qmp: add new qmp display-reload

This patch provides a new qmp to reload display configuration
without restart VM, but only reloading the vnc tls certificates
is implemented.
Example:
{"execute": "display-reload", "arguments":{"type": "vnc", "tls-certs": true}}

Signed-off-by: Zihao Chang <changzihao1@huawei.com>
Message-Id: <20210316075845.1476-4-changzihao1@huawei.com>
Signed-off-by: Gerd Hoffmann <kraxel@redhat.com>

monitor/qmp-cmds.c

@@ -334,3 +334,20 @@ MemoryInfo *qmp_query_memory_size_summary(Error **errp)
 
     return mem_info;
 }
+
+void qmp_display_reload(DisplayReloadOptions *arg, Error **errp)
+{
+    switch (arg->type) {
+    case DISPLAY_RELOAD_TYPE_VNC:
+#ifdef CONFIG_VNC
+        if (arg->u.vnc.has_tls_certs && arg->u.vnc.tls_certs) {
+            vnc_display_reload_certs(NULL, errp);
+        }
+#else
+        error_setg(errp, "vnc is invalid, missing 'CONFIG_VNC'");
+#endif
+        break;
+    default:
+        abort();
+    }
+}

qapi/ui.json

@@ -1168,3 +1168,64 @@
 ##
 { 'command': 'query-display-options',
   'returns': 'DisplayOptions' }
+
+##
+# @DisplayReloadType:
+#
+# Available DisplayReload types.
+#
+# @vnc: VNC display
+#
+# Since: 6.0
+#
+##
+{ 'enum': 'DisplayReloadType',
+  'data': ['vnc'] }
+
+##
+# @DisplayReloadOptionsVNC:
+#
+# Specify the VNC reload options.
+#
+# @tls-certs: reload tls certs or not.
+#
+# Since: 6.0
+#
+##
+{ 'struct': 'DisplayReloadOptionsVNC',
+  'data': { '*tls-certs': 'bool' } }
+
+##
+# @DisplayReloadOptions:
+#
+# Options of the display configuration reload.
+#
+# @type: Specify the display type.
+#
+# Since: 6.0
+#
+##
+{ 'union': 'DisplayReloadOptions',
+  'base': {'type': 'DisplayReloadType'},
+  'discriminator': 'type',
+  'data': { 'vnc': 'DisplayReloadOptionsVNC' } }
+
+##
+# @display-reload:
+#
+# Reload display configuration.
+#
+# Returns: Nothing on success.
+#
+# Since: 6.0
+#
+# Example:
+#
+# -> { "execute": "display-reload",
+#      "arguments": { "type": "vnc", "tls-certs": true  } }
+# <- { "return": {} }
+#
+##
+{ 'command': 'display-reload',
+  'data': 'DisplayReloadOptions',
+  'boxed' : true }