[PATCH v3 20/20] virtio-gpu: Add gl_flushed callback

[Vivek Kasireddy <vivek.kasireddy@intel.com>]

Adding this callback provides a way to determine when the UI
has submitted the buffer to the Host windowing system. Making
the guest wait for this event will ensure that the dmabuf/buffer
updates are synchronized.

Cc: Gerd Hoffmann <kraxel@redhat.com>
Signed-off-by: Vivek Kasireddy <vivek.kasireddy@intel.com>
---
 hw/display/virtio-gpu.c        | 47 +++++++++++++++++++++++++++++++++-
 include/hw/virtio/virtio-gpu.h |  1 +
 2 files changed, 47 insertions(+), 1 deletion(-)

diff --git a/hw/display/virtio-gpu.c b/hw/display/virtio-gpu.c
index 59cbc2b1df..47b3b2b244 100644
--- a/hw/display/virtio-gpu.c
+++ b/hw/display/virtio-gpu.c
@@ -1016,7 +1016,8 @@ void virtio_gpu_simple_process_cmd(VirtIOGPU *g,
         cmd->error = VIRTIO_GPU_RESP_ERR_UNSPEC;
         break;
     }
-    if (!cmd->finished) {
+    if ((!cmd->finished && !(cmd->cmd_hdr.flags & VIRTIO_GPU_FLAG_FENCE)) ||
+        (cmd->finished && (cmd->cmd_hdr.flags & VIRTIO_GPU_FLAG_FENCE))) {
         virtio_gpu_ctrl_response_nodata(g, cmd, cmd->error ? cmd->error :
                                         VIRTIO_GPU_RESP_OK_NODATA);
     }
@@ -1074,6 +1075,49 @@ void virtio_gpu_process_cmdq(VirtIOGPU *g)
     g->processing_cmdq = false;
 }
 
+static void virtio_gpu_signal_fence(VirtIOGPU *g,
+                                    struct virtio_gpu_ctrl_command *cmd,
+                                    enum virtio_gpu_ctrl_type type)
+{
+    struct virtio_gpu_simple_resource *res;
+    struct virtio_gpu_wait_flush wf;
+
+    VIRTIO_GPU_FILL_CMD(wf);
+    virtio_gpu_bswap_32(&wf, sizeof(wf));
+
+    res = virtio_gpu_find_check_resource(g, wf.resource_id, true,
+                                         __func__, &cmd->error);
+    if (res && virtio_gpu_resource_has_sync(g, res)) {
+        virtio_gpu_resource_wait_sync(g, res);
+    }
+
+    virtio_gpu_ctrl_response_nodata(g, cmd, VIRTIO_GPU_RESP_OK_NODATA);
+}
+
+static void virtio_gpu_process_fenceq(VirtIOGPU *g)
+{
+    struct virtio_gpu_ctrl_command *cmd, *tmp;
+
+    QTAILQ_FOREACH_SAFE(cmd, &g->fenceq, next, tmp) {
+        trace_virtio_gpu_fence_resp(cmd->cmd_hdr.fence_id);
+        virtio_gpu_signal_fence(g, cmd, VIRTIO_GPU_RESP_OK_NODATA);
+        QTAILQ_REMOVE(&g->fenceq, cmd, next);
+
+        g_free(cmd);
+        g->inflight--;
+        if (virtio_gpu_stats_enabled(g->parent_obj.conf)) {
+            fprintf(stderr, "inflight: %3d (-)\r", g->inflight);
+        }
+    }
+}
+
+static void virtio_gpu_gl_flushed(VirtIOGPU *g)
+{
+    if (virtio_gpu_expflush_enabled(g->parent_obj.conf)) {
+        virtio_gpu_process_fenceq(g);
+    }
+}
+
 static void virtio_gpu_handle_ctrl(VirtIODevice *vdev, VirtQueue *vq)
 {
     VirtIOGPU *g = VIRTIO_GPU(vdev);
@@ -1445,6 +1489,7 @@ static void virtio_gpu_class_init(ObjectClass *klass, void *data)
     vgc->handle_ctrl = virtio_gpu_handle_ctrl;
     vgc->process_cmd = virtio_gpu_simple_process_cmd;
     vgc->update_cursor_data = virtio_gpu_update_cursor_data;
+    vgc->gl_flushed = virtio_gpu_gl_flushed;
 
     vdc->realize = virtio_gpu_device_realize;
     vdc->reset = virtio_gpu_reset;
diff --git a/include/hw/virtio/virtio-gpu.h b/include/hw/virtio/virtio-gpu.h
index 41f74e9286..59edd6da7f 100644
--- a/include/hw/virtio/virtio-gpu.h
+++ b/include/hw/virtio/virtio-gpu.h
@@ -202,6 +202,7 @@ struct VirtIOGPUClass {
     void (*update_cursor_data)(VirtIOGPU *g,
                                struct virtio_gpu_scanout *s,
                                uint32_t resource_id);
+    void (*gl_flushed)(VirtIOGPU *g);
 };
 
 struct VirtIOGPUGL {
-- 
2.30.2