[PATCH] drm/vboxvideo: Vmap/vunmap cursor BO in prepare_fb and cleanup_fb
Thomas Zimmermann
tzimmermann at suse.de
Wed Feb 3 11:14:38 UTC 2021
Hi
Am 03.02.21 um 11:44 schrieb Daniel Vetter:
> 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 at suse.de>
>>>
>>> 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.
I have KASAN enabled and I might just have missed the error message. I
later saw the error with another driver after I already posted the vbox
and ast patches.
If you have the time, a look at the first half of the ast patchset might
still be worth it. It removes the cursor-code abstraction and shouldn't
be affected by the issue.
Best regards
Thomas
>
>>>
>>> Reviewed-by: Daniel Vetter <daniel.vetter at ffwll.ch>
>>
>> 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
>>
>
>
>
>
--
Thomas Zimmermann
Graphics Driver Developer
SUSE Software Solutions Germany GmbH
Maxfeldstr. 5, 90409 Nürnberg, Germany
(HRB 36809, AG Nürnberg)
Geschäftsführer: Felix Imendörffer
-------------- next part --------------
A non-text attachment was scrubbed...
Name: OpenPGP_signature
Type: application/pgp-signature
Size: 840 bytes
Desc: OpenPGP digital signature
URL: <https://lists.freedesktop.org/archives/dri-devel/attachments/20210203/cd7480ca/attachment.sig>
More information about the dri-devel
mailing list