[PATCH 1/6] drm/amdgpu: Generalize KFD dmabuf import

[Chen, Xiaogang]

On 1/11/2023 7:31 PM, Felix Kuehling wrote:
> Use proper amdgpu_gem_prime_import function to handle all kinds of
> imports. Remember the dmabuf reference to enable proper multi-GPU
> attachment to multiple VMs without erroneously re-exporting the
> underlying BO multiple times.
>
> Signed-off-by: Felix Kuehling <Felix.Kuehling at amd.com>
> ---
>   .../gpu/drm/amd/amdgpu/amdgpu_amdkfd_gpuvm.c  | 38 ++++++++++---------
>   1 file changed, 21 insertions(+), 17 deletions(-)
>
> diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_amdkfd_gpuvm.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_amdkfd_gpuvm.c
> index 6f236ded5f12..e13c3493b786 100644
> --- a/drivers/gpu/drm/amd/amdgpu/amdgpu_amdkfd_gpuvm.c
> +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_amdkfd_gpuvm.c
> @@ -2209,30 +2209,27 @@ int amdgpu_amdkfd_gpuvm_import_dmabuf(struct amdgpu_device *adev,
>   	struct amdgpu_bo *bo;
>   	int ret;
>   
> -	if (dma_buf->ops != &amdgpu_dmabuf_ops)
> -		/* Can't handle non-graphics buffers */
> -		return -EINVAL;
> -
> -	obj = dma_buf->priv;
> -	if (drm_to_adev(obj->dev) != adev)
> -		/* Can't handle buffers from other devices */
> -		return -EINVAL;
> +	obj = amdgpu_gem_prime_import(adev_to_drm(adev), dma_buf);
> +	if (IS_ERR(obj))
> +		return PTR_ERR(obj);
>   
>   	bo = gem_to_amdgpu_bo(obj);
>   	if (!(bo->preferred_domains & (AMDGPU_GEM_DOMAIN_VRAM |
> -				    AMDGPU_GEM_DOMAIN_GTT)))
> +				    AMDGPU_GEM_DOMAIN_GTT))) {
>   		/* Only VRAM and GTT BOs are supported */
> -		return -EINVAL;
> +		ret = -EINVAL;
> +		goto err_put_obj;
> +	}
>   
>   	*mem = kzalloc(sizeof(struct kgd_mem), GFP_KERNEL);
> -	if (!*mem)
> -		return -ENOMEM;
> +	if (!*mem) {
> +		ret = -ENOMEM;
> +		goto err_put_obj;
> +	}
>   
>   	ret = drm_vma_node_allow(&obj->vma_node, drm_priv);
> -	if (ret) {
> -		kfree(*mem);
> -		return ret;
> -	}
> +	if (ret)
> +		goto err_free_mem;
>   
>   	if (size)
>   		*size = amdgpu_bo_size(bo);

Hi Felix:

I have a question when using amdgpu_gem_prime_import. It will allow 
importing a dmabuf to different gpus, then can we still call 
amdgpu_bo_mmap_offset on the generated bo if 
amdgpu_amdkfd_gpuvm_import_dmabuf also ask mmap_offset?

> @@ -2249,7 +2246,8 @@ int amdgpu_amdkfd_gpuvm_import_dmabuf(struct amdgpu_device *adev,
>   		| KFD_IOC_ALLOC_MEM_FLAGS_WRITABLE
>   		| KFD_IOC_ALLOC_MEM_FLAGS_EXECUTABLE;
>   
> -	drm_gem_object_get(&bo->tbo.base);
> +	get_dma_buf(dma_buf);
> +	(*mem)->dmabuf = dma_buf;
>   	(*mem)->bo = bo;
>   	(*mem)->va = va;
>   	(*mem)->domain = (bo->preferred_domains & AMDGPU_GEM_DOMAIN_VRAM) ?
> @@ -2261,6 +2259,12 @@ int amdgpu_amdkfd_gpuvm_import_dmabuf(struct amdgpu_device *adev,
>   	(*mem)->is_imported = true;
>   
>   	return 0;
> +
> +err_free_mem:
> +	kfree(*mem);
> +err_put_obj:
> +	drm_gem_object_put(obj);
> +	return ret;
>   }
>   
>   /* Evict a userptr BO by stopping the queues if necessary