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