qapi: introduce new cmd option "allow-preconfig"

New option will be used to allow commands, which are prepared/need
to run, during preconfig state. Other commands that should be able
to run in preconfig state, should be amended to not expect machine
in initialized state or deal with it.

For compatibility reasons, commands that don't use new flag
'allow-preconfig' explicitly are not permitted to run in
preconfig state but allowed in all other states like they used
to be.

Within this patch allow following commands in preconfig state:
   qmp_capabilities
   query-qmp-schema
   query-commands
   query-command-line-options
   query-status
   exit-preconfig
to allow qmp connection, basic introspection and moving to the next
state.

PS:
set-numa-node and query-hotpluggable-cpus will be enabled later in
a separate patches.

Signed-off-by: Igor Mammedov <imammedo@redhat.com>
Message-Id: <1526057503-39287-1-git-send-email-imammedo@redhat.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
[ehabkost: Changed "since 2.13" to "since 3.0"]
Signed-off-by: Eduardo Habkost <ehabkost@redhat.com>

docs/devel/qapi-code-gen.txt

@@ -559,7 +559,7 @@ following example objects:
 Usage: { 'command': STRING, '*data': COMPLEX-TYPE-NAME-OR-DICT,
          '*returns': TYPE-NAME, '*boxed': true,
          '*gen': false, '*success-response': false,
-         '*allow-oob': true }
+         '*allow-oob': true, '*allow-preconfig': true }
 
 Commands are defined by using a dictionary containing several members,
 where three members are most common.  The 'command' member is a
@@ -683,6 +683,15 @@ OOB command handlers must satisfy the following conditions:
 
 If in doubt, do not implement OOB execution support.
 
+A command may use the optional 'allow-preconfig' key to permit its execution
+at early runtime configuration stage (preconfig runstate).
+If not specified then a command defaults to 'allow-preconfig': false.
+
+An example of declaring a command that is enabled during preconfig:
+ { 'command': 'qmp_capabilities',
+   'data': { '*enable': [ 'QMPCapability' ] },
+   'allow-preconfig': true }
+
 === Events ===
 
 Usage: { 'event': STRING, '*data': COMPLEX-TYPE-NAME-OR-DICT,

include/qapi/qmp/dispatch.h

@@ -23,6 +23,7 @@ typedef enum QmpCommandOptions
     QCO_NO_OPTIONS            =  0x0,
     QCO_NO_SUCCESS_RESP       =  (1U << 0),
     QCO_ALLOW_OOB             =  (1U << 1),
+    QCO_ALLOW_PRECONFIG       =  (1U << 2),
 } QmpCommandOptions;
 
 typedef struct QmpCommand

monitor.c

@@ -1179,8 +1179,7 @@ static void monitor_init_qmp_commands(void)
     qmp_init_marshal(&qmp_commands);
 
     qmp_register_command(&qmp_commands, "query-qmp-schema",
-                         qmp_query_qmp_schema,
-                         QCO_NO_OPTIONS);
+                         qmp_query_qmp_schema, QCO_ALLOW_PRECONFIG);
     qmp_register_command(&qmp_commands, "device_add", qmp_device_add,
                          QCO_NO_OPTIONS);
     qmp_register_command(&qmp_commands, "netdev_add", qmp_netdev_add,
@@ -1190,7 +1189,7 @@ static void monitor_init_qmp_commands(void)
 
     QTAILQ_INIT(&qmp_cap_negotiation_commands);
     qmp_register_command(&qmp_cap_negotiation_commands, "qmp_capabilities",
-                         qmp_marshal_qmp_capabilities, QCO_NO_OPTIONS);
+                         qmp_marshal_qmp_capabilities, QCO_ALLOW_PRECONFIG);
 }
 
 static bool qmp_cap_enabled(Monitor *mon, QMPCapability cap)

qapi/introspect.json

@@ -262,13 +262,16 @@
 # @allow-oob: whether the command allows out-of-band execution.
 #             (Since: 2.12)
 #
+# @allow-preconfig: command can be executed in preconfig runstate,
+#                   default: false (Since 3.0)
+#
 # TODO: @success-response (currently irrelevant, because it's QGA, not QMP)
 #
 # Since: 2.5
 ##
 { 'struct': 'SchemaInfoCommand',
   'data': { 'arg-type': 'str', 'ret-type': 'str',
-            'allow-oob': 'bool' } }
+            'allow-oob': 'bool', 'allow-preconfig': 'bool' } }
 
 ##
 # @SchemaInfoEvent:

qapi/misc.json

@@ -37,7 +37,8 @@
 #
 ##
 { 'command': 'qmp_capabilities',
-  'data': { '*enable': [ 'QMPCapability' ] } }
+  'data': { '*enable': [ 'QMPCapability' ] },
+  'allow-preconfig': true }
 
 ##
 # @QMPCapability:
@@ -155,7 +156,8 @@
 # Note: This example has been shortened as the real response is too long.
 #
 ##
-{ 'command': 'query-commands', 'returns': ['CommandInfo'] }
+{ 'command': 'query-commands', 'returns': ['CommandInfo'],
+  'allow-preconfig': true }
 
 ##
 # @LostTickPolicy:
@@ -2648,7 +2650,8 @@
 #
 ##
 {'command': 'query-command-line-options', 'data': { '*option': 'str' },
- 'returns': ['CommandLineOptionInfo'] }
+ 'returns': ['CommandLineOptionInfo'],
+ 'allow-preconfig': true }
 
 ##
 # @X86CPURegister32:

qapi/run-state.json

@@ -94,7 +94,8 @@
 #                  "status": "running" } }
 #
 ##
-{ 'command': 'query-status', 'returns': 'StatusInfo' }
+{ 'command': 'query-status', 'returns': 'StatusInfo',
+  'allow-preconfig': true }
 
 ##
 # @SHUTDOWN:

scripts/qapi/commands.py

@@ -193,13 +193,15 @@ def gen_marshal(name, arg_type, boxed, ret_type):
     return ret
 
 
-def gen_register_command(name, success_response, allow_oob):
+def gen_register_command(name, success_response, allow_oob, allow_preconfig):
     options = []
 
     if not success_response:
         options += ['QCO_NO_SUCCESS_RESP']
     if allow_oob:
         options += ['QCO_ALLOW_OOB']
+    if allow_preconfig:
+        options += ['QCO_ALLOW_PRECONFIG']
 
     if not options:
         options = ['QCO_NO_OPTIONS']
@@ -275,8 +277,8 @@ def visit_end(self):
                        c_prefix=c_name(self._prefix, protect=False)))
         genc.add(gen_registry(self._regy, self._prefix))
 
-    def visit_command(self, name, info, arg_type, ret_type,
-                      gen, success_response, boxed, allow_oob):
+    def visit_command(self, name, info, arg_type, ret_type, gen,
+                      success_response, boxed, allow_oob, allow_preconfig):
         if not gen:
             return
         self._genh.add(gen_command_decl(name, arg_type, boxed, ret_type))
@@ -285,7 +287,8 @@ def visit_command(self, name, info, arg_type, ret_type,
             self._genc.add(gen_marshal_output(ret_type))
         self._genh.add(gen_marshal_decl(name))
         self._genc.add(gen_marshal(name, arg_type, boxed, ret_type))
-        self._regy += gen_register_command(name, success_response, allow_oob)
+        self._regy += gen_register_command(name, success_response, allow_oob,
+                                           allow_preconfig)
 
 
 def gen_commands(schema, output_dir, prefix):

scripts/qapi/common.py

@@ -872,7 +872,8 @@ def check_keys(expr_elem, meta, required, optional=[]):
             raise QAPISemError(info,
                                "'%s' of %s '%s' should only use false value"
                                % (key, meta, name))
-        if (key == 'boxed' or key == 'allow-oob') and value is not True:
+        if (key == 'boxed' or key == 'allow-oob' or
+            key == 'allow-preconfig') and value is not True:
             raise QAPISemError(info,
                                "'%s' of %s '%s' should only use true value"
                                % (key, meta, name))
@@ -922,7 +923,7 @@ def check_exprs(exprs):
             meta = 'command'
             check_keys(expr_elem, 'command', [],
                        ['data', 'returns', 'gen', 'success-response',
-                        'boxed', 'allow-oob'])
+                        'boxed', 'allow-oob', 'allow-preconfig'])
         elif 'event' in expr:
             meta = 'event'
             check_keys(expr_elem, 'event', [], ['data', 'boxed'])
@@ -1044,8 +1045,8 @@ def visit_object_type_flat(self, name, info, members, variants):
     def visit_alternate_type(self, name, info, variants):
         pass
 
-    def visit_command(self, name, info, arg_type, ret_type,
-                      gen, success_response, boxed, allow_oob):
+    def visit_command(self, name, info, arg_type, ret_type, gen,
+                      success_response, boxed, allow_oob, allow_preconfig):
         pass
 
     def visit_event(self, name, info, arg_type, boxed):
@@ -1422,7 +1423,7 @@ def is_empty(self):
 
 class QAPISchemaCommand(QAPISchemaEntity):
     def __init__(self, name, info, doc, arg_type, ret_type,
-                 gen, success_response, boxed, allow_oob):
+                 gen, success_response, boxed, allow_oob, allow_preconfig):
         QAPISchemaEntity.__init__(self, name, info, doc)
         assert not arg_type or isinstance(arg_type, str)
         assert not ret_type or isinstance(ret_type, str)
@@ -1434,6 +1435,7 @@ def __init__(self, name, info, doc, arg_type, ret_type,
         self.success_response = success_response
         self.boxed = boxed
         self.allow_oob = allow_oob
+        self.allow_preconfig = allow_preconfig
 
     def check(self, schema):
         if self._arg_type_name:
@@ -1458,7 +1460,8 @@ def visit(self, visitor):
         visitor.visit_command(self.name, self.info,
                               self.arg_type, self.ret_type,
                               self.gen, self.success_response,
-                              self.boxed, self.allow_oob)
+                              self.boxed, self.allow_oob,
+                              self.allow_preconfig)
 
 
 class QAPISchemaEvent(QAPISchemaEntity):
@@ -1678,6 +1681,7 @@ def _def_command(self, expr, info, doc):
         success_response = expr.get('success-response', True)
         boxed = expr.get('boxed', False)
         allow_oob = expr.get('allow-oob', False)
+        allow_preconfig = expr.get('allow-preconfig', False)
         if isinstance(data, OrderedDict):
             data = self._make_implicit_object_type(
                 name, info, doc, 'arg', self._make_members(data, info))
@@ -1686,7 +1690,7 @@ def _def_command(self, expr, info, doc):
             rets = self._make_array_type(rets[0], info)
         self._def_entity(QAPISchemaCommand(name, info, doc, data, rets,
                                            gen, success_response,
-                                           boxed, allow_oob))
+                                           boxed, allow_oob, allow_preconfig))
 
     def _def_event(self, expr, info, doc):
         name = expr['event']

scripts/qapi/doc.py

@@ -226,8 +226,8 @@ def visit_alternate_type(self, name, info, variants):
                                name=doc.symbol,
                                body=texi_entity(doc, 'Members')))
 
-    def visit_command(self, name, info, arg_type, ret_type,
-                      gen, success_response, boxed, allow_oob):
+    def visit_command(self, name, info, arg_type, ret_type, gen,
+                      success_response, boxed, allow_oob, allow_preconfig):
         doc = self.cur_doc
         if boxed:
             body = texi_body(doc)

scripts/qapi/introspect.py

@@ -171,14 +171,15 @@ def visit_alternate_type(self, name, info, variants):
                        {'members': [{'type': self._use_type(m.type)}
                                     for m in variants.variants]})
 
-    def visit_command(self, name, info, arg_type, ret_type,
-                      gen, success_response, boxed, allow_oob):
+    def visit_command(self, name, info, arg_type, ret_type, gen,
+                      success_response, boxed, allow_oob, allow_preconfig):
         arg_type = arg_type or self._schema.the_empty_object_type
         ret_type = ret_type or self._schema.the_empty_object_type
         self._gen_qlit(name, 'command',
                        {'arg-type': self._use_type(arg_type),
                         'ret-type': self._use_type(ret_type),
-                        'allow-oob': allow_oob})
+                        'allow-oob': allow_oob,
+                        'allow-preconfig': allow_preconfig})
 
     def visit_event(self, name, info, arg_type, boxed):
         arg_type = arg_type or self._schema.the_empty_object_type

tests/qapi-schema/test-qapi.py

@@ -41,8 +41,8 @@ def visit_alternate_type(self, name, info, variants):
         print('alternate %s' % name)
         self._print_variants(variants)
 
-    def visit_command(self, name, info, arg_type, ret_type,
-                      gen, success_response, boxed, allow_oob):
+    def visit_command(self, name, info, arg_type, ret_type, gen,
+                      success_response, boxed, allow_oob, allow_preconfig):
         print('command %s %s -> %s' % \
               (name, arg_type and arg_type.name, ret_type and ret_type.name))
         print('   gen=%s success_response=%s boxed=%s oob=%s' % \