diff options
Diffstat (limited to 'qemu/main-loop.c')
| -rw-r--r-- | qemu/main-loop.c | 518 |
1 files changed, 518 insertions, 0 deletions
diff --git a/qemu/main-loop.c b/qemu/main-loop.c new file mode 100644 index 000000000..39970437f --- /dev/null +++ b/qemu/main-loop.c @@ -0,0 +1,518 @@ +/* + * QEMU System Emulator + * + * Copyright (c) 2003-2008 Fabrice Bellard + * + * Permission is hereby granted, free of charge, to any person obtaining a copy + * of this software and associated documentation files (the "Software"), to deal + * in the Software without restriction, including without limitation the rights + * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell + * copies of the Software, and to permit persons to whom the Software is + * furnished to do so, subject to the following conditions: + * + * The above copyright notice and this permission notice shall be included in + * all copies or substantial portions of the Software. + * + * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR + * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, + * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL + * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER + * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, + * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN + * THE SOFTWARE. + */ + +#include "qemu-common.h" +#include "qemu/timer.h" +#include "qemu/sockets.h" // struct in_addr needed for libslirp.h +#include "sysemu/qtest.h" +#include "slirp/libslirp.h" +#include "qemu/main-loop.h" +#include "block/aio.h" + +#ifndef _WIN32 + +#include "qemu/compatfd.h" + +/* If we have signalfd, we mask out the signals we want to handle and then + * use signalfd to listen for them. We rely on whatever the current signal + * handler is to dispatch the signals when we receive them. + */ +static void sigfd_handler(void *opaque) +{ + int fd = (intptr_t)opaque; + struct qemu_signalfd_siginfo info; + struct sigaction action; + ssize_t len; + + while (1) { + do { + len = read(fd, &info, sizeof(info)); + } while (len == -1 && errno == EINTR); + + if (len == -1 && errno == EAGAIN) { + break; + } + + if (len != sizeof(info)) { + printf("read from sigfd returned %zd: %m\n", len); + return; + } + + sigaction(info.ssi_signo, NULL, &action); + if ((action.sa_flags & SA_SIGINFO) && action.sa_sigaction) { + action.sa_sigaction(info.ssi_signo, + (siginfo_t *)&info, NULL); + } else if (action.sa_handler) { + action.sa_handler(info.ssi_signo); + } + } +} + +static int qemu_signal_init(void) +{ + int sigfd; + sigset_t set; + + /* + * SIG_IPI must be blocked in the main thread and must not be caught + * by sigwait() in the signal thread. Otherwise, the cpu thread will + * not catch it reliably. + */ + sigemptyset(&set); + sigaddset(&set, SIG_IPI); + sigaddset(&set, SIGIO); + sigaddset(&set, SIGALRM); + sigaddset(&set, SIGBUS); + /* SIGINT cannot be handled via signalfd, so that ^C can be used + * to interrupt QEMU when it is being run under gdb. SIGHUP and + * SIGTERM are also handled asynchronously, even though it is not + * strictly necessary, because they use the same handler as SIGINT. + */ + pthread_sigmask(SIG_BLOCK, &set, NULL); + + sigdelset(&set, SIG_IPI); + sigfd = qemu_signalfd(&set); + if (sigfd == -1) { + fprintf(stderr, "failed to create signalfd\n"); + return -errno; + } + + fcntl_setfl(sigfd, O_NONBLOCK); + + qemu_set_fd_handler(sigfd, sigfd_handler, NULL, (void *)(intptr_t)sigfd); + + return 0; +} + +#else /* _WIN32 */ + +static int qemu_signal_init(void) +{ + return 0; +} +#endif + +static AioContext *qemu_aio_context; +static QEMUBH *qemu_notify_bh; + +static void notify_event_cb(void *opaque) +{ + /* No need to do anything; this bottom half is only used to + * kick the kernel out of ppoll/poll/WaitForMultipleObjects. + */ +} + +AioContext *qemu_get_aio_context(void) +{ + return qemu_aio_context; +} + +void qemu_notify_event(void) +{ + if (!qemu_aio_context) { + return; + } + qemu_bh_schedule(qemu_notify_bh); +} + +static GArray *gpollfds; + +int qemu_init_main_loop(Error **errp) +{ + int ret; + GSource *src; + Error *local_error = NULL; + + init_clocks(); + + ret = qemu_signal_init(); + if (ret) { + return ret; + } + + qemu_aio_context = aio_context_new(&local_error); + qemu_notify_bh = qemu_bh_new(notify_event_cb, NULL); + if (!qemu_aio_context) { + error_propagate(errp, local_error); + return -EMFILE; + } + gpollfds = g_array_new(FALSE, FALSE, sizeof(GPollFD)); + src = aio_get_g_source(qemu_aio_context); + g_source_attach(src, NULL); + g_source_unref(src); + return 0; +} + +static int max_priority; + +#ifndef _WIN32 +static int glib_pollfds_idx; +static int glib_n_poll_fds; + +static void glib_pollfds_fill(int64_t *cur_timeout) +{ + GMainContext *context = g_main_context_default(); + int timeout = 0; + int64_t timeout_ns; + int n; + + g_main_context_prepare(context, &max_priority); + + glib_pollfds_idx = gpollfds->len; + n = glib_n_poll_fds; + do { + GPollFD *pfds; + glib_n_poll_fds = n; + g_array_set_size(gpollfds, glib_pollfds_idx + glib_n_poll_fds); + pfds = &g_array_index(gpollfds, GPollFD, glib_pollfds_idx); + n = g_main_context_query(context, max_priority, &timeout, pfds, + glib_n_poll_fds); + } while (n != glib_n_poll_fds); + + if (timeout < 0) { + timeout_ns = -1; + } else { + timeout_ns = (int64_t)timeout * (int64_t)SCALE_MS; + } + + *cur_timeout = qemu_soonest_timeout(timeout_ns, *cur_timeout); +} + +static void glib_pollfds_poll(void) +{ + GMainContext *context = g_main_context_default(); + GPollFD *pfds = &g_array_index(gpollfds, GPollFD, glib_pollfds_idx); + + if (g_main_context_check(context, max_priority, pfds, glib_n_poll_fds)) { + g_main_context_dispatch(context); + } +} + +#define MAX_MAIN_LOOP_SPIN (1000) + +static int os_host_main_loop_wait(int64_t timeout) +{ + int ret; + static int spin_counter; + + glib_pollfds_fill(&timeout); + + /* If the I/O thread is very busy or we are incorrectly busy waiting in + * the I/O thread, this can lead to starvation of the BQL such that the + * VCPU threads never run. To make sure we can detect the later case, + * print a message to the screen. If we run into this condition, create + * a fake timeout in order to give the VCPU threads a chance to run. + */ + if (!timeout && (spin_counter > MAX_MAIN_LOOP_SPIN)) { + static bool notified; + + if (!notified && !qtest_enabled()) { + fprintf(stderr, + "main-loop: WARNING: I/O thread spun for %d iterations\n", + MAX_MAIN_LOOP_SPIN); + notified = true; + } + + timeout = SCALE_MS; + } + + if (timeout) { + spin_counter = 0; + qemu_mutex_unlock_iothread(); + } else { + spin_counter++; + } + + ret = qemu_poll_ns((GPollFD *)gpollfds->data, gpollfds->len, timeout); + + if (timeout) { + qemu_mutex_lock_iothread(); + } + + glib_pollfds_poll(); + return ret; +} +#else +/***********************************************************/ +/* Polling handling */ + +typedef struct PollingEntry { + PollingFunc *func; + void *opaque; + struct PollingEntry *next; +} PollingEntry; + +static PollingEntry *first_polling_entry; + +int qemu_add_polling_cb(PollingFunc *func, void *opaque) +{ + PollingEntry **ppe, *pe; + pe = g_malloc0(sizeof(PollingEntry)); + pe->func = func; + pe->opaque = opaque; + for(ppe = &first_polling_entry; *ppe != NULL; ppe = &(*ppe)->next); + *ppe = pe; + return 0; +} + +void qemu_del_polling_cb(PollingFunc *func, void *opaque) +{ + PollingEntry **ppe, *pe; + for(ppe = &first_polling_entry; *ppe != NULL; ppe = &(*ppe)->next) { + pe = *ppe; + if (pe->func == func && pe->opaque == opaque) { + *ppe = pe->next; + g_free(pe); + break; + } + } +} + +/***********************************************************/ +/* Wait objects support */ +typedef struct WaitObjects { + int num; + int revents[MAXIMUM_WAIT_OBJECTS + 1]; + HANDLE events[MAXIMUM_WAIT_OBJECTS + 1]; + WaitObjectFunc *func[MAXIMUM_WAIT_OBJECTS + 1]; + void *opaque[MAXIMUM_WAIT_OBJECTS + 1]; +} WaitObjects; + +static WaitObjects wait_objects = {0}; + +int qemu_add_wait_object(HANDLE handle, WaitObjectFunc *func, void *opaque) +{ + WaitObjects *w = &wait_objects; + if (w->num >= MAXIMUM_WAIT_OBJECTS) { + return -1; + } + w->events[w->num] = handle; + w->func[w->num] = func; + w->opaque[w->num] = opaque; + w->revents[w->num] = 0; + w->num++; + return 0; +} + +void qemu_del_wait_object(HANDLE handle, WaitObjectFunc *func, void *opaque) +{ + int i, found; + WaitObjects *w = &wait_objects; + + found = 0; + for (i = 0; i < w->num; i++) { + if (w->events[i] == handle) { + found = 1; + } + if (found) { + w->events[i] = w->events[i + 1]; + w->func[i] = w->func[i + 1]; + w->opaque[i] = w->opaque[i + 1]; + w->revents[i] = w->revents[i + 1]; + } + } + if (found) { + w->num--; + } +} + +void qemu_fd_register(int fd) +{ + WSAEventSelect(fd, event_notifier_get_handle(&qemu_aio_context->notifier), + FD_READ | FD_ACCEPT | FD_CLOSE | + FD_CONNECT | FD_WRITE | FD_OOB); +} + +static int pollfds_fill(GArray *pollfds, fd_set *rfds, fd_set *wfds, + fd_set *xfds) +{ + int nfds = -1; + int i; + + for (i = 0; i < pollfds->len; i++) { + GPollFD *pfd = &g_array_index(pollfds, GPollFD, i); + int fd = pfd->fd; + int events = pfd->events; + if (events & G_IO_IN) { + FD_SET(fd, rfds); + nfds = MAX(nfds, fd); + } + if (events & G_IO_OUT) { + FD_SET(fd, wfds); + nfds = MAX(nfds, fd); + } + if (events & G_IO_PRI) { + FD_SET(fd, xfds); + nfds = MAX(nfds, fd); + } + } + return nfds; +} + +static void pollfds_poll(GArray *pollfds, int nfds, fd_set *rfds, + fd_set *wfds, fd_set *xfds) +{ + int i; + + for (i = 0; i < pollfds->len; i++) { + GPollFD *pfd = &g_array_index(pollfds, GPollFD, i); + int fd = pfd->fd; + int revents = 0; + + if (FD_ISSET(fd, rfds)) { + revents |= G_IO_IN; + } + if (FD_ISSET(fd, wfds)) { + revents |= G_IO_OUT; + } + if (FD_ISSET(fd, xfds)) { + revents |= G_IO_PRI; + } + pfd->revents = revents & pfd->events; + } +} + +static int os_host_main_loop_wait(int64_t timeout) +{ + GMainContext *context = g_main_context_default(); + GPollFD poll_fds[1024 * 2]; /* this is probably overkill */ + int select_ret = 0; + int g_poll_ret, ret, i, n_poll_fds; + PollingEntry *pe; + WaitObjects *w = &wait_objects; + gint poll_timeout; + int64_t poll_timeout_ns; + static struct timeval tv0; + fd_set rfds, wfds, xfds; + int nfds; + + /* XXX: need to suppress polling by better using win32 events */ + ret = 0; + for (pe = first_polling_entry; pe != NULL; pe = pe->next) { + ret |= pe->func(pe->opaque); + } + if (ret != 0) { + return ret; + } + + FD_ZERO(&rfds); + FD_ZERO(&wfds); + FD_ZERO(&xfds); + nfds = pollfds_fill(gpollfds, &rfds, &wfds, &xfds); + if (nfds >= 0) { + select_ret = select(nfds + 1, &rfds, &wfds, &xfds, &tv0); + if (select_ret != 0) { + timeout = 0; + } + if (select_ret > 0) { + pollfds_poll(gpollfds, nfds, &rfds, &wfds, &xfds); + } + } + + g_main_context_prepare(context, &max_priority); + n_poll_fds = g_main_context_query(context, max_priority, &poll_timeout, + poll_fds, ARRAY_SIZE(poll_fds)); + g_assert(n_poll_fds <= ARRAY_SIZE(poll_fds)); + + for (i = 0; i < w->num; i++) { + poll_fds[n_poll_fds + i].fd = (DWORD_PTR)w->events[i]; + poll_fds[n_poll_fds + i].events = G_IO_IN; + } + + if (poll_timeout < 0) { + poll_timeout_ns = -1; + } else { + poll_timeout_ns = (int64_t)poll_timeout * (int64_t)SCALE_MS; + } + + poll_timeout_ns = qemu_soonest_timeout(poll_timeout_ns, timeout); + + qemu_mutex_unlock_iothread(); + g_poll_ret = qemu_poll_ns(poll_fds, n_poll_fds + w->num, poll_timeout_ns); + + qemu_mutex_lock_iothread(); + if (g_poll_ret > 0) { + for (i = 0; i < w->num; i++) { + w->revents[i] = poll_fds[n_poll_fds + i].revents; + } + for (i = 0; i < w->num; i++) { + if (w->revents[i] && w->func[i]) { + w->func[i](w->opaque[i]); + } + } + } + + if (g_main_context_check(context, max_priority, poll_fds, n_poll_fds)) { + g_main_context_dispatch(context); + } + + return select_ret || g_poll_ret; +} +#endif + +int main_loop_wait(int nonblocking) +{ + int ret; + uint32_t timeout = UINT32_MAX; + int64_t timeout_ns; + + if (nonblocking) { + timeout = 0; + } + + /* poll any events */ + g_array_set_size(gpollfds, 0); /* reset for new iteration */ + /* XXX: separate device handlers from system ones */ +#ifdef CONFIG_SLIRP + slirp_pollfds_fill(gpollfds, &timeout); +#endif + qemu_iohandler_fill(gpollfds); + + if (timeout == UINT32_MAX) { + timeout_ns = -1; + } else { + timeout_ns = (uint64_t)timeout * (int64_t)(SCALE_MS); + } + + timeout_ns = qemu_soonest_timeout(timeout_ns, + timerlistgroup_deadline_ns( + &main_loop_tlg)); + + ret = os_host_main_loop_wait(timeout_ns); + qemu_iohandler_poll(gpollfds, ret); +#ifdef CONFIG_SLIRP + slirp_pollfds_poll(gpollfds, (ret < 0)); +#endif + + qemu_clock_run_all_timers(); + + return ret; +} + +/* Functions to operate on the main QEMU AioContext. */ + +QEMUBH *qemu_bh_new(QEMUBHFunc *cb, void *opaque) +{ + return aio_bh_new(qemu_aio_context, cb, opaque); +} |