virtio-gpu: replace the surface with null surface when resetting

The primary guest scanout shows the booting screen right after reboot
but additional guest displays (i.e. max_ouptuts > 1) will keep displaying
the old frames until the guest virtio gpu driver gets initialized, which
could cause some confusion. A better way is to to replace the surface with
a place holder that tells the display is not active during the reset of
virtio-gpu device.

And to immediately update the surface with the place holder image after
the switch, displaychangelistener_gfx_switch needs to be called with
'update == TRUE' in dpy_gfx_replace_surface when the new surface is NULL.

Cc: Gerd Hoffmann <kraxel@redhat.com>
Cc: Marc-André Lureau <marcandre.lureau@redhat.com>
Cc: Vivek Kasireddy <vivek.kasireddy@intel.com>
Signed-off-by: Dongwon Kim <dongwon.kim@intel.com>
Acked-by: Marc-André Lureau <marcandre.lureau@redhat.com>
Message-ID: <20230627224451.11739-1-dongwon.kim@intel.com>

1 files changed, 6 insertions, 5 deletions

diff --git a/ui/console.c b/ui/console.c
index c1544e0..8da2170 100644
--- a/ui/console.c
+++ b/ui/console.c
@@ -1898,6 +1898,7 @@ void dpy_gfx_replace_surface(QemuConsole *con,
     static const char placeholder_msg[] = "Display output is not active.";
     DisplayState *s = con->ds;
     DisplaySurface *old_surface = con->surface;
+    DisplaySurface *new_surface = surface;
     DisplayChangeListener *dcl;
     int width;
     int height;
@@ -1911,19 +1912,19 @@ void dpy_gfx_replace_surface(QemuConsole *con,
             height = 480;
         }
 
-        surface = qemu_create_placeholder_surface(width, height, placeholder_msg);
+        new_surface = qemu_create_placeholder_surface(width, height, placeholder_msg);
     }
 
-    assert(old_surface != surface);
+    assert(old_surface != new_surface);
 
     con->scanout.kind = SCANOUT_SURFACE;
-    con->surface = surface;
-    dpy_gfx_create_texture(con, surface);
+    con->surface = new_surface;
+    dpy_gfx_create_texture(con, new_surface);
     QLIST_FOREACH(dcl, &s->listeners, next) {
         if (con != (dcl->con ? dcl->con : active_console)) {
             continue;
         }
-        displaychangelistener_gfx_switch(dcl, surface, FALSE);
+        displaychangelistener_gfx_switch(dcl, new_surface, surface ? FALSE : TRUE);
     }
     dpy_gfx_destroy_texture(con, old_surface);
     qemu_free_displaysurface(old_surface);