migration-unix.c

   1 /*
   2  * QEMU live migration via Unix Domain Sockets
   3  *
   4  * Copyright Red Hat, Inc. 2009
   5  *
   6  * Authors:
   7  *  Chris Lalancette <clalance@redhat.com>
   8  *
   9  * This work is licensed under the terms of the GNU GPL, version 2.  See
  10  * the COPYING file in the top-level directory.
  11  *
  12  */
  13
  14 #include "qemu-common.h"
  15 #include "qemu_socket.h"
  16 #include "migration.h"
  17 #include "qemu-char.h"
  18 #include "sysemu.h"
  19 #include "buffered_file.h"
  20 #include "block.h"
  21
  22 //#define DEBUG_MIGRATION_UNIX
  23
  24 #ifdef DEBUG_MIGRATION_UNIX
  25 #define DPRINTF(fmt, ...) \
  26     do { printf("migration-unix: " fmt, ## __VA_ARGS__); } while (0)
  27 #else
  28 #define DPRINTF(fmt, ...) \
  29     do { } while (0)
  30 #endif
  31
  32 static int unix_errno(FdMigrationState *s)
  33 {
  34     return errno;
  35 }
  36
  37 static int unix_write(FdMigrationState *s, const void * buf, size_t size)
  38 {
  39     return write(s->fd, buf, size);
  40 }
  41
  42 static int unix_close(FdMigrationState *s)
  43 {
  44     DPRINTF("unix_close\n");
  45     if (s->fd != -1) {
  46         close(s->fd);
  47         s->fd = -1;
  48     }
  49     return 0;
  50 }
  51
  52 static void unix_wait_for_connect(void *opaque)
  53 {
  54     FdMigrationState *s = opaque;
  55     int val, ret;
  56     socklen_t valsize = sizeof(val);
  57
  58     DPRINTF("connect completed\n");
  59     do {
  60         ret = getsockopt(s->fd, SOL_SOCKET, SO_ERROR, (void *) &val, &valsize);
  61     } while (ret == -1 && (s->get_error(s)) == EINTR);
  62
  63     if (ret < 0) {
  64         migrate_fd_error(s);
  65         return;
  66     }
  67
  68     qemu_set_fd_handler2(s->fd, NULL, NULL, NULL, NULL);
  69
  70     if (val == 0)
  71         migrate_fd_connect(s);
  72     else {
  73         DPRINTF("error connecting %d\n", val);
  74         migrate_fd_error(s);
  75     }
  76 }
  77
  78 MigrationState *unix_start_outgoing_migration(Monitor *mon,
  79                                               const char *path,
  80                                               int64_t bandwidth_limit,
  81                                               int detach,
  82                                               int blk,
  83                                               int inc)
  84 {
  85     FdMigrationState *s;
  86     struct sockaddr_un addr;
  87     int ret;
  88
  89     addr.sun_family = AF_UNIX;
  90     snprintf(addr.sun_path, sizeof(addr.sun_path), "%s", path);
  91
  92     s = qemu_mallocz(sizeof(*s));
  93
  94     s->get_error = unix_errno;
  95     s->write = unix_write;
  96     s->close = unix_close;
  97     s->mig_state.cancel = migrate_fd_cancel;
  98     s->mig_state.get_status = migrate_fd_get_status;
  99     s->mig_state.release = migrate_fd_release;
 100
 101     s->mig_state.blk = blk;
 102     s->mig_state.shared = inc;
 103
 104     s->state = MIG_STATE_ACTIVE;
 105     s->mon = NULL;
 106     s->bandwidth_limit = bandwidth_limit;
 107     s->fd = qemu_socket(PF_UNIX, SOCK_STREAM, 0);
 108     if (s->fd < 0) {
 109         DPRINTF("Unable to open socket");
 110         goto err_after_alloc;
 111     }
 112
 113     socket_set_nonblock(s->fd);
 114
 115     do {
 116         ret = connect(s->fd, (struct sockaddr *)&addr, sizeof(addr));
 117         if (ret == -1)
 118             ret = -(s->get_error(s));
 119
 120         if (ret == -EINPROGRESS || ret == -EWOULDBLOCK)
 121             qemu_set_fd_handler2(s->fd, NULL, NULL, unix_wait_for_connect, s);
 122     } while (ret == -EINTR);
 123
 124     if (ret < 0 && ret != -EINPROGRESS && ret != -EWOULDBLOCK) {
 125         DPRINTF("connect failed\n");
 126         goto err_after_open;
 127     }
 128
 129     if (!detach) {
 130         migrate_fd_monitor_suspend(s, mon);
 131     }
 132
 133     if (ret >= 0)
 134         migrate_fd_connect(s);
 135
 136     return &s->mig_state;
 137
 138 err_after_open:
 139     close(s->fd);
 140
 141 err_after_alloc:
 142     qemu_free(s);
 143     return NULL;
 144 }
 145
 146 static void unix_accept_incoming_migration(void *opaque)
 147 {
 148     struct sockaddr_un addr;
 149     socklen_t addrlen = sizeof(addr);
 150     int s = (unsigned long)opaque;
 151     QEMUFile *f;
 152     int c, ret;
 153
 154     do {
 155         c = qemu_accept(s, (struct sockaddr *)&addr, &addrlen);
 156     } while (c == -1 && socket_error() == EINTR);
 157
 158     DPRINTF("accepted migration\n");
 159
 160     if (c == -1) {
 161         fprintf(stderr, "could not accept migration connection\n");
 162         return;
 163     }
 164
 165     f = qemu_fopen_socket(c);
 166     if (f == NULL) {
 167         fprintf(stderr, "could not qemu_fopen socket\n");
 168         goto out;
 169     }
 170
 171     ret = qemu_loadvm_state(f);
 172     if (ret < 0) {
 173         fprintf(stderr, "load of migration failed\n");
 174         goto out_fopen;
 175     }
 176     qemu_announce_self();
 177     DPRINTF("successfully loaded vm state\n");
 178
 179     /* we've successfully migrated, close the server socket */
 180     qemu_set_fd_handler2(s, NULL, NULL, NULL, NULL);
 181     close(s);
 182
 183 out_fopen:
 184     qemu_fclose(f);
 185 out:
 186     close(c);
 187 }
 188
 189 int unix_start_incoming_migration(const char *path)
 190 {
 191     struct sockaddr_un un;
 192     int sock;
 193
 194     DPRINTF("Attempting to start an incoming migration\n");
 195
 196     sock = qemu_socket(PF_UNIX, SOCK_STREAM, 0);
 197     if (sock < 0) {
 198         fprintf(stderr, "Could not open unix socket: %s\n", strerror(errno));
 199         return -EINVAL;
 200     }
 201
 202     memset(&un, 0, sizeof(un));
 203     un.sun_family = AF_UNIX;
 204     snprintf(un.sun_path, sizeof(un.sun_path), "%s", path);
 205
 206     unlink(un.sun_path);
 207     if (bind(sock, (struct sockaddr*) &un, sizeof(un)) < 0) {
 208         fprintf(stderr, "bind(unix:%s): %s\n", un.sun_path, strerror(errno));
 209         goto err;
 210     }
 211     if (listen(sock, 1) < 0) {
 212         fprintf(stderr, "listen(unix:%s): %s\n", un.sun_path, strerror(errno));
 213         goto err;
 214     }
 215
 216     qemu_set_fd_handler2(sock, NULL, unix_accept_incoming_migration, NULL,
 217                          (void *)(unsigned long)sock);
 218
 219     return 0;
 220
 221 err:
 222     close(sock);
 223
 224     return -EINVAL;
 225 }