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