[PATCH v2 1/1] drm/amdgpu: Add gem_prime_mmap support

[Christian König]

Am 14.09.2017 um 00:39 schrieb Samuel Li:
> v2: drop hdp invalidate/flush.
>
> Signed-off-by: Samuel Li <Samuel.Li at amd.com>
> ---
>   drivers/gpu/drm/amd/amdgpu/amdgpu.h       |  3 ++
>   drivers/gpu/drm/amd/amdgpu/amdgpu_drv.c   |  3 +-
>   drivers/gpu/drm/amd/amdgpu/amdgpu_prime.c | 77 ++++++++++++++++++++++++++++++-
>   3 files changed, 81 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu.h b/drivers/gpu/drm/amd/amdgpu/amdgpu.h
> index d2aaad7..188b705 100644
> --- a/drivers/gpu/drm/amd/amdgpu/amdgpu.h
> +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu.h
> @@ -395,11 +395,14 @@ amdgpu_gem_prime_import_sg_table(struct drm_device *dev,
>   struct dma_buf *amdgpu_gem_prime_export(struct drm_device *dev,
>   					struct drm_gem_object *gobj,
>   					int flags);
> +struct drm_gem_object *amdgpu_gem_prime_import(struct drm_device *dev,
> +					    struct dma_buf *dma_buf);
>   int amdgpu_gem_prime_pin(struct drm_gem_object *obj);
>   void amdgpu_gem_prime_unpin(struct drm_gem_object *obj);
>   struct reservation_object *amdgpu_gem_prime_res_obj(struct drm_gem_object *);
>   void *amdgpu_gem_prime_vmap(struct drm_gem_object *obj);
>   void amdgpu_gem_prime_vunmap(struct drm_gem_object *obj, void *vaddr);
> +int amdgpu_gem_prime_mmap(struct drm_gem_object *obj, struct vm_area_struct *vma);
>   int amdgpu_gem_debugfs_init(struct amdgpu_device *adev);
>   
>   /* sub-allocation manager, it has to be protected by another lock.
> diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_drv.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_drv.c
> index 2cdf844..9b63ac5 100644
> --- a/drivers/gpu/drm/amd/amdgpu/amdgpu_drv.c
> +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_drv.c
> @@ -835,7 +835,7 @@ static struct drm_driver kms_driver = {
>   	.prime_handle_to_fd = drm_gem_prime_handle_to_fd,
>   	.prime_fd_to_handle = drm_gem_prime_fd_to_handle,
>   	.gem_prime_export = amdgpu_gem_prime_export,
> -	.gem_prime_import = drm_gem_prime_import,
> +	.gem_prime_import = amdgpu_gem_prime_import,
>   	.gem_prime_pin = amdgpu_gem_prime_pin,
>   	.gem_prime_unpin = amdgpu_gem_prime_unpin,
>   	.gem_prime_res_obj = amdgpu_gem_prime_res_obj,
> @@ -843,6 +843,7 @@ static struct drm_driver kms_driver = {
>   	.gem_prime_import_sg_table = amdgpu_gem_prime_import_sg_table,
>   	.gem_prime_vmap = amdgpu_gem_prime_vmap,
>   	.gem_prime_vunmap = amdgpu_gem_prime_vunmap,
> +	.gem_prime_mmap = amdgpu_gem_prime_mmap,
>   
>   	.name = DRIVER_NAME,
>   	.desc = DRIVER_DESC,
> diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_prime.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_prime.c
> index 5b3f928..13c977a 100644
> --- a/drivers/gpu/drm/amd/amdgpu/amdgpu_prime.c
> +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_prime.c
> @@ -57,6 +57,40 @@ void amdgpu_gem_prime_vunmap(struct drm_gem_object *obj, void *vaddr)
>   	ttm_bo_kunmap(&bo->dma_buf_vmap);
>   }
>   
> +int amdgpu_gem_prime_mmap(struct drm_gem_object *obj, struct vm_area_struct *vma)
> +{
> +	struct amdgpu_bo *bo = gem_to_amdgpu_bo(obj);
> +	struct amdgpu_device *adev = amdgpu_ttm_adev(bo->tbo.bdev);
> +	unsigned asize = amdgpu_bo_size(bo);
> +	int ret;
> +
> +	if (!vma->vm_file)
> +		return -ENODEV;
> +
> +	if (adev == NULL)
> +		return -ENODEV;
> +
> +	/* Check for valid size. */
> +	if (asize < vma->vm_end - vma->vm_start)
> +		return -EINVAL;
> +
> +	if (amdgpu_ttm_tt_get_usermm(bo->tbo.ttm) ||
> +	    (bo->flags & AMDGPU_GEM_CREATE_NO_CPU_ACCESS)) {
> +		return -EPERM;
> +	}
> +	vma->vm_pgoff = amdgpu_bo_mmap_offset(bo) >> PAGE_SHIFT;

Maybe better use "vma->vm_pgoff += amdgpu_bo_mmap_offset(bo) >> 
PAGE_SHIFT;", but I'm not sure.

How other drivers handle this?

> +
> +	/* prime mmap does not need to check access, so allow here */
> +	ret = drm_vma_node_allow(&obj->vma_node, vma->vm_file->private_data);
> +	if (ret)
> +		return ret;
> +
> +	ret = ttm_bo_mmap(vma->vm_file, vma, &adev->mman.bdev);
> +	drm_vma_node_revoke(&obj->vma_node, vma->vm_file->private_data);
> +
> +	return ret;
> +}
> +
>   struct drm_gem_object *
>   amdgpu_gem_prime_import_sg_table(struct drm_device *dev,
>   				 struct dma_buf_attachment *attach,
> @@ -130,14 +164,55 @@ struct reservation_object *amdgpu_gem_prime_res_obj(struct drm_gem_object *obj)
>   	return bo->tbo.resv;
>   }
>   
> +static int amdgpu_gem_begin_cpu_access(struct dma_buf *dma_buf, enum dma_data_direction direction)
> +{
> +	return amdgpu_gem_prime_pin(dma_buf->priv);
> +}
> +
> +static int amdgpu_gem_end_cpu_access(struct dma_buf *dma_buf, enum dma_data_direction direction)
> +{
> +	amdgpu_gem_prime_unpin(dma_buf->priv);
> +
> +	return 0;
> +}
> +
> +static struct dma_buf_ops amdgpu_dmabuf_ops;
> +
>   struct dma_buf *amdgpu_gem_prime_export(struct drm_device *dev,
>   					struct drm_gem_object *gobj,
>   					int flags)
>   {
>   	struct amdgpu_bo *bo = gem_to_amdgpu_bo(gobj);
> +	struct dma_buf *dma_buf;
>   
>   	if (amdgpu_ttm_tt_get_usermm(bo->tbo.ttm))
>   		return ERR_PTR(-EPERM);
>   
> -	return drm_gem_prime_export(dev, gobj, flags);
> +	dma_buf = drm_gem_prime_export(dev, gobj, flags);
> +	amdgpu_dmabuf_ops = *(dma_buf->ops);
> +	amdgpu_dmabuf_ops.begin_cpu_access = amdgpu_gem_begin_cpu_access;
> +	amdgpu_dmabuf_ops.end_cpu_access = amdgpu_gem_end_cpu_access;
> +	dma_buf->ops = &amdgpu_dmabuf_ops;

This isn't race free and needs to be fixed.

Better add callbacks to drm_prime.c similar to drm_gem_dmabuf_mmap().

Alternative you could just completely drop amdgpu_gem_begin_cpu_access() 
and amdgpu_gem_end_cpu_access() as well.

When the buffer is shared between device it is pinned anyway and when it 
isn't shared ttm_bo_mmap() is able to handle VRAM mappings as well.

Regards,
Christian.

> +
> +	return dma_buf;
> +}
> +
> +struct drm_gem_object *amdgpu_gem_prime_import(struct drm_device *dev,
> +					    struct dma_buf *dma_buf)
> +{
> +	struct drm_gem_object *obj;
> +
> +	if (dma_buf->ops == &amdgpu_dmabuf_ops) {
> +		obj = dma_buf->priv;
> +		if (obj->dev == dev) {
> +			/*
> +			 * Importing dmabuf exported from out own gem increases
> +			 * refcount on gem itself instead of f_count of dmabuf.
> +			 */
> +			drm_gem_object_get(obj);
> +			return obj;
> +		}
> +	}
> +
> +	return drm_gem_prime_import(dev, dma_buf);
>   }