Pin and unpin the DMA-buf exported BOs only on demand and invalidate all
DMA-buf mappings when the underlying BO moves.

Signed-off-by: Christian König <christian.koe...@amd.com>
---
 drivers/gpu/drm/amd/amdgpu/amdgpu_object.c |  5 ++
 drivers/gpu/drm/amd/amdgpu/amdgpu_prime.c  | 73 ++++++++++++++++++++--
 2 files changed, 72 insertions(+), 6 deletions(-)

diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_object.c 
b/drivers/gpu/drm/amd/amdgpu/amdgpu_object.c
index ec9e45004bff..fdb98eb562db 100644
--- a/drivers/gpu/drm/amd/amdgpu/amdgpu_object.c
+++ b/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/drmP.h>
 #include <drm/amdgpu_drm.h>
 #include <drm/drm_cache.h>
@@ -1192,6 +1193,10 @@ void amdgpu_bo_move_notify(struct ttm_buffer_object *bo,
 
        amdgpu_bo_kunmap(abo);
 
+       if (abo->gem_base.dma_buf && !abo->gem_base.import_attach &&
+           bo->mem.mem_type != TTM_PL_SYSTEM)
+               dma_buf_invalidate_mappings(abo->gem_base.dma_buf);
+
        /* remember the eviction */
        if (evict)
                atomic64_inc(&adev->num_evictions);
diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_prime.c 
b/drivers/gpu/drm/amd/amdgpu/amdgpu_prime.c
index 56e2a606b9a1..40cd89271b20 100644
--- a/drivers/gpu/drm/amd/amdgpu/amdgpu_prime.c
+++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_prime.c
@@ -209,6 +209,61 @@ __reservation_object_make_exclusive(struct 
reservation_object *obj)
        return -ENOMEM;
 }
 
+/**
+ * amdgpu_gem_pin_dma_buf - &dma_buf_ops.pin_dma_buf implementation
+ *
+ * @dma_buf: DMA-buf to pin in memory
+ *
+ * Pin the BO which is backing the DMA-buf so that it can't move any more.
+ */
+static int amdgpu_gem_pin_dma_buf(struct dma_buf *dma_buf)
+{
+       struct drm_gem_object *obj = dma_buf->priv;
+       struct amdgpu_bo *bo = gem_to_amdgpu_bo(obj);
+
+       /* pin buffer into GTT */
+       return amdgpu_bo_pin(bo, AMDGPU_GEM_DOMAIN_GTT);
+}
+
+/**
+ * amdgpu_gem_unpin_dma_buf - &dma_buf_ops.unpin_dma_buf implementation
+ *
+ * @dma_buf: DMA-buf to unpin
+ *
+ * Unpin a previously pinned BO to make it movable again.
+ */
+static void amdgpu_gem_unpin_dma_buf(struct dma_buf *dma_buf)
+{
+       struct drm_gem_object *obj = dma_buf->priv;
+       struct amdgpu_bo *bo = gem_to_amdgpu_bo(obj);
+
+       amdgpu_bo_unpin(bo);
+}
+
+/**
+ * amdgpu_gem_dma_buf_attach - &dma_buf_ops.attach implementation
+ *
+ * @dma_buf: DMA-buf we attach to
+ * @attach: DMA-buf attachment
+ *
+ * Returns:
+ * Always zero for success.
+ */
+static int amdgpu_gem_dma_buf_attach(struct dma_buf *dma_buf,
+                                    struct dma_buf_attachment *attach)
+{
+       struct drm_gem_object *obj = dma_buf->priv;
+       struct amdgpu_bo *bo = gem_to_amdgpu_bo(obj);
+
+       /* Make sure the buffer is pinned when userspace didn't set GTT as
+        * preferred domain. This avoid ping/pong situations with scan out BOs.
+        */
+       if (!(bo->preferred_domains & AMDGPU_GEM_DOMAIN_GTT))
+               attach->invalidate = NULL;
+
+       return 0;
+}
+
 /**
  * amdgpu_gem_map_dma_buf - &dma_buf_ops.map_dma_buf implementation
  * @attach: DMA-buf attachment
@@ -247,10 +302,15 @@ amdgpu_gem_map_dma_buf(struct dma_buf_attachment *attach,
                        return ERR_PTR(r);
        }
 
-       /* pin buffer into GTT */
-       r = amdgpu_bo_pin(bo, AMDGPU_GEM_DOMAIN_GTT);
-       if (r)
-               return ERR_PTR(r);
+       if (attach->invalidate) {
+               /* 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);
+       }
 
        sgt = drm_prime_pages_to_sg(bo->tbo.ttm->pages, bo->tbo.num_pages);
        if (IS_ERR(sgt))
@@ -289,8 +349,6 @@ static void amdgpu_gem_unmap_dma_buf(struct 
dma_buf_attachment *attach,
        struct amdgpu_bo *bo = gem_to_amdgpu_bo(obj);
        struct amdgpu_device *adev = amdgpu_ttm_adev(bo->tbo.bdev);
 
-       amdgpu_bo_unpin(bo);
-
        if (attach->dev->driver != adev->dev->driver && bo->prime_shared_count)
                bo->prime_shared_count--;
 
@@ -357,6 +415,9 @@ static int amdgpu_gem_begin_cpu_access(struct dma_buf 
*dma_buf,
 
 const struct dma_buf_ops amdgpu_dmabuf_ops = {
        .dynamic_sgt_mapping = true,
+       .attach = amdgpu_gem_dma_buf_attach,
+       .pin = amdgpu_gem_pin_dma_buf,
+       .unpin = amdgpu_gem_unpin_dma_buf,
        .map_dma_buf = amdgpu_gem_map_dma_buf,
        .unmap_dma_buf = amdgpu_gem_unmap_dma_buf,
        .release = drm_gem_dmabuf_release,
-- 
2.17.1

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