[PATCH 03/11] drm/virtio: add virtio_gpu_vbuf_ctrl_hdr

[Chia-I Wu]

It is a helper to return the virtio_gpu_ctrl_hdr in a vbuf.

Signed-off-by: Chia-I Wu <olva...@gmail.com>
---
 drivers/gpu/drm/virtio/virtgpu_vq.c | 20 +++++++++++++++-----
 1 file changed, 15 insertions(+), 5 deletions(-)

diff --git a/drivers/gpu/drm/virtio/virtgpu_vq.c 
b/drivers/gpu/drm/virtio/virtgpu_vq.c
index 63d2df7fb0c98..312fd8a039a1e 100644
--- a/drivers/gpu/drm/virtio/virtgpu_vq.c
+++ b/drivers/gpu/drm/virtio/virtgpu_vq.c
@@ -95,7 +95,8 @@ virtio_gpu_get_vbuf(struct virtio_gpu_device *vgdev,
        if (!vbuf)
                return ERR_PTR(-ENOMEM);
 
-       BUG_ON(size > MAX_INLINE_CMD_SIZE);
+       BUG_ON(size > MAX_INLINE_CMD_SIZE ||
+              size < sizeof(struct virtio_gpu_ctrl_hdr));
        vbuf->buf = (void *)vbuf + sizeof(*vbuf);
        vbuf->size = size;
 
@@ -109,6 +110,16 @@ virtio_gpu_get_vbuf(struct virtio_gpu_device *vgdev,
        return vbuf;
 }
 
+static struct virtio_gpu_ctrl_hdr *
+virtio_gpu_vbuf_ctrl_hdr(struct virtio_gpu_vbuffer *vbuf)
+{
+       /* this assumes a vbuf contains a command that starts with a
+        * virtio_gpu_ctrl_hdr, which is true for both ctrl and cursor
+        * virtqueues.
+        */
+       return (struct virtio_gpu_ctrl_hdr *)vbuf->buf;
+}
+
 static void *virtio_gpu_alloc_cmd(struct virtio_gpu_device *vgdev,
                                  struct virtio_gpu_vbuffer **vbuffer_p,
                                  int size)
@@ -211,7 +222,7 @@ void virtio_gpu_dequeue_ctrl_func(struct work_struct *work)
                if (resp->type != cpu_to_le32(VIRTIO_GPU_RESP_OK_NODATA)) {
                        if (resp->type >= 
cpu_to_le32(VIRTIO_GPU_RESP_ERR_UNSPEC)) {
                                struct virtio_gpu_ctrl_hdr *cmd;
-                               cmd = (struct virtio_gpu_ctrl_hdr *)entry->buf;
+                               cmd = virtio_gpu_vbuf_ctrl_hdr(entry);
                                DRM_ERROR("response 0x%x (command 0x%x)\n",
                                          le32_to_cpu(resp->type),
                                          le32_to_cpu(cmd->type));
@@ -338,8 +349,7 @@ static bool virtio_gpu_queue_ctrl_buffer_locked(struct 
virtio_gpu_device *vgdev,
        ret = virtqueue_add_sgs(vq, sgs, outcnt, incnt, vbuf, GFP_ATOMIC);
        WARN_ON(ret);
 
-       trace_virtio_gpu_cmd_queue(vq,
-               (struct virtio_gpu_ctrl_hdr *)vbuf->buf);
+       trace_virtio_gpu_cmd_queue(vq, virtio_gpu_vbuf_ctrl_hdr(vbuf));
 
        notify = virtqueue_kick_prepare(vq);
 
@@ -458,7 +468,7 @@ static void virtio_gpu_queue_cursor(struct 
virtio_gpu_device *vgdev,
                goto retry;
        } else {
                trace_virtio_gpu_cmd_queue(vq,
-                       (struct virtio_gpu_ctrl_hdr *)vbuf->buf);
+                       virtio_gpu_vbuf_ctrl_hdr(vbuf));
 
                notify = virtqueue_kick_prepare(vq);
        }
-- 
2.25.0.341.g760bfbb309-goog

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