Re: [PATCH v3 1/3] accel/amdxdna: refuse an I/O memory mapping of an imported BO

[Lizhi Hou <lizhi.hou@amd.com>]

On 8/13/26 09:46, Taimuraz Kaitmazov wrote:
> amdxdna_gem_obj_vmap() takes whatever dma_buf_vmap() returns and only
> rejects a NULL vaddr. iosys_map is discriminated by is_iomem, so an
> exporter answering with an I/O mapping leaves a void __iomem pointer in
> abo->mem.kva, which amdxdna_cmd_set_error() memsets and memcpys through.
>
> amdxdna_drm_va_tbl takes a dmabuf_fd, so such a BO can be any exporter's
> buffer. amdgpu cannot reach this: its .pin forces GTT for a non peer to
> peer attachment like ours. An exporter on drm_gem_prime_dmabuf_ops has
> no .pin, and drm_gem_ttm_vmap() answers iomem for a VRAM resident
> object, so an NPU paired with nouveau or radeon does.
>
> Refuse the mapping. vmw_gem_vmap() does the same; unlike that one this
> path is reachable from an unprivileged ioctl, so it does not warn.
>
> Signed-off-by: Taimuraz Kaitmazov <taimuraz@kaitmazov.com>
> ---
>   drivers/accel/amdxdna/amdxdna_gem.c | 10 ++++++++--
>   1 file changed, 8 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/accel/amdxdna/amdxdna_gem.c b/drivers/accel/amdxdna/amdxdna_gem.c
> index 1f190b319bb..b66ec9e4828 100644
> --- a/drivers/accel/amdxdna/amdxdna_gem.c
> +++ b/drivers/accel/amdxdna/amdxdna_gem.c
> @@ -683,10 +683,16 @@ static int amdxdna_gem_obj_vmap(struct drm_gem_object *obj, struct iosys_map *ma
>   
>   	dma_resv_assert_held(obj->resv);
>   
> -	if (is_import_bo(abo))
> +	if (is_import_bo(abo)) {
>   		ret = dma_buf_vmap(abo->dma_buf, map);
> -	else
> +		/* Callers use mem.kva as an ordinary kernel address. */
> +		if (!ret && map->is_iomem) {
> +			dma_buf_vunmap(abo->dma_buf, map);
> +			return -EOPNOTSUPP;
> +		}

Thanks for the fix. The 'is_iomem' check should be moved to 
amdxdna_gem_vmap() to cover all the cases.

Lizhi

> +	} else {
>   		ret = drm_gem_shmem_object_vmap(obj, map);
> +	}
>   	if (ret)
>   		return ret;
>   	if (!map->vaddr)