf_map map = vbox_state->map;
> > > + u8 *src = map.vaddr; /* TODO: Use mapping abstraction properly */
> > > size_t data_size, mask_size;
> > > u32 flags;
> > > - struct dma_buf_map map;
> > > - int ret;
> > > - u8 *src;
> > > /*
> > > * VirtualBox uses the host windowing system to draw the cursor so
> > > @@ -401,17 +413,6 @@ static void vbox_cursor_atomic_update(struct drm_plane *plane,
> > > vbox_crtc->cursor_enabled = true;
> > > - ret = drm_gem_vram_vmap(gbo, &map);
> > > - if (ret) {
> > > - /*
> > > - * BUG: we should have pinned the BO in prepare_fb().
> > > - */
> > > - mutex_unlock(&vbox->hw_mutex);
> > > - DRM_WARN("Could not map cursor bo, skipping update\n");
> > > - return;
> > > - }
> > > - src = map.vaddr; /* TODO: Use mapping abstraction properly */
> > > -
> > > /*
> > > * The mask must be calculated based on the alpha
> > > * channel, one bit per ARGB word, and must be 32-bit
> > > @@ -421,7 +422,6 @@ static void vbox_cursor_atomic_update(struct drm_plane *plane,
> > > data_size = width * height * 4 + mask_size;
> > > copy_cursor_image(src, vbox->cursor_data, width, height, mask_size);
> > > - drm_gem_vram_vunmap(gbo, &map);
> > > flags = VBOX_MOUSE_POINTER_VISIBLE | VBOX_MOUSE_POINTER_SHAPE |
> > > VBOX_MOUSE_POINTER_ALPHA;
> > > @@ -458,6 +458,43 @@ static void vbox_cursor_atomic_disable(struct drm_plane *plane,
> > > mutex_unlock(&vbox->hw_mutex);
> > > }
> > > +static int vbox_cursor_prepare_fb(struct drm_plane *plane, struct drm_plane_state *new_state)
> > > +{
> > > + struct vbox_cursor_plane_state *new_vbox_state = to_vbox_cursor_plane_state(new_state);
> > > + struct drm_framebuffer *fb = new_state->fb;
> > > + struct drm_gem_vram_object *gbo;
> > > + struct dma_buf_map map;
> > > + int ret;
> > > +
> > > + if (!fb)
> > > + return 0;
> > > +
> > > + gbo = drm_gem_vram_of_gem(fb->obj[0]);
> > > +
> > > + ret = drm_gem_vram_vmap(gbo, &map);
> > > + if (ret)
> > > + return ret;
> > > +
> > > + new_vbox_state->map = map;
> > > +
> > > + return 0;
> > > +}
> > > +
> > > +static void vbox_cursor_cleanup_fb(struct drm_plane *plane, struct drm_plane_state *old_state)
> > > +{
> > > + struct vbox_cursor_plane_state *old_vbox_state = to_vbox_cursor_plane_state(old_state);
> > > + struct drm_framebuffer *fb = old_state->fb;
> > > + struct dma_buf_map map = old_vbox_state->map;
> > > + struct drm_gem_vram_object *gbo;
> > > +
> > > + if (!fb)
> > > + return;
> > > +
> > > + gbo = drm_gem_vram_of_gem(fb->obj[0]);
> > > +
> > > + drm_gem_vram_vunmap(gbo, &map);
> > > +}
> > > +
> > > static const u32 vbox_cursor_plane_formats[] = {
> > > DRM_FORMAT_ARGB8888,
> > > };
> > > @@ -466,17 +503,42 @@ static const struct drm_plane_helper_funcs vbox_cursor_helper_funcs = {
> > > .atomic_check = vbox_cursor_atomic_check,
> > > .atomic_update = vbox_cursor_atomic_update,
> > > .atomic_disable = vbox_cursor_atomic_disable,
> > > - .prepare_fb = drm_gem_vram_plane_helper_prepare_fb,
> > > - .cleanup_fb = drm_gem_vram_plane_helper_cleanup_fb,
> > > + .prepare_fb = vbox_cursor_prepare_fb,
> > > + .cleanup_fb = vbox_cursor_cleanup_fb,
> > > };
> > > +static struct drm_plane_state *vbox_cursor_atomic_duplicate_state(struct drm_plane *plane)
> > > +{
> > > + struct vbox_cursor_plane_state *new_vbox_state;
> > > + struct drm_device *dev = plane->dev;
> > > +
> > > + if (drm_WARN_ON(dev, !plane->state))
> > > + return NULL;
> > > +
> > > + new_vbox_state = kzalloc(sizeof(*new_vbox_state), GFP_KERNEL);
> > > + if (!new_vbox_state)
> > > + return NULL;
> > > + __drm_atomic_helper_plane_duplicate_state(plane, &new_vbox_state->base);
> > > +
> > > + return &new_vbox_state->base;
> > > +}
> > > +
> > > +static void vbox_cursor_atomic_destroy_state(struct drm_plane *plane,
> > > + struct drm_plane_state *state)
> > > +{
> > > + struct vbox_cursor_plane_state *vbox_state = to_vbox_cursor_plane_state(state);
> > > +
> > > + __drm_atomic_helper_plane_destroy_state(&vbox_state->base);
> > > + kfree(vbox_state);
> > > +}
> > > +
> > > static const struct drm_plane_funcs vbox_cursor_plane_funcs = {
> > > .update_plane = drm_atomic_helper_update_plane,
> > > .disable_plane = drm_atomic_helper_disable_plane,
> > > .destroy = drm_primary_helper_destroy,
> > > .reset = drm_atomic_helper_plane_reset,
> > > - .atomic_duplicate_state = drm_atomic_helper_plane_duplicate_state,
> > > - .atomic_destroy_state = drm_atomic_helper_plane_destroy_state,
> > > + .atomic_duplicate_state = vbox_cursor_atomic_duplicate_state,
> > > + .atomic_destroy_state = vbox_cursor_atomic_destroy_state,
> > > };
> > > static const u32 vbox_primary_plane_formats[] = {
> > >
> > > base-commit: 3836b7fdfad40e2bac5dc882332f42bed6942cf4
> > > prerequisite-patch-id: c2b2f08f0eccc9f5df0c0da49fa1d36267deb11d
> > > --
> > > 2.30.0
> > >
> >
>
> --
> Thomas Zimmermann
> Graphics Driver Developer
> SUSE Software Solutions Germany GmbH
> Maxfeldstr. 5, 90409 Nürnberg, Germany
> (HRB 36809, AG Nürnberg)
> Geschäftsführer: Felix Imendörffer
>
--
Daniel Vetter
Software Engineer, Intel Corporation
http://blog.ffwll.ch
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