qemu-timer.c

   1 /*
   2  * QEMU System Emulator
   3  *
   4  * Copyright (c) 2003-2008 Fabrice Bellard
   5  *
   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:
  12  *
  13  * The above copyright notice and this permission notice shall be included in
  14  * all copies or substantial portions of the Software.
  15  *
  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.
  23  */
  24
  25 #include "sysemu/sysemu.h"
  26 #include "monitor/monitor.h"
  27 #include "ui/console.h"
  28
  29 #include "hw/hw.h"
  30
  31 #include "qemu/timer.h"
  32 #ifdef CONFIG_POSIX
  33 #include <pthread.h>
  34 #endif
  35
  36 #ifdef CONFIG_PPOLL
  37 #include <poll.h>
  38 #endif
  39
  40 #ifdef CONFIG_PRCTL_PR_SET_TIMERSLACK
  41 #include <sys/prctl.h>
  42 #endif
  43
  44 /***********************************************************/
  45 /* timers */
  46
  47 typedef struct QEMUClock {
  48     /* We rely on BQL to protect the timerlists */
  49     QLIST_HEAD(, QEMUTimerList) timerlists;
  50
  51     NotifierList reset_notifiers;
  52     int64_t last;
  53
  54     QEMUClockType type;
  55     bool enabled;
  56 } QEMUClock;
  57
  58 QEMUTimerListGroup main_loop_tlg;
  59 static QEMUClock qemu_clocks[QEMU_CLOCK_MAX];
  60
  61 /* A QEMUTimerList is a list of timers attached to a clock. More
  62  * than one QEMUTimerList can be attached to each clock, for instance
  63  * used by different AioContexts / threads. Each clock also has
  64  * a list of the QEMUTimerLists associated with it, in order that
  65  * reenabling the clock can call all the notifiers.
  66  */
  67
  68 struct QEMUTimerList {
  69     QEMUClock *clock;
  70     QemuMutex active_timers_lock;
  71     QEMUTimer *active_timers;
  72     QLIST_ENTRY(QEMUTimerList) list;
  73     QEMUTimerListNotifyCB *notify_cb;
  74     void *notify_opaque;
  75
  76     /* lightweight method to mark the end of timerlist's running */
  77     QemuEvent timers_done_ev;
  78 };
  79
  80 /**
  81  * qemu_clock_ptr:
  82  * @type: type of clock
  83  *
  84  * Translate a clock type into a pointer to QEMUClock object.
  85  *
  86  * Returns: a pointer to the QEMUClock object
  87  */
  88 static inline QEMUClock *qemu_clock_ptr(QEMUClockType type)
  89 {
  90     return &qemu_clocks[type];
  91 }
  92
  93 static bool timer_expired_ns(QEMUTimer *timer_head, int64_t current_time)
  94 {
  95     return timer_head && (timer_head->expire_time <= current_time);
  96 }
  97
  98 QEMUTimerList *timerlist_new(QEMUClockType type,
  99                              QEMUTimerListNotifyCB *cb,
 100                              void *opaque)
 101 {
 102     QEMUTimerList *timer_list;
 103     QEMUClock *clock = qemu_clock_ptr(type);
 104
 105     timer_list = g_malloc0(sizeof(QEMUTimerList));
 106     qemu_event_init(&timer_list->timers_done_ev, false);
 107     timer_list->clock = clock;
 108     timer_list->notify_cb = cb;
 109     timer_list->notify_opaque = opaque;
 110     qemu_mutex_init(&timer_list->active_timers_lock);
 111     QLIST_INSERT_HEAD(&clock->timerlists, timer_list, list);
 112     return timer_list;
 113 }
 114
 115 void timerlist_free(QEMUTimerList *timer_list)
 116 {
 117     assert(!timerlist_has_timers(timer_list));
 118     if (timer_list->clock) {
 119         QLIST_REMOVE(timer_list, list);
 120     }
 121     qemu_mutex_destroy(&timer_list->active_timers_lock);
 122     g_free(timer_list);
 123 }
 124
 125 static void qemu_clock_init(QEMUClockType type)
 126 {
 127     QEMUClock *clock = qemu_clock_ptr(type);
 128
 129     /* Assert that the clock of type TYPE has not been initialized yet. */
 130     assert(main_loop_tlg.tl[type] == NULL);
 131
 132     clock->type = type;
 133     clock->enabled = true;
 134     clock->last = INT64_MIN;
 135     QLIST_INIT(&clock->timerlists);
 136     notifier_list_init(&clock->reset_notifiers);
 137     main_loop_tlg.tl[type] = timerlist_new(type, NULL, NULL);
 138 }
 139
 140 bool qemu_clock_use_for_deadline(QEMUClockType type)
 141 {
 142     return !(use_icount && (type == QEMU_CLOCK_VIRTUAL));
 143 }
 144
 145 void qemu_clock_notify(QEMUClockType type)
 146 {
 147     QEMUTimerList *timer_list;
 148     QEMUClock *clock = qemu_clock_ptr(type);
 149     QLIST_FOREACH(timer_list, &clock->timerlists, list) {
 150         timerlist_notify(timer_list);
 151     }
 152 }
 153
 154 /* Disabling the clock will wait for related timerlists to stop
 155  * executing qemu_run_timers.  Thus, this functions should not
 156  * be used from the callback of a timer that is based on @clock.
 157  * Doing so would cause a deadlock.
 158  *
 159  * Caller should hold BQL.
 160  */
 161 void qemu_clock_enable(QEMUClockType type, bool enabled)
 162 {
 163     QEMUClock *clock = qemu_clock_ptr(type);
 164     QEMUTimerList *tl;
 165     bool old = clock->enabled;
 166     clock->enabled = enabled;
 167     if (enabled && !old) {
 168         qemu_clock_notify(type);
 169     } else if (!enabled && old) {
 170         QLIST_FOREACH(tl, &clock->timerlists, list) {
 171             qemu_event_wait(&tl->timers_done_ev);
 172         }
 173     }
 174 }
 175
 176 bool timerlist_has_timers(QEMUTimerList *timer_list)
 177 {
 178     return !!timer_list->active_timers;
 179 }
 180
 181 bool qemu_clock_has_timers(QEMUClockType type)
 182 {
 183     return timerlist_has_timers(
 184         main_loop_tlg.tl[type]);
 185 }
 186
 187 bool timerlist_expired(QEMUTimerList *timer_list)
 188 {
 189     int64_t expire_time;
 190
 191     qemu_mutex_lock(&timer_list->active_timers_lock);
 192     if (!timer_list->active_timers) {
 193         qemu_mutex_unlock(&timer_list->active_timers_lock);
 194         return false;
 195     }
 196     expire_time = timer_list->active_timers->expire_time;
 197     qemu_mutex_unlock(&timer_list->active_timers_lock);
 198
 199     return expire_time < qemu_clock_get_ns(timer_list->clock->type);
 200 }
 201
 202 bool qemu_clock_expired(QEMUClockType type)
 203 {
 204     return timerlist_expired(
 205         main_loop_tlg.tl[type]);
 206 }
 207
 208 /*
 209  * As above, but return -1 for no deadline, and do not cap to 2^32
 210  * as we know the result is always positive.
 211  */
 212
 213 int64_t timerlist_deadline_ns(QEMUTimerList *timer_list)
 214 {
 215     int64_t delta;
 216     int64_t expire_time;
 217
 218     if (!timer_list->clock->enabled) {
 219         return -1;
 220     }
 221
 222     /* The active timers list may be modified before the caller uses our return
 223      * value but ->notify_cb() is called when the deadline changes.  Therefore
 224      * the caller should notice the change and there is no race condition.
 225      */
 226     qemu_mutex_lock(&timer_list->active_timers_lock);
 227     if (!timer_list->active_timers) {
 228         qemu_mutex_unlock(&timer_list->active_timers_lock);
 229         return -1;
 230     }
 231     expire_time = timer_list->active_timers->expire_time;
 232     qemu_mutex_unlock(&timer_list->active_timers_lock);
 233
 234     delta = expire_time - qemu_clock_get_ns(timer_list->clock->type);
 235
 236     if (delta <= 0) {
 237         return 0;
 238     }
 239
 240     return delta;
 241 }
 242
 243 /* Calculate the soonest deadline across all timerlists attached
 244  * to the clock. This is used for the icount timeout so we
 245  * ignore whether or not the clock should be used in deadline
 246  * calculations.
 247  */
 248 int64_t qemu_clock_deadline_ns_all(QEMUClockType type)
 249 {
 250     int64_t deadline = -1;
 251     QEMUTimerList *timer_list;
 252     QEMUClock *clock = qemu_clock_ptr(type);
 253     QLIST_FOREACH(timer_list, &clock->timerlists, list) {
 254         deadline = qemu_soonest_timeout(deadline,
 255                                         timerlist_deadline_ns(timer_list));
 256     }
 257     return deadline;
 258 }
 259
 260 QEMUClockType timerlist_get_clock(QEMUTimerList *timer_list)
 261 {
 262     return timer_list->clock->type;
 263 }
 264
 265 QEMUTimerList *qemu_clock_get_main_loop_timerlist(QEMUClockType type)
 266 {
 267     return main_loop_tlg.tl[type];
 268 }
 269
 270 void timerlist_notify(QEMUTimerList *timer_list)
 271 {
 272     if (timer_list->notify_cb) {
 273         timer_list->notify_cb(timer_list->notify_opaque);
 274     } else {
 275         qemu_notify_event();
 276     }
 277 }
 278
 279 /* Transition function to convert a nanosecond timeout to ms
 280  * This is used where a system does not support ppoll
 281  */
 282 int qemu_timeout_ns_to_ms(int64_t ns)
 283 {
 284     int64_t ms;
 285     if (ns < 0) {
 286         return -1;
 287     }
 288
 289     if (!ns) {
 290         return 0;
 291     }
 292
 293     /* Always round up, because it's better to wait too long than to wait too
 294      * little and effectively busy-wait
 295      */
 296     ms = (ns + SCALE_MS - 1) / SCALE_MS;
 297
 298     /* To avoid overflow problems, limit this to 2^31, i.e. approx 25 days */
 299     if (ms > (int64_t) INT32_MAX) {
 300         ms = INT32_MAX;
 301     }
 302
 303     return (int) ms;
 304 }
 305
 306
 307 /* qemu implementation of g_poll which uses a nanosecond timeout but is
 308  * otherwise identical to g_poll
 309  */
 310 int qemu_poll_ns(GPollFD *fds, guint nfds, int64_t timeout)
 311 {
 312 #ifdef CONFIG_PPOLL
 313     if (timeout < 0) {
 314         return ppoll((struct pollfd *)fds, nfds, NULL, NULL);
 315     } else {
 316         struct timespec ts;
 317         int64_t tvsec = timeout / 1000000000LL;
 318         /* Avoid possibly overflowing and specifying a negative number of
 319          * seconds, which would turn a very long timeout into a busy-wait.
 320          */
 321         if (tvsec > (int64_t)INT32_MAX) {
 322             tvsec = INT32_MAX;
 323         }
 324         ts.tv_sec = tvsec;
 325         ts.tv_nsec = timeout % 1000000000LL;
 326         return ppoll((struct pollfd *)fds, nfds, &ts, NULL);
 327     }
 328 #else
 329     return g_poll(fds, nfds, qemu_timeout_ns_to_ms(timeout));
 330 #endif
 331 }
 332
 333
 334 void timer_init(QEMUTimer *ts,
 335                 QEMUTimerList *timer_list, int scale,
 336                 QEMUTimerCB *cb, void *opaque)
 337 {
 338     ts->timer_list = timer_list;
 339     ts->cb = cb;
 340     ts->opaque = opaque;
 341     ts->scale = scale;
 342     ts->expire_time = -1;
 343 }
 344
 345 void timer_free(QEMUTimer *ts)
 346 {
 347     g_free(ts);
 348 }
 349
 350 static void timer_del_locked(QEMUTimerList *timer_list, QEMUTimer *ts)
 351 {
 352     QEMUTimer **pt, *t;
 353
 354     ts->expire_time = -1;
 355     pt = &timer_list->active_timers;
 356     for(;;) {
 357         t = *pt;
 358         if (!t)
 359             break;
 360         if (t == ts) {
 361             *pt = t->next;
 362             break;
 363         }
 364         pt = &t->next;
 365     }
 366 }
 367
 368 static bool timer_mod_ns_locked(QEMUTimerList *timer_list,
 369                                 QEMUTimer *ts, int64_t expire_time)
 370 {
 371     QEMUTimer **pt, *t;
 372
 373     /* add the timer in the sorted list */
 374     pt = &timer_list->active_timers;
 375     for (;;) {
 376         t = *pt;
 377         if (!timer_expired_ns(t, expire_time)) {
 378             break;
 379         }
 380         pt = &t->next;
 381     }
 382     ts->expire_time = MAX(expire_time, 0);
 383     ts->next = *pt;
 384     *pt = ts;
 385
 386     return pt == &timer_list->active_timers;
 387 }
 388
 389 static void timerlist_rearm(QEMUTimerList *timer_list)
 390 {
 391     /* Interrupt execution to force deadline recalculation.  */
 392     qemu_clock_warp(timer_list->clock->type);
 393     timerlist_notify(timer_list);
 394 }
 395
 396 /* stop a timer, but do not dealloc it */
 397 void timer_del(QEMUTimer *ts)
 398 {
 399     QEMUTimerList *timer_list = ts->timer_list;
 400
 401     qemu_mutex_lock(&timer_list->active_timers_lock);
 402     timer_del_locked(timer_list, ts);
 403     qemu_mutex_unlock(&timer_list->active_timers_lock);
 404 }
 405
 406 /* modify the current timer so that it will be fired when current_time
 407    >= expire_time. The corresponding callback will be called. */
 408 void timer_mod_ns(QEMUTimer *ts, int64_t expire_time)
 409 {
 410     QEMUTimerList *timer_list = ts->timer_list;
 411     bool rearm;
 412
 413     qemu_mutex_lock(&timer_list->active_timers_lock);
 414     timer_del_locked(timer_list, ts);
 415     rearm = timer_mod_ns_locked(timer_list, ts, expire_time);
 416     qemu_mutex_unlock(&timer_list->active_timers_lock);
 417
 418     if (rearm) {
 419         timerlist_rearm(timer_list);
 420     }
 421 }
 422
 423 /* modify the current timer so that it will be fired when current_time
 424    >= expire_time or the current deadline, whichever comes earlier.
 425    The corresponding callback will be called. */
 426 void timer_mod_anticipate_ns(QEMUTimer *ts, int64_t expire_time)
 427 {
 428     QEMUTimerList *timer_list = ts->timer_list;
 429     bool rearm;
 430
 431     qemu_mutex_lock(&timer_list->active_timers_lock);
 432     if (ts->expire_time == -1 || ts->expire_time > expire_time) {
 433         if (ts->expire_time != -1) {
 434             timer_del_locked(timer_list, ts);
 435         }
 436         rearm = timer_mod_ns_locked(timer_list, ts, expire_time);
 437     } else {
 438         rearm = false;
 439     }
 440     qemu_mutex_unlock(&timer_list->active_timers_lock);
 441
 442     if (rearm) {
 443         timerlist_rearm(timer_list);
 444     }
 445 }
 446
 447 void timer_mod(QEMUTimer *ts, int64_t expire_time)
 448 {
 449     timer_mod_ns(ts, expire_time * ts->scale);
 450 }
 451
 452 void timer_mod_anticipate(QEMUTimer *ts, int64_t expire_time)
 453 {
 454     timer_mod_anticipate_ns(ts, expire_time * ts->scale);
 455 }
 456
 457 bool timer_pending(QEMUTimer *ts)
 458 {
 459     return ts->expire_time >= 0;
 460 }
 461
 462 bool timer_expired(QEMUTimer *timer_head, int64_t current_time)
 463 {
 464     return timer_expired_ns(timer_head, current_time * timer_head->scale);
 465 }
 466
 467 bool timerlist_run_timers(QEMUTimerList *timer_list)
 468 {
 469     QEMUTimer *ts;
 470     int64_t current_time;
 471     bool progress = false;
 472     QEMUTimerCB *cb;
 473     void *opaque;
 474
 475     qemu_event_reset(&timer_list->timers_done_ev);
 476     if (!timer_list->clock->enabled) {
 477         goto out;
 478     }
 479
 480     current_time = qemu_clock_get_ns(timer_list->clock->type);
 481     for(;;) {
 482         qemu_mutex_lock(&timer_list->active_timers_lock);
 483         ts = timer_list->active_timers;
 484         if (!timer_expired_ns(ts, current_time)) {
 485             qemu_mutex_unlock(&timer_list->active_timers_lock);
 486             break;
 487         }
 488
 489         /* remove timer from the list before calling the callback */
 490         timer_list->active_timers = ts->next;
 491         ts->next = NULL;
 492         ts->expire_time = -1;
 493         cb = ts->cb;
 494         opaque = ts->opaque;
 495         qemu_mutex_unlock(&timer_list->active_timers_lock);
 496
 497         /* run the callback (the timer list can be modified) */
 498         cb(opaque);
 499         progress = true;
 500     }
 501
 502 out:
 503     qemu_event_set(&timer_list->timers_done_ev);
 504     return progress;
 505 }
 506
 507 bool qemu_clock_run_timers(QEMUClockType type)
 508 {
 509     return timerlist_run_timers(main_loop_tlg.tl[type]);
 510 }
 511
 512 void timerlistgroup_init(QEMUTimerListGroup *tlg,
 513                          QEMUTimerListNotifyCB *cb, void *opaque)
 514 {
 515     QEMUClockType type;
 516     for (type = 0; type < QEMU_CLOCK_MAX; type++) {
 517         tlg->tl[type] = timerlist_new(type, cb, opaque);
 518     }
 519 }
 520
 521 void timerlistgroup_deinit(QEMUTimerListGroup *tlg)
 522 {
 523     QEMUClockType type;
 524     for (type = 0; type < QEMU_CLOCK_MAX; type++) {
 525         timerlist_free(tlg->tl[type]);
 526     }
 527 }
 528
 529 bool timerlistgroup_run_timers(QEMUTimerListGroup *tlg)
 530 {
 531     QEMUClockType type;
 532     bool progress = false;
 533     for (type = 0; type < QEMU_CLOCK_MAX; type++) {
 534         progress |= timerlist_run_timers(tlg->tl[type]);
 535     }
 536     return progress;
 537 }
 538
 539 int64_t timerlistgroup_deadline_ns(QEMUTimerListGroup *tlg)
 540 {
 541     int64_t deadline = -1;
 542     QEMUClockType type;
 543     for (type = 0; type < QEMU_CLOCK_MAX; type++) {
 544         if (qemu_clock_use_for_deadline(tlg->tl[type]->clock->type)) {
 545             deadline = qemu_soonest_timeout(deadline,
 546                                             timerlist_deadline_ns(
 547                                                 tlg->tl[type]));
 548         }
 549     }
 550     return deadline;
 551 }
 552
 553 int64_t qemu_clock_get_ns(QEMUClockType type)
 554 {
 555     int64_t now, last;
 556     QEMUClock *clock = qemu_clock_ptr(type);
 557
 558     switch (type) {
 559     case QEMU_CLOCK_REALTIME:
 560         return get_clock();
 561     default:
 562     case QEMU_CLOCK_VIRTUAL:
 563         if (use_icount) {
 564             return cpu_get_icount();
 565         } else {
 566             return cpu_get_clock();
 567         }
 568     case QEMU_CLOCK_HOST:
 569         now = get_clock_realtime();
 570         last = clock->last;
 571         clock->last = now;
 572         if (now < last) {
 573             notifier_list_notify(&clock->reset_notifiers, &now);
 574         }
 575         return now;
 576     }
 577 }
 578
 579 void qemu_clock_register_reset_notifier(QEMUClockType type,
 580                                         Notifier *notifier)
 581 {
 582     QEMUClock *clock = qemu_clock_ptr(type);
 583     notifier_list_add(&clock->reset_notifiers, notifier);
 584 }
 585
 586 void qemu_clock_unregister_reset_notifier(QEMUClockType type,
 587                                           Notifier *notifier)
 588 {
 589     notifier_remove(notifier);
 590 }
 591
 592 void init_clocks(void)
 593 {
 594     QEMUClockType type;
 595     for (type = 0; type < QEMU_CLOCK_MAX; type++) {
 596         qemu_clock_init(type);
 597     }
 598
 599 #ifdef CONFIG_PRCTL_PR_SET_TIMERSLACK
 600     prctl(PR_SET_TIMERSLACK, 1, 0, 0, 0);
 601 #endif
 602 }
 603
 604 uint64_t timer_expire_time_ns(QEMUTimer *ts)
 605 {
 606     return timer_pending(ts) ? ts->expire_time : -1;
 607 }
 608
 609 bool qemu_clock_run_all_timers(void)
 610 {
 611     bool progress = false;
 612     QEMUClockType type;
 613
 614     for (type = 0; type < QEMU_CLOCK_MAX; type++) {
 615         progress |= qemu_clock_run_timers(type);
 616     }
 617
 618     return progress;
 619 }