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.h"
  26 #include "net.h"
  27 #include "monitor.h"
  28 #include "console.h"
  29
  30 #include "hw/hw.h"
  31
  32 #include <unistd.h>
  33 #include <fcntl.h>
  34 #include <time.h>
  35 #include <errno.h>
  36 #include <sys/time.h>
  37 #include <signal.h>
  38 #ifdef __FreeBSD__
  39 #include <sys/param.h>
  40 #endif
  41
  42 #ifdef _WIN32
  43 #include <windows.h>
  44 #include <mmsystem.h>
  45 #endif
  46
  47 #include "qemu-timer.h"
  48
  49 /***********************************************************/
  50 /* timers */
  51
  52 #define QEMU_CLOCK_REALTIME 0
  53 #define QEMU_CLOCK_VIRTUAL  1
  54 #define QEMU_CLOCK_HOST     2
  55
  56 struct QEMUClock {
  57     int type;
  58     int enabled;
  59
  60     QEMUTimer *active_timers;
  61
  62     NotifierList reset_notifiers;
  63     int64_t last;
  64 };
  65
  66 struct QEMUTimer {
  67     QEMUClock *clock;
  68     int64_t expire_time;        /* in nanoseconds */
  69     int scale;
  70     QEMUTimerCB *cb;
  71     void *opaque;
  72     struct QEMUTimer *next;
  73 };
  74
  75 struct qemu_alarm_timer {
  76     char const *name;
  77     int (*start)(struct qemu_alarm_timer *t);
  78     void (*stop)(struct qemu_alarm_timer *t);
  79     void (*rearm)(struct qemu_alarm_timer *t, int64_t nearest_delta_ns);
  80 #if defined(__linux__)
  81     int fd;
  82     timer_t timer;
  83 #elif defined(_WIN32)
  84     HANDLE timer;
  85 #endif
  86     char expired;
  87     char pending;
  88 };
  89
  90 static struct qemu_alarm_timer *alarm_timer;
  91
  92 static bool qemu_timer_expired_ns(QEMUTimer *timer_head, int64_t current_time)
  93 {
  94     return timer_head && (timer_head->expire_time <= current_time);
  95 }
  96
  97 int qemu_alarm_pending(void)
  98 {
  99     return alarm_timer->pending;
 100 }
 101
 102 static inline int alarm_has_dynticks(struct qemu_alarm_timer *t)
 103 {
 104     return !!t->rearm;
 105 }
 106
 107 static int64_t qemu_next_alarm_deadline(void)
 108 {
 109     int64_t delta;
 110     int64_t rtdelta;
 111
 112     if (!use_icount && vm_clock->active_timers) {
 113         delta = vm_clock->active_timers->expire_time -
 114                      qemu_get_clock_ns(vm_clock);
 115     } else {
 116         delta = INT32_MAX;
 117     }
 118     if (host_clock->active_timers) {
 119         int64_t hdelta = host_clock->active_timers->expire_time -
 120                  qemu_get_clock_ns(host_clock);
 121         if (hdelta < delta) {
 122             delta = hdelta;
 123         }
 124     }
 125     if (rt_clock->active_timers) {
 126         rtdelta = (rt_clock->active_timers->expire_time -
 127                  qemu_get_clock_ns(rt_clock));
 128         if (rtdelta < delta) {
 129             delta = rtdelta;
 130         }
 131     }
 132
 133     return delta;
 134 }
 135
 136 static void qemu_rearm_alarm_timer(struct qemu_alarm_timer *t)
 137 {
 138     int64_t nearest_delta_ns;
 139     assert(alarm_has_dynticks(t));
 140     if (!rt_clock->active_timers &&
 141         !vm_clock->active_timers &&
 142         !host_clock->active_timers) {
 143         return;
 144     }
 145     nearest_delta_ns = qemu_next_alarm_deadline();
 146     t->rearm(t, nearest_delta_ns);
 147 }
 148
 149 /* TODO: MIN_TIMER_REARM_NS should be optimized */
 150 #define MIN_TIMER_REARM_NS 250000
 151
 152 #ifdef _WIN32
 153
 154 static int mm_start_timer(struct qemu_alarm_timer *t);
 155 static void mm_stop_timer(struct qemu_alarm_timer *t);
 156 static void mm_rearm_timer(struct qemu_alarm_timer *t, int64_t delta);
 157
 158 static int win32_start_timer(struct qemu_alarm_timer *t);
 159 static void win32_stop_timer(struct qemu_alarm_timer *t);
 160 static void win32_rearm_timer(struct qemu_alarm_timer *t, int64_t delta);
 161
 162 #else
 163
 164 static int unix_start_timer(struct qemu_alarm_timer *t);
 165 static void unix_stop_timer(struct qemu_alarm_timer *t);
 166 static void unix_rearm_timer(struct qemu_alarm_timer *t, int64_t delta);
 167
 168 #ifdef __linux__
 169
 170 static int dynticks_start_timer(struct qemu_alarm_timer *t);
 171 static void dynticks_stop_timer(struct qemu_alarm_timer *t);
 172 static void dynticks_rearm_timer(struct qemu_alarm_timer *t, int64_t delta);
 173
 174 #endif /* __linux__ */
 175
 176 #endif /* _WIN32 */
 177
 178 static struct qemu_alarm_timer alarm_timers[] = {
 179 #ifndef _WIN32
 180 #ifdef __linux__
 181     {"dynticks", dynticks_start_timer,
 182      dynticks_stop_timer, dynticks_rearm_timer},
 183 #endif
 184     {"unix", unix_start_timer, unix_stop_timer, unix_rearm_timer},
 185 #else
 186     {"mmtimer", mm_start_timer, mm_stop_timer, NULL},
 187     {"mmtimer2", mm_start_timer, mm_stop_timer, mm_rearm_timer},
 188     {"dynticks", win32_start_timer, win32_stop_timer, win32_rearm_timer},
 189     {"win32", win32_start_timer, win32_stop_timer, NULL},
 190 #endif
 191     {NULL, }
 192 };
 193
 194 static void show_available_alarms(void)
 195 {
 196     int i;
 197
 198     printf("Available alarm timers, in order of precedence:\n");
 199     for (i = 0; alarm_timers[i].name; i++)
 200         printf("%s\n", alarm_timers[i].name);
 201 }
 202
 203 void configure_alarms(char const *opt)
 204 {
 205     int i;
 206     int cur = 0;
 207     int count = ARRAY_SIZE(alarm_timers) - 1;
 208     char *arg;
 209     char *name;
 210     struct qemu_alarm_timer tmp;
 211
 212     if (!strcmp(opt, "?")) {
 213         show_available_alarms();
 214         exit(0);
 215     }
 216
 217     arg = g_strdup(opt);
 218
 219     /* Reorder the array */
 220     name = strtok(arg, ",");
 221     while (name) {
 222         for (i = 0; i < count && alarm_timers[i].name; i++) {
 223             if (!strcmp(alarm_timers[i].name, name))
 224                 break;
 225         }
 226
 227         if (i == count) {
 228             fprintf(stderr, "Unknown clock %s\n", name);
 229             goto next;
 230         }
 231
 232         if (i < cur)
 233             /* Ignore */
 234             goto next;
 235
 236         /* Swap */
 237         tmp = alarm_timers[i];
 238         alarm_timers[i] = alarm_timers[cur];
 239         alarm_timers[cur] = tmp;
 240
 241         cur++;
 242 next:
 243         name = strtok(NULL, ",");
 244     }
 245
 246     g_free(arg);
 247
 248     if (cur) {
 249         /* Disable remaining timers */
 250         for (i = cur; i < count; i++)
 251             alarm_timers[i].name = NULL;
 252     } else {
 253         show_available_alarms();
 254         exit(1);
 255     }
 256 }
 257
 258 QEMUClock *rt_clock;
 259 QEMUClock *vm_clock;
 260 QEMUClock *host_clock;
 261
 262 static QEMUClock *qemu_new_clock(int type)
 263 {
 264     QEMUClock *clock;
 265
 266     clock = g_malloc0(sizeof(QEMUClock));
 267     clock->type = type;
 268     clock->enabled = 1;
 269     clock->last = INT64_MIN;
 270     notifier_list_init(&clock->reset_notifiers);
 271     return clock;
 272 }
 273
 274 void qemu_clock_enable(QEMUClock *clock, int enabled)
 275 {
 276     bool old = clock->enabled;
 277     clock->enabled = enabled;
 278     if (enabled && !old) {
 279         qemu_rearm_alarm_timer(alarm_timer);
 280     }
 281 }
 282
 283 int64_t qemu_clock_has_timers(QEMUClock *clock)
 284 {
 285     return !!clock->active_timers;
 286 }
 287
 288 int64_t qemu_clock_expired(QEMUClock *clock)
 289 {
 290     return (clock->active_timers &&
 291             clock->active_timers->expire_time < qemu_get_clock_ns(clock));
 292 }
 293
 294 int64_t qemu_clock_deadline(QEMUClock *clock)
 295 {
 296     /* To avoid problems with overflow limit this to 2^32.  */
 297     int64_t delta = INT32_MAX;
 298
 299     if (clock->active_timers) {
 300         delta = clock->active_timers->expire_time - qemu_get_clock_ns(clock);
 301     }
 302     if (delta < 0) {
 303         delta = 0;
 304     }
 305     return delta;
 306 }
 307
 308 QEMUTimer *qemu_new_timer(QEMUClock *clock, int scale,
 309                           QEMUTimerCB *cb, void *opaque)
 310 {
 311     QEMUTimer *ts;
 312
 313     ts = g_malloc0(sizeof(QEMUTimer));
 314     ts->clock = clock;
 315     ts->cb = cb;
 316     ts->opaque = opaque;
 317     ts->scale = scale;
 318     return ts;
 319 }
 320
 321 void qemu_free_timer(QEMUTimer *ts)
 322 {
 323     g_free(ts);
 324 }
 325
 326 /* stop a timer, but do not dealloc it */
 327 void qemu_del_timer(QEMUTimer *ts)
 328 {
 329     QEMUTimer **pt, *t;
 330
 331     /* NOTE: this code must be signal safe because
 332        qemu_timer_expired() can be called from a signal. */
 333     pt = &ts->clock->active_timers;
 334     for(;;) {
 335         t = *pt;
 336         if (!t)
 337             break;
 338         if (t == ts) {
 339             *pt = t->next;
 340             break;
 341         }
 342         pt = &t->next;
 343     }
 344 }
 345
 346 /* modify the current timer so that it will be fired when current_time
 347    >= expire_time. The corresponding callback will be called. */
 348 void qemu_mod_timer_ns(QEMUTimer *ts, int64_t expire_time)
 349 {
 350     QEMUTimer **pt, *t;
 351
 352     qemu_del_timer(ts);
 353
 354     /* add the timer in the sorted list */
 355     /* NOTE: this code must be signal safe because
 356        qemu_timer_expired() can be called from a signal. */
 357     pt = &ts->clock->active_timers;
 358     for(;;) {
 359         t = *pt;
 360         if (!qemu_timer_expired_ns(t, expire_time)) {
 361             break;
 362         }
 363         pt = &t->next;
 364     }
 365     ts->expire_time = expire_time;
 366     ts->next = *pt;
 367     *pt = ts;
 368
 369     /* Rearm if necessary  */
 370     if (pt == &ts->clock->active_timers) {
 371         if (!alarm_timer->pending) {
 372             qemu_rearm_alarm_timer(alarm_timer);
 373         }
 374         /* Interrupt execution to force deadline recalculation.  */
 375         qemu_clock_warp(ts->clock);
 376         if (use_icount) {
 377             qemu_notify_event();
 378         }
 379     }
 380 }
 381
 382 void qemu_mod_timer(QEMUTimer *ts, int64_t expire_time)
 383 {
 384     qemu_mod_timer_ns(ts, expire_time * ts->scale);
 385 }
 386
 387 int qemu_timer_pending(QEMUTimer *ts)
 388 {
 389     QEMUTimer *t;
 390     for (t = ts->clock->active_timers; t != NULL; t = t->next) {
 391         if (t == ts)
 392             return 1;
 393     }
 394     return 0;
 395 }
 396
 397 int qemu_timer_expired(QEMUTimer *timer_head, int64_t current_time)
 398 {
 399     return qemu_timer_expired_ns(timer_head, current_time * timer_head->scale);
 400 }
 401
 402 static void qemu_run_timers(QEMUClock *clock)
 403 {
 404     QEMUTimer **ptimer_head, *ts;
 405     int64_t current_time;
 406
 407     if (!clock->enabled)
 408         return;
 409
 410     current_time = qemu_get_clock_ns(clock);
 411     ptimer_head = &clock->active_timers;
 412     for(;;) {
 413         ts = *ptimer_head;
 414         if (!qemu_timer_expired_ns(ts, current_time)) {
 415             break;
 416         }
 417         /* remove timer from the list before calling the callback */
 418         *ptimer_head = ts->next;
 419         ts->next = NULL;
 420
 421         /* run the callback (the timer list can be modified) */
 422         ts->cb(ts->opaque);
 423     }
 424 }
 425
 426 int64_t qemu_get_clock_ns(QEMUClock *clock)
 427 {
 428     int64_t now, last;
 429
 430     switch(clock->type) {
 431     case QEMU_CLOCK_REALTIME:
 432         return get_clock();
 433     default:
 434     case QEMU_CLOCK_VIRTUAL:
 435         if (use_icount) {
 436             return cpu_get_icount();
 437         } else {
 438             return cpu_get_clock();
 439         }
 440     case QEMU_CLOCK_HOST:
 441         now = get_clock_realtime();
 442         last = clock->last;
 443         clock->last = now;
 444         if (now < last) {
 445             notifier_list_notify(&clock->reset_notifiers, &now);
 446         }
 447         return now;
 448     }
 449 }
 450
 451 void qemu_register_clock_reset_notifier(QEMUClock *clock, Notifier *notifier)
 452 {
 453     notifier_list_add(&clock->reset_notifiers, notifier);
 454 }
 455
 456 void qemu_unregister_clock_reset_notifier(QEMUClock *clock, Notifier *notifier)
 457 {
 458     notifier_list_remove(&clock->reset_notifiers, notifier);
 459 }
 460
 461 void init_clocks(void)
 462 {
 463     rt_clock = qemu_new_clock(QEMU_CLOCK_REALTIME);
 464     vm_clock = qemu_new_clock(QEMU_CLOCK_VIRTUAL);
 465     host_clock = qemu_new_clock(QEMU_CLOCK_HOST);
 466 }
 467
 468 uint64_t qemu_timer_expire_time_ns(QEMUTimer *ts)
 469 {
 470     return qemu_timer_pending(ts) ? ts->expire_time : -1;
 471 }
 472
 473 void qemu_run_all_timers(void)
 474 {
 475     alarm_timer->pending = 0;
 476
 477     /* rearm timer, if not periodic */
 478     if (alarm_timer->expired) {
 479         alarm_timer->expired = 0;
 480         qemu_rearm_alarm_timer(alarm_timer);
 481     }
 482
 483     /* vm time timers */
 484     qemu_run_timers(vm_clock);
 485     qemu_run_timers(rt_clock);
 486     qemu_run_timers(host_clock);
 487 }
 488
 489 #ifdef _WIN32
 490 static void CALLBACK host_alarm_handler(PVOID lpParam, BOOLEAN unused)
 491 #else
 492 static void host_alarm_handler(int host_signum)
 493 #endif
 494 {
 495     struct qemu_alarm_timer *t = alarm_timer;
 496     if (!t)
 497         return;
 498
 499 #if 0
 500 #define DISP_FREQ 1000
 501     {
 502         static int64_t delta_min = INT64_MAX;
 503         static int64_t delta_max, delta_cum, last_clock, delta, ti;
 504         static int count;
 505         ti = qemu_get_clock_ns(vm_clock);
 506         if (last_clock != 0) {
 507             delta = ti - last_clock;
 508             if (delta < delta_min)
 509                 delta_min = delta;
 510             if (delta > delta_max)
 511                 delta_max = delta;
 512             delta_cum += delta;
 513             if (++count == DISP_FREQ) {
 514                 printf("timer: min=%" PRId64 " us max=%" PRId64 " us avg=%" PRId64 " us avg_freq=%0.3f Hz\n",
 515                        muldiv64(delta_min, 1000000, get_ticks_per_sec()),
 516                        muldiv64(delta_max, 1000000, get_ticks_per_sec()),
 517                        muldiv64(delta_cum, 1000000 / DISP_FREQ, get_ticks_per_sec()),
 518                        (double)get_ticks_per_sec() / ((double)delta_cum / DISP_FREQ));
 519                 count = 0;
 520                 delta_min = INT64_MAX;
 521                 delta_max = 0;
 522                 delta_cum = 0;
 523             }
 524         }
 525         last_clock = ti;
 526     }
 527 #endif
 528     if (alarm_has_dynticks(t) ||
 529         qemu_next_alarm_deadline () <= 0) {
 530         t->expired = alarm_has_dynticks(t);
 531         t->pending = 1;
 532         qemu_notify_event();
 533     }
 534 }
 535
 536 #if defined(__linux__)
 537
 538 #include "compatfd.h"
 539
 540 static int dynticks_start_timer(struct qemu_alarm_timer *t)
 541 {
 542     struct sigevent ev;
 543     timer_t host_timer;
 544     struct sigaction act;
 545
 546     sigfillset(&act.sa_mask);
 547     act.sa_flags = 0;
 548     act.sa_handler = host_alarm_handler;
 549
 550     sigaction(SIGALRM, &act, NULL);
 551
 552     /*
 553      * Initialize ev struct to 0 to avoid valgrind complaining
 554      * about uninitialized data in timer_create call
 555      */
 556     memset(&ev, 0, sizeof(ev));
 557     ev.sigev_value.sival_int = 0;
 558     ev.sigev_notify = SIGEV_SIGNAL;
 559 #ifdef SIGEV_THREAD_ID
 560     if (qemu_signalfd_available()) {
 561         ev.sigev_notify = SIGEV_THREAD_ID;
 562         ev._sigev_un._tid = qemu_get_thread_id();
 563     }
 564 #endif /* SIGEV_THREAD_ID */
 565     ev.sigev_signo = SIGALRM;
 566
 567     if (timer_create(CLOCK_REALTIME, &ev, &host_timer)) {
 568         perror("timer_create");
 569
 570         /* disable dynticks */
 571         fprintf(stderr, "Dynamic Ticks disabled\n");
 572
 573         return -1;
 574     }
 575
 576     t->timer = host_timer;
 577
 578     return 0;
 579 }
 580
 581 static void dynticks_stop_timer(struct qemu_alarm_timer *t)
 582 {
 583     timer_t host_timer = t->timer;
 584
 585     timer_delete(host_timer);
 586 }
 587
 588 static void dynticks_rearm_timer(struct qemu_alarm_timer *t,
 589                                  int64_t nearest_delta_ns)
 590 {
 591     timer_t host_timer = t->timer;
 592     struct itimerspec timeout;
 593     int64_t current_ns;
 594
 595     if (nearest_delta_ns < MIN_TIMER_REARM_NS)
 596         nearest_delta_ns = MIN_TIMER_REARM_NS;
 597
 598     /* check whether a timer is already running */
 599     if (timer_gettime(host_timer, &timeout)) {
 600         perror("gettime");
 601         fprintf(stderr, "Internal timer error: aborting\n");
 602         exit(1);
 603     }
 604     current_ns = timeout.it_value.tv_sec * 1000000000LL + timeout.it_value.tv_nsec;
 605     if (current_ns && current_ns <= nearest_delta_ns)
 606         return;
 607
 608     timeout.it_interval.tv_sec = 0;
 609     timeout.it_interval.tv_nsec = 0; /* 0 for one-shot timer */
 610     timeout.it_value.tv_sec =  nearest_delta_ns / 1000000000;
 611     timeout.it_value.tv_nsec = nearest_delta_ns % 1000000000;
 612     if (timer_settime(host_timer, 0 /* RELATIVE */, &timeout, NULL)) {
 613         perror("settime");
 614         fprintf(stderr, "Internal timer error: aborting\n");
 615         exit(1);
 616     }
 617 }
 618
 619 #endif /* defined(__linux__) */
 620
 621 #if !defined(_WIN32)
 622
 623 static int unix_start_timer(struct qemu_alarm_timer *t)
 624 {
 625     struct sigaction act;
 626
 627     /* timer signal */
 628     sigfillset(&act.sa_mask);
 629     act.sa_flags = 0;
 630     act.sa_handler = host_alarm_handler;
 631
 632     sigaction(SIGALRM, &act, NULL);
 633     return 0;
 634 }
 635
 636 static void unix_rearm_timer(struct qemu_alarm_timer *t,
 637                              int64_t nearest_delta_ns)
 638 {
 639     struct itimerval itv;
 640     int err;
 641
 642     if (nearest_delta_ns < MIN_TIMER_REARM_NS)
 643         nearest_delta_ns = MIN_TIMER_REARM_NS;
 644
 645     itv.it_interval.tv_sec = 0;
 646     itv.it_interval.tv_usec = 0; /* 0 for one-shot timer */
 647     itv.it_value.tv_sec =  nearest_delta_ns / 1000000000;
 648     itv.it_value.tv_usec = (nearest_delta_ns % 1000000000) / 1000;
 649     err = setitimer(ITIMER_REAL, &itv, NULL);
 650     if (err) {
 651         perror("setitimer");
 652         fprintf(stderr, "Internal timer error: aborting\n");
 653         exit(1);
 654     }
 655 }
 656
 657 static void unix_stop_timer(struct qemu_alarm_timer *t)
 658 {
 659     struct itimerval itv;
 660
 661     memset(&itv, 0, sizeof(itv));
 662     setitimer(ITIMER_REAL, &itv, NULL);
 663 }
 664
 665 #endif /* !defined(_WIN32) */
 666
 667
 668 #ifdef _WIN32
 669
 670 static MMRESULT mm_timer;
 671 static unsigned mm_period;
 672
 673 static void CALLBACK mm_alarm_handler(UINT uTimerID, UINT uMsg,
 674                                       DWORD_PTR dwUser, DWORD_PTR dw1,
 675                                       DWORD_PTR dw2)
 676 {
 677     struct qemu_alarm_timer *t = alarm_timer;
 678     if (!t) {
 679         return;
 680     }
 681     if (alarm_has_dynticks(t) || qemu_next_alarm_deadline() <= 0) {
 682         t->expired = alarm_has_dynticks(t);
 683         t->pending = 1;
 684         qemu_notify_event();
 685     }
 686 }
 687
 688 static int mm_start_timer(struct qemu_alarm_timer *t)
 689 {
 690     TIMECAPS tc;
 691     UINT flags;
 692
 693     memset(&tc, 0, sizeof(tc));
 694     timeGetDevCaps(&tc, sizeof(tc));
 695
 696     mm_period = tc.wPeriodMin;
 697     timeBeginPeriod(mm_period);
 698
 699     flags = TIME_CALLBACK_FUNCTION;
 700     if (alarm_has_dynticks(t)) {
 701         flags |= TIME_ONESHOT;
 702     } else {
 703         flags |= TIME_PERIODIC;
 704     }
 705
 706     mm_timer = timeSetEvent(1,                  /* interval (ms) */
 707                             mm_period,          /* resolution */
 708                             mm_alarm_handler,   /* function */
 709                             (DWORD_PTR)t,       /* parameter */
 710                             flags);
 711
 712     if (!mm_timer) {
 713         fprintf(stderr, "Failed to initialize win32 alarm timer: %ld\n",
 714                 GetLastError());
 715         timeEndPeriod(mm_period);
 716         return -1;
 717     }
 718
 719     return 0;
 720 }
 721
 722 static void mm_stop_timer(struct qemu_alarm_timer *t)
 723 {
 724     timeKillEvent(mm_timer);
 725     timeEndPeriod(mm_period);
 726 }
 727
 728 static void mm_rearm_timer(struct qemu_alarm_timer *t, int64_t delta)
 729 {
 730     int nearest_delta_ms = (delta + 999999) / 1000000;
 731     if (nearest_delta_ms < 1) {
 732         nearest_delta_ms = 1;
 733     }
 734
 735     timeKillEvent(mm_timer);
 736     mm_timer = timeSetEvent(nearest_delta_ms,
 737                             mm_period,
 738                             mm_alarm_handler,
 739                             (DWORD_PTR)t,
 740                             TIME_ONESHOT | TIME_CALLBACK_FUNCTION);
 741
 742     if (!mm_timer) {
 743         fprintf(stderr, "Failed to re-arm win32 alarm timer %ld\n",
 744                 GetLastError());
 745
 746         timeEndPeriod(mm_period);
 747         exit(1);
 748     }
 749 }
 750
 751 static int win32_start_timer(struct qemu_alarm_timer *t)
 752 {
 753     HANDLE hTimer;
 754     BOOLEAN success;
 755
 756     /* If you call ChangeTimerQueueTimer on a one-shot timer (its period
 757        is zero) that has already expired, the timer is not updated.  Since
 758        creating a new timer is relatively expensive, set a bogus one-hour
 759        interval in the dynticks case.  */
 760     success = CreateTimerQueueTimer(&hTimer,
 761                           NULL,
 762                           host_alarm_handler,
 763                           t,
 764                           1,
 765                           alarm_has_dynticks(t) ? 3600000 : 1,
 766                           WT_EXECUTEINTIMERTHREAD);
 767
 768     if (!success) {
 769         fprintf(stderr, "Failed to initialize win32 alarm timer: %ld\n",
 770                 GetLastError());
 771         return -1;
 772     }
 773
 774     t->timer = hTimer;
 775     return 0;
 776 }
 777
 778 static void win32_stop_timer(struct qemu_alarm_timer *t)
 779 {
 780     HANDLE hTimer = t->timer;
 781
 782     if (hTimer) {
 783         DeleteTimerQueueTimer(NULL, hTimer, NULL);
 784     }
 785 }
 786
 787 static void win32_rearm_timer(struct qemu_alarm_timer *t,
 788                               int64_t nearest_delta_ns)
 789 {
 790     HANDLE hTimer = t->timer;
 791     int nearest_delta_ms;
 792     BOOLEAN success;
 793
 794     nearest_delta_ms = (nearest_delta_ns + 999999) / 1000000;
 795     if (nearest_delta_ms < 1) {
 796         nearest_delta_ms = 1;
 797     }
 798     success = ChangeTimerQueueTimer(NULL,
 799                                     hTimer,
 800                                     nearest_delta_ms,
 801                                     3600000);
 802
 803     if (!success) {
 804         fprintf(stderr, "Failed to rearm win32 alarm timer: %ld\n",
 805                 GetLastError());
 806         exit(-1);
 807     }
 808
 809 }
 810
 811 #endif /* _WIN32 */
 812
 813 static void quit_timers(void)
 814 {
 815     struct qemu_alarm_timer *t = alarm_timer;
 816     alarm_timer = NULL;
 817     t->stop(t);
 818 }
 819
 820 int init_timer_alarm(void)
 821 {
 822     struct qemu_alarm_timer *t = NULL;
 823     int i, err = -1;
 824
 825     for (i = 0; alarm_timers[i].name; i++) {
 826         t = &alarm_timers[i];
 827
 828         err = t->start(t);
 829         if (!err)
 830             break;
 831     }
 832
 833     if (err) {
 834         err = -ENOENT;
 835         goto fail;
 836     }
 837
 838     /* first event is at time 0 */
 839     atexit(quit_timers);
 840     t->pending = 1;
 841     alarm_timer = t;
 842
 843     return 0;
 844
 845 fail:
 846     return err;
 847 }
 848
 849 int qemu_calculate_timeout(void)
 850 {
 851     return 1000;
 852 }
 853