drm/amdgpu: add new bo flag that indicates BOs don't need fallback (v2)

user cases:
1. KFD wraps amdgpu_bo_create, they have no fallback case which is different
with amdgpu_gem_object_create.
since upstream branch has no amdgpu_amdkfd_gpuvm.c, which need KFD
guys add this flag to __alloc_memory_of_gpu:
+       flags |= AMDGPU_GEM_CREATE_NO_FALLBACK;
2. UMD can specify this flag for their allocation as well if they like.

v2: squash in merge conflict fix (Chunming)
Signed-off-by: Chunming Zhou <david1.zhou@amd.com>
Acked-by: Felix Kuehling <Felix.Kuehling@amd.com>
Cc: felix.kuehling@amd.com
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>

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

@@ -386,7 +386,8 @@ static int amdgpu_cs_bo_validate(struct amdgpu_cs_parser *p,
 	    bo->tbo.mem.start < adev->gmc.visible_vram_size >> PAGE_SHIFT)
 		p->bytes_moved_vis += ctx.bytes_moved;
 
-	if (unlikely(r == -ENOMEM) && domain != bo->allowed_domains) {
+	if (unlikely(r == -ENOMEM) && domain != bo->allowed_domains &&
+	    !(bo->flags & AMDGPU_GEM_CREATE_NO_FALLBACK)) {
 		domain = bo->allowed_domains;
 		goto retry;
 	}

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

@@ -388,6 +388,8 @@ static int amdgpu_bo_do_create(struct amdgpu_device *adev, unsigned long size,
 	drm_gem_private_object_init(adev->ddev, &bo->gem_base, size);
 	INIT_LIST_HEAD(&bo->shadow_list);
 	INIT_LIST_HEAD(&bo->va);
+	bo->preferred_domains = preferred_domains;
+	bo->allowed_domains = allowed_domains;
 
 	bo->flags = flags;
 
@@ -424,7 +426,8 @@ static int amdgpu_bo_do_create(struct amdgpu_device *adev, unsigned long size,
 	r = ttm_bo_init_reserved(&adev->mman.bdev, &bo->tbo, size, type,
 				 &bo->placement, page_align, &ctx, acc_size,
 				 NULL, resv, &amdgpu_ttm_bo_destroy);
-	if (unlikely(r && r != -ERESTARTSYS) && type == ttm_bo_type_device) {
+	if (unlikely(r && r != -ERESTARTSYS) && type == ttm_bo_type_device &&
+	    !(flags & AMDGPU_GEM_CREATE_NO_FALLBACK)) {
 		if (flags & AMDGPU_GEM_CREATE_CPU_ACCESS_REQUIRED) {
 			flags &= ~AMDGPU_GEM_CREATE_CPU_ACCESS_REQUIRED;
 			goto retry;

include/uapi/drm/amdgpu_drm.h

@@ -95,6 +95,8 @@ extern "C" {
 #define AMDGPU_GEM_CREATE_VM_ALWAYS_VALID	(1 << 6)
 /* Flag that BO sharing will be explicitly synchronized */
 #define AMDGPU_GEM_CREATE_EXPLICIT_SYNC		(1 << 7)
+/* Flag that BO doesn't need fallback */
+#define AMDGPU_GEM_CREATE_NO_FALLBACK		(1 << 8)
 
 struct drm_amdgpu_gem_create_in  {
 	/** the requested memory size */