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/cpu-timers.h"
  30 #include "sysemu/replay.h"
  31 #include "qemu/main-loop.h"
  32 #include "block/aio.h"
  33 #include "block/thread-pool.h"
  34 #include "qemu/error-report.h"
  35 #include "qemu/queue.h"
  36 #include "qom/object.h"
  37
  38 #ifndef _WIN32
  39 #include <sys/wait.h>
  40 #endif
  41
  42 #ifndef _WIN32
  43
  44 /* If we have signalfd, we mask out the signals we want to handle and then
  45  * use signalfd to listen for them.  We rely on whatever the current signal
  46  * handler is to dispatch the signals when we receive them.
  47  */
  48 /*
  49  * Disable CFI checks.
  50  * We are going to call a signal handler directly. Such handler may or may not
  51  * have been defined in our binary, so there's no guarantee that the pointer
  52  * used to set the handler is a cfi-valid pointer. Since the handlers are
  53  * stored in kernel memory, changing the handler to an attacker-defined
  54  * function requires being able to call a sigaction() syscall,
  55  * which is not as easy as overwriting a pointer in memory.
  56  */
  57 QEMU_DISABLE_CFI
  58 static void sigfd_handler(void *opaque)
  59 {
  60     int fd = (intptr_t)opaque;
  61     struct qemu_signalfd_siginfo info;
  62     struct sigaction action;
  63     ssize_t len;
  64
  65     while (1) {
  66         len = RETRY_ON_EINTR(read(fd, &info, sizeof(info)));
  67
  68         if (len == -1 && errno == EAGAIN) {
  69             break;
  70         }
  71
  72         if (len != sizeof(info)) {
  73             error_report("read from sigfd returned %zd: %s", len,
  74                          g_strerror(errno));
  75             return;
  76         }
  77
  78         sigaction(info.ssi_signo, NULL, &action);
  79         if ((action.sa_flags & SA_SIGINFO) && action.sa_sigaction) {
  80             sigaction_invoke(&action, &info);
  81         } else if (action.sa_handler) {
  82             action.sa_handler(info.ssi_signo);
  83         }
  84     }
  85 }
  86
  87 static int qemu_signal_init(Error **errp)
  88 {
  89     int sigfd;
  90     sigset_t set;
  91
  92     /*
  93      * SIG_IPI must be blocked in the main thread and must not be caught
  94      * by sigwait() in the signal thread. Otherwise, the cpu thread will
  95      * not catch it reliably.
  96      */
  97     sigemptyset(&set);
  98     sigaddset(&set, SIG_IPI);
  99     sigaddset(&set, SIGIO);
 100     sigaddset(&set, SIGALRM);
 101     sigaddset(&set, SIGBUS);
 102     /* SIGINT cannot be handled via signalfd, so that ^C can be used
 103      * to interrupt QEMU when it is being run under gdb.  SIGHUP and
 104      * SIGTERM are also handled asynchronously, even though it is not
 105      * strictly necessary, because they use the same handler as SIGINT.
 106      */
 107     pthread_sigmask(SIG_BLOCK, &set, NULL);
 108
 109     sigdelset(&set, SIG_IPI);
 110     sigfd = qemu_signalfd(&set);
 111     if (sigfd == -1) {
 112         error_setg_errno(errp, errno, "failed to create signalfd");
 113         return -errno;
 114     }
 115
 116     g_unix_set_fd_nonblocking(sigfd, true, NULL);
 117
 118     qemu_set_fd_handler(sigfd, sigfd_handler, NULL, (void *)(intptr_t)sigfd);
 119
 120     return 0;
 121 }
 122
 123 #else /* _WIN32 */
 124
 125 static int qemu_signal_init(Error **errp)
 126 {
 127     return 0;
 128 }
 129 #endif
 130
 131 static AioContext *qemu_aio_context;
 132 static QEMUBH *qemu_notify_bh;
 133
 134 static void notify_event_cb(void *opaque)
 135 {
 136     /* No need to do anything; this bottom half is only used to
 137      * kick the kernel out of ppoll/poll/WaitForMultipleObjects.
 138      */
 139 }
 140
 141 AioContext *qemu_get_aio_context(void)
 142 {
 143     return qemu_aio_context;
 144 }
 145
 146 void qemu_notify_event(void)
 147 {
 148     if (!qemu_aio_context) {
 149         return;
 150     }
 151     qemu_bh_schedule(qemu_notify_bh);
 152 }
 153
 154 static GArray *gpollfds;
 155
 156 int qemu_init_main_loop(Error **errp)
 157 {
 158     int ret;
 159     GSource *src;
 160
 161     init_clocks(qemu_timer_notify_cb);
 162
 163     ret = qemu_signal_init(errp);
 164     if (ret) {
 165         return ret;
 166     }
 167
 168     qemu_aio_context = aio_context_new(errp);
 169     if (!qemu_aio_context) {
 170         return -EMFILE;
 171     }
 172     qemu_set_current_aio_context(qemu_aio_context);
 173     qemu_notify_bh = qemu_bh_new(notify_event_cb, NULL);
 174     gpollfds = g_array_new(FALSE, FALSE, sizeof(GPollFD));
 175     src = aio_get_g_source(qemu_aio_context);
 176     g_source_set_name(src, "aio-context");
 177     g_source_attach(src, NULL);
 178     g_source_unref(src);
 179     src = iohandler_get_g_source();
 180     g_source_set_name(src, "io-handler");
 181     g_source_attach(src, NULL);
 182     g_source_unref(src);
 183     return 0;
 184 }
 185
 186 static void main_loop_update_params(EventLoopBase *base, Error **errp)
 187 {
 188     ERRP_GUARD();
 189
 190     if (!qemu_aio_context) {
 191         error_setg(errp, "qemu aio context not ready");
 192         return;
 193     }
 194
 195     aio_context_set_aio_params(qemu_aio_context, base->aio_max_batch);
 196
 197     aio_context_set_thread_pool_params(qemu_aio_context, base->thread_pool_min,
 198                                        base->thread_pool_max, errp);
 199 }
 200
 201 MainLoop *mloop;
 202
 203 static void main_loop_init(EventLoopBase *base, Error **errp)
 204 {
 205     MainLoop *m = MAIN_LOOP(base);
 206
 207     if (mloop) {
 208         error_setg(errp, "only one main-loop instance allowed");
 209         return;
 210     }
 211
 212     main_loop_update_params(base, errp);
 213
 214     mloop = m;
 215     return;
 216 }
 217
 218 static bool main_loop_can_be_deleted(EventLoopBase *base)
 219 {
 220     return false;
 221 }
 222
 223 static void main_loop_class_init(ObjectClass *oc, void *class_data)
 224 {
 225     EventLoopBaseClass *bc = EVENT_LOOP_BASE_CLASS(oc);
 226
 227     bc->init = main_loop_init;
 228     bc->update_params = main_loop_update_params;
 229     bc->can_be_deleted = main_loop_can_be_deleted;
 230 }
 231
 232 static const TypeInfo main_loop_info = {
 233     .name = TYPE_MAIN_LOOP,
 234     .parent = TYPE_EVENT_LOOP_BASE,
 235     .class_init = main_loop_class_init,
 236     .instance_size = sizeof(MainLoop),
 237 };
 238
 239 static void main_loop_register_types(void)
 240 {
 241     type_register_static(&main_loop_info);
 242 }
 243
 244 type_init(main_loop_register_types)
 245
 246 static int max_priority;
 247
 248 #ifndef _WIN32
 249 static int glib_pollfds_idx;
 250 static int glib_n_poll_fds;
 251
 252 static void glib_pollfds_fill(int64_t *cur_timeout)
 253 {
 254     GMainContext *context = g_main_context_default();
 255     int timeout = 0;
 256     int64_t timeout_ns;
 257     int n;
 258
 259     g_main_context_prepare(context, &max_priority);
 260
 261     glib_pollfds_idx = gpollfds->len;
 262     n = glib_n_poll_fds;
 263     do {
 264         GPollFD *pfds;
 265         glib_n_poll_fds = n;
 266         g_array_set_size(gpollfds, glib_pollfds_idx + glib_n_poll_fds);
 267         pfds = &g_array_index(gpollfds, GPollFD, glib_pollfds_idx);
 268         n = g_main_context_query(context, max_priority, &timeout, pfds,
 269                                  glib_n_poll_fds);
 270     } while (n != glib_n_poll_fds);
 271
 272     if (timeout < 0) {
 273         timeout_ns = -1;
 274     } else {
 275         timeout_ns = (int64_t)timeout * (int64_t)SCALE_MS;
 276     }
 277
 278     *cur_timeout = qemu_soonest_timeout(timeout_ns, *cur_timeout);
 279 }
 280
 281 static void glib_pollfds_poll(void)
 282 {
 283     GMainContext *context = g_main_context_default();
 284     GPollFD *pfds = &g_array_index(gpollfds, GPollFD, glib_pollfds_idx);
 285
 286     if (g_main_context_check(context, max_priority, pfds, glib_n_poll_fds)) {
 287         g_main_context_dispatch(context);
 288     }
 289 }
 290
 291 #define MAX_MAIN_LOOP_SPIN (1000)
 292
 293 static int os_host_main_loop_wait(int64_t timeout)
 294 {
 295     GMainContext *context = g_main_context_default();
 296     int ret;
 297
 298     g_main_context_acquire(context);
 299
 300     glib_pollfds_fill(&timeout);
 301
 302     bql_unlock();
 303     replay_mutex_unlock();
 304
 305     ret = qemu_poll_ns((GPollFD *)gpollfds->data, gpollfds->len, timeout);
 306
 307     replay_mutex_lock();
 308     bql_lock();
 309
 310     glib_pollfds_poll();
 311
 312     g_main_context_release(context);
 313
 314     return ret;
 315 }
 316 #else
 317 /***********************************************************/
 318 /* Polling handling */
 319
 320 typedef struct PollingEntry {
 321     PollingFunc *func;
 322     void *opaque;
 323     struct PollingEntry *next;
 324 } PollingEntry;
 325
 326 static PollingEntry *first_polling_entry;
 327
 328 int qemu_add_polling_cb(PollingFunc *func, void *opaque)
 329 {
 330     PollingEntry **ppe, *pe;
 331     pe = g_new0(PollingEntry, 1);
 332     pe->func = func;
 333     pe->opaque = opaque;
 334     for(ppe = &first_polling_entry; *ppe != NULL; ppe = &(*ppe)->next);
 335     *ppe = pe;
 336     return 0;
 337 }
 338
 339 void qemu_del_polling_cb(PollingFunc *func, void *opaque)
 340 {
 341     PollingEntry **ppe, *pe;
 342     for(ppe = &first_polling_entry; *ppe != NULL; ppe = &(*ppe)->next) {
 343         pe = *ppe;
 344         if (pe->func == func && pe->opaque == opaque) {
 345             *ppe = pe->next;
 346             g_free(pe);
 347             break;
 348         }
 349     }
 350 }
 351
 352 /***********************************************************/
 353 /* Wait objects support */
 354 typedef struct WaitObjects {
 355     int num;
 356     int revents[MAXIMUM_WAIT_OBJECTS];
 357     HANDLE events[MAXIMUM_WAIT_OBJECTS];
 358     WaitObjectFunc *func[MAXIMUM_WAIT_OBJECTS];
 359     void *opaque[MAXIMUM_WAIT_OBJECTS];
 360 } WaitObjects;
 361
 362 static WaitObjects wait_objects = {0};
 363
 364 int qemu_add_wait_object(HANDLE handle, WaitObjectFunc *func, void *opaque)
 365 {
 366     int i;
 367     WaitObjects *w = &wait_objects;
 368
 369     if (w->num >= MAXIMUM_WAIT_OBJECTS) {
 370         return -1;
 371     }
 372
 373     for (i = 0; i < w->num; i++) {
 374         /* check if the same handle is added twice */
 375         if (w->events[i] == handle) {
 376             return -1;
 377         }
 378     }
 379
 380     w->events[w->num] = handle;
 381     w->func[w->num] = func;
 382     w->opaque[w->num] = opaque;
 383     w->revents[w->num] = 0;
 384     w->num++;
 385     return 0;
 386 }
 387
 388 void qemu_del_wait_object(HANDLE handle, WaitObjectFunc *func, void *opaque)
 389 {
 390     int i, found;
 391     WaitObjects *w = &wait_objects;
 392
 393     found = 0;
 394     for (i = 0; i < w->num; i++) {
 395         if (w->events[i] == handle) {
 396             found = 1;
 397         }
 398         if (found && i < (MAXIMUM_WAIT_OBJECTS - 1)) {
 399             w->events[i] = w->events[i + 1];
 400             w->func[i] = w->func[i + 1];
 401             w->opaque[i] = w->opaque[i + 1];
 402             w->revents[i] = w->revents[i + 1];
 403         }
 404     }
 405     if (found) {
 406         w->num--;
 407     }
 408 }
 409
 410 static int pollfds_fill(GArray *pollfds, fd_set *rfds, fd_set *wfds,
 411                         fd_set *xfds)
 412 {
 413     int nfds = -1;
 414     int i;
 415
 416     for (i = 0; i < pollfds->len; i++) {
 417         GPollFD *pfd = &g_array_index(pollfds, GPollFD, i);
 418         int fd = pfd->fd;
 419         int events = pfd->events;
 420         if (events & G_IO_IN) {
 421             FD_SET(fd, rfds);
 422             nfds = MAX(nfds, fd);
 423         }
 424         if (events & G_IO_OUT) {
 425             FD_SET(fd, wfds);
 426             nfds = MAX(nfds, fd);
 427         }
 428         if (events & G_IO_PRI) {
 429             FD_SET(fd, xfds);
 430             nfds = MAX(nfds, fd);
 431         }
 432     }
 433     return nfds;
 434 }
 435
 436 static void pollfds_poll(GArray *pollfds, int nfds, fd_set *rfds,
 437                          fd_set *wfds, fd_set *xfds)
 438 {
 439     int i;
 440
 441     for (i = 0; i < pollfds->len; i++) {
 442         GPollFD *pfd = &g_array_index(pollfds, GPollFD, i);
 443         int fd = pfd->fd;
 444         int revents = 0;
 445
 446         if (FD_ISSET(fd, rfds)) {
 447             revents |= G_IO_IN;
 448         }
 449         if (FD_ISSET(fd, wfds)) {
 450             revents |= G_IO_OUT;
 451         }
 452         if (FD_ISSET(fd, xfds)) {
 453             revents |= G_IO_PRI;
 454         }
 455         pfd->revents = revents & pfd->events;
 456     }
 457 }
 458
 459 static int os_host_main_loop_wait(int64_t timeout)
 460 {
 461     GMainContext *context = g_main_context_default();
 462     GPollFD poll_fds[1024 * 2]; /* this is probably overkill */
 463     int select_ret = 0;
 464     int g_poll_ret, ret, i, n_poll_fds;
 465     PollingEntry *pe;
 466     WaitObjects *w = &wait_objects;
 467     gint poll_timeout;
 468     int64_t poll_timeout_ns;
 469     static struct timeval tv0;
 470     fd_set rfds, wfds, xfds;
 471     int nfds;
 472
 473     g_main_context_acquire(context);
 474
 475     /* XXX: need to suppress polling by better using win32 events */
 476     ret = 0;
 477     for (pe = first_polling_entry; pe != NULL; pe = pe->next) {
 478         ret |= pe->func(pe->opaque);
 479     }
 480     if (ret != 0) {
 481         g_main_context_release(context);
 482         return ret;
 483     }
 484
 485     FD_ZERO(&rfds);
 486     FD_ZERO(&wfds);
 487     FD_ZERO(&xfds);
 488     nfds = pollfds_fill(gpollfds, &rfds, &wfds, &xfds);
 489     if (nfds >= 0) {
 490         select_ret = select(nfds + 1, &rfds, &wfds, &xfds, &tv0);
 491         if (select_ret != 0) {
 492             timeout = 0;
 493         }
 494         if (select_ret > 0) {
 495             pollfds_poll(gpollfds, nfds, &rfds, &wfds, &xfds);
 496         }
 497     }
 498
 499     g_main_context_prepare(context, &max_priority);
 500     n_poll_fds = g_main_context_query(context, max_priority, &poll_timeout,
 501                                       poll_fds, ARRAY_SIZE(poll_fds));
 502     g_assert(n_poll_fds + w->num <= ARRAY_SIZE(poll_fds));
 503
 504     for (i = 0; i < w->num; i++) {
 505         poll_fds[n_poll_fds + i].fd = (DWORD_PTR)w->events[i];
 506         poll_fds[n_poll_fds + i].events = G_IO_IN;
 507     }
 508
 509     if (poll_timeout < 0) {
 510         poll_timeout_ns = -1;
 511     } else {
 512         poll_timeout_ns = (int64_t)poll_timeout * (int64_t)SCALE_MS;
 513     }
 514
 515     poll_timeout_ns = qemu_soonest_timeout(poll_timeout_ns, timeout);
 516
 517     bql_unlock();
 518
 519     replay_mutex_unlock();
 520
 521     g_poll_ret = qemu_poll_ns(poll_fds, n_poll_fds + w->num, poll_timeout_ns);
 522
 523     replay_mutex_lock();
 524
 525     bql_lock();
 526     if (g_poll_ret > 0) {
 527         for (i = 0; i < w->num; i++) {
 528             w->revents[i] = poll_fds[n_poll_fds + i].revents;
 529         }
 530         for (i = 0; i < w->num; i++) {
 531             if (w->revents[i] && w->func[i]) {
 532                 w->func[i](w->opaque[i]);
 533             }
 534         }
 535     }
 536
 537     if (g_main_context_check(context, max_priority, poll_fds, n_poll_fds)) {
 538         g_main_context_dispatch(context);
 539     }
 540
 541     g_main_context_release(context);
 542
 543     return select_ret || g_poll_ret;
 544 }
 545 #endif
 546
 547 static NotifierList main_loop_poll_notifiers =
 548     NOTIFIER_LIST_INITIALIZER(main_loop_poll_notifiers);
 549
 550 void main_loop_poll_add_notifier(Notifier *notify)
 551 {
 552     notifier_list_add(&main_loop_poll_notifiers, notify);
 553 }
 554
 555 void main_loop_poll_remove_notifier(Notifier *notify)
 556 {
 557     notifier_remove(notify);
 558 }
 559
 560 void main_loop_wait(int nonblocking)
 561 {
 562     MainLoopPoll mlpoll = {
 563         .state = MAIN_LOOP_POLL_FILL,
 564         .timeout = UINT32_MAX,
 565         .pollfds = gpollfds,
 566     };
 567     int ret;
 568     int64_t timeout_ns;
 569
 570     if (nonblocking) {
 571         mlpoll.timeout = 0;
 572     }
 573
 574     /* poll any events */
 575     g_array_set_size(gpollfds, 0); /* reset for new iteration */
 576     /* XXX: separate device handlers from system ones */
 577     notifier_list_notify(&main_loop_poll_notifiers, &mlpoll);
 578
 579     if (mlpoll.timeout == UINT32_MAX) {
 580         timeout_ns = -1;
 581     } else {
 582         timeout_ns = (uint64_t)mlpoll.timeout * (int64_t)(SCALE_MS);
 583     }
 584
 585     timeout_ns = qemu_soonest_timeout(timeout_ns,
 586                                       timerlistgroup_deadline_ns(
 587                                           &main_loop_tlg));
 588
 589     ret = os_host_main_loop_wait(timeout_ns);
 590     mlpoll.state = ret < 0 ? MAIN_LOOP_POLL_ERR : MAIN_LOOP_POLL_OK;
 591     notifier_list_notify(&main_loop_poll_notifiers, &mlpoll);
 592
 593     if (icount_enabled()) {
 594         /*
 595          * CPU thread can infinitely wait for event after
 596          * missing the warp
 597          */
 598         icount_start_warp_timer();
 599     }
 600     qemu_clock_run_all_timers();
 601 }
 602
 603 /* Functions to operate on the main QEMU AioContext.  */
 604
 605 QEMUBH *qemu_bh_new_full(QEMUBHFunc *cb, void *opaque, const char *name,
 606                          MemReentrancyGuard *reentrancy_guard)
 607 {
 608     return aio_bh_new_full(qemu_aio_context, cb, opaque, name,
 609                            reentrancy_guard);
 610 }
 611
 612 /*
 613  * Functions to operate on the I/O handler AioContext.
 614  * This context runs on top of main loop. We can't reuse qemu_aio_context
 615  * because iohandlers mustn't be polled by aio_poll(qemu_aio_context).
 616  */
 617 static AioContext *iohandler_ctx;
 618
 619 static void iohandler_init(void)
 620 {
 621     if (!iohandler_ctx) {
 622         iohandler_ctx = aio_context_new(&error_abort);
 623     }
 624 }
 625
 626 AioContext *iohandler_get_aio_context(void)
 627 {
 628     iohandler_init();
 629     return iohandler_ctx;
 630 }
 631
 632 GSource *iohandler_get_g_source(void)
 633 {
 634     iohandler_init();
 635     return aio_get_g_source(iohandler_ctx);
 636 }
 637
 638 void qemu_set_fd_handler(int fd,
 639                          IOHandler *fd_read,
 640                          IOHandler *fd_write,
 641                          void *opaque)
 642 {
 643     iohandler_init();
 644     aio_set_fd_handler(iohandler_ctx, fd, fd_read, fd_write, NULL, NULL,
 645                        opaque);
 646 }
 647
 648 void event_notifier_set_handler(EventNotifier *e,
 649                                 EventNotifierHandler *handler)
 650 {
 651     iohandler_init();
 652     aio_set_event_notifier(iohandler_ctx, e, handler, NULL, NULL);
 653 }