display/ui: add a callback to indicate GL state is flushed

Displaying rendered resources requires blocking qemu GPU to avoid extra
framebuffer copies. For an external display, via Spice currently, there
is a callback to block/unblock the rendering in the same thread.

But with the vhost-user-gpu backend, the qemu process doesn't handle
the rendering itself, and the blocking callback isn't effective.
Instead, the backend must be notified when the display code is done.

Fix this by adding a new GraphicHwOps callback to indicate the GL state
is flushed, and we are done manipulating the shared GL resources. Call
it from gtk and spice display.

Signed-off-by: Marc-André Lureau <marcandre.lureau@redhat.com>
Message-Id: <20210204105232.834642-19-marcandre.lureau@redhat.com>
Signed-off-by: Gerd Hoffmann <kraxel@redhat.com>

1 files changed, 12 insertions, 5 deletions

diff --git a/hw/display/virtio-gpu-base.c b/hw/display/virtio-gpu-base.c
index f27a6fbe75..4a57350917 100644
--- a/hw/display/virtio-gpu-base.c
+++ b/hw/display/virtio-gpu-base.c
@@ -97,21 +97,27 @@ static int virtio_gpu_ui_info(void *opaque, uint32_t idx, QemuUIInfo *info)
 }
 
 static void
-virtio_gpu_gl_block(void *opaque, bool block)
+virtio_gpu_gl_flushed(void *opaque)
 {
     VirtIOGPUBase *g = opaque;
     VirtIOGPUBaseClass *vgc = VIRTIO_GPU_BASE_GET_CLASS(g);
 
+    if (vgc->gl_flushed) {
+        vgc->gl_flushed(g);
+    }
+}
+
+static void
+virtio_gpu_gl_block(void *opaque, bool block)
+{
+    VirtIOGPUBase *g = opaque;
+
     if (block) {
         g->renderer_blocked++;
     } else {
         g->renderer_blocked--;
     }
     assert(g->renderer_blocked >= 0);
-
-    if (g->renderer_blocked == 0) {
-        vgc->gl_unblock(g);
-    }
 }
 
 static int
@@ -138,6 +144,7 @@ static const GraphicHwOps virtio_gpu_ops = {
     .text_update = virtio_gpu_text_update,
     .ui_info = virtio_gpu_ui_info,
     .gl_block = virtio_gpu_gl_block,
+    .gl_flushed = virtio_gpu_gl_flushed,
 };
 
 bool