contrib/ivshmem-server/ivshmem-server.c

   1 /*
   2  * Copyright 6WIND S.A., 2014
   3  *
   4  * This work is licensed under the terms of the GNU GPL, version 2 or
   5  * (at your option) any later version.  See the COPYING file in the
   6  * top-level directory.
   7  */
   8 #include "qemu/osdep.h"
   9 #include "qemu/host-utils.h"
  10 #include "qemu/sockets.h"
  11
  12 #include <sys/socket.h>
  13 #include <sys/un.h>
  14
  15 #include "ivshmem-server.h"
  16
  17 /* log a message on stdout if verbose=1 */
  18 #define IVSHMEM_SERVER_DEBUG(server, fmt, ...) do { \
  19         if ((server)->verbose) {         \
  20             printf(fmt, ## __VA_ARGS__); \
  21         }                                \
  22     } while (0)
  23
  24 /** maximum size of a huge page, used by ivshmem_server_ftruncate() */
  25 #define IVSHMEM_SERVER_MAX_HUGEPAGE_SIZE (1024 * 1024 * 1024)
  26
  27 /** default listen backlog (number of sockets not accepted) */
  28 #define IVSHMEM_SERVER_LISTEN_BACKLOG 10
  29
  30 /* send message to a client unix socket */
  31 static int
  32 ivshmem_server_send_one_msg(int sock_fd, int64_t peer_id, int fd)
  33 {
  34     int ret;
  35     struct msghdr msg;
  36     struct iovec iov[1];
  37     union {
  38         struct cmsghdr cmsg;
  39         char control[CMSG_SPACE(sizeof(int))];
  40     } msg_control;
  41     struct cmsghdr *cmsg;
  42
  43     peer_id = GINT64_TO_LE(peer_id);
  44     iov[0].iov_base = &peer_id;
  45     iov[0].iov_len = sizeof(peer_id);
  46
  47     memset(&msg, 0, sizeof(msg));
  48     msg.msg_iov = iov;
  49     msg.msg_iovlen = 1;
  50
  51     /* if fd is specified, add it in a cmsg */
  52     if (fd >= 0) {
  53         memset(&msg_control, 0, sizeof(msg_control));
  54         msg.msg_control = &msg_control;
  55         msg.msg_controllen = sizeof(msg_control);
  56         cmsg = CMSG_FIRSTHDR(&msg);
  57         cmsg->cmsg_level = SOL_SOCKET;
  58         cmsg->cmsg_type = SCM_RIGHTS;
  59         cmsg->cmsg_len = CMSG_LEN(sizeof(int));
  60         memcpy(CMSG_DATA(cmsg), &fd, sizeof(fd));
  61     }
  62
  63     ret = sendmsg(sock_fd, &msg, 0);
  64     if (ret <= 0) {
  65         return -1;
  66     }
  67
  68     return 0;
  69 }
  70
  71 /* free a peer when the server advertises a disconnection or when the
  72  * server is freed */
  73 static void
  74 ivshmem_server_free_peer(IvshmemServer *server, IvshmemServerPeer *peer)
  75 {
  76     unsigned vector;
  77     IvshmemServerPeer *other_peer;
  78
  79     IVSHMEM_SERVER_DEBUG(server, "free peer %" PRId64 "\n", peer->id);
  80     close(peer->sock_fd);
  81     QTAILQ_REMOVE(&server->peer_list, peer, next);
  82
  83     /* advertise the deletion to other peers */
  84     QTAILQ_FOREACH(other_peer, &server->peer_list, next) {
  85         ivshmem_server_send_one_msg(other_peer->sock_fd, peer->id, -1);
  86     }
  87
  88     for (vector = 0; vector < peer->vectors_count; vector++) {
  89         event_notifier_cleanup(&peer->vectors[vector]);
  90     }
  91
  92     g_free(peer);
  93 }
  94
  95 /* send the peer id and the shm_fd just after a new client connection */
  96 static int
  97 ivshmem_server_send_initial_info(IvshmemServer *server, IvshmemServerPeer *peer)
  98 {
  99     int ret;
 100
 101     /* send our protocol version first */
 102     ret = ivshmem_server_send_one_msg(peer->sock_fd, IVSHMEM_PROTOCOL_VERSION,
 103                                       -1);
 104     if (ret < 0) {
 105         IVSHMEM_SERVER_DEBUG(server, "cannot send version: %s\n",
 106                              strerror(errno));
 107         return -1;
 108     }
 109
 110     /* send the peer id to the client */
 111     ret = ivshmem_server_send_one_msg(peer->sock_fd, peer->id, -1);
 112     if (ret < 0) {
 113         IVSHMEM_SERVER_DEBUG(server, "cannot send peer id: %s\n",
 114                              strerror(errno));
 115         return -1;
 116     }
 117
 118     /* send the shm_fd */
 119     ret = ivshmem_server_send_one_msg(peer->sock_fd, -1, server->shm_fd);
 120     if (ret < 0) {
 121         IVSHMEM_SERVER_DEBUG(server, "cannot send shm fd: %s\n",
 122                              strerror(errno));
 123         return -1;
 124     }
 125
 126     return 0;
 127 }
 128
 129 /* handle message on listening unix socket (new client connection) */
 130 static int
 131 ivshmem_server_handle_new_conn(IvshmemServer *server)
 132 {
 133     IvshmemServerPeer *peer, *other_peer;
 134     struct sockaddr_un unaddr;
 135     socklen_t unaddr_len;
 136     int newfd;
 137     unsigned i;
 138
 139     /* accept the incoming connection */
 140     unaddr_len = sizeof(unaddr);
 141     newfd = qemu_accept(server->sock_fd,
 142                         (struct sockaddr *)&unaddr, &unaddr_len);
 143
 144     if (newfd < 0) {
 145         IVSHMEM_SERVER_DEBUG(server, "cannot accept() %s\n", strerror(errno));
 146         return -1;
 147     }
 148
 149     qemu_socket_set_nonblock(newfd);
 150     IVSHMEM_SERVER_DEBUG(server, "accept()=%d\n", newfd);
 151
 152     /* allocate new structure for this peer */
 153     peer = g_malloc0(sizeof(*peer));
 154     peer->sock_fd = newfd;
 155
 156     /* get an unused peer id */
 157     /* XXX: this could use id allocation such as Linux IDA, or simply
 158      * a free-list */
 159     for (i = 0; i < G_MAXUINT16; i++) {
 160         if (ivshmem_server_search_peer(server, server->cur_id) == NULL) {
 161             break;
 162         }
 163         server->cur_id++;
 164     }
 165     if (i == G_MAXUINT16) {
 166         IVSHMEM_SERVER_DEBUG(server, "cannot allocate new client id\n");
 167         close(newfd);
 168         g_free(peer);
 169         return -1;
 170     }
 171     peer->id = server->cur_id++;
 172
 173     /* create eventfd, one per vector */
 174     peer->vectors_count = server->n_vectors;
 175     for (i = 0; i < peer->vectors_count; i++) {
 176         if (event_notifier_init(&peer->vectors[i], FALSE) < 0) {
 177             IVSHMEM_SERVER_DEBUG(server, "cannot create eventfd\n");
 178             goto fail;
 179         }
 180     }
 181
 182     /* send peer id and shm fd */
 183     if (ivshmem_server_send_initial_info(server, peer) < 0) {
 184         IVSHMEM_SERVER_DEBUG(server, "cannot send initial info\n");
 185         goto fail;
 186     }
 187
 188     /* advertise the new peer to others */
 189     QTAILQ_FOREACH(other_peer, &server->peer_list, next) {
 190         for (i = 0; i < peer->vectors_count; i++) {
 191             ivshmem_server_send_one_msg(other_peer->sock_fd, peer->id,
 192                                         peer->vectors[i].wfd);
 193         }
 194     }
 195
 196     /* advertise the other peers to the new one */
 197     QTAILQ_FOREACH(other_peer, &server->peer_list, next) {
 198         for (i = 0; i < peer->vectors_count; i++) {
 199             ivshmem_server_send_one_msg(peer->sock_fd, other_peer->id,
 200                                         other_peer->vectors[i].wfd);
 201         }
 202     }
 203
 204     /* advertise the new peer to itself */
 205     for (i = 0; i < peer->vectors_count; i++) {
 206         ivshmem_server_send_one_msg(peer->sock_fd, peer->id,
 207                                     event_notifier_get_fd(&peer->vectors[i]));
 208     }
 209
 210     QTAILQ_INSERT_TAIL(&server->peer_list, peer, next);
 211     IVSHMEM_SERVER_DEBUG(server, "new peer id = %" PRId64 "\n",
 212                          peer->id);
 213     return 0;
 214
 215 fail:
 216     while (i--) {
 217         event_notifier_cleanup(&peer->vectors[i]);
 218     }
 219     close(newfd);
 220     g_free(peer);
 221     return -1;
 222 }
 223
 224 /* Try to ftruncate a file to next power of 2 of shmsize.
 225  * If it fails; all power of 2 above shmsize are tested until
 226  * we reach the maximum huge page size. This is useful
 227  * if the shm file is in a hugetlbfs that cannot be truncated to the
 228  * shm_size value. */
 229 static int
 230 ivshmem_server_ftruncate(int fd, unsigned shmsize)
 231 {
 232     int ret;
 233     struct stat mapstat;
 234
 235     /* align shmsize to next power of 2 */
 236     shmsize = pow2ceil(shmsize);
 237
 238     if (fstat(fd, &mapstat) != -1 && mapstat.st_size == shmsize) {
 239         return 0;
 240     }
 241
 242     while (shmsize <= IVSHMEM_SERVER_MAX_HUGEPAGE_SIZE) {
 243         ret = ftruncate(fd, shmsize);
 244         if (ret == 0) {
 245             return ret;
 246         }
 247         shmsize *= 2;
 248     }
 249
 250     return -1;
 251 }
 252
 253 /* Init a new ivshmem server */
 254 int
 255 ivshmem_server_init(IvshmemServer *server, const char *unix_sock_path,
 256                     const char *shm_path, bool use_shm_open,
 257                     size_t shm_size, unsigned n_vectors,
 258                     bool verbose)
 259 {
 260     int ret;
 261
 262     memset(server, 0, sizeof(*server));
 263     server->verbose = verbose;
 264
 265     ret = snprintf(server->unix_sock_path, sizeof(server->unix_sock_path),
 266                    "%s", unix_sock_path);
 267     if (ret < 0 || ret >= sizeof(server->unix_sock_path)) {
 268         IVSHMEM_SERVER_DEBUG(server, "could not copy unix socket path\n");
 269         return -1;
 270     }
 271     ret = snprintf(server->shm_path, sizeof(server->shm_path),
 272                    "%s", shm_path);
 273     if (ret < 0 || ret >= sizeof(server->shm_path)) {
 274         IVSHMEM_SERVER_DEBUG(server, "could not copy shm path\n");
 275         return -1;
 276     }
 277
 278     server->use_shm_open = use_shm_open;
 279     server->shm_size = shm_size;
 280     server->n_vectors = n_vectors;
 281
 282     QTAILQ_INIT(&server->peer_list);
 283
 284     return 0;
 285 }
 286
 287 /* open shm, create and bind to the unix socket */
 288 int
 289 ivshmem_server_start(IvshmemServer *server)
 290 {
 291     struct sockaddr_un s_un;
 292     int shm_fd, sock_fd, ret;
 293
 294     /* open shm file */
 295     if (server->use_shm_open) {
 296         IVSHMEM_SERVER_DEBUG(server, "Using POSIX shared memory: %s\n",
 297                              server->shm_path);
 298         shm_fd = shm_open(server->shm_path, O_CREAT | O_RDWR, S_IRWXU);
 299     } else {
 300         gchar *filename = g_strdup_printf("%s/ivshmem.XXXXXX", server->shm_path);
 301         IVSHMEM_SERVER_DEBUG(server, "Using file-backed shared memory: %s\n",
 302                              server->shm_path);
 303         shm_fd = mkstemp(filename);
 304         unlink(filename);
 305         g_free(filename);
 306     }
 307
 308     if (shm_fd < 0) {
 309         fprintf(stderr, "cannot open shm file %s: %s\n", server->shm_path,
 310                 strerror(errno));
 311         return -1;
 312     }
 313     if (ivshmem_server_ftruncate(shm_fd, server->shm_size) < 0) {
 314         fprintf(stderr, "ftruncate(%s) failed: %s\n", server->shm_path,
 315                 strerror(errno));
 316         goto err_close_shm;
 317     }
 318
 319     IVSHMEM_SERVER_DEBUG(server, "create & bind socket %s\n",
 320                          server->unix_sock_path);
 321
 322     /* create the unix listening socket */
 323     sock_fd = socket(AF_UNIX, SOCK_STREAM, 0);
 324     if (sock_fd < 0) {
 325         IVSHMEM_SERVER_DEBUG(server, "cannot create socket: %s\n",
 326                              strerror(errno));
 327         goto err_close_shm;
 328     }
 329
 330     s_un.sun_family = AF_UNIX;
 331     ret = snprintf(s_un.sun_path, sizeof(s_un.sun_path), "%s",
 332                    server->unix_sock_path);
 333     if (ret < 0 || ret >= sizeof(s_un.sun_path)) {
 334         IVSHMEM_SERVER_DEBUG(server, "could not copy unix socket path\n");
 335         goto err_close_sock;
 336     }
 337     if (bind(sock_fd, (struct sockaddr *)&s_un, sizeof(s_un)) < 0) {
 338         IVSHMEM_SERVER_DEBUG(server, "cannot connect to %s: %s\n", s_un.sun_path,
 339                              strerror(errno));
 340         goto err_close_sock;
 341     }
 342
 343     if (listen(sock_fd, IVSHMEM_SERVER_LISTEN_BACKLOG) < 0) {
 344         IVSHMEM_SERVER_DEBUG(server, "listen() failed: %s\n", strerror(errno));
 345         goto err_close_sock;
 346     }
 347
 348     server->sock_fd = sock_fd;
 349     server->shm_fd = shm_fd;
 350
 351     return 0;
 352
 353 err_close_sock:
 354     close(sock_fd);
 355 err_close_shm:
 356     if (server->use_shm_open) {
 357         shm_unlink(server->shm_path);
 358     }
 359     close(shm_fd);
 360     return -1;
 361 }
 362
 363 /* close connections to clients, the unix socket and the shm fd */
 364 void
 365 ivshmem_server_close(IvshmemServer *server)
 366 {
 367     IvshmemServerPeer *peer, *npeer;
 368
 369     IVSHMEM_SERVER_DEBUG(server, "close server\n");
 370
 371     QTAILQ_FOREACH_SAFE(peer, &server->peer_list, next, npeer) {
 372         ivshmem_server_free_peer(server, peer);
 373     }
 374
 375     unlink(server->unix_sock_path);
 376     if (server->use_shm_open) {
 377         shm_unlink(server->shm_path);
 378     }
 379     close(server->sock_fd);
 380     close(server->shm_fd);
 381     server->sock_fd = -1;
 382     server->shm_fd = -1;
 383 }
 384
 385 /* get the fd_set according to the unix socket and the peer list */
 386 void
 387 ivshmem_server_get_fds(const IvshmemServer *server, fd_set *fds, int *maxfd)
 388 {
 389     IvshmemServerPeer *peer;
 390
 391     if (server->sock_fd == -1) {
 392         return;
 393     }
 394
 395     FD_SET(server->sock_fd, fds);
 396     if (server->sock_fd >= *maxfd) {
 397         *maxfd = server->sock_fd + 1;
 398     }
 399
 400     QTAILQ_FOREACH(peer, &server->peer_list, next) {
 401         FD_SET(peer->sock_fd, fds);
 402         if (peer->sock_fd >= *maxfd) {
 403             *maxfd = peer->sock_fd + 1;
 404         }
 405     }
 406 }
 407
 408 /* process incoming messages on the sockets in fd_set */
 409 int
 410 ivshmem_server_handle_fds(IvshmemServer *server, fd_set *fds, int maxfd)
 411 {
 412     IvshmemServerPeer *peer, *peer_next;
 413
 414     if (server->sock_fd < maxfd && FD_ISSET(server->sock_fd, fds) &&
 415         ivshmem_server_handle_new_conn(server) < 0 && errno != EINTR) {
 416         IVSHMEM_SERVER_DEBUG(server, "ivshmem_server_handle_new_conn() "
 417                              "failed\n");
 418         return -1;
 419     }
 420
 421     QTAILQ_FOREACH_SAFE(peer, &server->peer_list, next, peer_next) {
 422         /* any message from a peer socket result in a close() */
 423         IVSHMEM_SERVER_DEBUG(server, "peer->sock_fd=%d\n", peer->sock_fd);
 424         if (peer->sock_fd < maxfd && FD_ISSET(peer->sock_fd, fds)) {
 425             ivshmem_server_free_peer(server, peer);
 426         }
 427     }
 428
 429     return 0;
 430 }
 431
 432 /* lookup peer from its id */
 433 IvshmemServerPeer *
 434 ivshmem_server_search_peer(IvshmemServer *server, int64_t peer_id)
 435 {
 436     IvshmemServerPeer *peer;
 437
 438     QTAILQ_FOREACH(peer, &server->peer_list, next) {
 439         if (peer->id == peer_id) {
 440             return peer;
 441         }
 442     }
 443     return NULL;
 444 }
 445
 446 /* dump our info, the list of peers their vectors on stdout */
 447 void
 448 ivshmem_server_dump(const IvshmemServer *server)
 449 {
 450     const IvshmemServerPeer *peer;
 451     unsigned vector;
 452
 453     /* dump peers */
 454     QTAILQ_FOREACH(peer, &server->peer_list, next) {
 455         printf("peer_id = %" PRId64 "\n", peer->id);
 456
 457         for (vector = 0; vector < peer->vectors_count; vector++) {
 458             printf("  vector %d is enabled (fd=%d)\n", vector,
 459                    event_notifier_get_fd(&peer->vectors[vector]));
 460         }
 461     }
 462 }