drm/amdgpu: add AMDGPU_GEM_CREATE_DISCARDABLE

Add a AMDGPU_GEM_CREATE_DISCARDABLE flag to note that the content of a BO
doesn't needs to be preserved during eviction.

KFD was already using a similar functionality for SVM BOs so replace the
internal flag with the new UAPI.
Signed-off-by: Christian König <christian.koenig@amd.com>
Reviewed-by: Alex Deucher <alexander.deucher@amd.com>
Reviewed-by: Marek Olšák <marek.olsak@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>

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

@@ -296,8 +296,8 @@ int amdgpu_gem_create_ioctl(struct drm_device *dev, void *data,
 		      AMDGPU_GEM_CREATE_VRAM_CLEARED |
 		      AMDGPU_GEM_CREATE_VM_ALWAYS_VALID |
 		      AMDGPU_GEM_CREATE_EXPLICIT_SYNC |
-		      AMDGPU_GEM_CREATE_ENCRYPTED))
-
+		      AMDGPU_GEM_CREATE_ENCRYPTED |
+		      AMDGPU_GEM_CREATE_DISCARDABLE))
 		return -EINVAL;
 
 	/* reject invalid gem domains */

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

@@ -567,6 +567,7 @@ int amdgpu_bo_create(struct amdgpu_device *adev,
 		bp->domain;
 	bo->allowed_domains = bo->preferred_domains;
 	if (bp->type != ttm_bo_type_kernel &&
+	    !(bp->flags & AMDGPU_GEM_CREATE_DISCARDABLE) &&
 	    bo->allowed_domains == AMDGPU_GEM_DOMAIN_VRAM)
 		bo->allowed_domains |= AMDGPU_GEM_DOMAIN_GTT;
 

drivers/gpu/drm/amd/amdgpu/amdgpu_object.h

@@ -41,7 +41,6 @@
 
 /* BO flag to indicate a KFD userptr BO */
 #define AMDGPU_AMDKFD_CREATE_USERPTR_BO	(1ULL << 63)
-#define AMDGPU_AMDKFD_CREATE_SVM_BO	(1ULL << 62)
 
 #define to_amdgpu_bo_user(abo) container_of((abo), struct amdgpu_bo_user, bo)
 #define to_amdgpu_bo_vm(abo) container_of((abo), struct amdgpu_bo_vm, bo)

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

@@ -117,7 +117,7 @@ static void amdgpu_evict_flags(struct ttm_buffer_object *bo,
 	}
 
 	abo = ttm_to_amdgpu_bo(bo);
-	if (abo->flags & AMDGPU_AMDKFD_CREATE_SVM_BO) {
+	if (abo->flags & AMDGPU_GEM_CREATE_DISCARDABLE) {
 		placement->num_placement = 0;
 		placement->num_busy_placement = 0;
 		return;

drivers/gpu/drm/amd/amdkfd/kfd_svm.c

@@ -531,7 +531,7 @@ svm_range_vram_node_new(struct amdgpu_device *adev, struct svm_range *prange,
 	bp.domain = AMDGPU_GEM_DOMAIN_VRAM;
 	bp.flags = AMDGPU_GEM_CREATE_NO_CPU_ACCESS;
 	bp.flags |= clear ? AMDGPU_GEM_CREATE_VRAM_CLEARED : 0;
-	bp.flags |= AMDGPU_AMDKFD_CREATE_SVM_BO;
+	bp.flags |= AMDGPU_GEM_CREATE_DISCARDABLE;
 	bp.type = ttm_bo_type_device;
 	bp.resv = NULL;
 

include/uapi/drm/amdgpu_drm.h

@@ -140,6 +140,10 @@ extern "C" {
  * not require GTT memory accounting
  */
 #define AMDGPU_GEM_CREATE_PREEMPTIBLE		(1 << 11)
+/* Flag that BO can be discarded under memory pressure without keeping the
+ * content.
+ */
+#define AMDGPU_GEM_CREATE_DISCARDABLE		(1 << 12)
 
 struct drm_amdgpu_gem_create_in  {
 	/** the requested memory size */