On 9/3/24 10:48, Jocelyn Falempe wrote:
> The host dumb buffer command needs a format, but the
> DRM_IOCTL_MODE_CREATE_DUMB only provides a buffer size.
> So wait for the DRM_IOCTL_MODE_ADDFB(2), to get the format, and create
> the host resources at this time.
>
> This will allow virtio-gpu to support multiple pixel formats.
>
> This problem was noticed in commit 42fd9e6c29b39 ("drm/virtio: fix
> DRM_FORMAT_* handling")
>
> Suggested-by: Gerd Hoffmann <kra...@redhat.com>
> Signed-off-by: Jocelyn Falempe <jfale...@redhat.com>
> ---
>
> v2:
> * Move virtio_gpu_object deferred field to its own block (Geerd Hoffmann)
> * Check that the size of the dumb buffer can hold the framebuffer (Geerd
> Hoffmann)
>
> drivers/gpu/drm/virtio/virtgpu_display.c | 33 ++++++++++++++++++++++++
> drivers/gpu/drm/virtio/virtgpu_drv.h | 5 ++++
> drivers/gpu/drm/virtio/virtgpu_gem.c | 1 -
> drivers/gpu/drm/virtio/virtgpu_object.c | 13 +++++++---
> 4 files changed, 47 insertions(+), 5 deletions(-)
>
> diff --git a/drivers/gpu/drm/virtio/virtgpu_display.c
> b/drivers/gpu/drm/virtio/virtgpu_display.c
> index 64baf2f22d9f0..5e8ca742c6d00 100644
> --- a/drivers/gpu/drm/virtio/virtgpu_display.c
> +++ b/drivers/gpu/drm/virtio/virtgpu_display.c
> @@ -290,6 +290,30 @@ static int vgdev_output_init(struct virtio_gpu_device
> *vgdev, int index)
> return 0;
> }
>
> +static int virtio_gpu_deferred_create(struct virtio_gpu_object *bo,
> + struct virtio_gpu_device *vgdev,
> + const struct drm_mode_fb_cmd2 *mode_cmd)
> +{
> + struct virtio_gpu_object_params params = { 0 };
> +
> + params.format = virtio_gpu_translate_format(mode_cmd->pixel_format);
> + params.dumb = true;
> + params.width = mode_cmd->width;
> + params.height = mode_cmd->height;
> + params.size = params.height * params.width * 4;
> + params.size = ALIGN(params.size, PAGE_SIZE);
> +
> + if (params.size > bo->base.base.size)
> + return -EINVAL;
> +
> + virtio_gpu_cmd_create_resource(vgdev, bo, ¶ms, NULL, NULL);
> + virtio_gpu_object_attach(vgdev, bo, bo->ents, bo->nents);
> +
> + bo->deferred = false;
> + bo->ents = NULL;
> + return 0;
> +}
> +
> static struct drm_framebuffer *
> virtio_gpu_user_framebuffer_create(struct drm_device *dev,
> struct drm_file *file_priv,
> @@ -297,6 +321,8 @@ virtio_gpu_user_framebuffer_create(struct drm_device *dev,
> {
> struct drm_gem_object *obj = NULL;
> struct virtio_gpu_framebuffer *virtio_gpu_fb;
> + struct virtio_gpu_device *vgdev = dev->dev_private;
> + struct virtio_gpu_object *bo;
> int ret;
>
> if (mode_cmd->pixel_format != DRM_FORMAT_HOST_XRGB8888 &&
> @@ -308,6 +334,13 @@ virtio_gpu_user_framebuffer_create(struct drm_device
> *dev,
> if (!obj)
> return ERR_PTR(-EINVAL);
>
> + bo = gem_to_virtio_gpu_obj(obj);
> + if (bo->deferred) {
> + ret = virtio_gpu_deferred_create(bo, vgdev, mode_cmd);
> + if (ret)
> + return ERR_PTR(ret);
> + }
> +
> virtio_gpu_fb = kzalloc(sizeof(*virtio_gpu_fb), GFP_KERNEL);
> if (virtio_gpu_fb == NULL) {
> drm_gem_object_put(obj);
> diff --git a/drivers/gpu/drm/virtio/virtgpu_drv.h
> b/drivers/gpu/drm/virtio/virtgpu_drv.h
> index 64c236169db88..4302933e5067c 100644
> --- a/drivers/gpu/drm/virtio/virtgpu_drv.h
> +++ b/drivers/gpu/drm/virtio/virtgpu_drv.h
> @@ -95,6 +95,11 @@ struct virtio_gpu_object {
> bool host3d_blob, guest_blob;
> uint32_t blob_mem, blob_flags;
>
> + /* For deferred dumb buffer creation */
> + bool deferred;
> + struct virtio_gpu_mem_entry *ents;
> + unsigned int nents;
> +
> int uuid_state;
> uuid_t uuid;
> };
> diff --git a/drivers/gpu/drm/virtio/virtgpu_gem.c
> b/drivers/gpu/drm/virtio/virtgpu_gem.c
> index 7db48d17ee3a8..33ad15fed30f6 100644
> --- a/drivers/gpu/drm/virtio/virtgpu_gem.c
> +++ b/drivers/gpu/drm/virtio/virtgpu_gem.c
> @@ -75,7 +75,6 @@ int virtio_gpu_mode_dumb_create(struct drm_file *file_priv,
> args->size = pitch * args->height;
> args->size = ALIGN(args->size, PAGE_SIZE);
>
> - params.format = virtio_gpu_translate_format(DRM_FORMAT_HOST_XRGB8888);
This will break the guest blob code path in virtio_gpu_object_create(),
AFAICT.
> params.width = args->width;
> params.height = args->height;
> params.size = args->size;
> diff --git a/drivers/gpu/drm/virtio/virtgpu_object.c
> b/drivers/gpu/drm/virtio/virtgpu_object.c
> index c7e74cf130221..b5a537a761294 100644
> --- a/drivers/gpu/drm/virtio/virtgpu_object.c
> +++ b/drivers/gpu/drm/virtio/virtgpu_object.c
> @@ -67,6 +67,8 @@ void virtio_gpu_cleanup_object(struct virtio_gpu_object *bo)
>
> virtio_gpu_resource_id_put(vgdev, bo->hw_res_handle);
> if (virtio_gpu_is_shmem(bo)) {
> + if (bo->deferred)
> + kvfree(bo->ents);
> drm_gem_shmem_free(&bo->base);
> } else if (virtio_gpu_is_vram(bo)) {
> struct virtio_gpu_object_vram *vram = to_virtio_gpu_vram(bo);
> @@ -228,10 +230,13 @@ int virtio_gpu_object_create(struct virtio_gpu_device
> *vgdev,
> virtio_gpu_cmd_resource_create_3d(vgdev, bo, params,
> objs, fence);
> virtio_gpu_object_attach(vgdev, bo, ents, nents);
> - } else {
> - virtio_gpu_cmd_create_resource(vgdev, bo, params,
> - objs, fence);
> - virtio_gpu_object_attach(vgdev, bo, ents, nents);
> + } else if (params->dumb) {
> + /* Create the host resource in
> virtio_gpu_user_framebuffer_create()
> + * because the pixel format is not specified yet
> + */
> + bo->ents = ents;
> + bo->nents = nents;
> + bo->deferred = true;
> }
AFAICS, the "params.dumb = true" should be set in
virtio_gpu_mode_dumb_create() and not in virtio_gpu_deferred_create().
Was this patch tested?
Overall, this deferred resource creation doesn't look robust. Could be
better to either add SET_SCANOUT2 with the format info or add cmd that
overrides the res fmt.
