util/main-loop.c

   1 /*
   2  * QEMU System Emulator
   3  *
   4  * Copyright (c) 2003-2008 Fabrice Bellard
   5  *
   6  * Permission is hereby granted, free of charge, to any person obtaining a copy
   7  * of this software and associated documentation files (the "Software"), to deal
   8  * in the Software without restriction, including without limitation the rights
   9  * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
  10  * copies of the Software, and to permit persons to whom the Software is
  11  * furnished to do so, subject to the following conditions:
  12  *
  13  * The above copyright notice and this permission notice shall be included in
  14  * all copies or substantial portions of the Software.
  15  *
  16  * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
  17  * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
  18  * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
  19  * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
  20  * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
  21  * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
  22  * THE SOFTWARE.
  23  */
  24
  25 #include "qemu/osdep.h"
  26 #include "qapi/error.h"
  27 #include "qemu/cutils.h"
  28 #include "qemu/timer.h"
  29 #include "sysemu/qtest.h"
  30 #include "sysemu/cpus.h"
  31 #include "sysemu/replay.h"
  32 #include "qemu/main-loop.h"
  33 #include "block/aio.h"
  34 #include "qemu/error-report.h"
  35 #include "qemu/queue.h"
  36
  37 #ifndef _WIN32
  38 #include <sys/wait.h>
  39 #endif
  40
  41 #ifndef _WIN32
  42
  43 /* If we have signalfd, we mask out the signals we want to handle and then
  44  * use signalfd to listen for them.  We rely on whatever the current signal
  45  * handler is to dispatch the signals when we receive them.
  46  */
  47 static void sigfd_handler(void *opaque)
  48 {
  49     int fd = (intptr_t)opaque;
  50     struct qemu_signalfd_siginfo info;
  51     struct sigaction action;
  52     ssize_t len;
  53
  54     while (1) {
  55         do {
  56             len = read(fd, &info, sizeof(info));
  57         } while (len == -1 && errno == EINTR);
  58
  59         if (len == -1 && errno == EAGAIN) {
  60             break;
  61         }
  62
  63         if (len != sizeof(info)) {
  64             printf("read from sigfd returned %zd: %m\n", len);
  65             return;
  66         }
  67
  68         sigaction(info.ssi_signo, NULL, &action);
  69         if ((action.sa_flags & SA_SIGINFO) && action.sa_sigaction) {
  70             sigaction_invoke(&action, &info);
  71         } else if (action.sa_handler) {
  72             action.sa_handler(info.ssi_signo);
  73         }
  74     }
  75 }
  76
  77 static int qemu_signal_init(Error **errp)
  78 {
  79     int sigfd;
  80     sigset_t set;
  81
  82     /*
  83      * SIG_IPI must be blocked in the main thread and must not be caught
  84      * by sigwait() in the signal thread. Otherwise, the cpu thread will
  85      * not catch it reliably.
  86      */
  87     sigemptyset(&set);
  88     sigaddset(&set, SIG_IPI);
  89     sigaddset(&set, SIGIO);
  90     sigaddset(&set, SIGALRM);
  91     sigaddset(&set, SIGBUS);
  92     /* SIGINT cannot be handled via signalfd, so that ^C can be used
  93      * to interrupt QEMU when it is being run under gdb.  SIGHUP and
  94      * SIGTERM are also handled asynchronously, even though it is not
  95      * strictly necessary, because they use the same handler as SIGINT.
  96      */
  97     pthread_sigmask(SIG_BLOCK, &set, NULL);
  98
  99     sigdelset(&set, SIG_IPI);
 100     sigfd = qemu_signalfd(&set);
 101     if (sigfd == -1) {
 102         error_setg_errno(errp, errno, "failed to create signalfd");
 103         return -errno;
 104     }
 105
 106     fcntl_setfl(sigfd, O_NONBLOCK);
 107
 108     qemu_set_fd_handler(sigfd, sigfd_handler, NULL, (void *)(intptr_t)sigfd);
 109
 110     return 0;
 111 }
 112
 113 #else /* _WIN32 */
 114
 115 static int qemu_signal_init(Error **errp)
 116 {
 117     return 0;
 118 }
 119 #endif
 120
 121 static AioContext *qemu_aio_context;
 122 static QEMUBH *qemu_notify_bh;
 123
 124 static void notify_event_cb(void *opaque)
 125 {
 126     /* No need to do anything; this bottom half is only used to
 127      * kick the kernel out of ppoll/poll/WaitForMultipleObjects.
 128      */
 129 }
 130
 131 AioContext *qemu_get_aio_context(void)
 132 {
 133     return qemu_aio_context;
 134 }
 135
 136 void qemu_notify_event(void)
 137 {
 138     if (!qemu_aio_context) {
 139         return;
 140     }
 141     qemu_bh_schedule(qemu_notify_bh);
 142 }
 143
 144 static GArray *gpollfds;
 145
 146 int qemu_init_main_loop(Error **errp)
 147 {
 148     int ret;
 149     GSource *src;
 150     Error *local_error = NULL;
 151
 152     init_clocks(qemu_timer_notify_cb);
 153
 154     ret = qemu_signal_init(errp);
 155     if (ret) {
 156         return ret;
 157     }
 158
 159     qemu_aio_context = aio_context_new(&local_error);
 160     if (!qemu_aio_context) {
 161         error_propagate(errp, local_error);
 162         return -EMFILE;
 163     }
 164     qemu_notify_bh = qemu_bh_new(notify_event_cb, NULL);
 165     gpollfds = g_array_new(FALSE, FALSE, sizeof(GPollFD));
 166     src = aio_get_g_source(qemu_aio_context);
 167     g_source_set_name(src, "aio-context");
 168     g_source_attach(src, NULL);
 169     g_source_unref(src);
 170     src = iohandler_get_g_source();
 171     g_source_set_name(src, "io-handler");
 172     g_source_attach(src, NULL);
 173     g_source_unref(src);
 174     return 0;
 175 }
 176
 177 static int max_priority;
 178
 179 #ifndef _WIN32
 180 static int glib_pollfds_idx;
 181 static int glib_n_poll_fds;
 182
 183 static void glib_pollfds_fill(int64_t *cur_timeout)
 184 {
 185     GMainContext *context = g_main_context_default();
 186     int timeout = 0;
 187     int64_t timeout_ns;
 188     int n;
 189
 190     g_main_context_prepare(context, &max_priority);
 191
 192     glib_pollfds_idx = gpollfds->len;
 193     n = glib_n_poll_fds;
 194     do {
 195         GPollFD *pfds;
 196         glib_n_poll_fds = n;
 197         g_array_set_size(gpollfds, glib_pollfds_idx + glib_n_poll_fds);
 198         pfds = &g_array_index(gpollfds, GPollFD, glib_pollfds_idx);
 199         n = g_main_context_query(context, max_priority, &timeout, pfds,
 200                                  glib_n_poll_fds);
 201     } while (n != glib_n_poll_fds);
 202
 203     if (timeout < 0) {
 204         timeout_ns = -1;
 205     } else {
 206         timeout_ns = (int64_t)timeout * (int64_t)SCALE_MS;
 207     }
 208
 209     *cur_timeout = qemu_soonest_timeout(timeout_ns, *cur_timeout);
 210 }
 211
 212 static void glib_pollfds_poll(void)
 213 {
 214     GMainContext *context = g_main_context_default();
 215     GPollFD *pfds = &g_array_index(gpollfds, GPollFD, glib_pollfds_idx);
 216
 217     if (g_main_context_check(context, max_priority, pfds, glib_n_poll_fds)) {
 218         g_main_context_dispatch(context);
 219     }
 220 }
 221
 222 #define MAX_MAIN_LOOP_SPIN (1000)
 223
 224 static int os_host_main_loop_wait(int64_t timeout)
 225 {
 226     GMainContext *context = g_main_context_default();
 227     int ret;
 228
 229     g_main_context_acquire(context);
 230
 231     glib_pollfds_fill(&timeout);
 232
 233     qemu_mutex_unlock_iothread();
 234     replay_mutex_unlock();
 235
 236     ret = qemu_poll_ns((GPollFD *)gpollfds->data, gpollfds->len, timeout);
 237
 238     replay_mutex_lock();
 239     qemu_mutex_lock_iothread();
 240
 241     glib_pollfds_poll();
 242
 243     g_main_context_release(context);
 244
 245     return ret;
 246 }
 247 #else
 248 /***********************************************************/
 249 /* Polling handling */
 250
 251 typedef struct PollingEntry {
 252     PollingFunc *func;
 253     void *opaque;
 254     struct PollingEntry *next;
 255 } PollingEntry;
 256
 257 static PollingEntry *first_polling_entry;
 258
 259 int qemu_add_polling_cb(PollingFunc *func, void *opaque)
 260 {
 261     PollingEntry **ppe, *pe;
 262     pe = g_malloc0(sizeof(PollingEntry));
 263     pe->func = func;
 264     pe->opaque = opaque;
 265     for(ppe = &first_polling_entry; *ppe != NULL; ppe = &(*ppe)->next);
 266     *ppe = pe;
 267     return 0;
 268 }
 269
 270 void qemu_del_polling_cb(PollingFunc *func, void *opaque)
 271 {
 272     PollingEntry **ppe, *pe;
 273     for(ppe = &first_polling_entry; *ppe != NULL; ppe = &(*ppe)->next) {
 274         pe = *ppe;
 275         if (pe->func == func && pe->opaque == opaque) {
 276             *ppe = pe->next;
 277             g_free(pe);
 278             break;
 279         }
 280     }
 281 }
 282
 283 /***********************************************************/
 284 /* Wait objects support */
 285 typedef struct WaitObjects {
 286     int num;
 287     int revents[MAXIMUM_WAIT_OBJECTS + 1];
 288     HANDLE events[MAXIMUM_WAIT_OBJECTS + 1];
 289     WaitObjectFunc *func[MAXIMUM_WAIT_OBJECTS + 1];
 290     void *opaque[MAXIMUM_WAIT_OBJECTS + 1];
 291 } WaitObjects;
 292
 293 static WaitObjects wait_objects = {0};
 294
 295 int qemu_add_wait_object(HANDLE handle, WaitObjectFunc *func, void *opaque)
 296 {
 297     WaitObjects *w = &wait_objects;
 298     if (w->num >= MAXIMUM_WAIT_OBJECTS) {
 299         return -1;
 300     }
 301     w->events[w->num] = handle;
 302     w->func[w->num] = func;
 303     w->opaque[w->num] = opaque;
 304     w->revents[w->num] = 0;
 305     w->num++;
 306     return 0;
 307 }
 308
 309 void qemu_del_wait_object(HANDLE handle, WaitObjectFunc *func, void *opaque)
 310 {
 311     int i, found;
 312     WaitObjects *w = &wait_objects;
 313
 314     found = 0;
 315     for (i = 0; i < w->num; i++) {
 316         if (w->events[i] == handle) {
 317             found = 1;
 318         }
 319         if (found) {
 320             w->events[i] = w->events[i + 1];
 321             w->func[i] = w->func[i + 1];
 322             w->opaque[i] = w->opaque[i + 1];
 323             w->revents[i] = w->revents[i + 1];
 324         }
 325     }
 326     if (found) {
 327         w->num--;
 328     }
 329 }
 330
 331 void qemu_fd_register(int fd)
 332 {
 333     WSAEventSelect(fd, event_notifier_get_handle(&qemu_aio_context->notifier),
 334                    FD_READ | FD_ACCEPT | FD_CLOSE |
 335                    FD_CONNECT | FD_WRITE | FD_OOB);
 336 }
 337
 338 static int pollfds_fill(GArray *pollfds, fd_set *rfds, fd_set *wfds,
 339                         fd_set *xfds)
 340 {
 341     int nfds = -1;
 342     int i;
 343
 344     for (i = 0; i < pollfds->len; i++) {
 345         GPollFD *pfd = &g_array_index(pollfds, GPollFD, i);
 346         int fd = pfd->fd;
 347         int events = pfd->events;
 348         if (events & G_IO_IN) {
 349             FD_SET(fd, rfds);
 350             nfds = MAX(nfds, fd);
 351         }
 352         if (events & G_IO_OUT) {
 353             FD_SET(fd, wfds);
 354             nfds = MAX(nfds, fd);
 355         }
 356         if (events & G_IO_PRI) {
 357             FD_SET(fd, xfds);
 358             nfds = MAX(nfds, fd);
 359         }
 360     }
 361     return nfds;
 362 }
 363
 364 static void pollfds_poll(GArray *pollfds, int nfds, fd_set *rfds,
 365                          fd_set *wfds, fd_set *xfds)
 366 {
 367     int i;
 368
 369     for (i = 0; i < pollfds->len; i++) {
 370         GPollFD *pfd = &g_array_index(pollfds, GPollFD, i);
 371         int fd = pfd->fd;
 372         int revents = 0;
 373
 374         if (FD_ISSET(fd, rfds)) {
 375             revents |= G_IO_IN;
 376         }
 377         if (FD_ISSET(fd, wfds)) {
 378             revents |= G_IO_OUT;
 379         }
 380         if (FD_ISSET(fd, xfds)) {
 381             revents |= G_IO_PRI;
 382         }
 383         pfd->revents = revents & pfd->events;
 384     }
 385 }
 386
 387 static int os_host_main_loop_wait(int64_t timeout)
 388 {
 389     GMainContext *context = g_main_context_default();
 390     GPollFD poll_fds[1024 * 2]; /* this is probably overkill */
 391     int select_ret = 0;
 392     int g_poll_ret, ret, i, n_poll_fds;
 393     PollingEntry *pe;
 394     WaitObjects *w = &wait_objects;
 395     gint poll_timeout;
 396     int64_t poll_timeout_ns;
 397     static struct timeval tv0;
 398     fd_set rfds, wfds, xfds;
 399     int nfds;
 400
 401     g_main_context_acquire(context);
 402
 403     /* XXX: need to suppress polling by better using win32 events */
 404     ret = 0;
 405     for (pe = first_polling_entry; pe != NULL; pe = pe->next) {
 406         ret |= pe->func(pe->opaque);
 407     }
 408     if (ret != 0) {
 409         g_main_context_release(context);
 410         return ret;
 411     }
 412
 413     FD_ZERO(&rfds);
 414     FD_ZERO(&wfds);
 415     FD_ZERO(&xfds);
 416     nfds = pollfds_fill(gpollfds, &rfds, &wfds, &xfds);
 417     if (nfds >= 0) {
 418         select_ret = select(nfds + 1, &rfds, &wfds, &xfds, &tv0);
 419         if (select_ret != 0) {
 420             timeout = 0;
 421         }
 422         if (select_ret > 0) {
 423             pollfds_poll(gpollfds, nfds, &rfds, &wfds, &xfds);
 424         }
 425     }
 426
 427     g_main_context_prepare(context, &max_priority);
 428     n_poll_fds = g_main_context_query(context, max_priority, &poll_timeout,
 429                                       poll_fds, ARRAY_SIZE(poll_fds));
 430     g_assert(n_poll_fds + w->num <= ARRAY_SIZE(poll_fds));
 431
 432     for (i = 0; i < w->num; i++) {
 433         poll_fds[n_poll_fds + i].fd = (DWORD_PTR)w->events[i];
 434         poll_fds[n_poll_fds + i].events = G_IO_IN;
 435     }
 436
 437     if (poll_timeout < 0) {
 438         poll_timeout_ns = -1;
 439     } else {
 440         poll_timeout_ns = (int64_t)poll_timeout * (int64_t)SCALE_MS;
 441     }
 442
 443     poll_timeout_ns = qemu_soonest_timeout(poll_timeout_ns, timeout);
 444
 445     qemu_mutex_unlock_iothread();
 446
 447     replay_mutex_unlock();
 448
 449     g_poll_ret = qemu_poll_ns(poll_fds, n_poll_fds + w->num, poll_timeout_ns);
 450
 451     replay_mutex_lock();
 452
 453     qemu_mutex_lock_iothread();
 454     if (g_poll_ret > 0) {
 455         for (i = 0; i < w->num; i++) {
 456             w->revents[i] = poll_fds[n_poll_fds + i].revents;
 457         }
 458         for (i = 0; i < w->num; i++) {
 459             if (w->revents[i] && w->func[i]) {
 460                 w->func[i](w->opaque[i]);
 461             }
 462         }
 463     }
 464
 465     if (g_main_context_check(context, max_priority, poll_fds, n_poll_fds)) {
 466         g_main_context_dispatch(context);
 467     }
 468
 469     g_main_context_release(context);
 470
 471     return select_ret || g_poll_ret;
 472 }
 473 #endif
 474
 475 static NotifierList main_loop_poll_notifiers =
 476     NOTIFIER_LIST_INITIALIZER(main_loop_poll_notifiers);
 477
 478 void main_loop_poll_add_notifier(Notifier *notify)
 479 {
 480     notifier_list_add(&main_loop_poll_notifiers, notify);
 481 }
 482
 483 void main_loop_poll_remove_notifier(Notifier *notify)
 484 {
 485     notifier_remove(notify);
 486 }
 487
 488 void main_loop_wait(int nonblocking)
 489 {
 490     MainLoopPoll mlpoll = {
 491         .state = MAIN_LOOP_POLL_FILL,
 492         .timeout = UINT32_MAX,
 493         .pollfds = gpollfds,
 494     };
 495     int ret;
 496     int64_t timeout_ns;
 497
 498     if (nonblocking) {
 499         mlpoll.timeout = 0;
 500     }
 501
 502     /* poll any events */
 503     g_array_set_size(gpollfds, 0); /* reset for new iteration */
 504     /* XXX: separate device handlers from system ones */
 505     notifier_list_notify(&main_loop_poll_notifiers, &mlpoll);
 506
 507     if (mlpoll.timeout == UINT32_MAX) {
 508         timeout_ns = -1;
 509     } else {
 510         timeout_ns = (uint64_t)mlpoll.timeout * (int64_t)(SCALE_MS);
 511     }
 512
 513     timeout_ns = qemu_soonest_timeout(timeout_ns,
 514                                       timerlistgroup_deadline_ns(
 515                                           &main_loop_tlg));
 516
 517     ret = os_host_main_loop_wait(timeout_ns);
 518     mlpoll.state = ret < 0 ? MAIN_LOOP_POLL_ERR : MAIN_LOOP_POLL_OK;
 519     notifier_list_notify(&main_loop_poll_notifiers, &mlpoll);
 520
 521     /* CPU thread can infinitely wait for event after
 522        missing the warp */
 523     qemu_start_warp_timer();
 524     qemu_clock_run_all_timers();
 525 }
 526
 527 /* Functions to operate on the main QEMU AioContext.  */
 528
 529 QEMUBH *qemu_bh_new(QEMUBHFunc *cb, void *opaque)
 530 {
 531     return aio_bh_new(qemu_aio_context, cb, opaque);
 532 }
 533
 534 /*
 535  * Functions to operate on the I/O handler AioContext.
 536  * This context runs on top of main loop. We can't reuse qemu_aio_context
 537  * because iohandlers mustn't be polled by aio_poll(qemu_aio_context).
 538  */
 539 static AioContext *iohandler_ctx;
 540
 541 static void iohandler_init(void)
 542 {
 543     if (!iohandler_ctx) {
 544         iohandler_ctx = aio_context_new(&error_abort);
 545     }
 546 }
 547
 548 AioContext *iohandler_get_aio_context(void)
 549 {
 550     iohandler_init();
 551     return iohandler_ctx;
 552 }
 553
 554 GSource *iohandler_get_g_source(void)
 555 {
 556     iohandler_init();
 557     return aio_get_g_source(iohandler_ctx);
 558 }
 559
 560 void qemu_set_fd_handler(int fd,
 561                          IOHandler *fd_read,
 562                          IOHandler *fd_write,
 563                          void *opaque)
 564 {
 565     iohandler_init();
 566     aio_set_fd_handler(iohandler_ctx, fd, false,
 567                        fd_read, fd_write, NULL, opaque);
 568 }
 569
 570 void event_notifier_set_handler(EventNotifier *e,
 571                                 EventNotifierHandler *handler)
 572 {
 573     iohandler_init();
 574     aio_set_event_notifier(iohandler_ctx, e, false,
 575                            handler, NULL);
 576 }
 577
 578 /* reaping of zombies.  right now we're not passing the status to
 579    anyone, but it would be possible to add a callback.  */
 580 #ifndef _WIN32
 581 typedef struct ChildProcessRecord {
 582     int pid;
 583     QLIST_ENTRY(ChildProcessRecord) next;
 584 } ChildProcessRecord;
 585
 586 static QLIST_HEAD(, ChildProcessRecord) child_watches =
 587     QLIST_HEAD_INITIALIZER(child_watches);
 588
 589 static QEMUBH *sigchld_bh;
 590
 591 static void sigchld_handler(int signal)
 592 {
 593     qemu_bh_schedule(sigchld_bh);
 594 }
 595
 596 static void sigchld_bh_handler(void *opaque)
 597 {
 598     ChildProcessRecord *rec, *next;
 599
 600     QLIST_FOREACH_SAFE(rec, &child_watches, next, next) {
 601         if (waitpid(rec->pid, NULL, WNOHANG) == rec->pid) {
 602             QLIST_REMOVE(rec, next);
 603             g_free(rec);
 604         }
 605     }
 606 }
 607
 608 static void qemu_init_child_watch(void)
 609 {
 610     struct sigaction act;
 611     sigchld_bh = qemu_bh_new(sigchld_bh_handler, NULL);
 612
 613     memset(&act, 0, sizeof(act));
 614     act.sa_handler = sigchld_handler;
 615     act.sa_flags = SA_NOCLDSTOP;
 616     sigaction(SIGCHLD, &act, NULL);
 617 }
 618
 619 int qemu_add_child_watch(pid_t pid)
 620 {
 621     ChildProcessRecord *rec;
 622
 623     if (!sigchld_bh) {
 624         qemu_init_child_watch();
 625     }
 626
 627     QLIST_FOREACH(rec, &child_watches, next) {
 628         if (rec->pid == pid) {
 629             return 1;
 630         }
 631     }
 632     rec = g_malloc0(sizeof(ChildProcessRecord));
 633     rec->pid = pid;
 634     QLIST_INSERT_HEAD(&child_watches, rec, next);
 635     return 0;
 636 }
 637 #endif