xen-bus/block: explicitly assign event channels to an AioContext
[qemu.git] / monitor / qmp.c
blob8379c8f96e0682aa73348ec4c28ceb5d81855b94
1 /*
2 * QEMU monitor
4 * Copyright (c) 2003-2004 Fabrice Bellard
6 * Permission is hereby granted, free of charge, to any person obtaining a copy
7 * of this software and associated documentation files (the "Software"), to deal
8 * in the Software without restriction, including without limitation the rights
9 * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
10 * copies of the Software, and to permit persons to whom the Software is
11 * furnished to do so, subject to the following conditions:
13 * The above copyright notice and this permission notice shall be included in
14 * all copies or substantial portions of the Software.
16 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
17 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
18 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
19 * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
20 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
21 * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
22 * THE SOFTWARE.
25 #include "qemu/osdep.h"
27 #include "chardev/char-io.h"
28 #include "monitor-internal.h"
29 #include "qapi/error.h"
30 #include "qapi/qapi-commands-control.h"
31 #include "qapi/qmp/qdict.h"
32 #include "qapi/qmp/qjson.h"
33 #include "qapi/qmp/qlist.h"
34 #include "qapi/qmp/qstring.h"
35 #include "trace.h"
37 struct QMPRequest {
38 /* Owner of the request */
39 MonitorQMP *mon;
41 * Request object to be handled or Error to be reported
42 * (exactly one of them is non-null)
44 QObject *req;
45 Error *err;
47 typedef struct QMPRequest QMPRequest;
49 QmpCommandList qmp_commands, qmp_cap_negotiation_commands;
51 static bool qmp_oob_enabled(MonitorQMP *mon)
53 return mon->capab[QMP_CAPABILITY_OOB];
56 static void monitor_qmp_caps_reset(MonitorQMP *mon)
58 memset(mon->capab_offered, 0, sizeof(mon->capab_offered));
59 memset(mon->capab, 0, sizeof(mon->capab));
60 mon->capab_offered[QMP_CAPABILITY_OOB] = mon->common.use_io_thread;
63 static void qmp_request_free(QMPRequest *req)
65 qobject_unref(req->req);
66 error_free(req->err);
67 g_free(req);
70 /* Caller must hold mon->qmp.qmp_queue_lock */
71 static void monitor_qmp_cleanup_req_queue_locked(MonitorQMP *mon)
73 while (!g_queue_is_empty(mon->qmp_requests)) {
74 qmp_request_free(g_queue_pop_head(mon->qmp_requests));
78 static void monitor_qmp_cleanup_queue_and_resume(MonitorQMP *mon)
80 qemu_mutex_lock(&mon->qmp_queue_lock);
83 * Same condition as in monitor_qmp_bh_dispatcher(), but before
84 * removing an element from the queue (hence no `- 1`).
85 * Also, the queue should not be empty either, otherwise the
86 * monitor hasn't been suspended yet (or was already resumed).
88 bool need_resume = (!qmp_oob_enabled(mon) ||
89 mon->qmp_requests->length == QMP_REQ_QUEUE_LEN_MAX)
90 && !g_queue_is_empty(mon->qmp_requests);
92 monitor_qmp_cleanup_req_queue_locked(mon);
94 if (need_resume) {
96 * handle_qmp_command() suspended the monitor because the
97 * request queue filled up, to be resumed when the queue has
98 * space again. We just emptied it; resume the monitor.
100 * Without this, the monitor would remain suspended forever
101 * when we get here while the monitor is suspended. An
102 * unfortunately timed CHR_EVENT_CLOSED can do the trick.
104 monitor_resume(&mon->common);
107 qemu_mutex_unlock(&mon->qmp_queue_lock);
110 void qmp_send_response(MonitorQMP *mon, const QDict *rsp)
112 const QObject *data = QOBJECT(rsp);
113 QString *json;
115 json = mon->pretty ? qobject_to_json_pretty(data) : qobject_to_json(data);
116 assert(json != NULL);
118 qstring_append_chr(json, '\n');
119 monitor_puts(&mon->common, qstring_get_str(json));
121 qobject_unref(json);
125 * Emit QMP response @rsp to @mon.
126 * Null @rsp can only happen for commands with QCO_NO_SUCCESS_RESP.
127 * Nothing is emitted then.
129 static void monitor_qmp_respond(MonitorQMP *mon, QDict *rsp)
131 if (rsp) {
132 qmp_send_response(mon, rsp);
136 static void monitor_qmp_dispatch(MonitorQMP *mon, QObject *req)
138 Monitor *old_mon;
139 QDict *rsp;
140 QDict *error;
142 old_mon = cur_mon;
143 cur_mon = &mon->common;
145 rsp = qmp_dispatch(mon->commands, req, qmp_oob_enabled(mon));
147 cur_mon = old_mon;
149 if (mon->commands == &qmp_cap_negotiation_commands) {
150 error = qdict_get_qdict(rsp, "error");
151 if (error
152 && !g_strcmp0(qdict_get_try_str(error, "class"),
153 QapiErrorClass_str(ERROR_CLASS_COMMAND_NOT_FOUND))) {
154 /* Provide a more useful error message */
155 qdict_del(error, "desc");
156 qdict_put_str(error, "desc", "Expecting capabilities negotiation"
157 " with 'qmp_capabilities'");
161 monitor_qmp_respond(mon, rsp);
162 qobject_unref(rsp);
166 * Pop a QMP request from a monitor request queue.
167 * Return the request, or NULL all request queues are empty.
168 * We are using round-robin fashion to pop the request, to avoid
169 * processing commands only on a very busy monitor. To achieve that,
170 * when we process one request on a specific monitor, we put that
171 * monitor to the end of mon_list queue.
173 * Note: if the function returned with non-NULL, then the caller will
174 * be with qmp_mon->qmp_queue_lock held, and the caller is responsible
175 * to release it.
177 static QMPRequest *monitor_qmp_requests_pop_any_with_lock(void)
179 QMPRequest *req_obj = NULL;
180 Monitor *mon;
181 MonitorQMP *qmp_mon;
183 qemu_mutex_lock(&monitor_lock);
185 QTAILQ_FOREACH(mon, &mon_list, entry) {
186 if (!monitor_is_qmp(mon)) {
187 continue;
190 qmp_mon = container_of(mon, MonitorQMP, common);
191 qemu_mutex_lock(&qmp_mon->qmp_queue_lock);
192 req_obj = g_queue_pop_head(qmp_mon->qmp_requests);
193 if (req_obj) {
194 /* With the lock of corresponding queue held */
195 break;
197 qemu_mutex_unlock(&qmp_mon->qmp_queue_lock);
200 if (req_obj) {
202 * We found one request on the monitor. Degrade this monitor's
203 * priority to lowest by re-inserting it to end of queue.
205 QTAILQ_REMOVE(&mon_list, mon, entry);
206 QTAILQ_INSERT_TAIL(&mon_list, mon, entry);
209 qemu_mutex_unlock(&monitor_lock);
211 return req_obj;
214 void monitor_qmp_bh_dispatcher(void *data)
216 QMPRequest *req_obj = monitor_qmp_requests_pop_any_with_lock();
217 QDict *rsp;
218 bool need_resume;
219 MonitorQMP *mon;
221 if (!req_obj) {
222 return;
225 mon = req_obj->mon;
226 /* qmp_oob_enabled() might change after "qmp_capabilities" */
227 need_resume = !qmp_oob_enabled(mon) ||
228 mon->qmp_requests->length == QMP_REQ_QUEUE_LEN_MAX - 1;
229 qemu_mutex_unlock(&mon->qmp_queue_lock);
230 if (req_obj->req) {
231 QDict *qdict = qobject_to(QDict, req_obj->req);
232 QObject *id = qdict ? qdict_get(qdict, "id") : NULL;
233 trace_monitor_qmp_cmd_in_band(qobject_get_try_str(id) ?: "");
234 monitor_qmp_dispatch(mon, req_obj->req);
235 } else {
236 assert(req_obj->err);
237 rsp = qmp_error_response(req_obj->err);
238 req_obj->err = NULL;
239 monitor_qmp_respond(mon, rsp);
240 qobject_unref(rsp);
243 if (need_resume) {
244 /* Pairs with the monitor_suspend() in handle_qmp_command() */
245 monitor_resume(&mon->common);
247 qmp_request_free(req_obj);
249 /* Reschedule instead of looping so the main loop stays responsive */
250 qemu_bh_schedule(qmp_dispatcher_bh);
253 static void handle_qmp_command(void *opaque, QObject *req, Error *err)
255 MonitorQMP *mon = opaque;
256 QObject *id = NULL;
257 QDict *qdict;
258 QMPRequest *req_obj;
260 assert(!req != !err);
262 qdict = qobject_to(QDict, req);
263 if (qdict) {
264 id = qdict_get(qdict, "id");
265 } /* else will fail qmp_dispatch() */
267 if (req && trace_event_get_state_backends(TRACE_HANDLE_QMP_COMMAND)) {
268 QString *req_json = qobject_to_json(req);
269 trace_handle_qmp_command(mon, qstring_get_str(req_json));
270 qobject_unref(req_json);
273 if (qdict && qmp_is_oob(qdict)) {
274 /* OOB commands are executed immediately */
275 trace_monitor_qmp_cmd_out_of_band(qobject_get_try_str(id) ?: "");
276 monitor_qmp_dispatch(mon, req);
277 qobject_unref(req);
278 return;
281 req_obj = g_new0(QMPRequest, 1);
282 req_obj->mon = mon;
283 req_obj->req = req;
284 req_obj->err = err;
286 /* Protect qmp_requests and fetching its length. */
287 qemu_mutex_lock(&mon->qmp_queue_lock);
290 * Suspend the monitor when we can't queue more requests after
291 * this one. Dequeuing in monitor_qmp_bh_dispatcher() or
292 * monitor_qmp_cleanup_queue_and_resume() will resume it.
293 * Note that when OOB is disabled, we queue at most one command,
294 * for backward compatibility.
296 if (!qmp_oob_enabled(mon) ||
297 mon->qmp_requests->length == QMP_REQ_QUEUE_LEN_MAX - 1) {
298 monitor_suspend(&mon->common);
302 * Put the request to the end of queue so that requests will be
303 * handled in time order. Ownership for req_obj, req,
304 * etc. will be delivered to the handler side.
306 assert(mon->qmp_requests->length < QMP_REQ_QUEUE_LEN_MAX);
307 g_queue_push_tail(mon->qmp_requests, req_obj);
308 qemu_mutex_unlock(&mon->qmp_queue_lock);
310 /* Kick the dispatcher routine */
311 qemu_bh_schedule(qmp_dispatcher_bh);
314 static void monitor_qmp_read(void *opaque, const uint8_t *buf, int size)
316 MonitorQMP *mon = opaque;
318 json_message_parser_feed(&mon->parser, (const char *) buf, size);
321 static QDict *qmp_greeting(MonitorQMP *mon)
323 QList *cap_list = qlist_new();
324 QObject *ver = NULL;
325 QMPCapability cap;
327 qmp_marshal_query_version(NULL, &ver, NULL);
329 for (cap = 0; cap < QMP_CAPABILITY__MAX; cap++) {
330 if (mon->capab_offered[cap]) {
331 qlist_append_str(cap_list, QMPCapability_str(cap));
335 return qdict_from_jsonf_nofail(
336 "{'QMP': {'version': %p, 'capabilities': %p}}",
337 ver, cap_list);
340 static void monitor_qmp_event(void *opaque, QEMUChrEvent event)
342 QDict *data;
343 MonitorQMP *mon = opaque;
345 switch (event) {
346 case CHR_EVENT_OPENED:
347 mon->commands = &qmp_cap_negotiation_commands;
348 monitor_qmp_caps_reset(mon);
349 data = qmp_greeting(mon);
350 qmp_send_response(mon, data);
351 qobject_unref(data);
352 mon_refcount++;
353 break;
354 case CHR_EVENT_CLOSED:
356 * Note: this is only useful when the output of the chardev
357 * backend is still open. For example, when the backend is
358 * stdio, it's possible that stdout is still open when stdin
359 * is closed.
361 monitor_qmp_cleanup_queue_and_resume(mon);
362 json_message_parser_destroy(&mon->parser);
363 json_message_parser_init(&mon->parser, handle_qmp_command,
364 mon, NULL);
365 mon_refcount--;
366 monitor_fdsets_cleanup();
367 break;
368 case CHR_EVENT_BREAK:
369 case CHR_EVENT_MUX_IN:
370 case CHR_EVENT_MUX_OUT:
371 /* Ignore */
372 break;
376 void monitor_data_destroy_qmp(MonitorQMP *mon)
378 json_message_parser_destroy(&mon->parser);
379 qemu_mutex_destroy(&mon->qmp_queue_lock);
380 monitor_qmp_cleanup_req_queue_locked(mon);
381 g_queue_free(mon->qmp_requests);
384 static void monitor_qmp_setup_handlers_bh(void *opaque)
386 MonitorQMP *mon = opaque;
387 GMainContext *context;
389 assert(mon->common.use_io_thread);
390 context = iothread_get_g_main_context(mon_iothread);
391 assert(context);
392 qemu_chr_fe_set_handlers(&mon->common.chr, monitor_can_read,
393 monitor_qmp_read, monitor_qmp_event,
394 NULL, &mon->common, context, true);
395 monitor_list_append(&mon->common);
398 void monitor_init_qmp(Chardev *chr, bool pretty)
400 MonitorQMP *mon = g_new0(MonitorQMP, 1);
402 /* Note: we run QMP monitor in I/O thread when @chr supports that */
403 monitor_data_init(&mon->common, true, false,
404 qemu_chr_has_feature(chr, QEMU_CHAR_FEATURE_GCONTEXT));
406 mon->pretty = pretty;
408 qemu_mutex_init(&mon->qmp_queue_lock);
409 mon->qmp_requests = g_queue_new();
411 qemu_chr_fe_init(&mon->common.chr, chr, &error_abort);
412 qemu_chr_fe_set_echo(&mon->common.chr, true);
414 json_message_parser_init(&mon->parser, handle_qmp_command, mon, NULL);
415 if (mon->common.use_io_thread) {
417 * Make sure the old iowatch is gone. It's possible when
418 * e.g. the chardev is in client mode, with wait=on.
420 remove_fd_in_watch(chr);
422 * We can't call qemu_chr_fe_set_handlers() directly here
423 * since chardev might be running in the monitor I/O
424 * thread. Schedule a bottom half.
426 aio_bh_schedule_oneshot(iothread_get_aio_context(mon_iothread),
427 monitor_qmp_setup_handlers_bh, mon);
428 /* The bottom half will add @mon to @mon_list */
429 } else {
430 qemu_chr_fe_set_handlers(&mon->common.chr, monitor_can_read,
431 monitor_qmp_read, monitor_qmp_event,
432 NULL, &mon->common, NULL, true);
433 monitor_list_append(&mon->common);