virtio-gpu: avoid re-entering cmdq processing

The next patch will notify the GL context got flush, which will resume
the queue processing. However, if this happens within the caller
context, it will end up with a stack overflow flush/update loop.

Signed-off-by: Marc-André Lureau <marcandre.lureau@redhat.com>
Message-Id: <20210204105232.834642-18-marcandre.lureau@redhat.com>
Signed-off-by: Gerd Hoffmann <kraxel@redhat.com>

2 files changed, 6 insertions, 0 deletions

diff --git a/hw/display/virtio-gpu.c b/hw/display/virtio-gpu.c
index 0e833a4..7eb4265 100644
--- a/hw/display/virtio-gpu.c
+++ b/hw/display/virtio-gpu.c
@@ -814,6 +814,10 @@ void virtio_gpu_process_cmdq(VirtIOGPU *g)
 {
     struct virtio_gpu_ctrl_command *cmd;
 
+    if (g->processing_cmdq) {
+        return;
+    }
+    g->processing_cmdq = true;
     while (!QTAILQ_EMPTY(&g->cmdq)) {
         cmd = QTAILQ_FIRST(&g->cmdq);
 
@@ -843,6 +847,7 @@ void virtio_gpu_process_cmdq(VirtIOGPU *g)
             g_free(cmd);
         }
     }
+    g->processing_cmdq = false;
 }
 
 static void virtio_gpu_gl_unblock(VirtIOGPUBase *b)
diff --git a/include/hw/virtio/virtio-gpu.h b/include/hw/virtio/virtio-gpu.h
index 4f3dbf7..0043268 100644
--- a/include/hw/virtio/virtio-gpu.h
+++ b/include/hw/virtio/virtio-gpu.h
@@ -148,6 +148,7 @@ struct VirtIOGPU {
 
     uint64_t hostmem;
 
+    bool processing_cmdq;
     bool renderer_inited;
     bool renderer_reset;
     QEMUTimer *fence_poll;