drivers/xen/xenbus/xenbus_probe.c

   1 /******************************************************************************
   2  * Talks to Xen Store to figure out what devices we have.
   3  *
   4  * Copyright (C) 2005 Rusty Russell, IBM Corporation
   5  * Copyright (C) 2005 Mike Wray, Hewlett-Packard
   6  * Copyright (C) 2005, 2006 XenSource Ltd
   7  *
   8  * This program is free software; you can redistribute it and/or
   9  * modify it under the terms of the GNU General Public License version 2
  10  * as published by the Free Software Foundation; or, when distributed
  11  * separately from the Linux kernel or incorporated into other
  12  * software packages, subject to the following license:
  13  *
  14  * Permission is hereby granted, free of charge, to any person obtaining a copy
  15  * of this source file (the "Software"), to deal in the Software without
  16  * restriction, including without limitation the rights to use, copy, modify,
  17  * merge, publish, distribute, sublicense, and/or sell copies of the Software,
  18  * and to permit persons to whom the Software is furnished to do so, subject to
  19  * the following conditions:
  20  *
  21  * The above copyright notice and this permission notice shall be included in
  22  * all copies or substantial portions of the Software.
  23  *
  24  * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
  25  * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
  26  * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
  27  * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
  28  * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
  29  * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS
  30  * IN THE SOFTWARE.
  31  */
  32
  33 #define DPRINTK(fmt, args...)                           \
  34         pr_debug("xenbus_probe (%s:%d) " fmt ".\n",     \
  35                  __func__, __LINE__, ##args)
  36
  37 #include <linux/kernel.h>
  38 #include <linux/err.h>
  39 #include <linux/string.h>
  40 #include <linux/ctype.h>
  41 #include <linux/fcntl.h>
  42 #include <linux/mm.h>
  43 #include <linux/proc_fs.h>
  44 #include <linux/notifier.h>
  45 #include <linux/kthread.h>
  46 #include <linux/mutex.h>
  47 #include <linux/io.h>
  48 #include <linux/slab.h>
  49 #include <linux/module.h>
  50
  51 #include <asm/page.h>
  52 #include <asm/pgtable.h>
  53 #include <asm/xen/hypervisor.h>
  54
  55 #include <xen/xen.h>
  56 #include <xen/xenbus.h>
  57 #include <xen/events.h>
  58 #include <xen/page.h>
  59
  60 #include <xen/hvm.h>
  61
  62 #include "xenbus_comms.h"
  63 #include "xenbus_probe.h"
  64
  65
  66 int xen_store_evtchn;
  67 EXPORT_SYMBOL_GPL(xen_store_evtchn);
  68
  69 struct xenstore_domain_interface *xen_store_interface;
  70 EXPORT_SYMBOL_GPL(xen_store_interface);
  71
  72 static unsigned long xen_store_mfn;
  73
  74 static BLOCKING_NOTIFIER_HEAD(xenstore_chain);
  75
  76 /* If something in array of ids matches this device, return it. */
  77 static const struct xenbus_device_id *
  78 match_device(const struct xenbus_device_id *arr, struct xenbus_device *dev)
  79 {
  80         for (; *arr->devicetype != '\0'; arr++) {
  81                 if (!strcmp(arr->devicetype, dev->devicetype))
  82                         return arr;
  83         }
  84         return NULL;
  85 }
  86
  87 int xenbus_match(struct device *_dev, struct device_driver *_drv)
  88 {
  89         struct xenbus_driver *drv = to_xenbus_driver(_drv);
  90
  91         if (!drv->ids)
  92                 return 0;
  93
  94         return match_device(drv->ids, to_xenbus_device(_dev)) != NULL;
  95 }
  96 EXPORT_SYMBOL_GPL(xenbus_match);
  97
  98
  99 static void free_otherend_details(struct xenbus_device *dev)
 100 {
 101         kfree(dev->otherend);
 102         dev->otherend = NULL;
 103 }
 104
 105
 106 static void free_otherend_watch(struct xenbus_device *dev)
 107 {
 108         if (dev->otherend_watch.node) {
 109                 unregister_xenbus_watch(&dev->otherend_watch);
 110                 kfree(dev->otherend_watch.node);
 111                 dev->otherend_watch.node = NULL;
 112         }
 113 }
 114
 115
 116 static int talk_to_otherend(struct xenbus_device *dev)
 117 {
 118         struct xenbus_driver *drv = to_xenbus_driver(dev->dev.driver);
 119
 120         free_otherend_watch(dev);
 121         free_otherend_details(dev);
 122
 123         return drv->read_otherend_details(dev);
 124 }
 125
 126
 127
 128 static int watch_otherend(struct xenbus_device *dev)
 129 {
 130         struct xen_bus_type *bus =
 131                 container_of(dev->dev.bus, struct xen_bus_type, bus);
 132
 133         return xenbus_watch_pathfmt(dev, &dev->otherend_watch,
 134                                     bus->otherend_changed,
 135                                     "%s/%s", dev->otherend, "state");
 136 }
 137
 138
 139 int xenbus_read_otherend_details(struct xenbus_device *xendev,
 140                                  char *id_node, char *path_node)
 141 {
 142         int err = xenbus_gather(XBT_NIL, xendev->nodename,
 143                                 id_node, "%i", &xendev->otherend_id,
 144                                 path_node, NULL, &xendev->otherend,
 145                                 NULL);
 146         if (err) {
 147                 xenbus_dev_fatal(xendev, err,
 148                                  "reading other end details from %s",
 149                                  xendev->nodename);
 150                 return err;
 151         }
 152         if (strlen(xendev->otherend) == 0 ||
 153             !xenbus_exists(XBT_NIL, xendev->otherend, "")) {
 154                 xenbus_dev_fatal(xendev, -ENOENT,
 155                                  "unable to read other end from %s.  "
 156                                  "missing or inaccessible.",
 157                                  xendev->nodename);
 158                 free_otherend_details(xendev);
 159                 return -ENOENT;
 160         }
 161
 162         return 0;
 163 }
 164 EXPORT_SYMBOL_GPL(xenbus_read_otherend_details);
 165
 166 void xenbus_otherend_changed(struct xenbus_watch *watch,
 167                              const char **vec, unsigned int len,
 168                              int ignore_on_shutdown)
 169 {
 170         struct xenbus_device *dev =
 171                 container_of(watch, struct xenbus_device, otherend_watch);
 172         struct xenbus_driver *drv = to_xenbus_driver(dev->dev.driver);
 173         enum xenbus_state state;
 174
 175         /* Protect us against watches firing on old details when the otherend
 176            details change, say immediately after a resume. */
 177         if (!dev->otherend ||
 178             strncmp(dev->otherend, vec[XS_WATCH_PATH],
 179                     strlen(dev->otherend))) {
 180                 dev_dbg(&dev->dev, "Ignoring watch at %s\n",
 181                         vec[XS_WATCH_PATH]);
 182                 return;
 183         }
 184
 185         state = xenbus_read_driver_state(dev->otherend);
 186
 187         dev_dbg(&dev->dev, "state is %d, (%s), %s, %s\n",
 188                 state, xenbus_strstate(state), dev->otherend_watch.node,
 189                 vec[XS_WATCH_PATH]);
 190
 191         /*
 192          * Ignore xenbus transitions during shutdown. This prevents us doing
 193          * work that can fail e.g., when the rootfs is gone.
 194          */
 195         if (system_state > SYSTEM_RUNNING) {
 196                 if (ignore_on_shutdown && (state == XenbusStateClosing))
 197                         xenbus_frontend_closed(dev);
 198                 return;
 199         }
 200
 201         if (drv->otherend_changed)
 202                 drv->otherend_changed(dev, state);
 203 }
 204 EXPORT_SYMBOL_GPL(xenbus_otherend_changed);
 205
 206 int xenbus_dev_probe(struct device *_dev)
 207 {
 208         struct xenbus_device *dev = to_xenbus_device(_dev);
 209         struct xenbus_driver *drv = to_xenbus_driver(_dev->driver);
 210         const struct xenbus_device_id *id;
 211         int err;
 212
 213         DPRINTK("%s", dev->nodename);
 214
 215         if (!drv->probe) {
 216                 err = -ENODEV;
 217                 goto fail;
 218         }
 219
 220         id = match_device(drv->ids, dev);
 221         if (!id) {
 222                 err = -ENODEV;
 223                 goto fail;
 224         }
 225
 226         err = talk_to_otherend(dev);
 227         if (err) {
 228                 dev_warn(&dev->dev, "talk_to_otherend on %s failed.\n",
 229                          dev->nodename);
 230                 return err;
 231         }
 232
 233         err = drv->probe(dev, id);
 234         if (err)
 235                 goto fail;
 236
 237         err = watch_otherend(dev);
 238         if (err) {
 239                 dev_warn(&dev->dev, "watch_otherend on %s failed.\n",
 240                        dev->nodename);
 241                 return err;
 242         }
 243
 244         return 0;
 245 fail:
 246         xenbus_dev_error(dev, err, "xenbus_dev_probe on %s", dev->nodename);
 247         xenbus_switch_state(dev, XenbusStateClosed);
 248         return err;
 249 }
 250 EXPORT_SYMBOL_GPL(xenbus_dev_probe);
 251
 252 int xenbus_dev_remove(struct device *_dev)
 253 {
 254         struct xenbus_device *dev = to_xenbus_device(_dev);
 255         struct xenbus_driver *drv = to_xenbus_driver(_dev->driver);
 256
 257         DPRINTK("%s", dev->nodename);
 258
 259         free_otherend_watch(dev);
 260         free_otherend_details(dev);
 261
 262         if (drv->remove)
 263                 drv->remove(dev);
 264
 265         xenbus_switch_state(dev, XenbusStateClosed);
 266         return 0;
 267 }
 268 EXPORT_SYMBOL_GPL(xenbus_dev_remove);
 269
 270 void xenbus_dev_shutdown(struct device *_dev)
 271 {
 272         struct xenbus_device *dev = to_xenbus_device(_dev);
 273         unsigned long timeout = 5*HZ;
 274
 275         DPRINTK("%s", dev->nodename);
 276
 277         get_device(&dev->dev);
 278         if (dev->state != XenbusStateConnected) {
 279                 printk(KERN_INFO "%s: %s: %s != Connected, skipping\n", __func__,
 280                        dev->nodename, xenbus_strstate(dev->state));
 281                 goto out;
 282         }
 283         xenbus_switch_state(dev, XenbusStateClosing);
 284         timeout = wait_for_completion_timeout(&dev->down, timeout);
 285         if (!timeout)
 286                 printk(KERN_INFO "%s: %s timeout closing device\n",
 287                        __func__, dev->nodename);
 288  out:
 289         put_device(&dev->dev);
 290 }
 291 EXPORT_SYMBOL_GPL(xenbus_dev_shutdown);
 292
 293 int xenbus_register_driver_common(struct xenbus_driver *drv,
 294                                   struct xen_bus_type *bus)
 295 {
 296         drv->driver.bus = &bus->bus;
 297
 298         return driver_register(&drv->driver);
 299 }
 300 EXPORT_SYMBOL_GPL(xenbus_register_driver_common);
 301
 302 void xenbus_unregister_driver(struct xenbus_driver *drv)
 303 {
 304         driver_unregister(&drv->driver);
 305 }
 306 EXPORT_SYMBOL_GPL(xenbus_unregister_driver);
 307
 308 struct xb_find_info {
 309         struct xenbus_device *dev;
 310         const char *nodename;
 311 };
 312
 313 static int cmp_dev(struct device *dev, void *data)
 314 {
 315         struct xenbus_device *xendev = to_xenbus_device(dev);
 316         struct xb_find_info *info = data;
 317
 318         if (!strcmp(xendev->nodename, info->nodename)) {
 319                 info->dev = xendev;
 320                 get_device(dev);
 321                 return 1;
 322         }
 323         return 0;
 324 }
 325
 326 struct xenbus_device *xenbus_device_find(const char *nodename,
 327                                          struct bus_type *bus)
 328 {
 329         struct xb_find_info info = { .dev = NULL, .nodename = nodename };
 330
 331         bus_for_each_dev(bus, NULL, &info, cmp_dev);
 332         return info.dev;
 333 }
 334
 335 static int cleanup_dev(struct device *dev, void *data)
 336 {
 337         struct xenbus_device *xendev = to_xenbus_device(dev);
 338         struct xb_find_info *info = data;
 339         int len = strlen(info->nodename);
 340
 341         DPRINTK("%s", info->nodename);
 342
 343         /* Match the info->nodename path, or any subdirectory of that path. */
 344         if (strncmp(xendev->nodename, info->nodename, len))
 345                 return 0;
 346
 347         /* If the node name is longer, ensure it really is a subdirectory. */
 348         if ((strlen(xendev->nodename) > len) && (xendev->nodename[len] != '/'))
 349                 return 0;
 350
 351         info->dev = xendev;
 352         get_device(dev);
 353         return 1;
 354 }
 355
 356 static void xenbus_cleanup_devices(const char *path, struct bus_type *bus)
 357 {
 358         struct xb_find_info info = { .nodename = path };
 359
 360         do {
 361                 info.dev = NULL;
 362                 bus_for_each_dev(bus, NULL, &info, cleanup_dev);
 363                 if (info.dev) {
 364                         device_unregister(&info.dev->dev);
 365                         put_device(&info.dev->dev);
 366                 }
 367         } while (info.dev);
 368 }
 369
 370 static void xenbus_dev_release(struct device *dev)
 371 {
 372         if (dev)
 373                 kfree(to_xenbus_device(dev));
 374 }
 375
 376 static ssize_t nodename_show(struct device *dev,
 377                              struct device_attribute *attr, char *buf)
 378 {
 379         return sprintf(buf, "%s\n", to_xenbus_device(dev)->nodename);
 380 }
 381
 382 static ssize_t devtype_show(struct device *dev,
 383                             struct device_attribute *attr, char *buf)
 384 {
 385         return sprintf(buf, "%s\n", to_xenbus_device(dev)->devicetype);
 386 }
 387
 388 static ssize_t modalias_show(struct device *dev,
 389                              struct device_attribute *attr, char *buf)
 390 {
 391         return sprintf(buf, "%s:%s\n", dev->bus->name,
 392                        to_xenbus_device(dev)->devicetype);
 393 }
 394
 395 struct device_attribute xenbus_dev_attrs[] = {
 396         __ATTR_RO(nodename),
 397         __ATTR_RO(devtype),
 398         __ATTR_RO(modalias),
 399         __ATTR_NULL
 400 };
 401 EXPORT_SYMBOL_GPL(xenbus_dev_attrs);
 402
 403 int xenbus_probe_node(struct xen_bus_type *bus,
 404                       const char *type,
 405                       const char *nodename)
 406 {
 407         char devname[XEN_BUS_ID_SIZE];
 408         int err;
 409         struct xenbus_device *xendev;
 410         size_t stringlen;
 411         char *tmpstring;
 412
 413         enum xenbus_state state = xenbus_read_driver_state(nodename);
 414
 415         if (state != XenbusStateInitialising) {
 416                 /* Device is not new, so ignore it.  This can happen if a
 417                    device is going away after switching to Closed.  */
 418                 return 0;
 419         }
 420
 421         stringlen = strlen(nodename) + 1 + strlen(type) + 1;
 422         xendev = kzalloc(sizeof(*xendev) + stringlen, GFP_KERNEL);
 423         if (!xendev)
 424                 return -ENOMEM;
 425
 426         xendev->state = XenbusStateInitialising;
 427
 428         /* Copy the strings into the extra space. */
 429
 430         tmpstring = (char *)(xendev + 1);
 431         strcpy(tmpstring, nodename);
 432         xendev->nodename = tmpstring;
 433
 434         tmpstring += strlen(tmpstring) + 1;
 435         strcpy(tmpstring, type);
 436         xendev->devicetype = tmpstring;
 437         init_completion(&xendev->down);
 438
 439         xendev->dev.bus = &bus->bus;
 440         xendev->dev.release = xenbus_dev_release;
 441
 442         err = bus->get_bus_id(devname, xendev->nodename);
 443         if (err)
 444                 goto fail;
 445
 446         dev_set_name(&xendev->dev, devname);
 447
 448         /* Register with generic device framework. */
 449         err = device_register(&xendev->dev);
 450         if (err)
 451                 goto fail;
 452
 453         return 0;
 454 fail:
 455         kfree(xendev);
 456         return err;
 457 }
 458 EXPORT_SYMBOL_GPL(xenbus_probe_node);
 459
 460 static int xenbus_probe_device_type(struct xen_bus_type *bus, const char *type)
 461 {
 462         int err = 0;
 463         char **dir;
 464         unsigned int dir_n = 0;
 465         int i;
 466
 467         dir = xenbus_directory(XBT_NIL, bus->root, type, &dir_n);
 468         if (IS_ERR(dir))
 469                 return PTR_ERR(dir);
 470
 471         for (i = 0; i < dir_n; i++) {
 472                 err = bus->probe(bus, type, dir[i]);
 473                 if (err)
 474                         break;
 475         }
 476
 477         kfree(dir);
 478         return err;
 479 }
 480
 481 int xenbus_probe_devices(struct xen_bus_type *bus)
 482 {
 483         int err = 0;
 484         char **dir;
 485         unsigned int i, dir_n;
 486
 487         dir = xenbus_directory(XBT_NIL, bus->root, "", &dir_n);
 488         if (IS_ERR(dir))
 489                 return PTR_ERR(dir);
 490
 491         for (i = 0; i < dir_n; i++) {
 492                 err = xenbus_probe_device_type(bus, dir[i]);
 493                 if (err)
 494                         break;
 495         }
 496
 497         kfree(dir);
 498         return err;
 499 }
 500 EXPORT_SYMBOL_GPL(xenbus_probe_devices);
 501
 502 static unsigned int char_count(const char *str, char c)
 503 {
 504         unsigned int i, ret = 0;
 505
 506         for (i = 0; str[i]; i++)
 507                 if (str[i] == c)
 508                         ret++;
 509         return ret;
 510 }
 511
 512 static int strsep_len(const char *str, char c, unsigned int len)
 513 {
 514         unsigned int i;
 515
 516         for (i = 0; str[i]; i++)
 517                 if (str[i] == c) {
 518                         if (len == 0)
 519                                 return i;
 520                         len--;
 521                 }
 522         return (len == 0) ? i : -ERANGE;
 523 }
 524
 525 void xenbus_dev_changed(const char *node, struct xen_bus_type *bus)
 526 {
 527         int exists, rootlen;
 528         struct xenbus_device *dev;
 529         char type[XEN_BUS_ID_SIZE];
 530         const char *p, *root;
 531
 532         if (char_count(node, '/') < 2)
 533                 return;
 534
 535         exists = xenbus_exists(XBT_NIL, node, "");
 536         if (!exists) {
 537                 xenbus_cleanup_devices(node, &bus->bus);
 538                 return;
 539         }
 540
 541         /* backend/<type>/... or device/<type>/... */
 542         p = strchr(node, '/') + 1;
 543         snprintf(type, XEN_BUS_ID_SIZE, "%.*s", (int)strcspn(p, "/"), p);
 544         type[XEN_BUS_ID_SIZE-1] = '\0';
 545
 546         rootlen = strsep_len(node, '/', bus->levels);
 547         if (rootlen < 0)
 548                 return;
 549         root = kasprintf(GFP_KERNEL, "%.*s", rootlen, node);
 550         if (!root)
 551                 return;
 552
 553         dev = xenbus_device_find(root, &bus->bus);
 554         if (!dev)
 555                 xenbus_probe_node(bus, type, root);
 556         else
 557                 put_device(&dev->dev);
 558
 559         kfree(root);
 560 }
 561 EXPORT_SYMBOL_GPL(xenbus_dev_changed);
 562
 563 int xenbus_dev_suspend(struct device *dev)
 564 {
 565         int err = 0;
 566         struct xenbus_driver *drv;
 567         struct xenbus_device *xdev
 568                 = container_of(dev, struct xenbus_device, dev);
 569
 570         DPRINTK("%s", xdev->nodename);
 571
 572         if (dev->driver == NULL)
 573                 return 0;
 574         drv = to_xenbus_driver(dev->driver);
 575         if (drv->suspend)
 576                 err = drv->suspend(xdev);
 577         if (err)
 578                 printk(KERN_WARNING
 579                        "xenbus: suspend %s failed: %i\n", dev_name(dev), err);
 580         return 0;
 581 }
 582 EXPORT_SYMBOL_GPL(xenbus_dev_suspend);
 583
 584 int xenbus_dev_resume(struct device *dev)
 585 {
 586         int err;
 587         struct xenbus_driver *drv;
 588         struct xenbus_device *xdev
 589                 = container_of(dev, struct xenbus_device, dev);
 590
 591         DPRINTK("%s", xdev->nodename);
 592
 593         if (dev->driver == NULL)
 594                 return 0;
 595         drv = to_xenbus_driver(dev->driver);
 596         err = talk_to_otherend(xdev);
 597         if (err) {
 598                 printk(KERN_WARNING
 599                        "xenbus: resume (talk_to_otherend) %s failed: %i\n",
 600                        dev_name(dev), err);
 601                 return err;
 602         }
 603
 604         xdev->state = XenbusStateInitialising;
 605
 606         if (drv->resume) {
 607                 err = drv->resume(xdev);
 608                 if (err) {
 609                         printk(KERN_WARNING
 610                                "xenbus: resume %s failed: %i\n",
 611                                dev_name(dev), err);
 612                         return err;
 613                 }
 614         }
 615
 616         err = watch_otherend(xdev);
 617         if (err) {
 618                 printk(KERN_WARNING
 619                        "xenbus_probe: resume (watch_otherend) %s failed: "
 620                        "%d.\n", dev_name(dev), err);
 621                 return err;
 622         }
 623
 624         return 0;
 625 }
 626 EXPORT_SYMBOL_GPL(xenbus_dev_resume);
 627
 628 int xenbus_dev_cancel(struct device *dev)
 629 {
 630         /* Do nothing */
 631         DPRINTK("cancel");
 632         return 0;
 633 }
 634 EXPORT_SYMBOL_GPL(xenbus_dev_cancel);
 635
 636 /* A flag to determine if xenstored is 'ready' (i.e. has started) */
 637 int xenstored_ready;
 638
 639
 640 int register_xenstore_notifier(struct notifier_block *nb)
 641 {
 642         int ret = 0;
 643
 644         if (xenstored_ready > 0)
 645                 ret = nb->notifier_call(nb, 0, NULL);
 646         else
 647                 blocking_notifier_chain_register(&xenstore_chain, nb);
 648
 649         return ret;
 650 }
 651 EXPORT_SYMBOL_GPL(register_xenstore_notifier);
 652
 653 void unregister_xenstore_notifier(struct notifier_block *nb)
 654 {
 655         blocking_notifier_chain_unregister(&xenstore_chain, nb);
 656 }
 657 EXPORT_SYMBOL_GPL(unregister_xenstore_notifier);
 658
 659 void xenbus_probe(struct work_struct *unused)
 660 {
 661         xenstored_ready = 1;
 662
 663         /* Notify others that xenstore is up */
 664         blocking_notifier_call_chain(&xenstore_chain, 0, NULL);
 665 }
 666 EXPORT_SYMBOL_GPL(xenbus_probe);
 667
 668 static int __init xenbus_probe_initcall(void)
 669 {
 670         if (!xen_domain())
 671                 return -ENODEV;
 672
 673         if (xen_initial_domain() || xen_hvm_domain())
 674                 return 0;
 675
 676         xenbus_probe(NULL);
 677         return 0;
 678 }
 679
 680 device_initcall(xenbus_probe_initcall);
 681
 682 /* Set up event channel for xenstored which is run as a local process
 683  * (this is normally used only in dom0)
 684  */
 685 static int __init xenstored_local_init(void)
 686 {
 687         int err = 0;
 688         unsigned long page = 0;
 689         struct evtchn_alloc_unbound alloc_unbound;
 690
 691         /* Allocate Xenstore page */
 692         page = get_zeroed_page(GFP_KERNEL);
 693         if (!page)
 694                 goto out_err;
 695
 696         xen_store_mfn = xen_start_info->store_mfn =
 697                 pfn_to_mfn(virt_to_phys((void *)page) >>
 698                            PAGE_SHIFT);
 699
 700         /* Next allocate a local port which xenstored can bind to */
 701         alloc_unbound.dom        = DOMID_SELF;
 702         alloc_unbound.remote_dom = DOMID_SELF;
 703
 704         err = HYPERVISOR_event_channel_op(EVTCHNOP_alloc_unbound,
 705                                           &alloc_unbound);
 706         if (err == -ENOSYS)
 707                 goto out_err;
 708
 709         BUG_ON(err);
 710         xen_store_evtchn = xen_start_info->store_evtchn =
 711                 alloc_unbound.port;
 712
 713         return 0;
 714
 715  out_err:
 716         if (page != 0)
 717                 free_page(page);
 718         return err;
 719 }
 720
 721 static int __init xenbus_init(void)
 722 {
 723         int err = 0;
 724
 725         if (!xen_domain())
 726                 return -ENODEV;
 727
 728         xenbus_ring_ops_init();
 729
 730         if (xen_hvm_domain()) {
 731                 uint64_t v = 0;
 732                 err = hvm_get_parameter(HVM_PARAM_STORE_EVTCHN, &v);
 733                 if (err)
 734                         goto out_error;
 735                 xen_store_evtchn = (int)v;
 736                 err = hvm_get_parameter(HVM_PARAM_STORE_PFN, &v);
 737                 if (err)
 738                         goto out_error;
 739                 xen_store_mfn = (unsigned long)v;
 740                 xen_store_interface = ioremap(xen_store_mfn << PAGE_SHIFT, PAGE_SIZE);
 741         } else {
 742                 xen_store_evtchn = xen_start_info->store_evtchn;
 743                 xen_store_mfn = xen_start_info->store_mfn;
 744                 if (xen_store_evtchn)
 745                         xenstored_ready = 1;
 746                 else {
 747                         err = xenstored_local_init();
 748                         if (err)
 749                                 goto out_error;
 750                 }
 751                 xen_store_interface = mfn_to_virt(xen_store_mfn);
 752         }
 753
 754         /* Initialize the interface to xenstore. */
 755         err = xs_init();
 756         if (err) {
 757                 printk(KERN_WARNING
 758                        "XENBUS: Error initializing xenstore comms: %i\n", err);
 759                 goto out_error;
 760         }
 761
 762 #ifdef CONFIG_XEN_COMPAT_XENFS
 763         /*
 764          * Create xenfs mountpoint in /proc for compatibility with
 765          * utilities that expect to find "xenbus" under "/proc/xen".
 766          */
 767         proc_mkdir("xen", NULL);
 768 #endif
 769
 770 out_error:
 771         return err;
 772 }
 773
 774 postcore_initcall(xenbus_init);
 775
 776 MODULE_LICENSE("GPL");