spice: use bottom half instead of refresh timer for cursor updates

Calling directly doesn't work due to the qxl-render code running in
spice server thread context.  Meanwhile bottom half scheduling is
thread-safe though, so we can use that to kick a cursor update in
main i/o thread context.

Cc: Marc-André Lureau <marcandre.lureau@gmail.com>
Signed-off-by: NGerd Hoffmann <kraxel@redhat.com>

hw/display/qxl-render.c

@@ -283,12 +283,14 @@ int qxl_render_cursor(PCIQXLDevice *qxl, QXLCommandExt *ext)
         qxl->ssd.mouse_x = cmd->u.set.position.x;
         qxl->ssd.mouse_y = cmd->u.set.position.y;
         qemu_mutex_unlock(&qxl->ssd.lock);
+        qemu_bh_schedule(qxl->ssd.cursor_bh);
         break;
     case QXL_CURSOR_MOVE:
         qemu_mutex_lock(&qxl->ssd.lock);
         qxl->ssd.mouse_x = cmd->u.position.x;
         qxl->ssd.mouse_y = cmd->u.position.y;
         qemu_mutex_unlock(&qxl->ssd.lock);
+        qemu_bh_schedule(qxl->ssd.cursor_bh);
         break;
     }
     return 0;

hw/display/qxl.c

@@ -1861,10 +1861,6 @@ static void display_refresh(DisplayChangeListener *dcl)
 
     if (qxl->mode == QXL_MODE_VGA) {
         qemu_spice_display_refresh(&qxl->ssd);
-    } else {
-        qemu_mutex_lock(&qxl->ssd.lock);
-        qemu_spice_cursor_refresh_unlocked(&qxl->ssd);
-        qemu_mutex_unlock(&qxl->ssd.lock);
     }
 }
 
@@ -2025,6 +2021,7 @@ static int qxl_init_common(PCIQXLDevice *qxl)
     qxl_reset_state(qxl);
 
     qxl->update_area_bh = qemu_bh_new(qxl_render_update_area_bh, qxl);
+    qxl->ssd.cursor_bh = qemu_bh_new(qemu_spice_cursor_refresh_bh, &qxl->ssd);
 
     return 0;
 }

include/ui/spice-display.h

@@ -102,6 +102,7 @@ struct SimpleSpiceDisplay {
     /* cursor (with qxl): qxl local renderer -> displaychangelistener */
     QEMUCursor *cursor;
     int mouse_x, mouse_y;
+    QEMUBH *cursor_bh;
 };
 
 struct SimpleSpiceUpdate {
@@ -134,7 +135,7 @@ void qemu_spice_display_update(SimpleSpiceDisplay *ssd,
 void qemu_spice_display_switch(SimpleSpiceDisplay *ssd,
                                DisplaySurface *surface);
 void qemu_spice_display_refresh(SimpleSpiceDisplay *ssd);
-void qemu_spice_cursor_refresh_unlocked(SimpleSpiceDisplay *ssd);
+void qemu_spice_cursor_refresh_bh(void *opaque);
 
 void qemu_spice_add_memslot(SimpleSpiceDisplay *ssd, QXLDevMemSlot *memslot,
                             qxl_async_io async);

ui/spice-display.c

@@ -438,7 +438,7 @@ void qemu_spice_display_switch(SimpleSpiceDisplay *ssd,
     ssd->notify++;
 }
 
-void qemu_spice_cursor_refresh_unlocked(SimpleSpiceDisplay *ssd)
+static void qemu_spice_cursor_refresh_unlocked(SimpleSpiceDisplay *ssd)
 {
     if (ssd->cursor) {
         assert(ssd->dcl.con);
@@ -454,6 +454,15 @@ void qemu_spice_cursor_refresh_unlocked(SimpleSpiceDisplay *ssd)
     }
 }
 
+void qemu_spice_cursor_refresh_bh(void *opaque)
+{
+    SimpleSpiceDisplay *ssd = opaque;
+
+    qemu_mutex_lock(&ssd->lock);
+    qemu_spice_cursor_refresh_unlocked(ssd);
+    qemu_mutex_unlock(&ssd->lock);
+}
+
 void qemu_spice_display_refresh(SimpleSpiceDisplay *ssd)
 {
     dprint(3, "%s/%d:\n", __func__, ssd->qxl.id);
@@ -464,7 +473,6 @@ void qemu_spice_display_refresh(SimpleSpiceDisplay *ssd)
         qemu_spice_create_update(ssd);
         ssd->notify++;
     }
-    qemu_spice_cursor_refresh_unlocked(ssd);
     qemu_mutex_unlock(&ssd->lock);
 
     if (ssd->notify) {