On Thu, Mar 28, 2024 at 01:32:57AM -0700, Vivek Kasireddy wrote:
> By importing scanout buffers from other devices, we should be able
> to use the virtio-gpu driver in KMS only mode. Note that we attach
> dynamically and register a move_notify() callback so that we can
> let the VMM know of any location changes associated with the backing
> store of the imported object by sending detach_backing cmd.
>
> Cc: Gerd Hoffmann <kraxel@xxxxxxxxxx>
> Signed-off-by: Vivek Kasireddy <vivek.kasireddy@xxxxxxxxx>
> ---
> drivers/gpu/drm/virtio/virtgpu_prime.c | 54 +++++++++++++++++++++++++-
> 1 file changed, 53 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/gpu/drm/virtio/virtgpu_prime.c b/drivers/gpu/drm/virtio/virtgpu_prime.c
> index 1e87dbc9a897..c65dacc1b2b5 100644
> --- a/drivers/gpu/drm/virtio/virtgpu_prime.c
> +++ b/drivers/gpu/drm/virtio/virtgpu_prime.c
> @@ -255,10 +255,36 @@ static int virtgpu_dma_buf_init_obj(struct drm_device *dev,
> return ret;
> }
>
> +static const struct drm_gem_object_funcs virtgpu_gem_dma_buf_funcs = {
> + .free = virtgpu_dma_buf_free_obj,
> +};
> +
> +static void virtgpu_dma_buf_move_notify(struct dma_buf_attachment *attach)
> +{
> + struct drm_gem_object *obj = attach->importer_priv;
> + struct virtio_gpu_device *vgdev = obj->dev->dev_private;
> + struct virtio_gpu_object *bo = gem_to_virtio_gpu_obj(obj);
> +
> + if (bo->created) {
> + virtio_gpu_cmd_resource_detach_backing(vgdev,
> + bo->hw_res_handle);
> + bo->has_backing = false;
> + }
> +}
> +
> +static const struct dma_buf_attach_ops virtgpu_dma_buf_attach_ops = {
> + .allow_peer2peer = true,
> + .move_notify = virtgpu_dma_buf_move_notify
> +};
> +
> struct drm_gem_object *virtgpu_gem_prime_import(struct drm_device *dev,
> struct dma_buf *buf)
> {
> + struct virtio_gpu_device *vgdev = dev->dev_private;
> + struct dma_buf_attachment *attach;
> + struct virtio_gpu_object *bo;
> struct drm_gem_object *obj;
> + int ret;
>
> if (buf->ops == &virtgpu_dmabuf_ops.ops) {
> obj = buf->priv;
> @@ -272,7 +298,32 @@ struct drm_gem_object *virtgpu_gem_prime_import(struct drm_device *dev,
> }
> }
>
> - return drm_gem_prime_import(dev, buf);
I think overall this (entire series) makes sense, but needs someone with
overall virtio understanding to make sure it all fits correctly. Just a
refactor thought here: I think instead of open-coding should we have a
drm_gem_prime_dynamic_import?
Similar in another patch for the dma_buf_pin, should that be also in the
gem helpers to automatically forward to dma_buf if it's imported?
Cheers, Sima
> + if (!vgdev->has_resource_blob || vgdev->has_virgl_3d)
> + return drm_gem_prime_import(dev, buf);
> +
> + bo = kzalloc(sizeof(*bo), GFP_KERNEL);
> + if (!bo)
> + return ERR_PTR(-ENOMEM);
> +
> + obj = &bo->base.base;
> + obj->funcs = &virtgpu_gem_dma_buf_funcs;
> + drm_gem_private_object_init(dev, obj, buf->size);
> +
> + attach = dma_buf_dynamic_attach(buf, dev->dev,
> + &virtgpu_dma_buf_attach_ops, obj);
> + if (IS_ERR(attach)) {
> + kfree(bo);
> + return ERR_CAST(attach);
> + }
> +
> + obj->import_attach = attach;
> + get_dma_buf(buf);
> +
> + ret = virtgpu_dma_buf_init_obj(dev, bo, attach);
> + if (ret < 0)
> + return ERR_PTR(ret);
> +
> + return obj;
> }
>
> struct drm_gem_object *virtgpu_gem_prime_import_sg_table(
> @@ -281,3 +332,4 @@ struct drm_gem_object *virtgpu_gem_prime_import_sg_table(
> {
> return ERR_PTR(-ENODEV);
> }
> +
> --
> 2.43.0
>
--
Daniel Vetter
Software Engineer, Intel Corporation
http://blog.ffwll.ch
