diff options
Diffstat (limited to 'monitor/qmp.c')
| -rw-r--r-- | monitor/qmp.c | 406 |
1 files changed, 406 insertions, 0 deletions
diff --git a/monitor/qmp.c b/monitor/qmp.c new file mode 100644 index 0000000000..7c3d081a72 --- /dev/null +++ b/monitor/qmp.c @@ -0,0 +1,406 @@ +/* + * QEMU monitor + * + * Copyright (c) 2003-2004 Fabrice Bellard + * + * Permission is hereby granted, free of charge, to any person obtaining a copy + * of this software and associated documentation files (the "Software"), to deal + * in the Software without restriction, including without limitation the rights + * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell + * copies of the Software, and to permit persons to whom the Software is + * furnished to do so, subject to the following conditions: + * + * The above copyright notice and this permission notice shall be included in + * all copies or substantial portions of the Software. + * + * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR + * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, + * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL + * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER + * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, + * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN + * THE SOFTWARE. + */ + +#include "qemu/osdep.h" + +#include "chardev/char-io.h" +#include "monitor-internal.h" +#include "qapi/error.h" +#include "qapi/qapi-commands-misc.h" +#include "qapi/qmp/qdict.h" +#include "qapi/qmp/qjson.h" +#include "qapi/qmp/qlist.h" +#include "qapi/qmp/qstring.h" +#include "trace.h" + +struct QMPRequest { + /* Owner of the request */ + MonitorQMP *mon; + /* + * Request object to be handled or Error to be reported + * (exactly one of them is non-null) + */ + QObject *req; + Error *err; +}; +typedef struct QMPRequest QMPRequest; + +QmpCommandList qmp_commands, qmp_cap_negotiation_commands; + +static bool qmp_oob_enabled(MonitorQMP *mon) +{ + return mon->capab[QMP_CAPABILITY_OOB]; +} + +static void monitor_qmp_caps_reset(MonitorQMP *mon) +{ + memset(mon->capab_offered, 0, sizeof(mon->capab_offered)); + memset(mon->capab, 0, sizeof(mon->capab)); + mon->capab_offered[QMP_CAPABILITY_OOB] = mon->common.use_io_thread; +} + +static void qmp_request_free(QMPRequest *req) +{ + qobject_unref(req->req); + error_free(req->err); + g_free(req); +} + +/* Caller must hold mon->qmp.qmp_queue_lock */ +static void monitor_qmp_cleanup_req_queue_locked(MonitorQMP *mon) +{ + while (!g_queue_is_empty(mon->qmp_requests)) { + qmp_request_free(g_queue_pop_head(mon->qmp_requests)); + } +} + +static void monitor_qmp_cleanup_queues(MonitorQMP *mon) +{ + qemu_mutex_lock(&mon->qmp_queue_lock); + monitor_qmp_cleanup_req_queue_locked(mon); + qemu_mutex_unlock(&mon->qmp_queue_lock); +} + +void qmp_send_response(MonitorQMP *mon, const QDict *rsp) +{ + const QObject *data = QOBJECT(rsp); + QString *json; + + json = mon->common.flags & MONITOR_USE_PRETTY ? + qobject_to_json_pretty(data) : qobject_to_json(data); + assert(json != NULL); + + qstring_append_chr(json, '\n'); + monitor_puts(&mon->common, qstring_get_str(json)); + + qobject_unref(json); +} + +/* + * Emit QMP response @rsp with ID @id to @mon. + * Null @rsp can only happen for commands with QCO_NO_SUCCESS_RESP. + * Nothing is emitted then. + */ +static void monitor_qmp_respond(MonitorQMP *mon, QDict *rsp) +{ + if (rsp) { + qmp_send_response(mon, rsp); + } +} + +static void monitor_qmp_dispatch(MonitorQMP *mon, QObject *req) +{ + Monitor *old_mon; + QDict *rsp; + QDict *error; + + old_mon = cur_mon; + cur_mon = &mon->common; + + rsp = qmp_dispatch(mon->commands, req, qmp_oob_enabled(mon)); + + cur_mon = old_mon; + + if (mon->commands == &qmp_cap_negotiation_commands) { + error = qdict_get_qdict(rsp, "error"); + if (error + && !g_strcmp0(qdict_get_try_str(error, "class"), + QapiErrorClass_str(ERROR_CLASS_COMMAND_NOT_FOUND))) { + /* Provide a more useful error message */ + qdict_del(error, "desc"); + qdict_put_str(error, "desc", "Expecting capabilities negotiation" + " with 'qmp_capabilities'"); + } + } + + monitor_qmp_respond(mon, rsp); + qobject_unref(rsp); +} + +/* + * Pop a QMP request from a monitor request queue. + * Return the request, or NULL all request queues are empty. + * We are using round-robin fashion to pop the request, to avoid + * processing commands only on a very busy monitor. To achieve that, + * when we process one request on a specific monitor, we put that + * monitor to the end of mon_list queue. + * + * Note: if the function returned with non-NULL, then the caller will + * be with qmp_mon->qmp_queue_lock held, and the caller is responsible + * to release it. + */ +static QMPRequest *monitor_qmp_requests_pop_any_with_lock(void) +{ + QMPRequest *req_obj = NULL; + Monitor *mon; + MonitorQMP *qmp_mon; + + qemu_mutex_lock(&monitor_lock); + + QTAILQ_FOREACH(mon, &mon_list, entry) { + if (!monitor_is_qmp(mon)) { + continue; + } + + qmp_mon = container_of(mon, MonitorQMP, common); + qemu_mutex_lock(&qmp_mon->qmp_queue_lock); + req_obj = g_queue_pop_head(qmp_mon->qmp_requests); + if (req_obj) { + /* With the lock of corresponding queue held */ + break; + } + qemu_mutex_unlock(&qmp_mon->qmp_queue_lock); + } + + if (req_obj) { + /* + * We found one request on the monitor. Degrade this monitor's + * priority to lowest by re-inserting it to end of queue. + */ + QTAILQ_REMOVE(&mon_list, mon, entry); + QTAILQ_INSERT_TAIL(&mon_list, mon, entry); + } + + qemu_mutex_unlock(&monitor_lock); + + return req_obj; +} + +void monitor_qmp_bh_dispatcher(void *data) +{ + QMPRequest *req_obj = monitor_qmp_requests_pop_any_with_lock(); + QDict *rsp; + bool need_resume; + MonitorQMP *mon; + + if (!req_obj) { + return; + } + + mon = req_obj->mon; + /* qmp_oob_enabled() might change after "qmp_capabilities" */ + need_resume = !qmp_oob_enabled(mon) || + mon->qmp_requests->length == QMP_REQ_QUEUE_LEN_MAX - 1; + qemu_mutex_unlock(&mon->qmp_queue_lock); + if (req_obj->req) { + QDict *qdict = qobject_to(QDict, req_obj->req); + QObject *id = qdict ? qdict_get(qdict, "id") : NULL; + trace_monitor_qmp_cmd_in_band(qobject_get_try_str(id) ?: ""); + monitor_qmp_dispatch(mon, req_obj->req); + } else { + assert(req_obj->err); + rsp = qmp_error_response(req_obj->err); + req_obj->err = NULL; + monitor_qmp_respond(mon, rsp); + qobject_unref(rsp); + } + + if (need_resume) { + /* Pairs with the monitor_suspend() in handle_qmp_command() */ + monitor_resume(&mon->common); + } + qmp_request_free(req_obj); + + /* Reschedule instead of looping so the main loop stays responsive */ + qemu_bh_schedule(qmp_dispatcher_bh); +} + +static void handle_qmp_command(void *opaque, QObject *req, Error *err) +{ + MonitorQMP *mon = opaque; + QObject *id = NULL; + QDict *qdict; + QMPRequest *req_obj; + + assert(!req != !err); + + qdict = qobject_to(QDict, req); + if (qdict) { + id = qdict_get(qdict, "id"); + } /* else will fail qmp_dispatch() */ + + if (req && trace_event_get_state_backends(TRACE_HANDLE_QMP_COMMAND)) { + QString *req_json = qobject_to_json(req); + trace_handle_qmp_command(mon, qstring_get_str(req_json)); + qobject_unref(req_json); + } + + if (qdict && qmp_is_oob(qdict)) { + /* OOB commands are executed immediately */ + trace_monitor_qmp_cmd_out_of_band(qobject_get_try_str(id) ?: ""); + monitor_qmp_dispatch(mon, req); + qobject_unref(req); + return; + } + + req_obj = g_new0(QMPRequest, 1); + req_obj->mon = mon; + req_obj->req = req; + req_obj->err = err; + + /* Protect qmp_requests and fetching its length. */ + qemu_mutex_lock(&mon->qmp_queue_lock); + + /* + * Suspend the monitor when we can't queue more requests after + * this one. Dequeuing in monitor_qmp_bh_dispatcher() will resume + * it. Note that when OOB is disabled, we queue at most one + * command, for backward compatibility. + */ + if (!qmp_oob_enabled(mon) || + mon->qmp_requests->length == QMP_REQ_QUEUE_LEN_MAX - 1) { + monitor_suspend(&mon->common); + } + + /* + * Put the request to the end of queue so that requests will be + * handled in time order. Ownership for req_obj, req, + * etc. will be delivered to the handler side. + */ + assert(mon->qmp_requests->length < QMP_REQ_QUEUE_LEN_MAX); + g_queue_push_tail(mon->qmp_requests, req_obj); + qemu_mutex_unlock(&mon->qmp_queue_lock); + + /* Kick the dispatcher routine */ + qemu_bh_schedule(qmp_dispatcher_bh); +} + +static void monitor_qmp_read(void *opaque, const uint8_t *buf, int size) +{ + MonitorQMP *mon = opaque; + + json_message_parser_feed(&mon->parser, (const char *) buf, size); +} + +static QDict *qmp_greeting(MonitorQMP *mon) +{ + QList *cap_list = qlist_new(); + QObject *ver = NULL; + QMPCapability cap; + + qmp_marshal_query_version(NULL, &ver, NULL); + + for (cap = 0; cap < QMP_CAPABILITY__MAX; cap++) { + if (mon->capab_offered[cap]) { + qlist_append_str(cap_list, QMPCapability_str(cap)); + } + } + + return qdict_from_jsonf_nofail( + "{'QMP': {'version': %p, 'capabilities': %p}}", + ver, cap_list); +} + +static void monitor_qmp_event(void *opaque, int event) +{ + QDict *data; + MonitorQMP *mon = opaque; + + switch (event) { + case CHR_EVENT_OPENED: + mon->commands = &qmp_cap_negotiation_commands; + monitor_qmp_caps_reset(mon); + data = qmp_greeting(mon); + qmp_send_response(mon, data); + qobject_unref(data); + mon_refcount++; + break; + case CHR_EVENT_CLOSED: + /* + * Note: this is only useful when the output of the chardev + * backend is still open. For example, when the backend is + * stdio, it's possible that stdout is still open when stdin + * is closed. + */ + monitor_qmp_cleanup_queues(mon); + json_message_parser_destroy(&mon->parser); + json_message_parser_init(&mon->parser, handle_qmp_command, + mon, NULL); + mon_refcount--; + monitor_fdsets_cleanup(); + break; + } +} + +void monitor_data_destroy_qmp(MonitorQMP *mon) +{ + json_message_parser_destroy(&mon->parser); + qemu_mutex_destroy(&mon->qmp_queue_lock); + monitor_qmp_cleanup_req_queue_locked(mon); + g_queue_free(mon->qmp_requests); +} + +static void monitor_qmp_setup_handlers_bh(void *opaque) +{ + MonitorQMP *mon = opaque; + GMainContext *context; + + assert(mon->common.use_io_thread); + context = iothread_get_g_main_context(mon_iothread); + assert(context); + qemu_chr_fe_set_handlers(&mon->common.chr, monitor_can_read, + monitor_qmp_read, monitor_qmp_event, + NULL, &mon->common, context, true); + monitor_list_append(&mon->common); +} + +void monitor_init_qmp(Chardev *chr, int flags) +{ + MonitorQMP *mon = g_new0(MonitorQMP, 1); + + /* Only HMP supports readline */ + assert(!(flags & MONITOR_USE_READLINE)); + + /* Note: we run QMP monitor in I/O thread when @chr supports that */ + monitor_data_init(&mon->common, flags, false, + qemu_chr_has_feature(chr, QEMU_CHAR_FEATURE_GCONTEXT)); + + qemu_mutex_init(&mon->qmp_queue_lock); + mon->qmp_requests = g_queue_new(); + + qemu_chr_fe_init(&mon->common.chr, chr, &error_abort); + qemu_chr_fe_set_echo(&mon->common.chr, true); + + json_message_parser_init(&mon->parser, handle_qmp_command, mon, NULL); + if (mon->common.use_io_thread) { + /* + * Make sure the old iowatch is gone. It's possible when + * e.g. the chardev is in client mode, with wait=on. + */ + remove_fd_in_watch(chr); + /* + * We can't call qemu_chr_fe_set_handlers() directly here + * since chardev might be running in the monitor I/O + * thread. Schedule a bottom half. + */ + aio_bh_schedule_oneshot(iothread_get_aio_context(mon_iothread), + monitor_qmp_setup_handlers_bh, mon); + /* The bottom half will add @mon to @mon_list */ + } else { + qemu_chr_fe_set_handlers(&mon->common.chr, monitor_can_read, + monitor_qmp_read, monitor_qmp_event, + NULL, &mon->common, NULL, true); + monitor_list_append(&mon->common); + } +} |