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