[PATCH v2 1/1] drm/virtio: Implement device_attach

[Julia Zhang]

As vram objects don't have backing pages and thus can't implement
drm_gem_object_funcs.get_sg_table callback. This removes drm dma-buf
callbacks in virtgpu_gem_map_dma_buf()/virtgpu_gem_unmap_dma_buf()
and implement virtgpu specific map/unmap/attach callbacks to support
both of shmem objects and vram objects.

Signed-off-by: Julia Zhang <julia.zhang at amd.com>
---
 drivers/gpu/drm/virtio/virtgpu_prime.c | 40 +++++++++++++++++++++++---
 1 file changed, 36 insertions(+), 4 deletions(-)

diff --git a/drivers/gpu/drm/virtio/virtgpu_prime.c b/drivers/gpu/drm/virtio/virtgpu_prime.c
index 44425f20d91a..b490a5343b06 100644
--- a/drivers/gpu/drm/virtio/virtgpu_prime.c
+++ b/drivers/gpu/drm/virtio/virtgpu_prime.c
@@ -49,11 +49,26 @@ virtgpu_gem_map_dma_buf(struct dma_buf_attachment *attach,
 {
 	struct drm_gem_object *obj = attach->dmabuf->priv;
 	struct virtio_gpu_object *bo = gem_to_virtio_gpu_obj(obj);
+	struct sg_table *sgt;
+	int ret;
 
 	if (virtio_gpu_is_vram(bo))
 		return virtio_gpu_vram_map_dma_buf(bo, attach->dev, dir);
 
-	return drm_gem_map_dma_buf(attach, dir);
+	sgt = drm_prime_pages_to_sg(obj->dev,
+				    to_drm_gem_shmem_obj(obj)->pages,
+				    obj->size >> PAGE_SHIFT);
+	if (IS_ERR(sgt))
+		return sgt;
+
+	ret = dma_map_sgtable(attach->dev, sgt, dir, DMA_ATTR_SKIP_CPU_SYNC);
+	if (ret) {
+		sg_free_table(sgt);
+		kfree(sgt);
+		return ERR_PTR(ret);
+	}
+
+	return sgt;
 }
 
 static void virtgpu_gem_unmap_dma_buf(struct dma_buf_attachment *attach,
@@ -63,12 +78,29 @@ static void virtgpu_gem_unmap_dma_buf(struct dma_buf_attachment *attach,
 	struct drm_gem_object *obj = attach->dmabuf->priv;
 	struct virtio_gpu_object *bo = gem_to_virtio_gpu_obj(obj);
 
+	if (!sgt)
+		return;
+
 	if (virtio_gpu_is_vram(bo)) {
 		virtio_gpu_vram_unmap_dma_buf(attach->dev, sgt, dir);
-		return;
+	} else {
+		dma_unmap_sgtable(attach->dev, sgt, dir, DMA_ATTR_SKIP_CPU_SYNC);
+		sg_free_table(sgt);
+		kfree(sgt);
 	}
+}
+
+static int virtgpu_gem_device_attach(struct dma_buf *dma_buf,
+				     struct dma_buf_attachment *attach)
+{
+	struct drm_gem_object *obj = attach->dmabuf->priv;
+	struct virtio_gpu_object *bo = gem_to_virtio_gpu_obj(obj);
+	int ret = 0;
+
+	if (!virtio_gpu_is_vram(bo) && obj->funcs->pin)
+		ret = obj->funcs->pin(obj);
 
-	drm_gem_unmap_dma_buf(attach, sgt, dir);
+	return ret;
 }
 
 static const struct virtio_dma_buf_ops virtgpu_dmabuf_ops =  {
@@ -83,7 +115,7 @@ static const struct virtio_dma_buf_ops virtgpu_dmabuf_ops =  {
 		.vmap = drm_gem_dmabuf_vmap,
 		.vunmap = drm_gem_dmabuf_vunmap,
 	},
-	.device_attach = drm_gem_map_attach,
+	.device_attach = virtgpu_gem_device_attach,
 	.get_uuid = virtgpu_virtio_get_uuid,
 };
 
-- 
2.34.1