drm/amdgpu: add amdgpu_dma_buf_pin/unpin v2

This implements the exporter side of unpinned DMA-buf handling.

v2: fix minor coding style issues
Signed-off-by: Christian König <christian.koenig@amd.com>
Acked-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Link: https://patchwork.freedesktop.org/patch/353999/?series=73646&rev=1

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

@@ -222,6 +222,37 @@ static void amdgpu_dma_buf_detach(struct dma_buf *dmabuf,
 		bo->prime_shared_count--;
 }
 
+/**
+ * amdgpu_dma_buf_pin - &dma_buf_ops.pin implementation
+ *
+ * @attach: attachment to pin down
+ *
+ * Pin the BO which is backing the DMA-buf so that it can't move any more.
+ */
+static int amdgpu_dma_buf_pin(struct dma_buf_attachment *attach)
+{
+	struct drm_gem_object *obj = attach->dmabuf->priv;
+	struct amdgpu_bo *bo = gem_to_amdgpu_bo(obj);
+
+	/* pin buffer into GTT */
+	return amdgpu_bo_pin(bo, AMDGPU_GEM_DOMAIN_GTT);
+}
+
+/**
+ * amdgpu_dma_buf_unpin - &dma_buf_ops.unpin implementation
+ *
+ * @attach: attachment to unpin
+ *
+ * Unpin a previously pinned BO to make it movable again.
+ */
+static void amdgpu_dma_buf_unpin(struct dma_buf_attachment *attach)
+{
+	struct drm_gem_object *obj = attach->dmabuf->priv;
+	struct amdgpu_bo *bo = gem_to_amdgpu_bo(obj);
+
+	amdgpu_bo_unpin(bo);
+}
+
 /**
  * amdgpu_dma_buf_map - &dma_buf_ops.map_dma_buf implementation
  * @attach: DMA-buf attachment
@@ -244,9 +275,19 @@ static struct sg_table *amdgpu_dma_buf_map(struct dma_buf_attachment *attach,
 	struct sg_table *sgt;
 	long r;
 
-	r = amdgpu_bo_pin(bo, AMDGPU_GEM_DOMAIN_GTT);
-	if (r)
-		return ERR_PTR(r);
+	if (!bo->pin_count) {
+		/* move buffer into GTT */
+		struct ttm_operation_ctx ctx = { false, false };
+
+		amdgpu_bo_placement_from_domain(bo, AMDGPU_GEM_DOMAIN_GTT);
+		r = ttm_bo_validate(&bo->tbo, &bo->placement, &ctx);
+		if (r)
+			return ERR_PTR(r);
+
+	} else if (!(amdgpu_mem_type_to_domain(bo->tbo.mem.mem_type) &
+		     AMDGPU_GEM_DOMAIN_GTT)) {
+		return ERR_PTR(-EBUSY);
+	}
 
 	sgt = drm_prime_pages_to_sg(bo->tbo.ttm->pages, bo->tbo.num_pages);
 	if (IS_ERR(sgt))
@@ -277,13 +318,9 @@ static void amdgpu_dma_buf_unmap(struct dma_buf_attachment *attach,
 				 struct sg_table *sgt,
 				 enum dma_data_direction dir)
 {
-	struct drm_gem_object *obj = attach->dmabuf->priv;
-	struct amdgpu_bo *bo = gem_to_amdgpu_bo(obj);
-
 	dma_unmap_sg(attach->dev, sgt->sgl, sgt->nents, dir);
 	sg_free_table(sgt);
 	kfree(sgt);
-	amdgpu_bo_unpin(bo);
 }
 
 /**
@@ -330,6 +367,8 @@ const struct dma_buf_ops amdgpu_dmabuf_ops = {
 	.dynamic_mapping = true,
 	.attach = amdgpu_dma_buf_attach,
 	.detach = amdgpu_dma_buf_detach,
+	.pin = amdgpu_dma_buf_pin,
+	.unpin = amdgpu_dma_buf_unpin,
 	.map_dma_buf = amdgpu_dma_buf_map,
 	.unmap_dma_buf = amdgpu_dma_buf_unmap,
 	.release = drm_gem_dmabuf_release,

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

@@ -31,6 +31,7 @@
  */
 #include <linux/list.h>
 #include <linux/slab.h>
+#include <linux/dma-buf.h>
 
 #include <drm/amdgpu_drm.h>
 #include <drm/drm_cache.h>
@@ -1274,6 +1275,10 @@ void amdgpu_bo_move_notify(struct ttm_buffer_object *bo,
 
 	amdgpu_bo_kunmap(abo);
 
+	if (abo->tbo.base.dma_buf && !abo->tbo.base.import_attach &&
+	    bo->mem.mem_type != TTM_PL_SYSTEM)
+		dma_buf_move_notify(abo->tbo.base.dma_buf);
+
 	/* remember the eviction */
 	if (evict)
 		atomic64_inc(&adev->num_evictions);