[RFC 1/2] drm/amdgpu: Re-validate evicted buffers

[Tvrtko Ursulin]

From: Tvrtko Ursulin <tvrtko.ursulin at igalia.com>

Currently the driver appears to be thinking that it will be attempting to
re-validate the evicted buffers on the next submission if they are not in
their preferred placement.

That however appears not to be true for the very common case of buffers
with allowed placements of VRAM+GTT. Simply because the check can only
detect if the current placement is *none* of the preferred ones, happily
leaving VRAM+GTT buffers in the GTT placement "forever".

Fix it by extending the VRAM+GTT special case to the re-validation logic.

Signed-off-by: Tvrtko Ursulin <tvrtko.ursulin at igalia.com>
Cc: Christian König <christian.koenig at amd.com>
Cc: Friedrich Vock <friedrich.vock at gmx.de>
---
 drivers/gpu/drm/amd/amdgpu/amdgpu_vm.c | 21 ++++++++++++++++++---
 1 file changed, 18 insertions(+), 3 deletions(-)

diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_vm.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_vm.c
index 6bddd43604bc..e53ff914b62e 100644
--- a/drivers/gpu/drm/amd/amdgpu/amdgpu_vm.c
+++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_vm.c
@@ -1248,10 +1248,25 @@ int amdgpu_vm_bo_update(struct amdgpu_device *adev, struct amdgpu_bo_va *bo_va,
 	 * next command submission.
 	 */
 	if (amdgpu_vm_is_bo_always_valid(vm, bo)) {
-		uint32_t mem_type = bo->tbo.resource->mem_type;
+		unsigned current_domain =
+			amdgpu_mem_type_to_domain(bo->tbo.resource->mem_type);
+		bool move_to_evict = false;
 
-		if (!(bo->preferred_domains &
-		      amdgpu_mem_type_to_domain(mem_type)))
+		if (!(bo->preferred_domains & current_domain)) {
+			move_to_evict = true;
+		} else if ((bo->preferred_domains & AMDGPU_GEM_DOMAIN_MASK) ==
+			   (AMDGPU_GEM_DOMAIN_VRAM | AMDGPU_GEM_DOMAIN_GTT) &&
+			   current_domain != AMDGPU_GEM_DOMAIN_VRAM) {
+			/*
+			 * If userspace has provided a list of possible
+			 * placements equal to VRAM+GTT, we assume VRAM is *the*
+			 * preferred placement and so try to move it back there
+			 * on the next submission.
+			 */
+			move_to_evict = true;
+		}
+
+		if (move_to_evict)
 			amdgpu_vm_bo_evicted(&bo_va->base);
 		else
 			amdgpu_vm_bo_idle(&bo_va->base);
-- 
2.44.0