drm/amdgpu: Try evicting from CPU visible to invisible VRAM first

This gives BOs which haven't been accessed by the CPU since they were
moved to visible VRAM another chance to stay in VRAM when another BO
needs to go to visible VRAM.

This should allow BOs to stay in VRAM longer in some cases.

v2:
* Only do this for BOs which don't have the
  AMDGPU_GEM_CREATE_CPU_ACCESS_REQUIRED flag set.
Reviewed-by: NChristian König <christian.koenig@amd.com>
Signed-off-by: NMichel Dänzer <michel.daenzer@amd.com>
Signed-off-by: NAlex Deucher <alexander.deucher@amd.com>

drivers/gpu/drm/amd/amdgpu/amdgpu_ttm.c

@@ -214,7 +214,35 @@ static void amdgpu_evict_flags(struct ttm_buffer_object *bo,
 		    adev->mman.buffer_funcs_ring &&
 		    adev->mman.buffer_funcs_ring->ready == false) {
 			amdgpu_ttm_placement_from_domain(abo, AMDGPU_GEM_DOMAIN_CPU);
+		} else if (adev->mc.visible_vram_size < adev->mc.real_vram_size &&
+			   !(abo->flags & AMDGPU_GEM_CREATE_CPU_ACCESS_REQUIRED)) {
+			unsigned fpfn = adev->mc.visible_vram_size >> PAGE_SHIFT;
+			struct drm_mm_node *node = bo->mem.mm_node;
+			unsigned long pages_left;
+
+			for (pages_left = bo->mem.num_pages;
+			     pages_left;
+			     pages_left -= node->size, node++) {
+				if (node->start < fpfn)
+					break;
+			}
+
+			if (!pages_left)
+				goto gtt;
+
+			/* Try evicting to the CPU inaccessible part of VRAM
+			 * first, but only set GTT as busy placement, so this
+			 * BO will be evicted to GTT rather than causing other
+			 * BOs to be evicted from VRAM
+			 */
+			amdgpu_ttm_placement_from_domain(abo, AMDGPU_GEM_DOMAIN_VRAM |
+							 AMDGPU_GEM_DOMAIN_GTT);
+			abo->placements[0].fpfn = fpfn;
+			abo->placements[0].lpfn = 0;
+			abo->placement.busy_placement = &abo->placements[1];
+			abo->placement.num_busy_placement = 1;
 		} else {
+gtt:
 			amdgpu_ttm_placement_from_domain(abo, AMDGPU_GEM_DOMAIN_GTT);
 		}
 		break;