qemu/qemu-timer.c
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   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
  31#ifdef CONFIG_POSIX
  32#include <pthread.h>
  33#endif
  34
  35#ifdef CONFIG_PPOLL
  36#include <poll.h>
  37#endif
  38
  39#ifdef CONFIG_PRCTL_PR_SET_TIMERSLACK
  40#include <sys/prctl.h>
  41#endif
  42
  43/***********************************************************/
  44/* timers */
  45
  46typedef struct QEMUClock {
  47    /* We rely on BQL to protect the timerlists */
  48    QLIST_HEAD(, QEMUTimerList) timerlists;
  49
  50    NotifierList reset_notifiers;
  51    int64_t last;
  52
  53    QEMUClockType type;
  54    bool enabled;
  55} QEMUClock;
  56
  57QEMUTimerListGroup main_loop_tlg;
  58static QEMUClock qemu_clocks[QEMU_CLOCK_MAX];
  59
  60/* A QEMUTimerList is a list of timers attached to a clock. More
  61 * than one QEMUTimerList can be attached to each clock, for instance
  62 * used by different AioContexts / threads. Each clock also has
  63 * a list of the QEMUTimerLists associated with it, in order that
  64 * reenabling the clock can call all the notifiers.
  65 */
  66
  67struct QEMUTimerList {
  68    QEMUClock *clock;
  69    QemuMutex active_timers_lock;
  70    QEMUTimer *active_timers;
  71    QLIST_ENTRY(QEMUTimerList) list;
  72    QEMUTimerListNotifyCB *notify_cb;
  73    void *notify_opaque;
  74
  75    /* lightweight method to mark the end of timerlist's running */
  76    QemuEvent timers_done_ev;
  77};
  78
  79/**
  80 * qemu_clock_ptr:
  81 * @type: type of clock
  82 *
  83 * Translate a clock type into a pointer to QEMUClock object.
  84 *
  85 * Returns: a pointer to the QEMUClock object
  86 */
  87static inline QEMUClock *qemu_clock_ptr(QEMUClockType type)
  88{
  89    return &qemu_clocks[type];
  90}
  91
  92static bool timer_expired_ns(QEMUTimer *timer_head, int64_t current_time)
  93{
  94    return timer_head && (timer_head->expire_time <= current_time);
  95}
  96
  97QEMUTimerList *timerlist_new(QEMUClockType type,
  98                             QEMUTimerListNotifyCB *cb,
  99                             void *opaque)
 100{
 101    QEMUTimerList *timer_list;
 102    QEMUClock *clock = qemu_clock_ptr(type);
 103
 104    timer_list = g_malloc0(sizeof(QEMUTimerList));
 105    qemu_event_init(&timer_list->timers_done_ev, true);
 106    timer_list->clock = clock;
 107    timer_list->notify_cb = cb;
 108    timer_list->notify_opaque = opaque;
 109    qemu_mutex_init(&timer_list->active_timers_lock);
 110    QLIST_INSERT_HEAD(&clock->timerlists, timer_list, list);
 111    return timer_list;
 112}
 113
 114void timerlist_free(QEMUTimerList *timer_list)
 115{
 116    assert(!timerlist_has_timers(timer_list));
 117    if (timer_list->clock) {
 118        QLIST_REMOVE(timer_list, list);
 119    }
 120    qemu_mutex_destroy(&timer_list->active_timers_lock);
 121    g_free(timer_list);
 122}
 123
 124static void qemu_clock_init(QEMUClockType type)
 125{
 126    QEMUClock *clock = qemu_clock_ptr(type);
 127
 128    /* Assert that the clock of type TYPE has not been initialized yet. */
 129    assert(main_loop_tlg.tl[type] == NULL);
 130
 131    clock->type = type;
 132    clock->enabled = (type == QEMU_CLOCK_VIRTUAL ? false : true);
 133    clock->last = INT64_MIN;
 134    QLIST_INIT(&clock->timerlists);
 135    notifier_list_init(&clock->reset_notifiers);
 136    main_loop_tlg.tl[type] = timerlist_new(type, NULL, NULL);
 137}
 138
 139bool qemu_clock_use_for_deadline(QEMUClockType type)
 140{
 141    return !(use_icount && (type == QEMU_CLOCK_VIRTUAL));
 142}
 143
 144void qemu_clock_notify(QEMUClockType type)
 145{
 146    QEMUTimerList *timer_list;
 147    QEMUClock *clock = qemu_clock_ptr(type);
 148    QLIST_FOREACH(timer_list, &clock->timerlists, list) {
 149        timerlist_notify(timer_list);
 150    }
 151}
 152
 153/* Disabling the clock will wait for related timerlists to stop
 154 * executing qemu_run_timers.  Thus, this functions should not
 155 * be used from the callback of a timer that is based on @clock.
 156 * Doing so would cause a deadlock.
 157 *
 158 * Caller should hold BQL.
 159 */
 160void qemu_clock_enable(QEMUClockType type, bool enabled)
 161{
 162    QEMUClock *clock = qemu_clock_ptr(type);
 163    QEMUTimerList *tl;
 164    bool old = clock->enabled;
 165    clock->enabled = enabled;
 166    if (enabled && !old) {
 167        qemu_clock_notify(type);
 168    } else if (!enabled && old) {
 169        QLIST_FOREACH(tl, &clock->timerlists, list) {
 170            qemu_event_wait(&tl->timers_done_ev);
 171        }
 172    }
 173}
 174
 175bool timerlist_has_timers(QEMUTimerList *timer_list)
 176{
 177    return !!timer_list->active_timers;
 178}
 179
 180bool qemu_clock_has_timers(QEMUClockType type)
 181{
 182    return timerlist_has_timers(
 183        main_loop_tlg.tl[type]);
 184}
 185
 186bool timerlist_expired(QEMUTimerList *timer_list)
 187{
 188    int64_t expire_time;
 189
 190    qemu_mutex_lock(&timer_list->active_timers_lock);
 191    if (!timer_list->active_timers) {
 192        qemu_mutex_unlock(&timer_list->active_timers_lock);
 193        return false;
 194    }
 195    expire_time = timer_list->active_timers->expire_time;
 196    qemu_mutex_unlock(&timer_list->active_timers_lock);
 197
 198    return expire_time < qemu_clock_get_ns(timer_list->clock->type);
 199}
 200
 201bool qemu_clock_expired(QEMUClockType type)
 202{
 203    return timerlist_expired(
 204        main_loop_tlg.tl[type]);
 205}
 206
 207/*
 208 * As above, but return -1 for no deadline, and do not cap to 2^32
 209 * as we know the result is always positive.
 210 */
 211
 212int64_t timerlist_deadline_ns(QEMUTimerList *timer_list)
 213{
 214    int64_t delta;
 215    int64_t expire_time;
 216
 217    if (!timer_list->clock->enabled) {
 218        return -1;
 219    }
 220
 221    /* The active timers list may be modified before the caller uses our return
 222     * value but ->notify_cb() is called when the deadline changes.  Therefore
 223     * the caller should notice the change and there is no race condition.
 224     */
 225    qemu_mutex_lock(&timer_list->active_timers_lock);
 226    if (!timer_list->active_timers) {
 227        qemu_mutex_unlock(&timer_list->active_timers_lock);
 228        return -1;
 229    }
 230    expire_time = timer_list->active_timers->expire_time;
 231    qemu_mutex_unlock(&timer_list->active_timers_lock);
 232
 233    delta = expire_time - qemu_clock_get_ns(timer_list->clock->type);
 234
 235    if (delta <= 0) {
 236        return 0;
 237    }
 238
 239    return delta;
 240}
 241
 242/* Calculate the soonest deadline across all timerlists attached
 243 * to the clock. This is used for the icount timeout so we
 244 * ignore whether or not the clock should be used in deadline
 245 * calculations.
 246 */
 247int64_t qemu_clock_deadline_ns_all(QEMUClockType type)
 248{
 249    int64_t deadline = -1;
 250    QEMUTimerList *timer_list;
 251    QEMUClock *clock = qemu_clock_ptr(type);
 252    QLIST_FOREACH(timer_list, &clock->timerlists, list) {
 253        deadline = qemu_soonest_timeout(deadline,
 254                                        timerlist_deadline_ns(timer_list));
 255    }
 256    return deadline;
 257}
 258
 259QEMUClockType timerlist_get_clock(QEMUTimerList *timer_list)
 260{
 261    return timer_list->clock->type;
 262}
 263
 264QEMUTimerList *qemu_clock_get_main_loop_timerlist(QEMUClockType type)
 265{
 266    return main_loop_tlg.tl[type];
 267}
 268
 269void timerlist_notify(QEMUTimerList *timer_list)
 270{
 271    if (timer_list->notify_cb) {
 272        timer_list->notify_cb(timer_list->notify_opaque);
 273    } else {
 274        qemu_notify_event();
 275    }
 276}
 277
 278/* Transition function to convert a nanosecond timeout to ms
 279 * This is used where a system does not support ppoll
 280 */
 281int qemu_timeout_ns_to_ms(int64_t ns)
 282{
 283    int64_t ms;
 284    if (ns < 0) {
 285        return -1;
 286    }
 287
 288    if (!ns) {
 289        return 0;
 290    }
 291
 292    /* Always round up, because it's better to wait too long than to wait too
 293     * little and effectively busy-wait
 294     */
 295    ms = DIV_ROUND_UP(ns, SCALE_MS);
 296
 297    /* To avoid overflow problems, limit this to 2^31, i.e. approx 25 days */
 298    if (ms > (int64_t) INT32_MAX) {
 299        ms = INT32_MAX;
 300    }
 301
 302    return (int) ms;
 303}
 304
 305
 306/* qemu implementation of g_poll which uses a nanosecond timeout but is
 307 * otherwise identical to g_poll
 308 */
 309int qemu_poll_ns(GPollFD *fds, guint nfds, int64_t timeout)
 310{
 311#ifdef CONFIG_PPOLL
 312    if (timeout < 0) {
 313        return ppoll((struct pollfd *)fds, nfds, NULL, NULL);
 314    } else {
 315        struct timespec ts;
 316        int64_t tvsec = timeout / 1000000000LL;
 317        /* Avoid possibly overflowing and specifying a negative number of
 318         * seconds, which would turn a very long timeout into a busy-wait.
 319         */
 320        if (tvsec > (int64_t)INT32_MAX) {
 321            tvsec = INT32_MAX;
 322        }
 323        ts.tv_sec = tvsec;
 324        ts.tv_nsec = timeout % 1000000000LL;
 325        return ppoll((struct pollfd *)fds, nfds, &ts, NULL);
 326    }
 327#else
 328    return g_poll(fds, nfds, qemu_timeout_ns_to_ms(timeout));
 329#endif
 330}
 331
 332
 333void timer_init_tl(QEMUTimer *ts,
 334                   QEMUTimerList *timer_list, int scale,
 335                   QEMUTimerCB *cb, void *opaque)
 336{
 337    ts->timer_list = timer_list;
 338    ts->cb = cb;
 339    ts->opaque = opaque;
 340    ts->scale = scale;
 341    ts->expire_time = -1;
 342}
 343
 344void timer_deinit(QEMUTimer *ts)
 345{
 346    assert(ts->expire_time == -1);
 347    ts->timer_list = NULL;
 348}
 349
 350void timer_free(QEMUTimer *ts)
 351{
 352    g_free(ts);
 353}
 354
 355static void timer_del_locked(QEMUTimerList *timer_list, QEMUTimer *ts)
 356{
 357    QEMUTimer **pt, *t;
 358
 359    ts->expire_time = -1;
 360    pt = &timer_list->active_timers;
 361    for(;;) {
 362        t = *pt;
 363        if (!t)
 364            break;
 365        if (t == ts) {
 366            *pt = t->next;
 367            break;
 368        }
 369        pt = &t->next;
 370    }
 371}
 372
 373static bool timer_mod_ns_locked(QEMUTimerList *timer_list,
 374                                QEMUTimer *ts, int64_t expire_time)
 375{
 376    QEMUTimer **pt, *t;
 377
 378    /* add the timer in the sorted list */
 379    pt = &timer_list->active_timers;
 380    for (;;) {
 381        t = *pt;
 382        if (!timer_expired_ns(t, expire_time)) {
 383            break;
 384        }
 385        pt = &t->next;
 386    }
 387    ts->expire_time = MAX(expire_time, 0);
 388    ts->next = *pt;
 389    *pt = ts;
 390
 391    return pt == &timer_list->active_timers;
 392}
 393
 394static void timerlist_rearm(QEMUTimerList *timer_list)
 395{
 396    /* Interrupt execution to force deadline recalculation.  */
 397    if (timer_list->clock->type == QEMU_CLOCK_VIRTUAL) {
 398        qemu_start_warp_timer();
 399    }
 400    timerlist_notify(timer_list);
 401}
 402
 403/* stop a timer, but do not dealloc it */
 404void timer_del(QEMUTimer *ts)
 405{
 406    QEMUTimerList *timer_list = ts->timer_list;
 407
 408    if (timer_list) {
 409        qemu_mutex_lock(&timer_list->active_timers_lock);
 410        timer_del_locked(timer_list, ts);
 411        qemu_mutex_unlock(&timer_list->active_timers_lock);
 412    }
 413}
 414
 415/* modify the current timer so that it will be fired when current_time
 416   >= expire_time. The corresponding callback will be called. */
 417void timer_mod_ns(QEMUTimer *ts, int64_t expire_time)
 418{
 419    QEMUTimerList *timer_list = ts->timer_list;
 420    bool rearm;
 421
 422    qemu_mutex_lock(&timer_list->active_timers_lock);
 423    timer_del_locked(timer_list, ts);
 424    rearm = timer_mod_ns_locked(timer_list, ts, expire_time);
 425    qemu_mutex_unlock(&timer_list->active_timers_lock);
 426
 427    if (rearm) {
 428        timerlist_rearm(timer_list);
 429    }
 430}
 431
 432/* modify the current timer so that it will be fired when current_time
 433   >= expire_time or the current deadline, whichever comes earlier.
 434   The corresponding callback will be called. */
 435void timer_mod_anticipate_ns(QEMUTimer *ts, int64_t expire_time)
 436{
 437    QEMUTimerList *timer_list = ts->timer_list;
 438    bool rearm;
 439
 440    qemu_mutex_lock(&timer_list->active_timers_lock);
 441    if (ts->expire_time == -1 || ts->expire_time > expire_time) {
 442        if (ts->expire_time != -1) {
 443            timer_del_locked(timer_list, ts);
 444        }
 445        rearm = timer_mod_ns_locked(timer_list, ts, expire_time);
 446    } else {
 447        rearm = false;
 448    }
 449    qemu_mutex_unlock(&timer_list->active_timers_lock);
 450
 451    if (rearm) {
 452        timerlist_rearm(timer_list);
 453    }
 454}
 455
 456void timer_mod(QEMUTimer *ts, int64_t expire_time)
 457{
 458    timer_mod_ns(ts, expire_time * ts->scale);
 459}
 460
 461void timer_mod_anticipate(QEMUTimer *ts, int64_t expire_time)
 462{
 463    timer_mod_anticipate_ns(ts, expire_time * ts->scale);
 464}
 465
 466bool timer_pending(QEMUTimer *ts)
 467{
 468    return ts->expire_time >= 0;
 469}
 470
 471bool timer_expired(QEMUTimer *timer_head, int64_t current_time)
 472{
 473    return timer_expired_ns(timer_head, current_time * timer_head->scale);
 474}
 475
 476bool timerlist_run_timers(QEMUTimerList *timer_list)
 477{
 478    QEMUTimer *ts;
 479    int64_t current_time;
 480    bool progress = false;
 481    QEMUTimerCB *cb;
 482    void *opaque;
 483
 484    qemu_event_reset(&timer_list->timers_done_ev);
 485    if (!timer_list->clock->enabled || !timer_list->active_timers) {
 486        goto out;
 487    }
 488
 489    switch (timer_list->clock->type) {
 490    case QEMU_CLOCK_REALTIME:
 491        break;
 492    default:
 493    case QEMU_CLOCK_VIRTUAL:
 494        if (!replay_checkpoint(CHECKPOINT_CLOCK_VIRTUAL)) {
 495            goto out;
 496        }
 497        break;
 498    case QEMU_CLOCK_HOST:
 499        if (!replay_checkpoint(CHECKPOINT_CLOCK_HOST)) {
 500            goto out;
 501        }
 502        break;
 503    case QEMU_CLOCK_VIRTUAL_RT:
 504        if (!replay_checkpoint(CHECKPOINT_CLOCK_VIRTUAL_RT)) {
 505            goto out;
 506        }
 507        break;
 508    }
 509
 510    current_time = qemu_clock_get_ns(timer_list->clock->type);
 511    for(;;) {
 512        qemu_mutex_lock(&timer_list->active_timers_lock);
 513        ts = timer_list->active_timers;
 514        if (!timer_expired_ns(ts, current_time)) {
 515            qemu_mutex_unlock(&timer_list->active_timers_lock);
 516            break;
 517        }
 518
 519        /* remove timer from the list before calling the callback */
 520        timer_list->active_timers = ts->next;
 521        ts->next = NULL;
 522        ts->expire_time = -1;
 523        cb = ts->cb;
 524        opaque = ts->opaque;
 525        qemu_mutex_unlock(&timer_list->active_timers_lock);
 526
 527        /* run the callback (the timer list can be modified) */
 528        cb(opaque);
 529        progress = true;
 530    }
 531
 532out:
 533    qemu_event_set(&timer_list->timers_done_ev);
 534    return progress;
 535}
 536
 537bool qemu_clock_run_timers(QEMUClockType type)
 538{
 539    return timerlist_run_timers(main_loop_tlg.tl[type]);
 540}
 541
 542void timerlistgroup_init(QEMUTimerListGroup *tlg,
 543                         QEMUTimerListNotifyCB *cb, void *opaque)
 544{
 545    QEMUClockType type;
 546    for (type = 0; type < QEMU_CLOCK_MAX; type++) {
 547        tlg->tl[type] = timerlist_new(type, cb, opaque);
 548    }
 549}
 550
 551void timerlistgroup_deinit(QEMUTimerListGroup *tlg)
 552{
 553    QEMUClockType type;
 554    for (type = 0; type < QEMU_CLOCK_MAX; type++) {
 555        timerlist_free(tlg->tl[type]);
 556    }
 557}
 558
 559bool timerlistgroup_run_timers(QEMUTimerListGroup *tlg)
 560{
 561    QEMUClockType type;
 562    bool progress = false;
 563    for (type = 0; type < QEMU_CLOCK_MAX; type++) {
 564        progress |= timerlist_run_timers(tlg->tl[type]);
 565    }
 566    return progress;
 567}
 568
 569int64_t timerlistgroup_deadline_ns(QEMUTimerListGroup *tlg)
 570{
 571    int64_t deadline = -1;
 572    QEMUClockType type;
 573    bool play = replay_mode == REPLAY_MODE_PLAY;
 574    for (type = 0; type < QEMU_CLOCK_MAX; type++) {
 575        if (qemu_clock_use_for_deadline(type)) {
 576            if (!play || type == QEMU_CLOCK_REALTIME) {
 577                deadline = qemu_soonest_timeout(deadline,
 578                                                timerlist_deadline_ns(tlg->tl[type]));
 579            } else {
 580                /* Read clock from the replay file and
 581                   do not calculate the deadline, based on virtual clock. */
 582                qemu_clock_get_ns(type);
 583            }
 584        }
 585    }
 586    return deadline;
 587}
 588
 589int64_t qemu_clock_get_ns(QEMUClockType type)
 590{
 591    int64_t now, last;
 592    QEMUClock *clock = qemu_clock_ptr(type);
 593
 594    switch (type) {
 595    case QEMU_CLOCK_REALTIME:
 596        return get_clock();
 597    default:
 598    case QEMU_CLOCK_VIRTUAL:
 599        if (use_icount) {
 600            return cpu_get_icount();
 601        } else {
 602            return cpu_get_clock();
 603        }
 604    case QEMU_CLOCK_HOST:
 605        now = REPLAY_CLOCK(REPLAY_CLOCK_HOST, get_clock_realtime());
 606        last = clock->last;
 607        clock->last = now;
 608        if (now < last || now > (last + get_max_clock_jump())) {
 609            notifier_list_notify(&clock->reset_notifiers, &now);
 610        }
 611        return now;
 612    case QEMU_CLOCK_VIRTUAL_RT:
 613        return REPLAY_CLOCK(REPLAY_CLOCK_VIRTUAL_RT, cpu_get_clock());
 614    }
 615}
 616
 617void qemu_clock_register_reset_notifier(QEMUClockType type,
 618                                        Notifier *notifier)
 619{
 620    QEMUClock *clock = qemu_clock_ptr(type);
 621    notifier_list_add(&clock->reset_notifiers, notifier);
 622}
 623
 624void qemu_clock_unregister_reset_notifier(QEMUClockType type,
 625                                          Notifier *notifier)
 626{
 627    notifier_remove(notifier);
 628}
 629
 630void init_clocks(void)
 631{
 632    QEMUClockType type;
 633    for (type = 0; type < QEMU_CLOCK_MAX; type++) {
 634        qemu_clock_init(type);
 635    }
 636
 637#ifdef CONFIG_PRCTL_PR_SET_TIMERSLACK
 638    prctl(PR_SET_TIMERSLACK, 1, 0, 0, 0);
 639#endif
 640}
 641
 642uint64_t timer_expire_time_ns(QEMUTimer *ts)
 643{
 644    return timer_pending(ts) ? ts->expire_time : -1;
 645}
 646
 647bool qemu_clock_run_all_timers(void)
 648{
 649    bool progress = false;
 650    QEMUClockType type;
 651
 652    for (type = 0; type < QEMU_CLOCK_MAX; type++) {
 653        progress |= qemu_clock_run_timers(type);
 654    }
 655
 656    return progress;
 657}
 658