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1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 152 153 154 155 156 157 158 159 160 161 162 163 164 165 166 167 168 169 170 171 172 173 174 175 176 177 178 179 180 181 182 183 184 185 186 187 188 189 190 191 192 193 194 195 196 197 198 199 200 201 202 203 204 205 206 207 208 209 210 211 212 213 214 215 216 217 218 219 220 221 222 223 224 225 226 227 228 229 230 231 232 233 234 235 236 237 238 239 240 241 242 243 244 245 246 247 248 249 250 251 252 253 254 255 256 257 258 259 260 261 262 263 264 265 266 267 268 269 270 271 272 273 274 275 276 277 278 279 280 281 282 283 284 285 286 287 288 289 290 291 292 293 294 295 296 297 298 299 300 301 302 303 304 305 306 307 308 309 310 311 312 313 314 315 316 317 318 319 320 321 322 323 324 325 326 327 328 329 330 331 332 333 334 335 336 337 338 339 340 341 342 343 344 345 346 347 348 349 350 351 352 353 354 355 356 357 358 359 360 361 362 363 364 365 366 367 368 369 370 371 372 373 374 375 376 377 378 379 380 381 382 383 384 385 386 387 388 389 390 391 392 393 394 395 396 397 398 399 400 401 402 403 404 405 406 407 408 409 410 411 412 413 414 415 416 417 418 419 420 421 422 423 424 425 426 427 428 429 430 431 432 433 434 435 436 437 438 439 440 441 442 443 444 445 446 447 448 449 450 451 452 453 454 455 456 457 458 459 460 461 462 463 464 465 466 467 468 469 470 471 472 473 474 475 476 477 478 479 480 481 482 483 484 485 486 487 488 489 490 491 492 493 494 495 496 497 498 499 500 501 502 503 504 505 506 507 508 509 510 511 512 513 514 515 516 517 518 519 520 521 522 523 524 525 526 527 528 529 530 531 532 533 534 535 536 537 538 539 540 541 542 543 544 545 546 547 548 549 550 551 552 553 554 555 | /* * 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-control.h" #include "qapi/qmp/qdict.h" #include "qapi/qmp/qjson.h" #include "qapi/qmp/qlist.h" #include "trace.h" /* * qmp_dispatcher_co_busy is used for synchronisation between the * monitor thread and the main thread to ensure that the dispatcher * coroutine never gets scheduled a second time when it's already * scheduled (scheduling the same coroutine twice is forbidden). * * It is true if the coroutine will process at least one more request * before going to sleep. Either it has been kicked already, or it * is active and processing requests. Additional requests may therefore * be pushed onto mon->qmp_requests, and @qmp_dispatcher_co_shutdown may * be set without further ado. @qmp_dispatcher_co must not be woken up * in this case. * * If false, you have to wake up @qmp_dispatcher_co after pushing new * requests. You also have to set @qmp_dispatcher_co_busy to true * before waking up the coroutine. * * The coroutine will automatically change this variable back to false * before it yields. Nobody else may set the variable to false. * * Access must be atomic for thread safety. */ static bool qmp_dispatcher_co_busy = true; 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_queue_and_resume(MonitorQMP *mon) { QEMU_LOCK_GUARD(&mon->qmp_queue_lock); /* * Same condition as in monitor_qmp_dispatcher_co(), but before * removing an element from the queue (hence no `- 1`). * Also, the queue should not be empty either, otherwise the * monitor hasn't been suspended yet (or was already resumed). */ bool need_resume = (!qmp_oob_enabled(mon) || mon->qmp_requests->length == QMP_REQ_QUEUE_LEN_MAX) && !g_queue_is_empty(mon->qmp_requests); monitor_qmp_cleanup_req_queue_locked(mon); if (need_resume) { /* * handle_qmp_command() suspended the monitor because the * request queue filled up, to be resumed when the queue has * space again. We just emptied it; resume the monitor. * * Without this, the monitor would remain suspended forever * when we get here while the monitor is suspended. An * unfortunately timed CHR_EVENT_CLOSED can do the trick. */ monitor_resume(&mon->common); } } void qmp_send_response(MonitorQMP *mon, const QDict *rsp) { const QObject *data = QOBJECT(rsp); GString *json; json = qobject_to_json_pretty(data, mon->pretty); assert(json != NULL); trace_monitor_qmp_respond(mon, json->str); g_string_append_c(json, '\n'); monitor_puts(&mon->common, json->str); g_string_free(json, true); } /* * Emit QMP response @rsp 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); } } /* * Runs outside of coroutine context for OOB commands, but in * coroutine context for everything else. */ static void monitor_qmp_dispatch(MonitorQMP *mon, QObject *req) { QDict *rsp; QDict *error; rsp = qmp_dispatch(mon->commands, req, qmp_oob_enabled(mon), &mon->common); 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; 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); } return req_obj; } static QMPRequest *monitor_qmp_dispatcher_pop_any(void) { while (true) { /* * To avoid double scheduling, busy is true on entry to * monitor_qmp_dispatcher_co(), and must be set again before * aio_co_wake()-ing it. */ assert(qatomic_read(&qmp_dispatcher_co_busy) == true); /* * Mark the dispatcher as not busy already here so that we * don't miss any new requests coming in the middle of our * processing. * * Clear qmp_dispatcher_co_busy before reading request. */ qatomic_set_mb(&qmp_dispatcher_co_busy, false); WITH_QEMU_LOCK_GUARD(&monitor_lock) { QMPRequest *req_obj; /* On shutdown, don't take any more requests from the queue */ if (qmp_dispatcher_co_shutdown) { return NULL; } req_obj = monitor_qmp_requests_pop_any_with_lock(); if (req_obj) { return req_obj; } } /* * No more requests to process. Wait to be reentered from * handle_qmp_command() when it pushes more requests, or * from monitor_cleanup() when it requests shutdown. */ qemu_coroutine_yield(); } } void coroutine_fn monitor_qmp_dispatcher_co(void *data) { QMPRequest *req_obj; QDict *rsp; bool oob_enabled; MonitorQMP *mon; while ((req_obj = monitor_qmp_dispatcher_pop_any()) != NULL) { trace_monitor_qmp_in_band_dequeue(req_obj, req_obj->mon->qmp_requests->length); /* * @req_obj has a request, we hold req_obj->mon->qmp_queue_lock */ mon = req_obj->mon; /* * We need to resume the monitor if handle_qmp_command() * suspended it. Two cases: * 1. OOB enabled: mon->qmp_requests has no more space * Resume right away, so that OOB commands can get executed while * this request is being processed. * 2. OOB disabled: always * Resume only after we're done processing the request, * We need to save qmp_oob_enabled() for later, because * qmp_qmp_capabilities() can change it. */ oob_enabled = qmp_oob_enabled(mon); if (oob_enabled && mon->qmp_requests->length == QMP_REQ_QUEUE_LEN_MAX - 1) { monitor_resume(&mon->common); } /* * Drop the queue mutex now, before yielding, otherwise we might * deadlock if the main thread tries to lock it. */ qemu_mutex_unlock(&mon->qmp_queue_lock); if (qatomic_xchg(&qmp_dispatcher_co_busy, true) == true) { /* * Someone rescheduled us (probably because a new requests * came in), but we didn't actually yield. Do that now, * only to be immediately reentered and removed from the * list of scheduled coroutines. */ qemu_coroutine_yield(); } /* Process request */ if (req_obj->req) { if (trace_event_get_state(TRACE_MONITOR_QMP_CMD_IN_BAND)) { QDict *qdict = qobject_to(QDict, req_obj->req); QObject *id = qdict ? qdict_get(qdict, "id") : NULL; GString *id_json; id_json = id ? qobject_to_json(id) : g_string_new(NULL); trace_monitor_qmp_cmd_in_band(id_json->str); g_string_free(id_json, true); } monitor_qmp_dispatch(mon, req_obj->req); } else { assert(req_obj->err); trace_monitor_qmp_err_in_band(error_get_pretty(req_obj->err)); rsp = qmp_error_response(req_obj->err); req_obj->err = NULL; monitor_qmp_respond(mon, rsp); qobject_unref(rsp); } if (!oob_enabled) { monitor_resume(&mon->common); } qmp_request_free(req_obj); } qatomic_set(&qmp_dispatcher_co, NULL); } void qmp_dispatcher_co_wake(void) { /* Write request before reading qmp_dispatcher_co_busy. */ smp_mb__before_rmw(); if (!qatomic_xchg(&qmp_dispatcher_co_busy, true)) { aio_co_wake(qmp_dispatcher_co); } } static void handle_qmp_command(void *opaque, QObject *req, Error *err) { MonitorQMP *mon = opaque; QDict *qdict = qobject_to(QDict, req); QMPRequest *req_obj; assert(!req != !err); if (req && trace_event_get_state_backends(TRACE_HANDLE_QMP_COMMAND)) { GString *req_json = qobject_to_json(req); trace_handle_qmp_command(mon, req_json->str); g_string_free(req_json, true); } if (qdict && qmp_is_oob(qdict)) { /* OOB commands are executed immediately */ if (trace_event_get_state(TRACE_MONITOR_QMP_CMD_OUT_OF_BAND)) { QObject *id = qdict_get(qdict, "id"); GString *id_json; id_json = id ? qobject_to_json(id) : g_string_new(NULL); trace_monitor_qmp_cmd_out_of_band(id_json->str); g_string_free(id_json, true); } 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. */ WITH_QEMU_LOCK_GUARD(&mon->qmp_queue_lock) { /* * Suspend the monitor when we can't queue more requests after * this one. Dequeuing in monitor_qmp_dispatcher_co() or * monitor_qmp_cleanup_queue_and_resume() 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. */ trace_monitor_qmp_in_band_enqueue(req_obj, mon, mon->qmp_requests->length); assert(mon->qmp_requests->length < QMP_REQ_QUEUE_LEN_MAX); g_queue_push_tail(mon->qmp_requests, req_obj); } /* Kick the dispatcher routine */ qmp_dispatcher_co_wake(); } 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; QDict *args; QMPCapability cap; args = qdict_new(); qmp_marshal_query_version(args, &ver, NULL); qobject_unref(args); 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, QEMUChrEvent 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_queue_and_resume(mon); json_message_parser_destroy(&mon->parser); json_message_parser_init(&mon->parser, handle_qmp_command, mon, NULL); mon_refcount--; monitor_fdsets_cleanup(); break; case CHR_EVENT_BREAK: case CHR_EVENT_MUX_IN: case CHR_EVENT_MUX_OUT: /* Ignore */ 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, bool pretty, Error **errp) { MonitorQMP *mon = g_new0(MonitorQMP, 1); if (!qemu_chr_fe_init(&mon->common.chr, chr, errp)) { g_free(mon); return; } qemu_chr_fe_set_echo(&mon->common.chr, true); /* Note: we run QMP monitor in I/O thread when @chr supports that */ monitor_data_init(&mon->common, true, false, qemu_chr_has_feature(chr, QEMU_CHAR_FEATURE_GCONTEXT)); mon->pretty = pretty; qemu_mutex_init(&mon->qmp_queue_lock); mon->qmp_requests = g_queue_new(); 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); } } |