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