hw/xen/xen_backend.c

   1 /*
   2  *  xen backend driver infrastructure
   3  *  (c) 2008 Gerd Hoffmann <kraxel@redhat.com>
   4  *
   5  *  This program is free software; you can redistribute it and/or modify
   6  *  it under the terms of the GNU General Public License as published by
   7  *  the Free Software Foundation; under version 2 of the License.
   8  *
   9  *  This program is distributed in the hope that it will be useful,
  10  *  but WITHOUT ANY WARRANTY; without even the implied warranty of
  11  *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  12  *  GNU General Public License for more details.
  13  *
  14  *  You should have received a copy of the GNU General Public License along
  15  *  with this program; if not, see <http://www.gnu.org/licenses/>.
  16  *
  17  *  Contributions after 2012-01-13 are licensed under the terms of the
  18  *  GNU GPL, version 2 or (at your option) any later version.
  19  */
  20
  21 /*
  22  * TODO: add some xenbus / xenstore concepts overview here.
  23  */
  24
  25 #include "qemu/osdep.h"
  26 #include <sys/mman.h>
  27 #include <sys/signal.h>
  28
  29 #include "hw/hw.h"
  30 #include "sysemu/char.h"
  31 #include "qemu/log.h"
  32 #include "hw/xen/xen_backend.h"
  33
  34 #include <xen/grant_table.h>
  35
  36 /* ------------------------------------------------------------- */
  37
  38 /* public */
  39 xc_interface *xen_xc = NULL;
  40 xenforeignmemory_handle *xen_fmem = NULL;
  41 struct xs_handle *xenstore = NULL;
  42 const char *xen_protocol;
  43
  44 /* private */
  45 struct xs_dirs {
  46     char *xs_dir;
  47     QTAILQ_ENTRY(xs_dirs) list;
  48 };
  49 static QTAILQ_HEAD(xs_dirs_head, xs_dirs) xs_cleanup =
  50     QTAILQ_HEAD_INITIALIZER(xs_cleanup);
  51
  52 static QTAILQ_HEAD(XenDeviceHead, XenDevice) xendevs = QTAILQ_HEAD_INITIALIZER(xendevs);
  53 static int debug = 0;
  54
  55 /* ------------------------------------------------------------- */
  56
  57 static void xenstore_cleanup_dir(char *dir)
  58 {
  59     struct xs_dirs *d;
  60
  61     d = g_malloc(sizeof(*d));
  62     d->xs_dir = dir;
  63     QTAILQ_INSERT_TAIL(&xs_cleanup, d, list);
  64 }
  65
  66 void xen_config_cleanup(void)
  67 {
  68     struct xs_dirs *d;
  69
  70     QTAILQ_FOREACH(d, &xs_cleanup, list) {
  71         xs_rm(xenstore, 0, d->xs_dir);
  72     }
  73 }
  74
  75 int xenstore_write_str(const char *base, const char *node, const char *val)
  76 {
  77     char abspath[XEN_BUFSIZE];
  78
  79     snprintf(abspath, sizeof(abspath), "%s/%s", base, node);
  80     if (!xs_write(xenstore, 0, abspath, val, strlen(val))) {
  81         return -1;
  82     }
  83     return 0;
  84 }
  85
  86 char *xenstore_read_str(const char *base, const char *node)
  87 {
  88     char abspath[XEN_BUFSIZE];
  89     unsigned int len;
  90     char *str, *ret = NULL;
  91
  92     snprintf(abspath, sizeof(abspath), "%s/%s", base, node);
  93     str = xs_read(xenstore, 0, abspath, &len);
  94     if (str != NULL) {
  95         /* move to qemu-allocated memory to make sure
  96          * callers can savely g_free() stuff. */
  97         ret = g_strdup(str);
  98         free(str);
  99     }
 100     return ret;
 101 }
 102
 103 int xenstore_mkdir(char *path, int p)
 104 {
 105     struct xs_permissions perms[2] = {
 106         {
 107             .id    = 0, /* set owner: dom0 */
 108         }, {
 109             .id    = xen_domid,
 110             .perms = p,
 111         }
 112     };
 113
 114     if (!xs_mkdir(xenstore, 0, path)) {
 115         xen_be_printf(NULL, 0, "xs_mkdir %s: failed\n", path);
 116         return -1;
 117     }
 118     xenstore_cleanup_dir(g_strdup(path));
 119
 120     if (!xs_set_permissions(xenstore, 0, path, perms, 2)) {
 121         xen_be_printf(NULL, 0, "xs_set_permissions %s: failed\n", path);
 122         return -1;
 123     }
 124     return 0;
 125 }
 126
 127 int xenstore_write_int(const char *base, const char *node, int ival)
 128 {
 129     char val[12];
 130
 131     snprintf(val, sizeof(val), "%d", ival);
 132     return xenstore_write_str(base, node, val);
 133 }
 134
 135 int xenstore_write_int64(const char *base, const char *node, int64_t ival)
 136 {
 137     char val[21];
 138
 139     snprintf(val, sizeof(val), "%"PRId64, ival);
 140     return xenstore_write_str(base, node, val);
 141 }
 142
 143 int xenstore_read_int(const char *base, const char *node, int *ival)
 144 {
 145     char *val;
 146     int rc = -1;
 147
 148     val = xenstore_read_str(base, node);
 149     if (val && 1 == sscanf(val, "%d", ival)) {
 150         rc = 0;
 151     }
 152     g_free(val);
 153     return rc;
 154 }
 155
 156 int xenstore_read_uint64(const char *base, const char *node, uint64_t *uval)
 157 {
 158     char *val;
 159     int rc = -1;
 160
 161     val = xenstore_read_str(base, node);
 162     if (val && 1 == sscanf(val, "%"SCNu64, uval)) {
 163         rc = 0;
 164     }
 165     g_free(val);
 166     return rc;
 167 }
 168
 169 int xenstore_write_be_str(struct XenDevice *xendev, const char *node, const char *val)
 170 {
 171     return xenstore_write_str(xendev->be, node, val);
 172 }
 173
 174 int xenstore_write_be_int(struct XenDevice *xendev, const char *node, int ival)
 175 {
 176     return xenstore_write_int(xendev->be, node, ival);
 177 }
 178
 179 int xenstore_write_be_int64(struct XenDevice *xendev, const char *node, int64_t ival)
 180 {
 181     return xenstore_write_int64(xendev->be, node, ival);
 182 }
 183
 184 char *xenstore_read_be_str(struct XenDevice *xendev, const char *node)
 185 {
 186     return xenstore_read_str(xendev->be, node);
 187 }
 188
 189 int xenstore_read_be_int(struct XenDevice *xendev, const char *node, int *ival)
 190 {
 191     return xenstore_read_int(xendev->be, node, ival);
 192 }
 193
 194 char *xenstore_read_fe_str(struct XenDevice *xendev, const char *node)
 195 {
 196     return xenstore_read_str(xendev->fe, node);
 197 }
 198
 199 int xenstore_read_fe_int(struct XenDevice *xendev, const char *node, int *ival)
 200 {
 201     return xenstore_read_int(xendev->fe, node, ival);
 202 }
 203
 204 int xenstore_read_fe_uint64(struct XenDevice *xendev, const char *node, uint64_t *uval)
 205 {
 206     return xenstore_read_uint64(xendev->fe, node, uval);
 207 }
 208
 209 /* ------------------------------------------------------------- */
 210
 211 const char *xenbus_strstate(enum xenbus_state state)
 212 {
 213     static const char *const name[] = {
 214         [ XenbusStateUnknown      ] = "Unknown",
 215         [ XenbusStateInitialising ] = "Initialising",
 216         [ XenbusStateInitWait     ] = "InitWait",
 217         [ XenbusStateInitialised  ] = "Initialised",
 218         [ XenbusStateConnected    ] = "Connected",
 219         [ XenbusStateClosing      ] = "Closing",
 220         [ XenbusStateClosed       ] = "Closed",
 221     };
 222     return (state < ARRAY_SIZE(name)) ? name[state] : "INVALID";
 223 }
 224
 225 int xen_be_set_state(struct XenDevice *xendev, enum xenbus_state state)
 226 {
 227     int rc;
 228
 229     rc = xenstore_write_be_int(xendev, "state", state);
 230     if (rc < 0) {
 231         return rc;
 232     }
 233     xen_be_printf(xendev, 1, "backend state: %s -> %s\n",
 234                   xenbus_strstate(xendev->be_state), xenbus_strstate(state));
 235     xendev->be_state = state;
 236     return 0;
 237 }
 238
 239 /* ------------------------------------------------------------- */
 240
 241 struct XenDevice *xen_be_find_xendev(const char *type, int dom, int dev)
 242 {
 243     struct XenDevice *xendev;
 244
 245     QTAILQ_FOREACH(xendev, &xendevs, next) {
 246         if (xendev->dom != dom) {
 247             continue;
 248         }
 249         if (xendev->dev != dev) {
 250             continue;
 251         }
 252         if (strcmp(xendev->type, type) != 0) {
 253             continue;
 254         }
 255         return xendev;
 256     }
 257     return NULL;
 258 }
 259
 260 /*
 261  * get xen backend device, allocate a new one if it doesn't exist.
 262  */
 263 static struct XenDevice *xen_be_get_xendev(const char *type, int dom, int dev,
 264                                            struct XenDevOps *ops)
 265 {
 266     struct XenDevice *xendev;
 267
 268     xendev = xen_be_find_xendev(type, dom, dev);
 269     if (xendev) {
 270         return xendev;
 271     }
 272
 273     /* init new xendev */
 274     xendev = g_malloc0(ops->size);
 275     xendev->type  = type;
 276     xendev->dom   = dom;
 277     xendev->dev   = dev;
 278     xendev->ops   = ops;
 279
 280     snprintf(xendev->be, sizeof(xendev->be), "backend/%s/%d/%d",
 281              xendev->type, xendev->dom, xendev->dev);
 282     snprintf(xendev->name, sizeof(xendev->name), "%s-%d",
 283              xendev->type, xendev->dev);
 284
 285     xendev->debug      = debug;
 286     xendev->local_port = -1;
 287
 288     xendev->evtchndev = xenevtchn_open(NULL, 0);
 289     if (xendev->evtchndev == NULL) {
 290         xen_be_printf(NULL, 0, "can't open evtchn device\n");
 291         g_free(xendev);
 292         return NULL;
 293     }
 294     fcntl(xenevtchn_fd(xendev->evtchndev), F_SETFD, FD_CLOEXEC);
 295
 296     if (ops->flags & DEVOPS_FLAG_NEED_GNTDEV) {
 297         xendev->gnttabdev = xengnttab_open(NULL, 0);
 298         if (xendev->gnttabdev == NULL) {
 299             xen_be_printf(NULL, 0, "can't open gnttab device\n");
 300             xenevtchn_close(xendev->evtchndev);
 301             g_free(xendev);
 302             return NULL;
 303         }
 304     } else {
 305         xendev->gnttabdev = NULL;
 306     }
 307
 308     QTAILQ_INSERT_TAIL(&xendevs, xendev, next);
 309
 310     if (xendev->ops->alloc) {
 311         xendev->ops->alloc(xendev);
 312     }
 313
 314     return xendev;
 315 }
 316
 317 /*
 318  * release xen backend device.
 319  */
 320 static struct XenDevice *xen_be_del_xendev(int dom, int dev)
 321 {
 322     struct XenDevice *xendev, *xnext;
 323
 324     /*
 325      * This is pretty much like QTAILQ_FOREACH(xendev, &xendevs, next) but
 326      * we save the next pointer in xnext because we might free xendev.
 327      */
 328     xnext = xendevs.tqh_first;
 329     while (xnext) {
 330         xendev = xnext;
 331         xnext = xendev->next.tqe_next;
 332
 333         if (xendev->dom != dom) {
 334             continue;
 335         }
 336         if (xendev->dev != dev && dev != -1) {
 337             continue;
 338         }
 339
 340         if (xendev->ops->free) {
 341             xendev->ops->free(xendev);
 342         }
 343
 344         if (xendev->fe) {
 345             char token[XEN_BUFSIZE];
 346             snprintf(token, sizeof(token), "fe:%p", xendev);
 347             xs_unwatch(xenstore, xendev->fe, token);
 348             g_free(xendev->fe);
 349         }
 350
 351         if (xendev->evtchndev != NULL) {
 352             xenevtchn_close(xendev->evtchndev);
 353         }
 354         if (xendev->gnttabdev != NULL) {
 355             xengnttab_close(xendev->gnttabdev);
 356         }
 357
 358         QTAILQ_REMOVE(&xendevs, xendev, next);
 359         g_free(xendev);
 360     }
 361     return NULL;
 362 }
 363
 364 /*
 365  * Sync internal data structures on xenstore updates.
 366  * Node specifies the changed field.  node = NULL means
 367  * update all fields (used for initialization).
 368  */
 369 static void xen_be_backend_changed(struct XenDevice *xendev, const char *node)
 370 {
 371     if (node == NULL  ||  strcmp(node, "online") == 0) {
 372         if (xenstore_read_be_int(xendev, "online", &xendev->online) == -1) {
 373             xendev->online = 0;
 374         }
 375     }
 376
 377     if (node) {
 378         xen_be_printf(xendev, 2, "backend update: %s\n", node);
 379         if (xendev->ops->backend_changed) {
 380             xendev->ops->backend_changed(xendev, node);
 381         }
 382     }
 383 }
 384
 385 static void xen_be_frontend_changed(struct XenDevice *xendev, const char *node)
 386 {
 387     int fe_state;
 388
 389     if (node == NULL  ||  strcmp(node, "state") == 0) {
 390         if (xenstore_read_fe_int(xendev, "state", &fe_state) == -1) {
 391             fe_state = XenbusStateUnknown;
 392         }
 393         if (xendev->fe_state != fe_state) {
 394             xen_be_printf(xendev, 1, "frontend state: %s -> %s\n",
 395                           xenbus_strstate(xendev->fe_state),
 396                           xenbus_strstate(fe_state));
 397         }
 398         xendev->fe_state = fe_state;
 399     }
 400     if (node == NULL  ||  strcmp(node, "protocol") == 0) {
 401         g_free(xendev->protocol);
 402         xendev->protocol = xenstore_read_fe_str(xendev, "protocol");
 403         if (xendev->protocol) {
 404             xen_be_printf(xendev, 1, "frontend protocol: %s\n", xendev->protocol);
 405         }
 406     }
 407
 408     if (node) {
 409         xen_be_printf(xendev, 2, "frontend update: %s\n", node);
 410         if (xendev->ops->frontend_changed) {
 411             xendev->ops->frontend_changed(xendev, node);
 412         }
 413     }
 414 }
 415
 416 /* ------------------------------------------------------------- */
 417 /* Check for possible state transitions and perform them.        */
 418
 419 /*
 420  * Initial xendev setup.  Read frontend path, register watch for it.
 421  * Should succeed once xend finished setting up the backend device.
 422  *
 423  * Also sets initial state (-> Initializing) when done.  Which
 424  * only affects the xendev->be_state variable as xenbus should
 425  * already be put into that state by xend.
 426  */
 427 static int xen_be_try_setup(struct XenDevice *xendev)
 428 {
 429     char token[XEN_BUFSIZE];
 430     int be_state;
 431
 432     if (xenstore_read_be_int(xendev, "state", &be_state) == -1) {
 433         xen_be_printf(xendev, 0, "reading backend state failed\n");
 434         return -1;
 435     }
 436
 437     if (be_state != XenbusStateInitialising) {
 438         xen_be_printf(xendev, 0, "initial backend state is wrong (%s)\n",
 439                       xenbus_strstate(be_state));
 440         return -1;
 441     }
 442
 443     xendev->fe = xenstore_read_be_str(xendev, "frontend");
 444     if (xendev->fe == NULL) {
 445         xen_be_printf(xendev, 0, "reading frontend path failed\n");
 446         return -1;
 447     }
 448
 449     /* setup frontend watch */
 450     snprintf(token, sizeof(token), "fe:%p", xendev);
 451     if (!xs_watch(xenstore, xendev->fe, token)) {
 452         xen_be_printf(xendev, 0, "watching frontend path (%s) failed\n",
 453                       xendev->fe);
 454         return -1;
 455     }
 456     xen_be_set_state(xendev, XenbusStateInitialising);
 457
 458     xen_be_backend_changed(xendev, NULL);
 459     xen_be_frontend_changed(xendev, NULL);
 460     return 0;
 461 }
 462
 463 /*
 464  * Try initialize xendev.  Prepare everything the backend can do
 465  * without synchronizing with the frontend.  Fakes hotplug-status.  No
 466  * hotplug involved here because this is about userspace drivers, thus
 467  * there are kernel backend devices which could invoke hotplug.
 468  *
 469  * Goes to InitWait on success.
 470  */
 471 static int xen_be_try_init(struct XenDevice *xendev)
 472 {
 473     int rc = 0;
 474
 475     if (!xendev->online) {
 476         xen_be_printf(xendev, 1, "not online\n");
 477         return -1;
 478     }
 479
 480     if (xendev->ops->init) {
 481         rc = xendev->ops->init(xendev);
 482     }
 483     if (rc != 0) {
 484         xen_be_printf(xendev, 1, "init() failed\n");
 485         return rc;
 486     }
 487
 488     xenstore_write_be_str(xendev, "hotplug-status", "connected");
 489     xen_be_set_state(xendev, XenbusStateInitWait);
 490     return 0;
 491 }
 492
 493 /*
 494  * Try to initialise xendev.  Depends on the frontend being ready
 495  * for it (shared ring and evtchn info in xenstore, state being
 496  * Initialised or Connected).
 497  *
 498  * Goes to Connected on success.
 499  */
 500 static int xen_be_try_initialise(struct XenDevice *xendev)
 501 {
 502     int rc = 0;
 503
 504     if (xendev->fe_state != XenbusStateInitialised  &&
 505         xendev->fe_state != XenbusStateConnected) {
 506         if (xendev->ops->flags & DEVOPS_FLAG_IGNORE_STATE) {
 507             xen_be_printf(xendev, 2, "frontend not ready, ignoring\n");
 508         } else {
 509             xen_be_printf(xendev, 2, "frontend not ready (yet)\n");
 510             return -1;
 511         }
 512     }
 513
 514     if (xendev->ops->initialise) {
 515         rc = xendev->ops->initialise(xendev);
 516     }
 517     if (rc != 0) {
 518         xen_be_printf(xendev, 0, "initialise() failed\n");
 519         return rc;
 520     }
 521
 522     xen_be_set_state(xendev, XenbusStateConnected);
 523     return 0;
 524 }
 525
 526 /*
 527  * Try to let xendev know that it is connected.  Depends on the
 528  * frontend being Connected.  Note that this may be called more
 529  * than once since the backend state is not modified.
 530  */
 531 static void xen_be_try_connected(struct XenDevice *xendev)
 532 {
 533     if (!xendev->ops->connected) {
 534         return;
 535     }
 536
 537     if (xendev->fe_state != XenbusStateConnected) {
 538         if (xendev->ops->flags & DEVOPS_FLAG_IGNORE_STATE) {
 539             xen_be_printf(xendev, 2, "frontend not ready, ignoring\n");
 540         } else {
 541             xen_be_printf(xendev, 2, "frontend not ready (yet)\n");
 542             return;
 543         }
 544     }
 545
 546     xendev->ops->connected(xendev);
 547 }
 548
 549 /*
 550  * Teardown connection.
 551  *
 552  * Goes to Closed when done.
 553  */
 554 static void xen_be_disconnect(struct XenDevice *xendev, enum xenbus_state state)
 555 {
 556     if (xendev->be_state != XenbusStateClosing &&
 557         xendev->be_state != XenbusStateClosed  &&
 558         xendev->ops->disconnect) {
 559         xendev->ops->disconnect(xendev);
 560     }
 561     if (xendev->be_state != state) {
 562         xen_be_set_state(xendev, state);
 563     }
 564 }
 565
 566 /*
 567  * Try to reset xendev, for reconnection by another frontend instance.
 568  */
 569 static int xen_be_try_reset(struct XenDevice *xendev)
 570 {
 571     if (xendev->fe_state != XenbusStateInitialising) {
 572         return -1;
 573     }
 574
 575     xen_be_printf(xendev, 1, "device reset (for re-connect)\n");
 576     xen_be_set_state(xendev, XenbusStateInitialising);
 577     return 0;
 578 }
 579
 580 /*
 581  * state change dispatcher function
 582  */
 583 void xen_be_check_state(struct XenDevice *xendev)
 584 {
 585     int rc = 0;
 586
 587     /* frontend may request shutdown from almost anywhere */
 588     if (xendev->fe_state == XenbusStateClosing ||
 589         xendev->fe_state == XenbusStateClosed) {
 590         xen_be_disconnect(xendev, xendev->fe_state);
 591         return;
 592     }
 593
 594     /* check for possible backend state transitions */
 595     for (;;) {
 596         switch (xendev->be_state) {
 597         case XenbusStateUnknown:
 598             rc = xen_be_try_setup(xendev);
 599             break;
 600         case XenbusStateInitialising:
 601             rc = xen_be_try_init(xendev);
 602             break;
 603         case XenbusStateInitWait:
 604             rc = xen_be_try_initialise(xendev);
 605             break;
 606         case XenbusStateConnected:
 607             /* xendev->be_state doesn't change */
 608             xen_be_try_connected(xendev);
 609             rc = -1;
 610             break;
 611         case XenbusStateClosed:
 612             rc = xen_be_try_reset(xendev);
 613             break;
 614         default:
 615             rc = -1;
 616         }
 617         if (rc != 0) {
 618             break;
 619         }
 620     }
 621 }
 622
 623 /* ------------------------------------------------------------- */
 624
 625 static int xenstore_scan(const char *type, int dom, struct XenDevOps *ops)
 626 {
 627     struct XenDevice *xendev;
 628     char path[XEN_BUFSIZE], token[XEN_BUFSIZE];
 629     char **dev = NULL;
 630     unsigned int cdev, j;
 631
 632     /* setup watch */
 633     snprintf(token, sizeof(token), "be:%p:%d:%p", type, dom, ops);
 634     snprintf(path, sizeof(path), "backend/%s/%d", type, dom);
 635     if (!xs_watch(xenstore, path, token)) {
 636         xen_be_printf(NULL, 0, "xen be: watching backend path (%s) failed\n", path);
 637         return -1;
 638     }
 639
 640     /* look for backends */
 641     dev = xs_directory(xenstore, 0, path, &cdev);
 642     if (!dev) {
 643         return 0;
 644     }
 645     for (j = 0; j < cdev; j++) {
 646         xendev = xen_be_get_xendev(type, dom, atoi(dev[j]), ops);
 647         if (xendev == NULL) {
 648             continue;
 649         }
 650         xen_be_check_state(xendev);
 651     }
 652     free(dev);
 653     return 0;
 654 }
 655
 656 static void xenstore_update_be(char *watch, char *type, int dom,
 657                                struct XenDevOps *ops)
 658 {
 659     struct XenDevice *xendev;
 660     char path[XEN_BUFSIZE], *bepath;
 661     unsigned int len, dev;
 662
 663     len = snprintf(path, sizeof(path), "backend/%s/%d", type, dom);
 664     if (strncmp(path, watch, len) != 0) {
 665         return;
 666     }
 667     if (sscanf(watch+len, "/%u/%255s", &dev, path) != 2) {
 668         strcpy(path, "");
 669         if (sscanf(watch+len, "/%u", &dev) != 1) {
 670             dev = -1;
 671         }
 672     }
 673     if (dev == -1) {
 674         return;
 675     }
 676
 677     xendev = xen_be_get_xendev(type, dom, dev, ops);
 678     if (xendev != NULL) {
 679         bepath = xs_read(xenstore, 0, xendev->be, &len);
 680         if (bepath == NULL) {
 681             xen_be_del_xendev(dom, dev);
 682         } else {
 683             free(bepath);
 684             xen_be_backend_changed(xendev, path);
 685             xen_be_check_state(xendev);
 686         }
 687     }
 688 }
 689
 690 static void xenstore_update_fe(char *watch, struct XenDevice *xendev)
 691 {
 692     char *node;
 693     unsigned int len;
 694
 695     len = strlen(xendev->fe);
 696     if (strncmp(xendev->fe, watch, len) != 0) {
 697         return;
 698     }
 699     if (watch[len] != '/') {
 700         return;
 701     }
 702     node = watch + len + 1;
 703
 704     xen_be_frontend_changed(xendev, node);
 705     xen_be_check_state(xendev);
 706 }
 707
 708 static void xenstore_update(void *unused)
 709 {
 710     char **vec = NULL;
 711     intptr_t type, ops, ptr;
 712     unsigned int dom, count;
 713
 714     vec = xs_read_watch(xenstore, &count);
 715     if (vec == NULL) {
 716         goto cleanup;
 717     }
 718
 719     if (sscanf(vec[XS_WATCH_TOKEN], "be:%" PRIxPTR ":%d:%" PRIxPTR,
 720                &type, &dom, &ops) == 3) {
 721         xenstore_update_be(vec[XS_WATCH_PATH], (void*)type, dom, (void*)ops);
 722     }
 723     if (sscanf(vec[XS_WATCH_TOKEN], "fe:%" PRIxPTR, &ptr) == 1) {
 724         xenstore_update_fe(vec[XS_WATCH_PATH], (void*)ptr);
 725     }
 726
 727 cleanup:
 728     free(vec);
 729 }
 730
 731 static void xen_be_evtchn_event(void *opaque)
 732 {
 733     struct XenDevice *xendev = opaque;
 734     evtchn_port_t port;
 735
 736     port = xenevtchn_pending(xendev->evtchndev);
 737     if (port != xendev->local_port) {
 738         xen_be_printf(xendev, 0,
 739                       "xenevtchn_pending returned %d (expected %d)\n",
 740                       port, xendev->local_port);
 741         return;
 742     }
 743     xenevtchn_unmask(xendev->evtchndev, port);
 744
 745     if (xendev->ops->event) {
 746         xendev->ops->event(xendev);
 747     }
 748 }
 749
 750 /* -------------------------------------------------------------------- */
 751
 752 int xen_be_init(void)
 753 {
 754     xenstore = xs_daemon_open();
 755     if (!xenstore) {
 756         xen_be_printf(NULL, 0, "can't connect to xenstored\n");
 757         return -1;
 758     }
 759
 760     qemu_set_fd_handler(xs_fileno(xenstore), xenstore_update, NULL, NULL);
 761
 762     if (xen_xc == NULL || xen_fmem == NULL) {
 763         /* Check if xen_init() have been called */
 764         goto err;
 765     }
 766     return 0;
 767
 768 err:
 769     qemu_set_fd_handler(xs_fileno(xenstore), NULL, NULL, NULL);
 770     xs_daemon_close(xenstore);
 771     xenstore = NULL;
 772
 773     return -1;
 774 }
 775
 776 int xen_be_register(const char *type, struct XenDevOps *ops)
 777 {
 778     char path[50];
 779     int rc;
 780
 781     if (ops->backend_register) {
 782         rc = ops->backend_register();
 783         if (rc) {
 784             return rc;
 785         }
 786     }
 787
 788     snprintf(path, sizeof(path), "device-model/%u/backends/%s", xen_domid,
 789              type);
 790     xenstore_mkdir(path, XS_PERM_NONE);
 791
 792     return xenstore_scan(type, xen_domid, ops);
 793 }
 794
 795 int xen_be_bind_evtchn(struct XenDevice *xendev)
 796 {
 797     if (xendev->local_port != -1) {
 798         return 0;
 799     }
 800     xendev->local_port = xenevtchn_bind_interdomain
 801         (xendev->evtchndev, xendev->dom, xendev->remote_port);
 802     if (xendev->local_port == -1) {
 803         xen_be_printf(xendev, 0, "xenevtchn_bind_interdomain failed\n");
 804         return -1;
 805     }
 806     xen_be_printf(xendev, 2, "bind evtchn port %d\n", xendev->local_port);
 807     qemu_set_fd_handler(xenevtchn_fd(xendev->evtchndev),
 808                         xen_be_evtchn_event, NULL, xendev);
 809     return 0;
 810 }
 811
 812 void xen_be_unbind_evtchn(struct XenDevice *xendev)
 813 {
 814     if (xendev->local_port == -1) {
 815         return;
 816     }
 817     qemu_set_fd_handler(xenevtchn_fd(xendev->evtchndev), NULL, NULL, NULL);
 818     xenevtchn_unbind(xendev->evtchndev, xendev->local_port);
 819     xen_be_printf(xendev, 2, "unbind evtchn port %d\n", xendev->local_port);
 820     xendev->local_port = -1;
 821 }
 822
 823 int xen_be_send_notify(struct XenDevice *xendev)
 824 {
 825     return xenevtchn_notify(xendev->evtchndev, xendev->local_port);
 826 }
 827
 828 /*
 829  * msg_level:
 830  *  0 == errors (stderr + logfile).
 831  *  1 == informative debug messages (logfile only).
 832  *  2 == noisy debug messages (logfile only).
 833  *  3 == will flood your log (logfile only).
 834  */
 835 void xen_be_printf(struct XenDevice *xendev, int msg_level, const char *fmt, ...)
 836 {
 837     va_list args;
 838
 839     if (xendev) {
 840         if (msg_level > xendev->debug) {
 841             return;
 842         }
 843         qemu_log("xen be: %s: ", xendev->name);
 844         if (msg_level == 0) {
 845             fprintf(stderr, "xen be: %s: ", xendev->name);
 846         }
 847     } else {
 848         if (msg_level > debug) {
 849             return;
 850         }
 851         qemu_log("xen be core: ");
 852         if (msg_level == 0) {
 853             fprintf(stderr, "xen be core: ");
 854         }
 855     }
 856     va_start(args, fmt);
 857     qemu_log_vprintf(fmt, args);
 858     va_end(args);
 859     if (msg_level == 0) {
 860         va_start(args, fmt);
 861         vfprintf(stderr, fmt, args);
 862         va_end(args);
 863     }
 864     qemu_log_flush();
 865 }