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-common.h"
  26 #include "qemu-timer.h"
  27 #include "slirp/slirp.h"
  28 #include "main-loop.h"
  29
  30 #ifndef _WIN32
  31
  32 #include "compatfd.h"
  33
  34 static int io_thread_fd = -1;
  35
  36 void qemu_notify_event(void)
  37 {
  38     /* Write 8 bytes to be compatible with eventfd.  */
  39     static const uint64_t val = 1;
  40     ssize_t ret;
  41
  42     if (io_thread_fd == -1) {
  43         return;
  44     }
  45     do {
  46         ret = write(io_thread_fd, &val, sizeof(val));
  47     } while (ret < 0 && errno == EINTR);
  48
  49     /* EAGAIN is fine, a read must be pending.  */
  50     if (ret < 0 && errno != EAGAIN) {
  51         fprintf(stderr, "qemu_notify_event: write() failed: %s\n",
  52                 strerror(errno));
  53         exit(1);
  54     }
  55 }
  56
  57 static void qemu_event_read(void *opaque)
  58 {
  59     int fd = (intptr_t)opaque;
  60     ssize_t len;
  61     char buffer[512];
  62
  63     /* Drain the notify pipe.  For eventfd, only 8 bytes will be read.  */
  64     do {
  65         len = read(fd, buffer, sizeof(buffer));
  66     } while ((len == -1 && errno == EINTR) || len == sizeof(buffer));
  67 }
  68
  69 static int qemu_event_init(void)
  70 {
  71     int err;
  72     int fds[2];
  73
  74     err = qemu_eventfd(fds);
  75     if (err == -1) {
  76         return -errno;
  77     }
  78     err = fcntl_setfl(fds[0], O_NONBLOCK);
  79     if (err < 0) {
  80         goto fail;
  81     }
  82     err = fcntl_setfl(fds[1], O_NONBLOCK);
  83     if (err < 0) {
  84         goto fail;
  85     }
  86     qemu_set_fd_handler2(fds[0], NULL, qemu_event_read, NULL,
  87                          (void *)(intptr_t)fds[0]);
  88
  89     io_thread_fd = fds[1];
  90     return 0;
  91
  92 fail:
  93     close(fds[0]);
  94     close(fds[1]);
  95     return err;
  96 }
  97
  98 /* If we have signalfd, we mask out the signals we want to handle and then
  99  * use signalfd to listen for them.  We rely on whatever the current signal
 100  * handler is to dispatch the signals when we receive them.
 101  */
 102 static void sigfd_handler(void *opaque)
 103 {
 104     int fd = (intptr_t)opaque;
 105     struct qemu_signalfd_siginfo info;
 106     struct sigaction action;
 107     ssize_t len;
 108
 109     while (1) {
 110         do {
 111             len = read(fd, &info, sizeof(info));
 112         } while (len == -1 && errno == EINTR);
 113
 114         if (len == -1 && errno == EAGAIN) {
 115             break;
 116         }
 117
 118         if (len != sizeof(info)) {
 119             printf("read from sigfd returned %zd: %m\n", len);
 120             return;
 121         }
 122
 123         sigaction(info.ssi_signo, NULL, &action);
 124         if ((action.sa_flags & SA_SIGINFO) && action.sa_sigaction) {
 125             action.sa_sigaction(info.ssi_signo,
 126                                 (siginfo_t *)&info, NULL);
 127         } else if (action.sa_handler) {
 128             action.sa_handler(info.ssi_signo);
 129         }
 130     }
 131 }
 132
 133 static int qemu_signal_init(void)
 134 {
 135     int sigfd;
 136     sigset_t set;
 137
 138     /*
 139      * SIG_IPI must be blocked in the main thread and must not be caught
 140      * by sigwait() in the signal thread. Otherwise, the cpu thread will
 141      * not catch it reliably.
 142      */
 143     sigemptyset(&set);
 144     sigaddset(&set, SIG_IPI);
 145     sigaddset(&set, SIGIO);
 146     sigaddset(&set, SIGALRM);
 147     sigaddset(&set, SIGBUS);
 148     pthread_sigmask(SIG_BLOCK, &set, NULL);
 149
 150     sigdelset(&set, SIG_IPI);
 151     sigfd = qemu_signalfd(&set);
 152     if (sigfd == -1) {
 153         fprintf(stderr, "failed to create signalfd\n");
 154         return -errno;
 155     }
 156
 157     fcntl_setfl(sigfd, O_NONBLOCK);
 158
 159     qemu_set_fd_handler2(sigfd, NULL, sigfd_handler, NULL,
 160                          (void *)(intptr_t)sigfd);
 161
 162     return 0;
 163 }
 164
 165 #else /* _WIN32 */
 166
 167 HANDLE qemu_event_handle = NULL;
 168
 169 static void dummy_event_handler(void *opaque)
 170 {
 171 }
 172
 173 static int qemu_event_init(void)
 174 {
 175     qemu_event_handle = CreateEvent(NULL, FALSE, FALSE, NULL);
 176     if (!qemu_event_handle) {
 177         fprintf(stderr, "Failed CreateEvent: %ld\n", GetLastError());
 178         return -1;
 179     }
 180     qemu_add_wait_object(qemu_event_handle, dummy_event_handler, NULL);
 181     return 0;
 182 }
 183
 184 void qemu_notify_event(void)
 185 {
 186     if (!qemu_event_handle) {
 187         return;
 188     }
 189     if (!SetEvent(qemu_event_handle)) {
 190         fprintf(stderr, "qemu_notify_event: SetEvent failed: %ld\n",
 191                 GetLastError());
 192         exit(1);
 193     }
 194 }
 195
 196 static int qemu_signal_init(void)
 197 {
 198     return 0;
 199 }
 200 #endif
 201
 202 int main_loop_init(void)
 203 {
 204     int ret;
 205
 206     qemu_mutex_lock_iothread();
 207     ret = qemu_signal_init();
 208     if (ret) {
 209         return ret;
 210     }
 211
 212     /* Note eventfd must be drained before signalfd handlers run */
 213     ret = qemu_event_init();
 214     if (ret) {
 215         return ret;
 216     }
 217
 218     return 0;
 219 }
 220
 221
 222 static GPollFD poll_fds[1024 * 2]; /* this is probably overkill */
 223 static int n_poll_fds;
 224 static int max_priority;
 225
 226 static void glib_select_fill(int *max_fd, fd_set *rfds, fd_set *wfds,
 227                              fd_set *xfds, struct timeval *tv)
 228 {
 229     GMainContext *context = g_main_context_default();
 230     int i;
 231     int timeout = 0, cur_timeout;
 232
 233     g_main_context_prepare(context, &max_priority);
 234
 235     n_poll_fds = g_main_context_query(context, max_priority, &timeout,
 236                                       poll_fds, ARRAY_SIZE(poll_fds));
 237     g_assert(n_poll_fds <= ARRAY_SIZE(poll_fds));
 238
 239     for (i = 0; i < n_poll_fds; i++) {
 240         GPollFD *p = &poll_fds[i];
 241
 242         if ((p->events & G_IO_IN)) {
 243             FD_SET(p->fd, rfds);
 244             *max_fd = MAX(*max_fd, p->fd);
 245         }
 246         if ((p->events & G_IO_OUT)) {
 247             FD_SET(p->fd, wfds);
 248             *max_fd = MAX(*max_fd, p->fd);
 249         }
 250         if ((p->events & G_IO_ERR)) {
 251             FD_SET(p->fd, xfds);
 252             *max_fd = MAX(*max_fd, p->fd);
 253         }
 254     }
 255
 256     cur_timeout = (tv->tv_sec * 1000) + ((tv->tv_usec + 500) / 1000);
 257     if (timeout >= 0 && timeout < cur_timeout) {
 258         tv->tv_sec = timeout / 1000;
 259         tv->tv_usec = (timeout % 1000) * 1000;
 260     }
 261 }
 262
 263 static void glib_select_poll(fd_set *rfds, fd_set *wfds, fd_set *xfds,
 264                              bool err)
 265 {
 266     GMainContext *context = g_main_context_default();
 267
 268     if (!err) {
 269         int i;
 270
 271         for (i = 0; i < n_poll_fds; i++) {
 272             GPollFD *p = &poll_fds[i];
 273
 274             if ((p->events & G_IO_IN) && FD_ISSET(p->fd, rfds)) {
 275                 p->revents |= G_IO_IN;
 276             }
 277             if ((p->events & G_IO_OUT) && FD_ISSET(p->fd, wfds)) {
 278                 p->revents |= G_IO_OUT;
 279             }
 280             if ((p->events & G_IO_ERR) && FD_ISSET(p->fd, xfds)) {
 281                 p->revents |= G_IO_ERR;
 282             }
 283         }
 284     }
 285
 286     if (g_main_context_check(context, max_priority, poll_fds, n_poll_fds)) {
 287         g_main_context_dispatch(context);
 288     }
 289 }
 290
 291 #ifdef _WIN32
 292 /***********************************************************/
 293 /* Polling handling */
 294
 295 typedef struct PollingEntry {
 296     PollingFunc *func;
 297     void *opaque;
 298     struct PollingEntry *next;
 299 } PollingEntry;
 300
 301 static PollingEntry *first_polling_entry;
 302
 303 int qemu_add_polling_cb(PollingFunc *func, void *opaque)
 304 {
 305     PollingEntry **ppe, *pe;
 306     pe = g_malloc0(sizeof(PollingEntry));
 307     pe->func = func;
 308     pe->opaque = opaque;
 309     for(ppe = &first_polling_entry; *ppe != NULL; ppe = &(*ppe)->next);
 310     *ppe = pe;
 311     return 0;
 312 }
 313
 314 void qemu_del_polling_cb(PollingFunc *func, void *opaque)
 315 {
 316     PollingEntry **ppe, *pe;
 317     for(ppe = &first_polling_entry; *ppe != NULL; ppe = &(*ppe)->next) {
 318         pe = *ppe;
 319         if (pe->func == func && pe->opaque == opaque) {
 320             *ppe = pe->next;
 321             g_free(pe);
 322             break;
 323         }
 324     }
 325 }
 326
 327 /***********************************************************/
 328 /* Wait objects support */
 329 typedef struct WaitObjects {
 330     int num;
 331     HANDLE events[MAXIMUM_WAIT_OBJECTS + 1];
 332     WaitObjectFunc *func[MAXIMUM_WAIT_OBJECTS + 1];
 333     void *opaque[MAXIMUM_WAIT_OBJECTS + 1];
 334 } WaitObjects;
 335
 336 static WaitObjects wait_objects = {0};
 337
 338 int qemu_add_wait_object(HANDLE handle, WaitObjectFunc *func, void *opaque)
 339 {
 340     WaitObjects *w = &wait_objects;
 341     if (w->num >= MAXIMUM_WAIT_OBJECTS) {
 342         return -1;
 343     }
 344     w->events[w->num] = handle;
 345     w->func[w->num] = func;
 346     w->opaque[w->num] = opaque;
 347     w->num++;
 348     return 0;
 349 }
 350
 351 void qemu_del_wait_object(HANDLE handle, WaitObjectFunc *func, void *opaque)
 352 {
 353     int i, found;
 354     WaitObjects *w = &wait_objects;
 355
 356     found = 0;
 357     for (i = 0; i < w->num; i++) {
 358         if (w->events[i] == handle) {
 359             found = 1;
 360         }
 361         if (found) {
 362             w->events[i] = w->events[i + 1];
 363             w->func[i] = w->func[i + 1];
 364             w->opaque[i] = w->opaque[i + 1];
 365         }
 366     }
 367     if (found) {
 368         w->num--;
 369     }
 370 }
 371
 372 static void os_host_main_loop_wait(int *timeout)
 373 {
 374     int ret, ret2, i;
 375     PollingEntry *pe;
 376
 377     /* XXX: need to suppress polling by better using win32 events */
 378     ret = 0;
 379     for (pe = first_polling_entry; pe != NULL; pe = pe->next) {
 380         ret |= pe->func(pe->opaque);
 381     }
 382     if (ret == 0) {
 383         int err;
 384         WaitObjects *w = &wait_objects;
 385
 386         qemu_mutex_unlock_iothread();
 387         ret = WaitForMultipleObjects(w->num, w->events, FALSE, *timeout);
 388         qemu_mutex_lock_iothread();
 389         if (WAIT_OBJECT_0 + 0 <= ret && ret <= WAIT_OBJECT_0 + w->num - 1) {
 390             if (w->func[ret - WAIT_OBJECT_0]) {
 391                 w->func[ret - WAIT_OBJECT_0](w->opaque[ret - WAIT_OBJECT_0]);
 392             }
 393
 394             /* Check for additional signaled events */
 395             for (i = (ret - WAIT_OBJECT_0 + 1); i < w->num; i++) {
 396                 /* Check if event is signaled */
 397                 ret2 = WaitForSingleObject(w->events[i], 0);
 398                 if (ret2 == WAIT_OBJECT_0) {
 399                     if (w->func[i]) {
 400                         w->func[i](w->opaque[i]);
 401                     }
 402                 } else if (ret2 != WAIT_TIMEOUT) {
 403                     err = GetLastError();
 404                     fprintf(stderr, "WaitForSingleObject error %d %d\n", i, err);
 405                 }
 406             }
 407         } else if (ret != WAIT_TIMEOUT) {
 408             err = GetLastError();
 409             fprintf(stderr, "WaitForMultipleObjects error %d %d\n", ret, err);
 410         }
 411     }
 412
 413     *timeout = 0;
 414 }
 415 #else
 416 static inline void os_host_main_loop_wait(int *timeout)
 417 {
 418 }
 419 #endif
 420
 421 int main_loop_wait(int nonblocking)
 422 {
 423     fd_set rfds, wfds, xfds;
 424     int ret, nfds;
 425     struct timeval tv;
 426     int timeout;
 427
 428     if (nonblocking) {
 429         timeout = 0;
 430     } else {
 431         timeout = qemu_calculate_timeout();
 432         qemu_bh_update_timeout(&timeout);
 433     }
 434
 435     os_host_main_loop_wait(&timeout);
 436
 437     tv.tv_sec = timeout / 1000;
 438     tv.tv_usec = (timeout % 1000) * 1000;
 439
 440     /* poll any events */
 441     /* XXX: separate device handlers from system ones */
 442     nfds = -1;
 443     FD_ZERO(&rfds);
 444     FD_ZERO(&wfds);
 445     FD_ZERO(&xfds);
 446
 447 #ifdef CONFIG_SLIRP
 448     slirp_select_fill(&nfds, &rfds, &wfds, &xfds);
 449 #endif
 450     qemu_iohandler_fill(&nfds, &rfds, &wfds, &xfds);
 451     glib_select_fill(&nfds, &rfds, &wfds, &xfds, &tv);
 452
 453     if (timeout > 0) {
 454         qemu_mutex_unlock_iothread();
 455     }
 456
 457     ret = select(nfds + 1, &rfds, &wfds, &xfds, &tv);
 458
 459     if (timeout > 0) {
 460         qemu_mutex_lock_iothread();
 461     }
 462
 463     glib_select_poll(&rfds, &wfds, &xfds, (ret < 0));
 464     qemu_iohandler_poll(&rfds, &wfds, &xfds, ret);
 465 #ifdef CONFIG_SLIRP
 466     slirp_select_poll(&rfds, &wfds, &xfds, (ret < 0));
 467 #endif
 468
 469     qemu_run_all_timers();
 470
 471     /* Check bottom-halves last in case any of the earlier events triggered
 472        them.  */
 473     qemu_bh_poll();
 474
 475     return ret;
 476 }