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

From: Julia Zhang
Date: Mon Jan 29 2024 - 05:32:10 EST


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@xxxxxxx>
---
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