xref: /openbmc/qemu/util/qemu-timer.c (revision c719573d)
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 "qemu/lockable.h"
29  #include "sysemu/cpu-timers.h"
30  #include "sysemu/replay.h"
31  #include "sysemu/cpus.h"
32  
33  #ifdef CONFIG_POSIX
34  #include <pthread.h>
35  #endif
36  
37  #ifdef CONFIG_PPOLL
38  #include <poll.h>
39  #endif
40  
41  #ifdef CONFIG_PRCTL_PR_SET_TIMERSLACK
42  #include <sys/prctl.h>
43  #endif
44  
45  /***********************************************************/
46  /* timers */
47  
48  typedef struct QEMUClock {
49      /* We rely on BQL to protect the timerlists */
50      QLIST_HEAD(, QEMUTimerList) timerlists;
51  
52      QEMUClockType type;
53      bool enabled;
54  } QEMUClock;
55  
56  QEMUTimerListGroup main_loop_tlg;
57  static QEMUClock qemu_clocks[QEMU_CLOCK_MAX];
58  
59  /* A QEMUTimerList is a list of timers attached to a clock. More
60   * than one QEMUTimerList can be attached to each clock, for instance
61   * used by different AioContexts / threads. Each clock also has
62   * a list of the QEMUTimerLists associated with it, in order that
63   * reenabling the clock can call all the notifiers.
64   */
65  
66  struct QEMUTimerList {
67      QEMUClock *clock;
68      QemuMutex active_timers_lock;
69      QEMUTimer *active_timers;
70      QLIST_ENTRY(QEMUTimerList) list;
71      QEMUTimerListNotifyCB *notify_cb;
72      void *notify_opaque;
73  
74      /* lightweight method to mark the end of timerlist's running */
75      QemuEvent timers_done_ev;
76  };
77  
78  /**
79   * qemu_clock_ptr:
80   * @type: type of clock
81   *
82   * Translate a clock type into a pointer to QEMUClock object.
83   *
84   * Returns: a pointer to the QEMUClock object
85   */
86  static inline QEMUClock *qemu_clock_ptr(QEMUClockType type)
87  {
88      return &qemu_clocks[type];
89  }
90  
91  static bool timer_expired_ns(QEMUTimer *timer_head, int64_t current_time)
92  {
93      return timer_head && (timer_head->expire_time <= current_time);
94  }
95  
96  QEMUTimerList *timerlist_new(QEMUClockType type,
97                               QEMUTimerListNotifyCB *cb,
98                               void *opaque)
99  {
100      QEMUTimerList *timer_list;
101      QEMUClock *clock = qemu_clock_ptr(type);
102  
103      timer_list = g_new0(QEMUTimerList, 1);
104      qemu_event_init(&timer_list->timers_done_ev, true);
105      timer_list->clock = clock;
106      timer_list->notify_cb = cb;
107      timer_list->notify_opaque = opaque;
108      qemu_mutex_init(&timer_list->active_timers_lock);
109      QLIST_INSERT_HEAD(&clock->timerlists, timer_list, list);
110      return timer_list;
111  }
112  
113  void timerlist_free(QEMUTimerList *timer_list)
114  {
115      assert(!timerlist_has_timers(timer_list));
116      if (timer_list->clock) {
117          QLIST_REMOVE(timer_list, list);
118      }
119      qemu_mutex_destroy(&timer_list->active_timers_lock);
120      g_free(timer_list);
121  }
122  
123  static void qemu_clock_init(QEMUClockType type, QEMUTimerListNotifyCB *notify_cb)
124  {
125      QEMUClock *clock = qemu_clock_ptr(type);
126  
127      /* Assert that the clock of type TYPE has not been initialized yet. */
128      assert(main_loop_tlg.tl[type] == NULL);
129  
130      clock->type = type;
131      clock->enabled = (type == QEMU_CLOCK_VIRTUAL ? false : true);
132      QLIST_INIT(&clock->timerlists);
133      main_loop_tlg.tl[type] = timerlist_new(type, notify_cb, NULL);
134  }
135  
136  bool qemu_clock_use_for_deadline(QEMUClockType type)
137  {
138      return !(icount_enabled() && (type == QEMU_CLOCK_VIRTUAL));
139  }
140  
141  void qemu_clock_notify(QEMUClockType type)
142  {
143      QEMUTimerList *timer_list;
144      QEMUClock *clock = qemu_clock_ptr(type);
145      QLIST_FOREACH(timer_list, &clock->timerlists, list) {
146          timerlist_notify(timer_list);
147      }
148  }
149  
150  /* Disabling the clock will wait for related timerlists to stop
151   * executing qemu_run_timers.  Thus, this functions should not
152   * be used from the callback of a timer that is based on @clock.
153   * Doing so would cause a deadlock.
154   *
155   * Caller should hold BQL.
156   */
157  void qemu_clock_enable(QEMUClockType type, bool enabled)
158  {
159      QEMUClock *clock = qemu_clock_ptr(type);
160      QEMUTimerList *tl;
161      bool old = clock->enabled;
162      clock->enabled = enabled;
163      if (enabled && !old) {
164          qemu_clock_notify(type);
165      } else if (!enabled && old) {
166          QLIST_FOREACH(tl, &clock->timerlists, list) {
167              qemu_event_wait(&tl->timers_done_ev);
168          }
169      }
170  }
171  
172  bool timerlist_has_timers(QEMUTimerList *timer_list)
173  {
174      return !!qatomic_read(&timer_list->active_timers);
175  }
176  
177  bool qemu_clock_has_timers(QEMUClockType type)
178  {
179      return timerlist_has_timers(
180          main_loop_tlg.tl[type]);
181  }
182  
183  bool timerlist_expired(QEMUTimerList *timer_list)
184  {
185      int64_t expire_time;
186  
187      if (!qatomic_read(&timer_list->active_timers)) {
188          return false;
189      }
190  
191      WITH_QEMU_LOCK_GUARD(&timer_list->active_timers_lock) {
192          if (!timer_list->active_timers) {
193              return false;
194          }
195          expire_time = timer_list->active_timers->expire_time;
196      }
197  
198      return expire_time <= qemu_clock_get_ns(timer_list->clock->type);
199  }
200  
201  bool 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  
212  int64_t timerlist_deadline_ns(QEMUTimerList *timer_list)
213  {
214      int64_t delta;
215      int64_t expire_time;
216  
217      if (!qatomic_read(&timer_list->active_timers)) {
218          return -1;
219      }
220  
221      if (!timer_list->clock->enabled) {
222          return -1;
223      }
224  
225      /* The active timers list may be modified before the caller uses our return
226       * value but ->notify_cb() is called when the deadline changes.  Therefore
227       * the caller should notice the change and there is no race condition.
228       */
229      WITH_QEMU_LOCK_GUARD(&timer_list->active_timers_lock) {
230          if (!timer_list->active_timers) {
231              return -1;
232          }
233          expire_time = timer_list->active_timers->expire_time;
234      }
235  
236      delta = expire_time - qemu_clock_get_ns(timer_list->clock->type);
237  
238      if (delta <= 0) {
239          return 0;
240      }
241  
242      return delta;
243  }
244  
245  /* Calculate the soonest deadline across all timerlists attached
246   * to the clock. This is used for the icount timeout so we
247   * ignore whether or not the clock should be used in deadline
248   * calculations.
249   */
250  int64_t qemu_clock_deadline_ns_all(QEMUClockType type, int attr_mask)
251  {
252      int64_t deadline = -1;
253      int64_t delta;
254      int64_t expire_time;
255      QEMUTimer *ts;
256      QEMUTimerList *timer_list;
257      QEMUClock *clock = qemu_clock_ptr(type);
258  
259      if (!clock->enabled) {
260          return -1;
261      }
262  
263      QLIST_FOREACH(timer_list, &clock->timerlists, list) {
264          if (!qatomic_read(&timer_list->active_timers)) {
265              continue;
266          }
267          qemu_mutex_lock(&timer_list->active_timers_lock);
268          ts = timer_list->active_timers;
269          /* Skip all external timers */
270          while (ts && (ts->attributes & ~attr_mask)) {
271              ts = ts->next;
272          }
273          if (!ts) {
274              qemu_mutex_unlock(&timer_list->active_timers_lock);
275              continue;
276          }
277          expire_time = ts->expire_time;
278          qemu_mutex_unlock(&timer_list->active_timers_lock);
279  
280          delta = expire_time - qemu_clock_get_ns(type);
281          if (delta <= 0) {
282              delta = 0;
283          }
284          deadline = qemu_soonest_timeout(deadline, delta);
285      }
286      return deadline;
287  }
288  
289  QEMUClockType timerlist_get_clock(QEMUTimerList *timer_list)
290  {
291      return timer_list->clock->type;
292  }
293  
294  QEMUTimerList *qemu_clock_get_main_loop_timerlist(QEMUClockType type)
295  {
296      return main_loop_tlg.tl[type];
297  }
298  
299  void timerlist_notify(QEMUTimerList *timer_list)
300  {
301      if (timer_list->notify_cb) {
302          timer_list->notify_cb(timer_list->notify_opaque, timer_list->clock->type);
303      } else {
304          qemu_notify_event();
305      }
306  }
307  
308  /* Transition function to convert a nanosecond timeout to ms
309   * This is used where a system does not support ppoll
310   */
311  int qemu_timeout_ns_to_ms(int64_t ns)
312  {
313      int64_t ms;
314      if (ns < 0) {
315          return -1;
316      }
317  
318      if (!ns) {
319          return 0;
320      }
321  
322      /* Always round up, because it's better to wait too long than to wait too
323       * little and effectively busy-wait
324       */
325      ms = DIV_ROUND_UP(ns, SCALE_MS);
326  
327      /* To avoid overflow problems, limit this to 2^31, i.e. approx 25 days */
328      return MIN(ms, INT32_MAX);
329  }
330  
331  
332  /* qemu implementation of g_poll which uses a nanosecond timeout but is
333   * otherwise identical to g_poll
334   */
335  int qemu_poll_ns(GPollFD *fds, guint nfds, int64_t timeout)
336  {
337  #ifdef CONFIG_PPOLL
338      if (timeout < 0) {
339          return ppoll((struct pollfd *)fds, nfds, NULL, NULL);
340      } else {
341          struct timespec ts;
342          int64_t tvsec = timeout / 1000000000LL;
343          /* Avoid possibly overflowing and specifying a negative number of
344           * seconds, which would turn a very long timeout into a busy-wait.
345           */
346          if (tvsec > (int64_t)INT32_MAX) {
347              tvsec = INT32_MAX;
348          }
349          ts.tv_sec = tvsec;
350          ts.tv_nsec = timeout % 1000000000LL;
351          return ppoll((struct pollfd *)fds, nfds, &ts, NULL);
352      }
353  #else
354      return g_poll(fds, nfds, qemu_timeout_ns_to_ms(timeout));
355  #endif
356  }
357  
358  
359  void timer_init_full(QEMUTimer *ts,
360                       QEMUTimerListGroup *timer_list_group, QEMUClockType type,
361                       int scale, int attributes,
362                       QEMUTimerCB *cb, void *opaque)
363  {
364      if (!timer_list_group) {
365          timer_list_group = &main_loop_tlg;
366      }
367      ts->timer_list = timer_list_group->tl[type];
368      ts->cb = cb;
369      ts->opaque = opaque;
370      ts->scale = scale;
371      ts->attributes = attributes;
372      ts->expire_time = -1;
373  }
374  
375  void timer_deinit(QEMUTimer *ts)
376  {
377      assert(ts->expire_time == -1);
378      ts->timer_list = NULL;
379  }
380  
381  static void timer_del_locked(QEMUTimerList *timer_list, QEMUTimer *ts)
382  {
383      QEMUTimer **pt, *t;
384  
385      ts->expire_time = -1;
386      pt = &timer_list->active_timers;
387      for(;;) {
388          t = *pt;
389          if (!t)
390              break;
391          if (t == ts) {
392              qatomic_set(pt, t->next);
393              break;
394          }
395          pt = &t->next;
396      }
397  }
398  
399  static bool timer_mod_ns_locked(QEMUTimerList *timer_list,
400                                  QEMUTimer *ts, int64_t expire_time)
401  {
402      QEMUTimer **pt, *t;
403  
404      /* add the timer in the sorted list */
405      pt = &timer_list->active_timers;
406      for (;;) {
407          t = *pt;
408          if (!timer_expired_ns(t, expire_time)) {
409              break;
410          }
411          pt = &t->next;
412      }
413      ts->expire_time = MAX(expire_time, 0);
414      ts->next = *pt;
415      qatomic_set(pt, ts);
416  
417      return pt == &timer_list->active_timers;
418  }
419  
420  static void timerlist_rearm(QEMUTimerList *timer_list)
421  {
422      /* Interrupt execution to force deadline recalculation.  */
423      if (icount_enabled() && timer_list->clock->type == QEMU_CLOCK_VIRTUAL) {
424          icount_start_warp_timer();
425      }
426      timerlist_notify(timer_list);
427  }
428  
429  /* stop a timer, but do not dealloc it */
430  void timer_del(QEMUTimer *ts)
431  {
432      QEMUTimerList *timer_list = ts->timer_list;
433  
434      if (timer_list) {
435          qemu_mutex_lock(&timer_list->active_timers_lock);
436          timer_del_locked(timer_list, ts);
437          qemu_mutex_unlock(&timer_list->active_timers_lock);
438      }
439  }
440  
441  /* modify the current timer so that it will be fired when current_time
442     >= expire_time. The corresponding callback will be called. */
443  void timer_mod_ns(QEMUTimer *ts, int64_t expire_time)
444  {
445      QEMUTimerList *timer_list = ts->timer_list;
446      bool rearm;
447  
448      qemu_mutex_lock(&timer_list->active_timers_lock);
449      timer_del_locked(timer_list, ts);
450      rearm = timer_mod_ns_locked(timer_list, ts, expire_time);
451      qemu_mutex_unlock(&timer_list->active_timers_lock);
452  
453      if (rearm) {
454          timerlist_rearm(timer_list);
455      }
456  }
457  
458  /* modify the current timer so that it will be fired when current_time
459     >= expire_time or the current deadline, whichever comes earlier.
460     The corresponding callback will be called. */
461  void timer_mod_anticipate_ns(QEMUTimer *ts, int64_t expire_time)
462  {
463      QEMUTimerList *timer_list = ts->timer_list;
464      bool rearm;
465  
466      WITH_QEMU_LOCK_GUARD(&timer_list->active_timers_lock) {
467          if (ts->expire_time == -1 || ts->expire_time > expire_time) {
468              if (ts->expire_time != -1) {
469                  timer_del_locked(timer_list, ts);
470              }
471              rearm = timer_mod_ns_locked(timer_list, ts, expire_time);
472          } else {
473              rearm = false;
474          }
475      }
476      if (rearm) {
477          timerlist_rearm(timer_list);
478      }
479  }
480  
481  void timer_mod(QEMUTimer *ts, int64_t expire_time)
482  {
483      timer_mod_ns(ts, expire_time * ts->scale);
484  }
485  
486  void timer_mod_anticipate(QEMUTimer *ts, int64_t expire_time)
487  {
488      timer_mod_anticipate_ns(ts, expire_time * ts->scale);
489  }
490  
491  bool timer_pending(QEMUTimer *ts)
492  {
493      return ts->expire_time >= 0;
494  }
495  
496  bool timer_expired(QEMUTimer *timer_head, int64_t current_time)
497  {
498      return timer_expired_ns(timer_head, current_time * timer_head->scale);
499  }
500  
501  bool timerlist_run_timers(QEMUTimerList *timer_list)
502  {
503      QEMUTimer *ts;
504      int64_t current_time;
505      bool progress = false;
506      QEMUTimerCB *cb;
507      void *opaque;
508  
509      if (!qatomic_read(&timer_list->active_timers)) {
510          return false;
511      }
512  
513      qemu_event_reset(&timer_list->timers_done_ev);
514      if (!timer_list->clock->enabled) {
515          goto out;
516      }
517  
518      switch (timer_list->clock->type) {
519      case QEMU_CLOCK_REALTIME:
520          break;
521      default:
522      case QEMU_CLOCK_VIRTUAL:
523          break;
524      case QEMU_CLOCK_HOST:
525          if (!replay_checkpoint(CHECKPOINT_CLOCK_HOST)) {
526              goto out;
527          }
528          break;
529      case QEMU_CLOCK_VIRTUAL_RT:
530          if (!replay_checkpoint(CHECKPOINT_CLOCK_VIRTUAL_RT)) {
531              goto out;
532          }
533          break;
534      }
535  
536      /*
537       * Extract expired timers from active timers list and process them.
538       *
539       * In rr mode we need "filtered" checkpointing for virtual clock.  The
540       * checkpoint must be recorded/replayed before processing any non-EXTERNAL timer,
541       * and that must only be done once since the clock value stays the same. Because
542       * non-EXTERNAL timers may appear in the timers list while it being processed,
543       * the checkpoint can be issued at a time until no timers are left and we are
544       * done".
545       */
546      current_time = qemu_clock_get_ns(timer_list->clock->type);
547      qemu_mutex_lock(&timer_list->active_timers_lock);
548      while ((ts = timer_list->active_timers)) {
549          if (!timer_expired_ns(ts, current_time)) {
550              /* No expired timers left.  The checkpoint can be skipped
551               * if no timers fired or they were all external.
552               */
553              break;
554          }
555          /* Checkpoint for virtual clock is redundant in cases where
556           * it's being triggered with only non-EXTERNAL timers, because
557           * these timers don't change guest state directly.
558           */
559          if (replay_mode != REPLAY_MODE_NONE
560              && timer_list->clock->type == QEMU_CLOCK_VIRTUAL
561              && !(ts->attributes & QEMU_TIMER_ATTR_EXTERNAL)
562              && !replay_checkpoint(CHECKPOINT_CLOCK_VIRTUAL)) {
563              qemu_mutex_unlock(&timer_list->active_timers_lock);
564              goto out;
565          }
566  
567          /* remove timer from the list before calling the callback */
568          timer_list->active_timers = ts->next;
569          ts->next = NULL;
570          ts->expire_time = -1;
571          cb = ts->cb;
572          opaque = ts->opaque;
573  
574          /* run the callback (the timer list can be modified) */
575          qemu_mutex_unlock(&timer_list->active_timers_lock);
576          cb(opaque);
577          qemu_mutex_lock(&timer_list->active_timers_lock);
578  
579          progress = true;
580      }
581      qemu_mutex_unlock(&timer_list->active_timers_lock);
582  
583  out:
584      qemu_event_set(&timer_list->timers_done_ev);
585      return progress;
586  }
587  
588  bool qemu_clock_run_timers(QEMUClockType type)
589  {
590      return timerlist_run_timers(main_loop_tlg.tl[type]);
591  }
592  
593  void timerlistgroup_init(QEMUTimerListGroup *tlg,
594                           QEMUTimerListNotifyCB *cb, void *opaque)
595  {
596      QEMUClockType type;
597      for (type = 0; type < QEMU_CLOCK_MAX; type++) {
598          tlg->tl[type] = timerlist_new(type, cb, opaque);
599      }
600  }
601  
602  void timerlistgroup_deinit(QEMUTimerListGroup *tlg)
603  {
604      QEMUClockType type;
605      for (type = 0; type < QEMU_CLOCK_MAX; type++) {
606          timerlist_free(tlg->tl[type]);
607      }
608  }
609  
610  bool timerlistgroup_run_timers(QEMUTimerListGroup *tlg)
611  {
612      QEMUClockType type;
613      bool progress = false;
614      for (type = 0; type < QEMU_CLOCK_MAX; type++) {
615          progress |= timerlist_run_timers(tlg->tl[type]);
616      }
617      return progress;
618  }
619  
620  int64_t timerlistgroup_deadline_ns(QEMUTimerListGroup *tlg)
621  {
622      int64_t deadline = -1;
623      QEMUClockType type;
624      for (type = 0; type < QEMU_CLOCK_MAX; type++) {
625          if (qemu_clock_use_for_deadline(type)) {
626              deadline = qemu_soonest_timeout(deadline,
627                                              timerlist_deadline_ns(tlg->tl[type]));
628          }
629      }
630      return deadline;
631  }
632  
633  int64_t qemu_clock_get_ns(QEMUClockType type)
634  {
635      switch (type) {
636      case QEMU_CLOCK_REALTIME:
637          return get_clock();
638      default:
639      case QEMU_CLOCK_VIRTUAL:
640          return cpus_get_virtual_clock();
641      case QEMU_CLOCK_HOST:
642          return REPLAY_CLOCK(REPLAY_CLOCK_HOST, get_clock_realtime());
643      case QEMU_CLOCK_VIRTUAL_RT:
644          return REPLAY_CLOCK(REPLAY_CLOCK_VIRTUAL_RT, cpu_get_clock());
645      }
646  }
647  
648  static void qemu_virtual_clock_set_ns(int64_t time)
649  {
650      return cpus_set_virtual_clock(time);
651  }
652  
653  void init_clocks(QEMUTimerListNotifyCB *notify_cb)
654  {
655      QEMUClockType type;
656      for (type = 0; type < QEMU_CLOCK_MAX; type++) {
657          qemu_clock_init(type, notify_cb);
658      }
659  
660  #ifdef CONFIG_PRCTL_PR_SET_TIMERSLACK
661      prctl(PR_SET_TIMERSLACK, 1, 0, 0, 0);
662  #endif
663  }
664  
665  uint64_t timer_expire_time_ns(QEMUTimer *ts)
666  {
667      return timer_pending(ts) ? ts->expire_time : -1;
668  }
669  
670  bool qemu_clock_run_all_timers(void)
671  {
672      bool progress = false;
673      QEMUClockType type;
674  
675      for (type = 0; type < QEMU_CLOCK_MAX; type++) {
676          if (qemu_clock_use_for_deadline(type)) {
677              progress |= qemu_clock_run_timers(type);
678          }
679      }
680  
681      return progress;
682  }
683  
684  int64_t qemu_clock_advance_virtual_time(int64_t dest)
685  {
686      int64_t clock = qemu_clock_get_ns(QEMU_CLOCK_VIRTUAL);
687      AioContext *aio_context;
688      aio_context = qemu_get_aio_context();
689      while (clock < dest) {
690          int64_t deadline = qemu_clock_deadline_ns_all(QEMU_CLOCK_VIRTUAL,
691                                                        QEMU_TIMER_ATTR_ALL);
692          int64_t warp = qemu_soonest_timeout(dest - clock, deadline);
693  
694          qemu_virtual_clock_set_ns(qemu_clock_get_ns(QEMU_CLOCK_VIRTUAL) + warp);
695  
696          qemu_clock_run_timers(QEMU_CLOCK_VIRTUAL);
697          timerlist_run_timers(aio_context->tlg.tl[QEMU_CLOCK_VIRTUAL]);
698          clock = qemu_clock_get_ns(QEMU_CLOCK_VIRTUAL);
699      }
700      qemu_clock_notify(QEMU_CLOCK_VIRTUAL);
701  
702      return clock;
703  }
704