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