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     clock->enabled = enabled;
 277 }
 278
 279 int64_t qemu_clock_has_timers(QEMUClock *clock)
 280 {
 281     return !!clock->active_timers;
 282 }
 283
 284 int64_t qemu_clock_expired(QEMUClock *clock)
 285 {
 286     return (clock->active_timers &&
 287             clock->active_timers->expire_time < qemu_get_clock_ns(clock));
 288 }
 289
 290 int64_t qemu_clock_deadline(QEMUClock *clock)
 291 {
 292     /* To avoid problems with overflow limit this to 2^32.  */
 293     int64_t delta = INT32_MAX;
 294
 295     if (clock->active_timers) {
 296         delta = clock->active_timers->expire_time - qemu_get_clock_ns(clock);
 297     }
 298     if (delta < 0) {
 299         delta = 0;
 300     }
 301     return delta;
 302 }
 303
 304 QEMUTimer *qemu_new_timer(QEMUClock *clock, int scale,
 305                           QEMUTimerCB *cb, void *opaque)
 306 {
 307     QEMUTimer *ts;
 308
 309     ts = g_malloc0(sizeof(QEMUTimer));
 310     ts->clock = clock;
 311     ts->cb = cb;
 312     ts->opaque = opaque;
 313     ts->scale = scale;
 314     return ts;
 315 }
 316
 317 void qemu_free_timer(QEMUTimer *ts)
 318 {
 319     g_free(ts);
 320 }
 321
 322 /* stop a timer, but do not dealloc it */
 323 void qemu_del_timer(QEMUTimer *ts)
 324 {
 325     QEMUTimer **pt, *t;
 326
 327     /* NOTE: this code must be signal safe because
 328        qemu_timer_expired() can be called from a signal. */
 329     pt = &ts->clock->active_timers;
 330     for(;;) {
 331         t = *pt;
 332         if (!t)
 333             break;
 334         if (t == ts) {
 335             *pt = t->next;
 336             break;
 337         }
 338         pt = &t->next;
 339     }
 340 }
 341
 342 /* modify the current timer so that it will be fired when current_time
 343    >= expire_time. The corresponding callback will be called. */
 344 void qemu_mod_timer_ns(QEMUTimer *ts, int64_t expire_time)
 345 {
 346     QEMUTimer **pt, *t;
 347
 348     qemu_del_timer(ts);
 349
 350     /* add the timer in the sorted list */
 351     /* NOTE: this code must be signal safe because
 352        qemu_timer_expired() can be called from a signal. */
 353     pt = &ts->clock->active_timers;
 354     for(;;) {
 355         t = *pt;
 356         if (!qemu_timer_expired_ns(t, expire_time)) {
 357             break;
 358         }
 359         pt = &t->next;
 360     }
 361     ts->expire_time = expire_time;
 362     ts->next = *pt;
 363     *pt = ts;
 364
 365     /* Rearm if necessary  */
 366     if (pt == &ts->clock->active_timers) {
 367         if (!alarm_timer->pending) {
 368             qemu_rearm_alarm_timer(alarm_timer);
 369         }
 370         /* Interrupt execution to force deadline recalculation.  */
 371         qemu_clock_warp(ts->clock);
 372         if (use_icount) {
 373             qemu_notify_event();
 374         }
 375     }
 376 }
 377
 378 void qemu_mod_timer(QEMUTimer *ts, int64_t expire_time)
 379 {
 380     qemu_mod_timer_ns(ts, expire_time * ts->scale);
 381 }
 382
 383 int qemu_timer_pending(QEMUTimer *ts)
 384 {
 385     QEMUTimer *t;
 386     for (t = ts->clock->active_timers; t != NULL; t = t->next) {
 387         if (t == ts)
 388             return 1;
 389     }
 390     return 0;
 391 }
 392
 393 int qemu_timer_expired(QEMUTimer *timer_head, int64_t current_time)
 394 {
 395     return qemu_timer_expired_ns(timer_head, current_time * timer_head->scale);
 396 }
 397
 398 static void qemu_run_timers(QEMUClock *clock)
 399 {
 400     QEMUTimer **ptimer_head, *ts;
 401     int64_t current_time;
 402
 403     if (!clock->enabled)
 404         return;
 405
 406     current_time = qemu_get_clock_ns(clock);
 407     ptimer_head = &clock->active_timers;
 408     for(;;) {
 409         ts = *ptimer_head;
 410         if (!qemu_timer_expired_ns(ts, current_time)) {
 411             break;
 412         }
 413         /* remove timer from the list before calling the callback */
 414         *ptimer_head = ts->next;
 415         ts->next = NULL;
 416
 417         /* run the callback (the timer list can be modified) */
 418         ts->cb(ts->opaque);
 419     }
 420 }
 421
 422 int64_t qemu_get_clock_ns(QEMUClock *clock)
 423 {
 424     int64_t now, last;
 425
 426     switch(clock->type) {
 427     case QEMU_CLOCK_REALTIME:
 428         return get_clock();
 429     default:
 430     case QEMU_CLOCK_VIRTUAL:
 431         if (use_icount) {
 432             return cpu_get_icount();
 433         } else {
 434             return cpu_get_clock();
 435         }
 436     case QEMU_CLOCK_HOST:
 437         now = get_clock_realtime();
 438         last = clock->last;
 439         clock->last = now;
 440         if (now < last) {
 441             notifier_list_notify(&clock->reset_notifiers, &now);
 442         }
 443         return now;
 444     }
 445 }
 446
 447 void qemu_register_clock_reset_notifier(QEMUClock *clock, Notifier *notifier)
 448 {
 449     notifier_list_add(&clock->reset_notifiers, notifier);
 450 }
 451
 452 void qemu_unregister_clock_reset_notifier(QEMUClock *clock, Notifier *notifier)
 453 {
 454     notifier_list_remove(&clock->reset_notifiers, notifier);
 455 }
 456
 457 void init_clocks(void)
 458 {
 459     rt_clock = qemu_new_clock(QEMU_CLOCK_REALTIME);
 460     vm_clock = qemu_new_clock(QEMU_CLOCK_VIRTUAL);
 461     host_clock = qemu_new_clock(QEMU_CLOCK_HOST);
 462 }
 463
 464 uint64_t qemu_timer_expire_time_ns(QEMUTimer *ts)
 465 {
 466     return qemu_timer_pending(ts) ? ts->expire_time : -1;
 467 }
 468
 469 void qemu_run_all_timers(void)
 470 {
 471     alarm_timer->pending = 0;
 472
 473     /* rearm timer, if not periodic */
 474     if (alarm_timer->expired) {
 475         alarm_timer->expired = 0;
 476         qemu_rearm_alarm_timer(alarm_timer);
 477     }
 478
 479     /* vm time timers */
 480     qemu_run_timers(vm_clock);
 481     qemu_run_timers(rt_clock);
 482     qemu_run_timers(host_clock);
 483 }
 484
 485 #ifdef _WIN32
 486 static void CALLBACK host_alarm_handler(PVOID lpParam, BOOLEAN unused)
 487 #else
 488 static void host_alarm_handler(int host_signum)
 489 #endif
 490 {
 491     struct qemu_alarm_timer *t = alarm_timer;
 492     if (!t)
 493         return;
 494
 495 #if 0
 496 #define DISP_FREQ 1000
 497     {
 498         static int64_t delta_min = INT64_MAX;
 499         static int64_t delta_max, delta_cum, last_clock, delta, ti;
 500         static int count;
 501         ti = qemu_get_clock_ns(vm_clock);
 502         if (last_clock != 0) {
 503             delta = ti - last_clock;
 504             if (delta < delta_min)
 505                 delta_min = delta;
 506             if (delta > delta_max)
 507                 delta_max = delta;
 508             delta_cum += delta;
 509             if (++count == DISP_FREQ) {
 510                 printf("timer: min=%" PRId64 " us max=%" PRId64 " us avg=%" PRId64 " us avg_freq=%0.3f Hz\n",
 511                        muldiv64(delta_min, 1000000, get_ticks_per_sec()),
 512                        muldiv64(delta_max, 1000000, get_ticks_per_sec()),
 513                        muldiv64(delta_cum, 1000000 / DISP_FREQ, get_ticks_per_sec()),
 514                        (double)get_ticks_per_sec() / ((double)delta_cum / DISP_FREQ));
 515                 count = 0;
 516                 delta_min = INT64_MAX;
 517                 delta_max = 0;
 518                 delta_cum = 0;
 519             }
 520         }
 521         last_clock = ti;
 522     }
 523 #endif
 524     if (alarm_has_dynticks(t) ||
 525         qemu_next_alarm_deadline () <= 0) {
 526         t->expired = alarm_has_dynticks(t);
 527         t->pending = 1;
 528         qemu_notify_event();
 529     }
 530 }
 531
 532 #if defined(__linux__)
 533
 534 #include "compatfd.h"
 535
 536 static int dynticks_start_timer(struct qemu_alarm_timer *t)
 537 {
 538     struct sigevent ev;
 539     timer_t host_timer;
 540     struct sigaction act;
 541
 542     sigfillset(&act.sa_mask);
 543     act.sa_flags = 0;
 544     act.sa_handler = host_alarm_handler;
 545
 546     sigaction(SIGALRM, &act, NULL);
 547
 548     /*
 549      * Initialize ev struct to 0 to avoid valgrind complaining
 550      * about uninitialized data in timer_create call
 551      */
 552     memset(&ev, 0, sizeof(ev));
 553     ev.sigev_value.sival_int = 0;
 554     ev.sigev_notify = SIGEV_SIGNAL;
 555 #ifdef SIGEV_THREAD_ID
 556     if (qemu_signalfd_available()) {
 557         ev.sigev_notify = SIGEV_THREAD_ID;
 558         ev._sigev_un._tid = qemu_get_thread_id();
 559     }
 560 #endif /* SIGEV_THREAD_ID */
 561     ev.sigev_signo = SIGALRM;
 562
 563     if (timer_create(CLOCK_REALTIME, &ev, &host_timer)) {
 564         perror("timer_create");
 565
 566         /* disable dynticks */
 567         fprintf(stderr, "Dynamic Ticks disabled\n");
 568
 569         return -1;
 570     }
 571
 572     t->timer = host_timer;
 573
 574     return 0;
 575 }
 576
 577 static void dynticks_stop_timer(struct qemu_alarm_timer *t)
 578 {
 579     timer_t host_timer = t->timer;
 580
 581     timer_delete(host_timer);
 582 }
 583
 584 static void dynticks_rearm_timer(struct qemu_alarm_timer *t,
 585                                  int64_t nearest_delta_ns)
 586 {
 587     timer_t host_timer = t->timer;
 588     struct itimerspec timeout;
 589     int64_t current_ns;
 590
 591     if (nearest_delta_ns < MIN_TIMER_REARM_NS)
 592         nearest_delta_ns = MIN_TIMER_REARM_NS;
 593
 594     /* check whether a timer is already running */
 595     if (timer_gettime(host_timer, &timeout)) {
 596         perror("gettime");
 597         fprintf(stderr, "Internal timer error: aborting\n");
 598         exit(1);
 599     }
 600     current_ns = timeout.it_value.tv_sec * 1000000000LL + timeout.it_value.tv_nsec;
 601     if (current_ns && current_ns <= nearest_delta_ns)
 602         return;
 603
 604     timeout.it_interval.tv_sec = 0;
 605     timeout.it_interval.tv_nsec = 0; /* 0 for one-shot timer */
 606     timeout.it_value.tv_sec =  nearest_delta_ns / 1000000000;
 607     timeout.it_value.tv_nsec = nearest_delta_ns % 1000000000;
 608     if (timer_settime(host_timer, 0 /* RELATIVE */, &timeout, NULL)) {
 609         perror("settime");
 610         fprintf(stderr, "Internal timer error: aborting\n");
 611         exit(1);
 612     }
 613 }
 614
 615 #endif /* defined(__linux__) */
 616
 617 #if !defined(_WIN32)
 618
 619 static int unix_start_timer(struct qemu_alarm_timer *t)
 620 {
 621     struct sigaction act;
 622
 623     /* timer signal */
 624     sigfillset(&act.sa_mask);
 625     act.sa_flags = 0;
 626     act.sa_handler = host_alarm_handler;
 627
 628     sigaction(SIGALRM, &act, NULL);
 629     return 0;
 630 }
 631
 632 static void unix_rearm_timer(struct qemu_alarm_timer *t,
 633                              int64_t nearest_delta_ns)
 634 {
 635     struct itimerval itv;
 636     int err;
 637
 638     if (nearest_delta_ns < MIN_TIMER_REARM_NS)
 639         nearest_delta_ns = MIN_TIMER_REARM_NS;
 640
 641     itv.it_interval.tv_sec = 0;
 642     itv.it_interval.tv_usec = 0; /* 0 for one-shot timer */
 643     itv.it_value.tv_sec =  nearest_delta_ns / 1000000000;
 644     itv.it_value.tv_usec = (nearest_delta_ns % 1000000000) / 1000;
 645     err = setitimer(ITIMER_REAL, &itv, NULL);
 646     if (err) {
 647         perror("setitimer");
 648         fprintf(stderr, "Internal timer error: aborting\n");
 649         exit(1);
 650     }
 651 }
 652
 653 static void unix_stop_timer(struct qemu_alarm_timer *t)
 654 {
 655     struct itimerval itv;
 656
 657     memset(&itv, 0, sizeof(itv));
 658     setitimer(ITIMER_REAL, &itv, NULL);
 659 }
 660
 661 #endif /* !defined(_WIN32) */
 662
 663
 664 #ifdef _WIN32
 665
 666 static MMRESULT mm_timer;
 667 static unsigned mm_period;
 668
 669 static void CALLBACK mm_alarm_handler(UINT uTimerID, UINT uMsg,
 670                                       DWORD_PTR dwUser, DWORD_PTR dw1,
 671                                       DWORD_PTR dw2)
 672 {
 673     struct qemu_alarm_timer *t = alarm_timer;
 674     if (!t) {
 675         return;
 676     }
 677     if (alarm_has_dynticks(t) || qemu_next_alarm_deadline() <= 0) {
 678         t->expired = alarm_has_dynticks(t);
 679         t->pending = 1;
 680         qemu_notify_event();
 681     }
 682 }
 683
 684 static int mm_start_timer(struct qemu_alarm_timer *t)
 685 {
 686     TIMECAPS tc;
 687     UINT flags;
 688
 689     memset(&tc, 0, sizeof(tc));
 690     timeGetDevCaps(&tc, sizeof(tc));
 691
 692     mm_period = tc.wPeriodMin;
 693     timeBeginPeriod(mm_period);
 694
 695     flags = TIME_CALLBACK_FUNCTION;
 696     if (alarm_has_dynticks(t)) {
 697         flags |= TIME_ONESHOT;
 698     } else {
 699         flags |= TIME_PERIODIC;
 700     }
 701
 702     mm_timer = timeSetEvent(1,                  /* interval (ms) */
 703                             mm_period,          /* resolution */
 704                             mm_alarm_handler,   /* function */
 705                             (DWORD_PTR)t,       /* parameter */
 706                             flags);
 707
 708     if (!mm_timer) {
 709         fprintf(stderr, "Failed to initialize win32 alarm timer: %ld\n",
 710                 GetLastError());
 711         timeEndPeriod(mm_period);
 712         return -1;
 713     }
 714
 715     return 0;
 716 }
 717
 718 static void mm_stop_timer(struct qemu_alarm_timer *t)
 719 {
 720     timeKillEvent(mm_timer);
 721     timeEndPeriod(mm_period);
 722 }
 723
 724 static void mm_rearm_timer(struct qemu_alarm_timer *t, int64_t delta)
 725 {
 726     int nearest_delta_ms = (delta + 999999) / 1000000;
 727     if (nearest_delta_ms < 1) {
 728         nearest_delta_ms = 1;
 729     }
 730
 731     timeKillEvent(mm_timer);
 732     mm_timer = timeSetEvent(nearest_delta_ms,
 733                             mm_period,
 734                             mm_alarm_handler,
 735                             (DWORD_PTR)t,
 736                             TIME_ONESHOT | TIME_CALLBACK_FUNCTION);
 737
 738     if (!mm_timer) {
 739         fprintf(stderr, "Failed to re-arm win32 alarm timer %ld\n",
 740                 GetLastError());
 741
 742         timeEndPeriod(mm_period);
 743         exit(1);
 744     }
 745 }
 746
 747 static int win32_start_timer(struct qemu_alarm_timer *t)
 748 {
 749     HANDLE hTimer;
 750     BOOLEAN success;
 751
 752     /* If you call ChangeTimerQueueTimer on a one-shot timer (its period
 753        is zero) that has already expired, the timer is not updated.  Since
 754        creating a new timer is relatively expensive, set a bogus one-hour
 755        interval in the dynticks case.  */
 756     success = CreateTimerQueueTimer(&hTimer,
 757                           NULL,
 758                           host_alarm_handler,
 759                           t,
 760                           1,
 761                           alarm_has_dynticks(t) ? 3600000 : 1,
 762                           WT_EXECUTEINTIMERTHREAD);
 763
 764     if (!success) {
 765         fprintf(stderr, "Failed to initialize win32 alarm timer: %ld\n",
 766                 GetLastError());
 767         return -1;
 768     }
 769
 770     t->timer = hTimer;
 771     return 0;
 772 }
 773
 774 static void win32_stop_timer(struct qemu_alarm_timer *t)
 775 {
 776     HANDLE hTimer = t->timer;
 777
 778     if (hTimer) {
 779         DeleteTimerQueueTimer(NULL, hTimer, NULL);
 780     }
 781 }
 782
 783 static void win32_rearm_timer(struct qemu_alarm_timer *t,
 784                               int64_t nearest_delta_ns)
 785 {
 786     HANDLE hTimer = t->timer;
 787     int nearest_delta_ms;
 788     BOOLEAN success;
 789
 790     nearest_delta_ms = (nearest_delta_ns + 999999) / 1000000;
 791     if (nearest_delta_ms < 1) {
 792         nearest_delta_ms = 1;
 793     }
 794     success = ChangeTimerQueueTimer(NULL,
 795                                     hTimer,
 796                                     nearest_delta_ms,
 797                                     3600000);
 798
 799     if (!success) {
 800         fprintf(stderr, "Failed to rearm win32 alarm timer: %ld\n",
 801                 GetLastError());
 802         exit(-1);
 803     }
 804
 805 }
 806
 807 #endif /* _WIN32 */
 808
 809 static void alarm_timer_on_change_state_rearm(void *opaque, int running,
 810                                               RunState state)
 811 {
 812     if (running)
 813         qemu_rearm_alarm_timer((struct qemu_alarm_timer *) opaque);
 814 }
 815
 816 static void quit_timers(void)
 817 {
 818     struct qemu_alarm_timer *t = alarm_timer;
 819     alarm_timer = NULL;
 820     t->stop(t);
 821 }
 822
 823 int init_timer_alarm(void)
 824 {
 825     struct qemu_alarm_timer *t = NULL;
 826     int i, err = -1;
 827
 828     for (i = 0; alarm_timers[i].name; i++) {
 829         t = &alarm_timers[i];
 830
 831         err = t->start(t);
 832         if (!err)
 833             break;
 834     }
 835
 836     if (err) {
 837         err = -ENOENT;
 838         goto fail;
 839     }
 840
 841     /* first event is at time 0 */
 842     atexit(quit_timers);
 843     t->pending = 1;
 844     alarm_timer = t;
 845     qemu_add_vm_change_state_handler(alarm_timer_on_change_state_rearm, t);
 846
 847     return 0;
 848
 849 fail:
 850     return err;
 851 }
 852
 853 int qemu_calculate_timeout(void)
 854 {
 855     return 1000;
 856 }
 857