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