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

["Huang, Honglei1" <Honglei1.Huang@amd.com>]

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.

>