Commit 4951f65b authored by Chris Lalancette's avatar Chris Lalancette Committed by Anthony Liguori
Browse files

Migration via unix sockets. 



Implement migration via unix sockets.  While you can fake this using
exec and netcat, this involves forking another process and is
generally not very nice.  By doing this directly in qemu, we can avoid
the copy through the external nc command.  This is useful for
implementations (such as libvirt) that want to do "secure" migration;
we pipe the data on the sending side into the unix socket, libvirt
picks it up, encrypts it, and transports it, and then on the remote
side libvirt decrypts it, dumps it to another unix socket, and
feeds it into qemu.

The implementation is straightforward and looks very similar to
migration-exec.c and migration-tcp.c

Signed-off-by: default avatarChris Lalancette <clalance@redhat.com>
Signed-off-by: default avatarAnthony Liguori <aliguori@us.ibm.com>
parent 1632dc6a

Makefile

+1 −1
Original line number Diff line number Diff line
@@ -93,7 +93,7 @@ obj-y += qdev.o qdev-properties.o ssi.o 


obj-$(CONFIG_BRLAPI) += baum.o

obj-$(CONFIG_WIN32) += tap-win32.o

obj-$(CONFIG_POSIX) += migration-exec.o

obj-$(CONFIG_POSIX) += migration-exec.o migration-unix.o



audio/audio.o audio/fmodaudio.o: QEMU_CFLAGS += $(FMOD_CFLAGS)

migration-unix.c

0 → 100644
+216 −0
Original line number Diff line number Diff line 
/*

 * QEMU live migration via Unix Domain Sockets

 *

 * Copyright Red Hat, Inc. 2009

 *

 * Authors:

 *  Chris Lalancette <clalance@redhat.com>

 *

 * This work is licensed under the terms of the GNU GPL, version 2.  See

 * the COPYING file in the top-level directory.

 *

 */



#include "qemu-common.h"

#include "qemu_socket.h"

#include "migration.h"

#include "qemu-char.h"

#include "sysemu.h"

#include "buffered_file.h"

#include "block.h"



//#define DEBUG_MIGRATION_UNIX



#ifdef DEBUG_MIGRATION_UNIX

#define dprintf(fmt, ...) \

    do { printf("migration-unix: " fmt, ## __VA_ARGS__); } while (0)

#else

#define dprintf(fmt, ...) \

    do { } while (0)

#endif



static int unix_errno(FdMigrationState *s)

{

    return errno;

}



static int unix_write(FdMigrationState *s, const void * buf, size_t size)

{

    return write(s->fd, buf, size);

}



static int unix_close(FdMigrationState *s)

{

    dprintf("unix_close\n");

    if (s->fd != -1) {

        close(s->fd);

        s->fd = -1;

    }

    return 0;

}



static void unix_wait_for_connect(void *opaque)

{

    FdMigrationState *s = opaque;

    int val, ret;

    socklen_t valsize = sizeof(val);



    dprintf("connect completed\n");

    do {

        ret = getsockopt(s->fd, SOL_SOCKET, SO_ERROR, (void *) &val, &valsize);

    } while (ret == -1 && (s->get_error(s)) == EINTR);



    if (ret < 0) {

        migrate_fd_error(s);

        return;

    }



    qemu_set_fd_handler2(s->fd, NULL, NULL, NULL, NULL);



    if (val == 0)

        migrate_fd_connect(s);

    else {

        dprintf("error connecting %d\n", val);

        migrate_fd_error(s);

    }

}



MigrationState *unix_start_outgoing_migration(const char *path,

					      int64_t bandwidth_limit,

					      int detach)

{

    FdMigrationState *s;

    struct sockaddr_un addr;

    int ret;



    addr.sun_family = AF_UNIX;

    snprintf(addr.sun_path, sizeof(addr.sun_path), "%s", path);



    s = qemu_mallocz(sizeof(*s));



    s->get_error = unix_errno;

    s->write = unix_write;

    s->close = unix_close;

    s->mig_state.cancel = migrate_fd_cancel;

    s->mig_state.get_status = migrate_fd_get_status;

    s->mig_state.release = migrate_fd_release;



    s->state = MIG_STATE_ACTIVE;

    s->mon_resume = NULL;

    s->bandwidth_limit = bandwidth_limit;

    s->fd = socket(PF_UNIX, SOCK_STREAM, 0);

    if (s->fd < 0) {

        dprintf("Unable to open socket");

        goto err_after_alloc;

    }



    socket_set_nonblock(s->fd);



    if (!detach)

        migrate_fd_monitor_suspend(s);



    do {

        ret = connect(s->fd, (struct sockaddr *)&addr, sizeof(addr));

        if (ret == -1)

	    ret = -(s->get_error(s));



        if (ret == -EINPROGRESS || ret == -EWOULDBLOCK)

	    qemu_set_fd_handler2(s->fd, NULL, NULL, unix_wait_for_connect, s);

    } while (ret == -EINTR);



    if (ret < 0 && ret != -EINPROGRESS && ret != -EWOULDBLOCK) {

        dprintf("connect failed\n");

        goto err_after_open;

    } else if (ret >= 0)

        migrate_fd_connect(s);



    return &s->mig_state;



err_after_open:

    close(s->fd);



err_after_alloc:

    qemu_free(s);

    return NULL;

}



static void unix_accept_incoming_migration(void *opaque)

{

    struct sockaddr_un addr;

    socklen_t addrlen = sizeof(addr);

    int s = (unsigned long)opaque;

    QEMUFile *f;

    int c, ret;



    do {

        c = accept(s, (struct sockaddr *)&addr, &addrlen);

    } while (c == -1 && socket_error() == EINTR);



    dprintf("accepted migration\n");



    if (c == -1) {

        fprintf(stderr, "could not accept migration connection\n");

        return;

    }



    f = qemu_fopen_socket(c);

    if (f == NULL) {

        fprintf(stderr, "could not qemu_fopen socket\n");

        goto out;

    }



    ret = qemu_loadvm_state(f);

    if (ret < 0) {

        fprintf(stderr, "load of migration failed\n");

        goto out_fopen;

    }

    qemu_announce_self();

    dprintf("successfully loaded vm state\n");



    /* we've successfully migrated, close the server socket */

    qemu_set_fd_handler2(s, NULL, NULL, NULL, NULL);

    close(s);



out_fopen:

    qemu_fclose(f);

out:

    close(c);

}



int unix_start_incoming_migration(const char *path)

{

    struct sockaddr_un un;

    int sock;



    dprintf("Attempting to start an incoming migration\n");



    sock = socket(PF_UNIX, SOCK_STREAM, 0);

    if (sock < 0) {

        fprintf(stderr, "Could not open unix socket: %s\n", strerror(errno));

        return -EINVAL;

    }



    memset(&un, 0, sizeof(un));

    un.sun_family = AF_UNIX;

    snprintf(un.sun_path, sizeof(un.sun_path), "%s", path);



    unlink(un.sun_path);

    if (bind(sock, (struct sockaddr*) &un, sizeof(un)) < 0) {

        fprintf(stderr, "bind(unix:%s): %s\n", un.sun_path, strerror(errno));

        goto err;

    }

    if (listen(sock, 1) < 0) {

        fprintf(stderr, "listen(unix:%s): %s\n", un.sun_path, strerror(errno));

        goto err;

    }



    qemu_set_fd_handler2(sock, NULL, unix_accept_incoming_migration, NULL,

			 (void *)(unsigned long)sock);



    return 0;



err:

    close(sock);



    return -EINVAL;

}

migration.c

+4 −0
Original line number Diff line number Diff line
@@ -43,6 +43,8 @@ void qemu_start_incoming_migration(const char *uri) 
#if !defined(WIN32)

    else if (strstart(uri, "exec:", &p))

        exec_start_incoming_migration(p);

    else if (strstart(uri, "unix:", &p))

        unix_start_incoming_migration(p);

#endif

    else

        fprintf(stderr, "unknown migration protocol: %s\n", uri);
@@ -58,6 +60,8 @@ void do_migrate(Monitor *mon, int detach, const char *uri) 
#if !defined(WIN32)

    else if (strstart(uri, "exec:", &p))

        s = exec_start_outgoing_migration(p, max_throttle, detach);

    else if (strstart(uri, "unix:", &p))

        s = unix_start_outgoing_migration(p, max_throttle, detach);

#endif

    else

        monitor_printf(mon, "unknown migration protocol: %s\n", uri);

migration.h

+6 −0
Original line number Diff line number Diff line
@@ -73,6 +73,12 @@ MigrationState *tcp_start_outgoing_migration(const char *host_port, 
					     int64_t bandwidth_limit,

					     int detach);



int unix_start_incoming_migration(const char *path);



MigrationState *unix_start_outgoing_migration(const char *path,

					      int64_t bandwidth_limit,

					      int detach);



void migrate_fd_monitor_suspend(FdMigrationState *s);



void migrate_fd_error(FdMigrationState *s);