Re: [PATCH v2 7/7] drm/virtio: implement userptr: add interval tree

[Huang, Honglei1]

On 2025/3/30 19:57, Dmitry Osipenko wrote:
> If the purpose of this feature is to dedup usrptr BOs of a the single
> process/application, can this can be done in userspace?
>
> On 3/21/25 11:00, Honglei Huang wrote:
> >   int virtio_gpu_userptr_create(struct virtio_gpu_device *vgdev,
> >   			      struct drm_file *file,
> >   			      struct virtio_gpu_object_params *params,
> > -			      struct virtio_gpu_object **bo_ptr)
> > +			      struct virtio_gpu_object **bo_ptr,
> > +			      struct drm_virtgpu_resource_create_blob *rc_blob)
> >   {
> > +	struct virtio_gpu_fpriv *vfpriv = file->driver_priv;
> >   	struct virtio_gpu_object_userptr *userptr;
> >   	int ret, si;
> >   	struct sg_table *sgt;
> > @@ -187,6 +290,20 @@ int virtio_gpu_userptr_create(struct virtio_gpu_device *vgdev,
> >   		       params->size))
> >   		return -EFAULT;
> >   
> > +	mutex_lock(&vfpriv->userptrs_tree_lock);
> > +
> > +	userptr = virtio_gpu_userptr_from_addr_range(
> > +		vfpriv, params->userptr, params->userptr + params->size - 1UL);
>
> Is it possible that userptr address will be same for two different
> processes?
>
> What if userptr->flags mismatch?

This situation need to be considered, I will add flag check, and add
handle the situation of increasing write permissions.

> > +	if (userptr) {
> > +		*bo_ptr = &userptr->base;
> > +		rc_blob->res_handle = userptr->base.hw_res_handle;
> > +		rc_blob->bo_handle = userptr->bo_handle;
>
> Doesn't BO refcount need to be bumped?

Will add Bo refcount in next version.

> > +		rc_blob->offset = virtio_gpu_userptr_get_offset(
> > +			&userptr->base, rc_blob->userptr);
> > +		mutex_unlock(&vfpriv->userptrs_tree_lock);
> > +		return STATE_RES_EXISTS;
>
> STATE_RES_EXISTS isn't a error code

Will use the system's built-in error code, really thanks for the review.

>