Archipelago » qemu

/*

 * 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 "slirp/slirp.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);

    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_handler2(sigfd, NULL, 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;

AioContext *qemu_get_aio_context(void)

{

    return qemu_aio_context;

}

void qemu_notify_event(void)

{

    if (!qemu_aio_context) {

        return;

    }

    aio_notify(qemu_aio_context);

}

static GArray *gpollfds;

int qemu_init_main_loop(void)

{

    int ret;

    GSource *src;

    init_clocks();

    if (init_timer_alarm() < 0) {

        fprintf(stderr, "could not initialize alarm timer\n");

        exit(1);

    }

    ret = qemu_signal_init();

    if (ret) {

        return ret;

    }

    gpollfds = g_array_new(FALSE, FALSE, sizeof(GPollFD));

    qemu_aio_context = aio_context_new();

    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(uint32_t *cur_timeout)

{

    GMainContext *context = g_main_context_default();

    int timeout = 0;

    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 < *cur_timeout) {

        *cur_timeout = 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(uint32_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 (spin_counter > MAX_MAIN_LOOP_SPIN) {

        static bool notified;

        if (!notified) {

            fprintf(stderr,

                    "main-loop: WARNING: I/O thread spun for %d iterations\n",

                    MAX_MAIN_LOOP_SPIN);

            notified = true;

        }

        timeout = 1;

    }

    if (timeout > 0) {

        spin_counter = 0;

        qemu_mutex_unlock_iothread();

    } else {

        spin_counter++;

    }

    ret = g_poll((GPollFD *)gpollfds->data, gpollfds->len, timeout);

    if (timeout > 0) {

        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(uint32_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;

    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 || timeout < poll_timeout) {

        poll_timeout = timeout;

    }

    qemu_mutex_unlock_iothread();

    g_poll_ret = g_poll(poll_fds, n_poll_fds + w->num, poll_timeout);

    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;

    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_update_timeout(&timeout);

    slirp_pollfds_fill(gpollfds);

#endif

    qemu_iohandler_fill(gpollfds);

    ret = os_host_main_loop_wait(timeout);

    qemu_iohandler_poll(gpollfds, ret);

#ifdef CONFIG_SLIRP

    slirp_pollfds_poll(gpollfds, (ret < 0));

#endif

    qemu_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);

}

bool qemu_aio_wait(void)

{

    return aio_poll(qemu_aio_context, true);

}

#ifdef CONFIG_POSIX

void qemu_aio_set_fd_handler(int fd,

                             IOHandler *io_read,

                             IOHandler *io_write,

                             AioFlushHandler *io_flush,

                             void *opaque)

{

    aio_set_fd_handler(qemu_aio_context, fd, io_read, io_write, io_flush,

                       opaque);

}

#endif

void qemu_aio_set_event_notifier(EventNotifier *notifier,

                                 EventNotifierHandler *io_read,

                                 AioFlushEventNotifierHandler *io_flush)

{

    aio_set_event_notifier(qemu_aio_context, notifier, io_read, io_flush);

}