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