drm/amdgpu: add shadow bo support V2

shadow bo is the shadow of a bo, which is always in GTT,
which can be used to backup the original bo.
V2:
reference shadow parent, shadow bo will be freed by who allocted him.

Signed-off-by: Chunming Zhou <David1.Zhou@amd.com>
Reviewed-by: Christian König <christian.koenig@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>

3 files changed, 48 insertions, 3 deletions

diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu.h b/drivers/gpu/drm/amd/amdgpu/amdgpu.h
index c54f5b962b80..26f6028bb72b 100644
--- a/drivers/gpu/drm/amd/amdgpu/amdgpu.h
+++ b/drivers/gpu/drm/amd/amdgpu/amdgpu.h
@@ -505,6 +505,7 @@ struct amdgpu_bo {
         struct amdgpu_device            *adev;
         struct drm_gem_object           gem_base;
         struct amdgpu_bo                *parent;
+        struct amdgpu_bo                *shadow;
 
         struct ttm_bo_kmap_obj          dma_buf_vmap;
         struct amdgpu_mn                *mn;
diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_object.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_object.c
index d8e69a7e51f9..278017d3dc3f 100644
--- a/drivers/gpu/drm/amd/amdgpu/amdgpu_object.c
+++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_object.c
@@ -380,6 +380,37 @@ fail_free:
         return r;
 }
 
+static int amdgpu_bo_create_shadow(struct amdgpu_device *adev,
+                                   unsigned long size, int byte_align,
+                                   struct amdgpu_bo *bo)
+{
+        struct ttm_placement placement = {0};
+        struct ttm_place placements[AMDGPU_GEM_DOMAIN_MAX + 1];
+        int r;
+
+        if (bo->shadow)
+                return 0;
+
+        bo->flags |= AMDGPU_GEM_CREATE_SHADOW;
+        memset(&placements, 0,
+               (AMDGPU_GEM_DOMAIN_MAX + 1) * sizeof(struct ttm_place));
+
+        amdgpu_ttm_placement_init(adev, &placement,
+                                  placements, AMDGPU_GEM_DOMAIN_GTT,
+                                  AMDGPU_GEM_CREATE_CPU_GTT_USWC);
+
+        r = amdgpu_bo_create_restricted(adev, size, byte_align, true,
+                                        AMDGPU_GEM_DOMAIN_GTT,
+                                        AMDGPU_GEM_CREATE_CPU_GTT_USWC,
+                                        NULL, &placement,
+                                        bo->tbo.resv,
+                                        &bo->shadow);
+        if (!r)
+                bo->shadow->parent = amdgpu_bo_ref(bo);
+
+        return r;
+}
+
 int amdgpu_bo_create(struct amdgpu_device *adev,
                      unsigned long size, int byte_align,
                      bool kernel, u32 domain, u64 flags,
@@ -389,6 +420,7 @@ int amdgpu_bo_create(struct amdgpu_device *adev,
 {
         struct ttm_placement placement = {0};
         struct ttm_place placements[AMDGPU_GEM_DOMAIN_MAX + 1];
+        int r;
 
         memset(&placements, 0,
                (AMDGPU_GEM_DOMAIN_MAX + 1) * sizeof(struct ttm_place));
@@ -396,9 +428,19 @@ int amdgpu_bo_create(struct amdgpu_device *adev,
         amdgpu_ttm_placement_init(adev, &placement,
                                   placements, domain, flags);
 
-        return amdgpu_bo_create_restricted(adev, size, byte_align, kernel,
-                                           domain, flags, sg, &placement,
-                                           resv, bo_ptr);
+        r = amdgpu_bo_create_restricted(adev, size, byte_align, kernel,
+                                        domain, flags, sg, &placement,
+                                        resv, bo_ptr);
+        if (r)
+                return r;
+
+        if (flags & AMDGPU_GEM_CREATE_SHADOW) {
+                r = amdgpu_bo_create_shadow(adev, size, byte_align, (*bo_ptr));
+                if (r)
+                        amdgpu_bo_unref(bo_ptr);
+        }
+
+        return r;
 }
 
 int amdgpu_bo_kmap(struct amdgpu_bo *bo, void **ptr)
diff --git a/include/uapi/drm/amdgpu_drm.h b/include/uapi/drm/amdgpu_drm.h
index a902a602490b..5aef0b71079b 100644
--- a/include/uapi/drm/amdgpu_drm.h
+++ b/include/uapi/drm/amdgpu_drm.h
@@ -79,6 +79,8 @@ extern "C" {
 #define AMDGPU_GEM_CREATE_CPU_GTT_USWC          (1 << 2)
 /* Flag that the memory should be in VRAM and cleared */
 #define AMDGPU_GEM_CREATE_VRAM_CLEARED          (1 << 3)
+/* Flag that create shadow bo(GTT) while allocating vram bo */
+#define AMDGPU_GEM_CREATE_SHADOW                (1 << 4)
 
 struct drm_amdgpu_gem_create_in  {
         /** the requested memory size */