util/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 "qemu/osdep.h"
  26 #include "qemu/main-loop.h"
  27 #include "qemu/timer.h"
  28 #include "sysemu/replay.h"
  29 #include "sysemu/sysemu.h"
  30 #include "sysemu/cpus.h"
  31
  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, true);
 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, QEMUTimerListNotifyCB *notify_cb)
 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 = (type == QEMU_CLOCK_VIRTUAL ? false : 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, notify_cb, 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 !!atomic_read(&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     if (!atomic_read(&timer_list->active_timers)) {
 192         return false;
 193     }
 194
 195     qemu_mutex_lock(&timer_list->active_timers_lock);
 196     if (!timer_list->active_timers) {
 197         qemu_mutex_unlock(&timer_list->active_timers_lock);
 198         return false;
 199     }
 200     expire_time = timer_list->active_timers->expire_time;
 201     qemu_mutex_unlock(&timer_list->active_timers_lock);
 202
 203     return expire_time <= qemu_clock_get_ns(timer_list->clock->type);
 204 }
 205
 206 bool qemu_clock_expired(QEMUClockType type)
 207 {
 208     return timerlist_expired(
 209         main_loop_tlg.tl[type]);
 210 }
 211
 212 /*
 213  * As above, but return -1 for no deadline, and do not cap to 2^32
 214  * as we know the result is always positive.
 215  */
 216
 217 int64_t timerlist_deadline_ns(QEMUTimerList *timer_list)
 218 {
 219     int64_t delta;
 220     int64_t expire_time;
 221
 222     if (!atomic_read(&timer_list->active_timers)) {
 223         return -1;
 224     }
 225
 226     if (!timer_list->clock->enabled) {
 227         return -1;
 228     }
 229
 230     /* The active timers list may be modified before the caller uses our return
 231      * value but ->notify_cb() is called when the deadline changes.  Therefore
 232      * the caller should notice the change and there is no race condition.
 233      */
 234     qemu_mutex_lock(&timer_list->active_timers_lock);
 235     if (!timer_list->active_timers) {
 236         qemu_mutex_unlock(&timer_list->active_timers_lock);
 237         return -1;
 238     }
 239     expire_time = timer_list->active_timers->expire_time;
 240     qemu_mutex_unlock(&timer_list->active_timers_lock);
 241
 242     delta = expire_time - qemu_clock_get_ns(timer_list->clock->type);
 243
 244     if (delta <= 0) {
 245         return 0;
 246     }
 247
 248     return delta;
 249 }
 250
 251 /* Calculate the soonest deadline across all timerlists attached
 252  * to the clock. This is used for the icount timeout so we
 253  * ignore whether or not the clock should be used in deadline
 254  * calculations.
 255  */
 256 int64_t qemu_clock_deadline_ns_all(QEMUClockType type)
 257 {
 258     int64_t deadline = -1;
 259     QEMUTimerList *timer_list;
 260     QEMUClock *clock = qemu_clock_ptr(type);
 261     QLIST_FOREACH(timer_list, &clock->timerlists, list) {
 262         deadline = qemu_soonest_timeout(deadline,
 263                                         timerlist_deadline_ns(timer_list));
 264     }
 265     return deadline;
 266 }
 267
 268 QEMUClockType timerlist_get_clock(QEMUTimerList *timer_list)
 269 {
 270     return timer_list->clock->type;
 271 }
 272
 273 QEMUTimerList *qemu_clock_get_main_loop_timerlist(QEMUClockType type)
 274 {
 275     return main_loop_tlg.tl[type];
 276 }
 277
 278 void timerlist_notify(QEMUTimerList *timer_list)
 279 {
 280     if (timer_list->notify_cb) {
 281         timer_list->notify_cb(timer_list->notify_opaque, timer_list->clock->type);
 282     } else {
 283         qemu_notify_event();
 284     }
 285 }
 286
 287 /* Transition function to convert a nanosecond timeout to ms
 288  * This is used where a system does not support ppoll
 289  */
 290 int qemu_timeout_ns_to_ms(int64_t ns)
 291 {
 292     int64_t ms;
 293     if (ns < 0) {
 294         return -1;
 295     }
 296
 297     if (!ns) {
 298         return 0;
 299     }
 300
 301     /* Always round up, because it's better to wait too long than to wait too
 302      * little and effectively busy-wait
 303      */
 304     ms = DIV_ROUND_UP(ns, SCALE_MS);
 305
 306     /* To avoid overflow problems, limit this to 2^31, i.e. approx 25 days */
 307     if (ms > (int64_t) INT32_MAX) {
 308         ms = INT32_MAX;
 309     }
 310
 311     return (int) ms;
 312 }
 313
 314
 315 /* qemu implementation of g_poll which uses a nanosecond timeout but is
 316  * otherwise identical to g_poll
 317  */
 318 int qemu_poll_ns(GPollFD *fds, guint nfds, int64_t timeout)
 319 {
 320 #ifdef CONFIG_PPOLL
 321     if (timeout < 0) {
 322         return ppoll((struct pollfd *)fds, nfds, NULL, NULL);
 323     } else {
 324         struct timespec ts;
 325         int64_t tvsec = timeout / 1000000000LL;
 326         /* Avoid possibly overflowing and specifying a negative number of
 327          * seconds, which would turn a very long timeout into a busy-wait.
 328          */
 329         if (tvsec > (int64_t)INT32_MAX) {
 330             tvsec = INT32_MAX;
 331         }
 332         ts.tv_sec = tvsec;
 333         ts.tv_nsec = timeout % 1000000000LL;
 334         return ppoll((struct pollfd *)fds, nfds, &ts, NULL);
 335     }
 336 #else
 337     return g_poll(fds, nfds, qemu_timeout_ns_to_ms(timeout));
 338 #endif
 339 }
 340
 341
 342 void timer_init_tl(QEMUTimer *ts,
 343                    QEMUTimerList *timer_list, int scale,
 344                    QEMUTimerCB *cb, void *opaque)
 345 {
 346     ts->timer_list = timer_list;
 347     ts->cb = cb;
 348     ts->opaque = opaque;
 349     ts->scale = scale;
 350     ts->expire_time = -1;
 351 }
 352
 353 void timer_deinit(QEMUTimer *ts)
 354 {
 355     assert(ts->expire_time == -1);
 356     ts->timer_list = NULL;
 357 }
 358
 359 static void timer_del_locked(QEMUTimerList *timer_list, QEMUTimer *ts)
 360 {
 361     QEMUTimer **pt, *t;
 362
 363     ts->expire_time = -1;
 364     pt = &timer_list->active_timers;
 365     for(;;) {
 366         t = *pt;
 367         if (!t)
 368             break;
 369         if (t == ts) {
 370             atomic_set(pt, t->next);
 371             break;
 372         }
 373         pt = &t->next;
 374     }
 375 }
 376
 377 static bool timer_mod_ns_locked(QEMUTimerList *timer_list,
 378                                 QEMUTimer *ts, int64_t expire_time)
 379 {
 380     QEMUTimer **pt, *t;
 381
 382     /* add the timer in the sorted list */
 383     pt = &timer_list->active_timers;
 384     for (;;) {
 385         t = *pt;
 386         if (!timer_expired_ns(t, expire_time)) {
 387             break;
 388         }
 389         pt = &t->next;
 390     }
 391     ts->expire_time = MAX(expire_time, 0);
 392     ts->next = *pt;
 393     atomic_set(pt, ts);
 394
 395     return pt == &timer_list->active_timers;
 396 }
 397
 398 static void timerlist_rearm(QEMUTimerList *timer_list)
 399 {
 400     /* Interrupt execution to force deadline recalculation.  */
 401     if (timer_list->clock->type == QEMU_CLOCK_VIRTUAL) {
 402         qemu_start_warp_timer();
 403     }
 404     timerlist_notify(timer_list);
 405 }
 406
 407 /* stop a timer, but do not dealloc it */
 408 void timer_del(QEMUTimer *ts)
 409 {
 410     QEMUTimerList *timer_list = ts->timer_list;
 411
 412     if (timer_list) {
 413         qemu_mutex_lock(&timer_list->active_timers_lock);
 414         timer_del_locked(timer_list, ts);
 415         qemu_mutex_unlock(&timer_list->active_timers_lock);
 416     }
 417 }
 418
 419 /* modify the current timer so that it will be fired when current_time
 420    >= expire_time. The corresponding callback will be called. */
 421 void timer_mod_ns(QEMUTimer *ts, int64_t expire_time)
 422 {
 423     QEMUTimerList *timer_list = ts->timer_list;
 424     bool rearm;
 425
 426     qemu_mutex_lock(&timer_list->active_timers_lock);
 427     timer_del_locked(timer_list, ts);
 428     rearm = timer_mod_ns_locked(timer_list, ts, expire_time);
 429     qemu_mutex_unlock(&timer_list->active_timers_lock);
 430
 431     if (rearm) {
 432         timerlist_rearm(timer_list);
 433     }
 434 }
 435
 436 /* modify the current timer so that it will be fired when current_time
 437    >= expire_time or the current deadline, whichever comes earlier.
 438    The corresponding callback will be called. */
 439 void timer_mod_anticipate_ns(QEMUTimer *ts, int64_t expire_time)
 440 {
 441     QEMUTimerList *timer_list = ts->timer_list;
 442     bool rearm;
 443
 444     qemu_mutex_lock(&timer_list->active_timers_lock);
 445     if (ts->expire_time == -1 || ts->expire_time > expire_time) {
 446         if (ts->expire_time != -1) {
 447             timer_del_locked(timer_list, ts);
 448         }
 449         rearm = timer_mod_ns_locked(timer_list, ts, expire_time);
 450     } else {
 451         rearm = false;
 452     }
 453     qemu_mutex_unlock(&timer_list->active_timers_lock);
 454
 455     if (rearm) {
 456         timerlist_rearm(timer_list);
 457     }
 458 }
 459
 460 void timer_mod(QEMUTimer *ts, int64_t expire_time)
 461 {
 462     timer_mod_ns(ts, expire_time * ts->scale);
 463 }
 464
 465 void timer_mod_anticipate(QEMUTimer *ts, int64_t expire_time)
 466 {
 467     timer_mod_anticipate_ns(ts, expire_time * ts->scale);
 468 }
 469
 470 bool timer_pending(QEMUTimer *ts)
 471 {
 472     return ts->expire_time >= 0;
 473 }
 474
 475 bool timer_expired(QEMUTimer *timer_head, int64_t current_time)
 476 {
 477     return timer_expired_ns(timer_head, current_time * timer_head->scale);
 478 }
 479
 480 bool timerlist_run_timers(QEMUTimerList *timer_list)
 481 {
 482     QEMUTimer *ts;
 483     int64_t current_time;
 484     bool progress = false;
 485     QEMUTimerCB *cb;
 486     void *opaque;
 487
 488     if (!atomic_read(&timer_list->active_timers)) {
 489         return false;
 490     }
 491
 492     qemu_event_reset(&timer_list->timers_done_ev);
 493     if (!timer_list->clock->enabled) {
 494         goto out;
 495     }
 496
 497     switch (timer_list->clock->type) {
 498     case QEMU_CLOCK_REALTIME:
 499         break;
 500     default:
 501     case QEMU_CLOCK_VIRTUAL:
 502         if (!replay_checkpoint(CHECKPOINT_CLOCK_VIRTUAL)) {
 503             goto out;
 504         }
 505         break;
 506     case QEMU_CLOCK_HOST:
 507         if (!replay_checkpoint(CHECKPOINT_CLOCK_HOST)) {
 508             goto out;
 509         }
 510         break;
 511     case QEMU_CLOCK_VIRTUAL_RT:
 512         if (!replay_checkpoint(CHECKPOINT_CLOCK_VIRTUAL_RT)) {
 513             goto out;
 514         }
 515         break;
 516     }
 517
 518     current_time = qemu_clock_get_ns(timer_list->clock->type);
 519     for(;;) {
 520         qemu_mutex_lock(&timer_list->active_timers_lock);
 521         ts = timer_list->active_timers;
 522         if (!timer_expired_ns(ts, current_time)) {
 523             qemu_mutex_unlock(&timer_list->active_timers_lock);
 524             break;
 525         }
 526
 527         /* remove timer from the list before calling the callback */
 528         timer_list->active_timers = ts->next;
 529         ts->next = NULL;
 530         ts->expire_time = -1;
 531         cb = ts->cb;
 532         opaque = ts->opaque;
 533         qemu_mutex_unlock(&timer_list->active_timers_lock);
 534
 535         /* run the callback (the timer list can be modified) */
 536         cb(opaque);
 537         progress = true;
 538     }
 539
 540 out:
 541     qemu_event_set(&timer_list->timers_done_ev);
 542     return progress;
 543 }
 544
 545 bool qemu_clock_run_timers(QEMUClockType type)
 546 {
 547     return timerlist_run_timers(main_loop_tlg.tl[type]);
 548 }
 549
 550 void timerlistgroup_init(QEMUTimerListGroup *tlg,
 551                          QEMUTimerListNotifyCB *cb, void *opaque)
 552 {
 553     QEMUClockType type;
 554     for (type = 0; type < QEMU_CLOCK_MAX; type++) {
 555         tlg->tl[type] = timerlist_new(type, cb, opaque);
 556     }
 557 }
 558
 559 void timerlistgroup_deinit(QEMUTimerListGroup *tlg)
 560 {
 561     QEMUClockType type;
 562     for (type = 0; type < QEMU_CLOCK_MAX; type++) {
 563         timerlist_free(tlg->tl[type]);
 564     }
 565 }
 566
 567 bool timerlistgroup_run_timers(QEMUTimerListGroup *tlg)
 568 {
 569     QEMUClockType type;
 570     bool progress = false;
 571     for (type = 0; type < QEMU_CLOCK_MAX; type++) {
 572         progress |= timerlist_run_timers(tlg->tl[type]);
 573     }
 574     return progress;
 575 }
 576
 577 int64_t timerlistgroup_deadline_ns(QEMUTimerListGroup *tlg)
 578 {
 579     int64_t deadline = -1;
 580     QEMUClockType type;
 581     for (type = 0; type < QEMU_CLOCK_MAX; type++) {
 582         if (qemu_clock_use_for_deadline(type)) {
 583             deadline = qemu_soonest_timeout(deadline,
 584                                             timerlist_deadline_ns(tlg->tl[type]));
 585         }
 586     }
 587     return deadline;
 588 }
 589
 590 int64_t qemu_clock_get_ns(QEMUClockType type)
 591 {
 592     int64_t now, last;
 593     QEMUClock *clock = qemu_clock_ptr(type);
 594
 595     switch (type) {
 596     case QEMU_CLOCK_REALTIME:
 597         return get_clock();
 598     default:
 599     case QEMU_CLOCK_VIRTUAL:
 600         if (use_icount) {
 601             return cpu_get_icount();
 602         } else {
 603             return cpu_get_clock();
 604         }
 605     case QEMU_CLOCK_HOST:
 606         now = REPLAY_CLOCK(REPLAY_CLOCK_HOST, get_clock_realtime());
 607         last = clock->last;
 608         clock->last = now;
 609         if (now < last || now > (last + get_max_clock_jump())) {
 610             notifier_list_notify(&clock->reset_notifiers, &now);
 611         }
 612         return now;
 613     case QEMU_CLOCK_VIRTUAL_RT:
 614         return REPLAY_CLOCK(REPLAY_CLOCK_VIRTUAL_RT, cpu_get_clock());
 615     }
 616 }
 617
 618 uint64_t qemu_clock_get_last(QEMUClockType type)
 619 {
 620     QEMUClock *clock = qemu_clock_ptr(type);
 621     return clock->last;
 622 }
 623
 624 void qemu_clock_set_last(QEMUClockType type, uint64_t last)
 625 {
 626     QEMUClock *clock = qemu_clock_ptr(type);
 627     clock->last = last;
 628 }
 629
 630 void qemu_clock_register_reset_notifier(QEMUClockType type,
 631                                         Notifier *notifier)
 632 {
 633     QEMUClock *clock = qemu_clock_ptr(type);
 634     notifier_list_add(&clock->reset_notifiers, notifier);
 635 }
 636
 637 void qemu_clock_unregister_reset_notifier(QEMUClockType type,
 638                                           Notifier *notifier)
 639 {
 640     notifier_remove(notifier);
 641 }
 642
 643 void init_clocks(QEMUTimerListNotifyCB *notify_cb)
 644 {
 645     QEMUClockType type;
 646     for (type = 0; type < QEMU_CLOCK_MAX; type++) {
 647         qemu_clock_init(type, notify_cb);
 648     }
 649
 650 #ifdef CONFIG_PRCTL_PR_SET_TIMERSLACK
 651     prctl(PR_SET_TIMERSLACK, 1, 0, 0, 0);
 652 #endif
 653 }
 654
 655 uint64_t timer_expire_time_ns(QEMUTimer *ts)
 656 {
 657     return timer_pending(ts) ? ts->expire_time : -1;
 658 }
 659
 660 bool qemu_clock_run_all_timers(void)
 661 {
 662     bool progress = false;
 663     QEMUClockType type;
 664
 665     for (type = 0; type < QEMU_CLOCK_MAX; type++) {
 666         if (qemu_clock_use_for_deadline(type)) {
 667             progress |= qemu_clock_run_timers(type);
 668         }
 669     }
 670
 671     return progress;
 672 }