[PATCH] drm/amdgpu: fix size calculation in amdgpu_ttm_copy_mem_to_mem

[Felix Kuehling]

Am 2020-04-03 um 11:21 a.m. schrieb Christian König:
> When the node is larger than 4GB we overrun the size calculation.
>
> Fix this by correctly limiting the size to the window as well.
>
> Signed-off-by: Christian König <christian.koenig at amd.com>
> ---
>  drivers/gpu/drm/amd/amdgpu/amdgpu_ttm.c | 6 +++---
>  1 file changed, 3 insertions(+), 3 deletions(-)
>
> diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_ttm.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_ttm.c
> index 029b661faef6..1b658e905620 100644
> --- a/drivers/gpu/drm/amd/amdgpu/amdgpu_ttm.c
> +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_ttm.c
> @@ -454,9 +454,9 @@ int amdgpu_ttm_copy_mem_to_mem(struct amdgpu_device *adev,
>  		/* Copy size cannot exceed GTT_MAX_BYTES. So if src or dst
>  		 * begins at an offset, then adjust the size accordingly
>  		 */
> -		cur_size = min3(src_node_size, dst_node_size, size);
> -		cur_size = min(GTT_MAX_BYTES - src_page_offset, cur_size);
> -		cur_size = min(GTT_MAX_BYTES - dst_page_offset, cur_size);
> +		cur_size = max(src_page_offset, dst_page_offset);
> +		cur_size = min(min3(src_node_size, dst_node_size, size),
> +			       (uint64_t)(GTT_MAX_BYTES - cur_size));

This makes me wish for a min4 macro. I think the most efficient way to
write this would be

	cur_size = min(min(src_node_size, dst_node_size),
		       min(size, (uint64_t)(GTT_MAX_BYTES - cur_size)));

Either way, this patch is

Reviewed-by: Felix Kuehling <Felix.Kuehling at amd.com>


>  
>  		/* Map src to window 0 and dst to window 1. */
>  		r = amdgpu_ttm_map_buffer(src->bo, src->mem, src_mm,
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