Re: [PATCH] drm/xe/dma-buf: Add xe_dma_buf_to_gem() self-import helper

[Matthew Brost <matthew.brost@intel.com>]

On Thu, Oct 29, 2026 at 07:21:12AM -0700, Niranjana Vishwanathapura wrote:
> Factor the dma-buf self-import detection out of xe_gem_prime_import()
> into a standalone xe_dma_buf_to_gem() helper. The helper checks that the
> dma-buf was exported by this Xe device (matching ops and drm_device) and,
> if so, takes an extra reference on the backing GEM object instead of the
> dma-buf file. Expose it for future use within Xe.
> 
> Signed-off-by: Niranjana Vishwanathapura <niranjana.vishwanathapura@intel.com>
> Signed-off-by: Farah Kassabri <farah.kassabri@intel.com>

Reviewed-by: Matthew Brost <matthew.brost@intel.com>

> ---
>  drivers/gpu/drm/xe/xe_dma_buf.c | 38 ++++++++++++++++++++++++---------
>  drivers/gpu/drm/xe/xe_dma_buf.h |  2 ++
>  2 files changed, 30 insertions(+), 10 deletions(-)
> 
> diff --git a/drivers/gpu/drm/xe/xe_dma_buf.c b/drivers/gpu/drm/xe/xe_dma_buf.c
> index 6a85b292dee7..5bf13dc4b61d 100644
> --- a/drivers/gpu/drm/xe/xe_dma_buf.c
> +++ b/drivers/gpu/drm/xe/xe_dma_buf.c
> @@ -239,6 +239,27 @@ static const struct dma_buf_ops xe_dmabuf_ops = {
>  	.vunmap = drm_gem_dmabuf_vunmap,
>  };
>  
> +struct drm_gem_object *xe_dma_buf_to_gem(struct drm_device *dev,
> +					 struct dma_buf *dma_buf)
> +{
> +	struct drm_gem_object *obj;
> +
> +	if (dma_buf->ops != &xe_dmabuf_ops)
> +		return NULL;
> +
> +	obj = dma_buf->priv;
> +	if (obj->dev != dev)
> +		return NULL;
> +
> +	/*
> +	 * Importing dmabuf exported from our own gem increases
> +	 * refcount on gem itself instead of f_count of dmabuf.
> +	 */
> +	drm_gem_object_get(obj);
> +
> +	return obj;
> +}
> +
>  struct dma_buf *xe_gem_prime_export(struct drm_gem_object *obj, int flags)
>  {
>  	struct xe_bo *bo = gem_to_xe_bo(obj);
> @@ -372,17 +393,14 @@ struct drm_gem_object *xe_gem_prime_import(struct drm_device *dev,
>  	struct dma_buf_attachment *attach;
>  	struct drm_gem_object *obj;
>  
> -	if (dma_buf->ops == &xe_dmabuf_ops) {
> -		obj = dma_buf->priv;
> -		if (obj->dev == dev &&
> -		    !XE_TEST_ONLY(test && test->force_different_devices)) {
> -			/*
> -			 * Importing dmabuf exported from out own gem increases
> -			 * refcount on gem itself instead of f_count of dmabuf.
> -			 */
> -			drm_gem_object_get(obj);
> +	obj = xe_dma_buf_to_gem(dev, dma_buf);
> +	if (obj) {
> +		if (!XE_TEST_ONLY(test && test->force_different_devices))
>  			return obj;
> -		}
> +
> +		/* Test only: force different devices */
> +		drm_gem_object_put(obj);
> +		obj = NULL;
>  	}
>  
>  	/*
> diff --git a/drivers/gpu/drm/xe/xe_dma_buf.h b/drivers/gpu/drm/xe/xe_dma_buf.h
> index 861dd28a862c..d0c7893a5a6f 100644
> --- a/drivers/gpu/drm/xe/xe_dma_buf.h
> +++ b/drivers/gpu/drm/xe/xe_dma_buf.h
> @@ -8,6 +8,8 @@
>  
>  #include <drm/drm_gem.h>
>  
> +struct drm_gem_object *xe_dma_buf_to_gem(struct drm_device *dev,
> +					 struct dma_buf *dma_buf);
>  struct dma_buf *xe_gem_prime_export(struct drm_gem_object *obj, int flags);
>  struct drm_gem_object *xe_gem_prime_import(struct drm_device *dev,
>  					   struct dma_buf *dma_buf);
> -- 
> 2.43.0
>