[PATCH] drm/amd/amdgpu: cast mem->num_pages to 64-bits when shifting

[StDenis, Tom]

On 32-bit hosts mem->num_pages is 32-bits and can overflow
when shifted.  Add a cast to avoid this.

Signed-off-by: Tom St Denis <tom.stdenis at amd.com>
---
 drivers/gpu/drm/amd/amdgpu/amdgpu_vram_mgr.c | 8 +++++---
 1 file changed, 5 insertions(+), 3 deletions(-)

diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_vram_mgr.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_vram_mgr.c
index c963ad86072e..31895d3c33de 100644
--- a/drivers/gpu/drm/amd/amdgpu/amdgpu_vram_mgr.c
+++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_vram_mgr.c
@@ -279,14 +279,16 @@ static int amdgpu_vram_mgr_new(struct ttm_mem_type_manager *man,
 	uint64_t vis_usage = 0;
 	unsigned i;
 	int r;
+	uint64_t mem_bytes;
 
 	lpfn = place->lpfn;
 	if (!lpfn)
 		lpfn = man->size;
 
 	/* bail out quickly if there's likely not enough VRAM for this BO */
-	if (atomic64_add_return(mem->num_pages << PAGE_SHIFT, &mgr->usage) > adev->gmc.mc_vram_size) {
-		atomic64_sub(mem->num_pages << PAGE_SHIFT, &mgr->usage);
+	mem_bytes = (u64)mem->num_pages << PAGE_SHIFT;
+	if (atomic64_add_return(mem_bytes, &mgr->usage) > adev->gmc.mc_vram_size) {
+		atomic64_sub(mem_bytes, &mgr->usage);
 		mem->mm_node = NULL;
 		return 0;
 	}
@@ -308,7 +310,7 @@ static int amdgpu_vram_mgr_new(struct ttm_mem_type_manager *man,
 	nodes = kvmalloc_array((uint32_t)num_nodes, sizeof(*nodes),
 			       GFP_KERNEL | __GFP_ZERO);
 	if (!nodes) {
-		atomic64_sub(mem->num_pages << PAGE_SHIFT, &mgr->usage);
+		atomic64_sub(mem_bytes, &mgr->usage);
 		return -ENOMEM;
 	}
 
-- 
2.21.0