qapi/monitor: only allow 'keep' SetPasswordAction for VNC and deprecate

VNC only supports 'keep' here, enforce this via a seperate
SetPasswordActionVnc enum and mark the option 'deprecated' (as it is
useless with only one value possible).

Also add a deprecation note to docs.

Suggested-by: Eric Blake <eblake@redhat.com>
Reviewed-by: Markus Armbruster <armbru@redhat.com>
Signed-off-by: Stefan Reiter <s.reiter@proxmox.com>
Message-Id: <20211021100135.4146766-5-s.reiter@proxmox.com>
Acked-by: Gerd Hoffmann <kraxel@redhat.com>
Signed-off-by: Markus Armbruster <armbru@redhat.com>

docs/about/deprecated.rst

@@ -234,6 +234,12 @@ single ``bitmap``, the new ``block-export-add`` uses a list of ``bitmaps``.
 Member ``values`` in return value elements with meta-type ``enum`` is
 deprecated.  Use ``members`` instead.
 
+``set_password`` argument ``connected`` for VNC protocol (since 6.2)
+''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''
+
+Only the value ``keep`` is and was ever supported for VNC. The (useless)
+argument will be dropped in a future version of QEMU.
+
 System accelerators
 -------------------
 

monitor/qmp-cmds.c

@@ -176,11 +176,6 @@ void qmp_set_password(SetPasswordOptions *opts, Error **errp)
                 opts->u.spice.connected == SET_PASSWORD_ACTION_DISCONNECT);
     } else {
         assert(opts->protocol == DISPLAY_PROTOCOL_VNC);
-        if (opts->u.vnc.connected != SET_PASSWORD_ACTION_KEEP) {
-            /* vnc supports "connected=keep" only */
-            error_setg(errp, QERR_INVALID_PARAMETER, "connected");
-            return;
-        }
         /* Note that setting an empty password will not disable login through
          * this interface. */
         rc = vnc_display_password(opts->u.vnc.display, opts->password);

qapi/ui.json

@@ -38,6 +38,20 @@
 { 'enum': 'SetPasswordAction',
   'data': [ 'fail', 'disconnect', 'keep' ] }
 
+##
+# @SetPasswordActionVnc:
+#
+# See @SetPasswordAction. VNC only supports the keep action. 'connection'
+# should just be omitted for VNC, this is kept for backwards compatibility.
+#
+# @keep: maintain existing clients
+#
+# Since: 6.2
+#
+##
+{ 'enum': 'SetPasswordActionVnc',
+  'data': [ 'keep' ] }
+
 ##
 # @SetPasswordOptions:
 #
@@ -83,12 +97,17 @@
 # @connected: How to handle existing clients when changing the
 #             password.
 #
+# Features:
+# @deprecated: For VNC, @connected will always be 'keep', parameter should be
+#              omitted.
+#
 # Since: 6.2
 #
 ##
 { 'struct': 'SetPasswordOptionsVnc',
   'data': { '*display': 'str',
-            '*connected': 'SetPasswordAction' }}
+            '*connected': { 'type': 'SetPasswordActionVnc',
+                            'features': ['deprecated'] } } }
 
 ##
 # @set_password: