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
  50 #include <asm/page.h>
  51 #include <asm/pgtable.h>
  52 #include <asm/xen/hypervisor.h>
  53
  54 #include <xen/xen.h>
  55 #include <xen/xenbus.h>
  56 #include <xen/events.h>
  57 #include <xen/page.h>
  58
  59 #include <xen/hvm.h>
  60
  61 #include "xenbus_comms.h"
  62 #include "xenbus_probe.h"
  63
  64
  65 int xen_store_evtchn;
  66 EXPORT_SYMBOL_GPL(xen_store_evtchn);
  67
  68 struct xenstore_domain_interface *xen_store_interface;
  69 EXPORT_SYMBOL_GPL(xen_store_interface);
  70
  71 static unsigned long xen_store_mfn;
  72
  73 static BLOCKING_NOTIFIER_HEAD(xenstore_chain);
  74
  75 /* If something in array of ids matches this device, return it. */
  76 static const struct xenbus_device_id *
  77 match_device(const struct xenbus_device_id *arr, struct xenbus_device *dev)
  78 {
  79         for (; *arr->devicetype != '\0'; arr++) {
  80                 if (!strcmp(arr->devicetype, dev->devicetype))
  81                         return arr;
  82         }
  83         return NULL;
  84 }
  85
  86 int xenbus_match(struct device *_dev, struct device_driver *_drv)
  87 {
  88         struct xenbus_driver *drv = to_xenbus_driver(_drv);
  89
  90         if (!drv->ids)
  91                 return 0;
  92
  93         return match_device(drv->ids, to_xenbus_device(_dev)) != NULL;
  94 }
  95 EXPORT_SYMBOL_GPL(xenbus_match);
  96
  97
  98 static void free_otherend_details(struct xenbus_device *dev)
  99 {
 100         kfree(dev->otherend);
 101         dev->otherend = NULL;
 102 }
 103
 104
 105 static void free_otherend_watch(struct xenbus_device *dev)
 106 {
 107         if (dev->otherend_watch.node) {
 108                 unregister_xenbus_watch(&dev->otherend_watch);
 109                 kfree(dev->otherend_watch.node);
 110                 dev->otherend_watch.node = NULL;
 111         }
 112 }
 113
 114
 115 static int talk_to_otherend(struct xenbus_device *dev)
 116 {
 117         struct xenbus_driver *drv = to_xenbus_driver(dev->dev.driver);
 118
 119         free_otherend_watch(dev);
 120         free_otherend_details(dev);
 121
 122         return drv->read_otherend_details(dev);
 123 }
 124
 125
 126
 127 static int watch_otherend(struct xenbus_device *dev)
 128 {
 129         struct xen_bus_type *bus =
 130                 container_of(dev->dev.bus, struct xen_bus_type, bus);
 131
 132         return xenbus_watch_pathfmt(dev, &dev->otherend_watch,
 133                                     bus->otherend_changed,
 134                                     "%s/%s", dev->otherend, "state");
 135 }
 136
 137
 138 int xenbus_read_otherend_details(struct xenbus_device *xendev,
 139                                  char *id_node, char *path_node)
 140 {
 141         int err = xenbus_gather(XBT_NIL, xendev->nodename,
 142                                 id_node, "%i", &xendev->otherend_id,
 143                                 path_node, NULL, &xendev->otherend,
 144                                 NULL);
 145         if (err) {
 146                 xenbus_dev_fatal(xendev, err,
 147                                  "reading other end details from %s",
 148                                  xendev->nodename);
 149                 return err;
 150         }
 151         if (strlen(xendev->otherend) == 0 ||
 152             !xenbus_exists(XBT_NIL, xendev->otherend, "")) {
 153                 xenbus_dev_fatal(xendev, -ENOENT,
 154                                  "unable to read other end from %s.  "
 155                                  "missing or inaccessible.",
 156                                  xendev->nodename);
 157                 free_otherend_details(xendev);
 158                 return -ENOENT;
 159         }
 160
 161         return 0;
 162 }
 163 EXPORT_SYMBOL_GPL(xenbus_read_otherend_details);
 164
 165 void xenbus_otherend_changed(struct xenbus_watch *watch,
 166                              const char **vec, unsigned int len,
 167                              int ignore_on_shutdown)
 168 {
 169         struct xenbus_device *dev =
 170                 container_of(watch, struct xenbus_device, otherend_watch);
 171         struct xenbus_driver *drv = to_xenbus_driver(dev->dev.driver);
 172         enum xenbus_state state;
 173
 174         /* Protect us against watches firing on old details when the otherend
 175            details change, say immediately after a resume. */
 176         if (!dev->otherend ||
 177             strncmp(dev->otherend, vec[XS_WATCH_PATH],
 178                     strlen(dev->otherend))) {
 179                 dev_dbg(&dev->dev, "Ignoring watch at %s\n",
 180                         vec[XS_WATCH_PATH]);
 181                 return;
 182         }
 183
 184         state = xenbus_read_driver_state(dev->otherend);
 185
 186         dev_dbg(&dev->dev, "state is %d, (%s), %s, %s\n",
 187                 state, xenbus_strstate(state), dev->otherend_watch.node,
 188                 vec[XS_WATCH_PATH]);
 189
 190         /*
 191          * Ignore xenbus transitions during shutdown. This prevents us doing
 192          * work that can fail e.g., when the rootfs is gone.
 193          */
 194         if (system_state > SYSTEM_RUNNING) {
 195                 if (ignore_on_shutdown && (state == XenbusStateClosing))
 196                         xenbus_frontend_closed(dev);
 197                 return;
 198         }
 199
 200         if (drv->otherend_changed)
 201                 drv->otherend_changed(dev, state);
 202 }
 203 EXPORT_SYMBOL_GPL(xenbus_otherend_changed);
 204
 205 int xenbus_dev_probe(struct device *_dev)
 206 {
 207         struct xenbus_device *dev = to_xenbus_device(_dev);
 208         struct xenbus_driver *drv = to_xenbus_driver(_dev->driver);
 209         const struct xenbus_device_id *id;
 210         int err;
 211
 212         DPRINTK("%s", dev->nodename);
 213
 214         if (!drv->probe) {
 215                 err = -ENODEV;
 216                 goto fail;
 217         }
 218
 219         id = match_device(drv->ids, dev);
 220         if (!id) {
 221                 err = -ENODEV;
 222                 goto fail;
 223         }
 224
 225         err = talk_to_otherend(dev);
 226         if (err) {
 227                 dev_warn(&dev->dev, "talk_to_otherend on %s failed.\n",
 228                          dev->nodename);
 229                 return err;
 230         }
 231
 232         err = drv->probe(dev, id);
 233         if (err)
 234                 goto fail;
 235
 236         err = watch_otherend(dev);
 237         if (err) {
 238                 dev_warn(&dev->dev, "watch_otherend on %s failed.\n",
 239                        dev->nodename);
 240                 return err;
 241         }
 242
 243         return 0;
 244 fail:
 245         xenbus_dev_error(dev, err, "xenbus_dev_probe on %s", dev->nodename);
 246         xenbus_switch_state(dev, XenbusStateClosed);
 247         return err;
 248 }
 249 EXPORT_SYMBOL_GPL(xenbus_dev_probe);
 250
 251 int xenbus_dev_remove(struct device *_dev)
 252 {
 253         struct xenbus_device *dev = to_xenbus_device(_dev);
 254         struct xenbus_driver *drv = to_xenbus_driver(_dev->driver);
 255
 256         DPRINTK("%s", dev->nodename);
 257
 258         free_otherend_watch(dev);
 259         free_otherend_details(dev);
 260
 261         if (drv->remove)
 262                 drv->remove(dev);
 263
 264         xenbus_switch_state(dev, XenbusStateClosed);
 265         return 0;
 266 }
 267 EXPORT_SYMBOL_GPL(xenbus_dev_remove);
 268
 269 void xenbus_dev_shutdown(struct device *_dev)
 270 {
 271         struct xenbus_device *dev = to_xenbus_device(_dev);
 272         unsigned long timeout = 5*HZ;
 273
 274         DPRINTK("%s", dev->nodename);
 275
 276         get_device(&dev->dev);
 277         if (dev->state != XenbusStateConnected) {
 278                 printk(KERN_INFO "%s: %s: %s != Connected, skipping\n", __func__,
 279                        dev->nodename, xenbus_strstate(dev->state));
 280                 goto out;
 281         }
 282         xenbus_switch_state(dev, XenbusStateClosing);
 283         timeout = wait_for_completion_timeout(&dev->down, timeout);
 284         if (!timeout)
 285                 printk(KERN_INFO "%s: %s timeout closing device\n",
 286                        __func__, dev->nodename);
 287  out:
 288         put_device(&dev->dev);
 289 }
 290 EXPORT_SYMBOL_GPL(xenbus_dev_shutdown);
 291
 292 int xenbus_register_driver_common(struct xenbus_driver *drv,
 293                                   struct xen_bus_type *bus,
 294                                   struct module *owner,
 295                                   const char *mod_name)
 296 {
 297         drv->driver.name = drv->name;
 298         drv->driver.bus = &bus->bus;
 299         drv->driver.owner = owner;
 300         drv->driver.mod_name = mod_name;
 301
 302         return driver_register(&drv->driver);
 303 }
 304 EXPORT_SYMBOL_GPL(xenbus_register_driver_common);
 305
 306 void xenbus_unregister_driver(struct xenbus_driver *drv)
 307 {
 308         driver_unregister(&drv->driver);
 309 }
 310 EXPORT_SYMBOL_GPL(xenbus_unregister_driver);
 311
 312 struct xb_find_info
 313 {
 314         struct xenbus_device *dev;
 315         const char *nodename;
 316 };
 317
 318 static int cmp_dev(struct device *dev, void *data)
 319 {
 320         struct xenbus_device *xendev = to_xenbus_device(dev);
 321         struct xb_find_info *info = data;
 322
 323         if (!strcmp(xendev->nodename, info->nodename)) {
 324                 info->dev = xendev;
 325                 get_device(dev);
 326                 return 1;
 327         }
 328         return 0;
 329 }
 330
 331 struct xenbus_device *xenbus_device_find(const char *nodename,
 332                                          struct bus_type *bus)
 333 {
 334         struct xb_find_info info = { .dev = NULL, .nodename = nodename };
 335
 336         bus_for_each_dev(bus, NULL, &info, cmp_dev);
 337         return info.dev;
 338 }
 339
 340 static int cleanup_dev(struct device *dev, void *data)
 341 {
 342         struct xenbus_device *xendev = to_xenbus_device(dev);
 343         struct xb_find_info *info = data;
 344         int len = strlen(info->nodename);
 345
 346         DPRINTK("%s", info->nodename);
 347
 348         /* Match the info->nodename path, or any subdirectory of that path. */
 349         if (strncmp(xendev->nodename, info->nodename, len))
 350                 return 0;
 351
 352         /* If the node name is longer, ensure it really is a subdirectory. */
 353         if ((strlen(xendev->nodename) > len) && (xendev->nodename[len] != '/'))
 354                 return 0;
 355
 356         info->dev = xendev;
 357         get_device(dev);
 358         return 1;
 359 }
 360
 361 static void xenbus_cleanup_devices(const char *path, struct bus_type *bus)
 362 {
 363         struct xb_find_info info = { .nodename = path };
 364
 365         do {
 366                 info.dev = NULL;
 367                 bus_for_each_dev(bus, NULL, &info, cleanup_dev);
 368                 if (info.dev) {
 369                         device_unregister(&info.dev->dev);
 370                         put_device(&info.dev->dev);
 371                 }
 372         } while (info.dev);
 373 }
 374
 375 static void xenbus_dev_release(struct device *dev)
 376 {
 377         if (dev)
 378                 kfree(to_xenbus_device(dev));
 379 }
 380
 381 static ssize_t nodename_show(struct device *dev,
 382                              struct device_attribute *attr, char *buf)
 383 {
 384         return sprintf(buf, "%s\n", to_xenbus_device(dev)->nodename);
 385 }
 386
 387 static ssize_t devtype_show(struct device *dev,
 388                             struct device_attribute *attr, char *buf)
 389 {
 390         return sprintf(buf, "%s\n", to_xenbus_device(dev)->devicetype);
 391 }
 392
 393 static ssize_t modalias_show(struct device *dev,
 394                              struct device_attribute *attr, char *buf)
 395 {
 396         return sprintf(buf, "%s:%s\n", dev->bus->name,
 397                        to_xenbus_device(dev)->devicetype);
 398 }
 399
 400 struct device_attribute xenbus_dev_attrs[] = {
 401         __ATTR_RO(nodename),
 402         __ATTR_RO(devtype),
 403         __ATTR_RO(modalias),
 404         __ATTR_NULL
 405 };
 406 EXPORT_SYMBOL_GPL(xenbus_dev_attrs);
 407
 408 int xenbus_probe_node(struct xen_bus_type *bus,
 409                       const char *type,
 410                       const char *nodename)
 411 {
 412         char devname[XEN_BUS_ID_SIZE];
 413         int err;
 414         struct xenbus_device *xendev;
 415         size_t stringlen;
 416         char *tmpstring;
 417
 418         enum xenbus_state state = xenbus_read_driver_state(nodename);
 419
 420         if (state != XenbusStateInitialising) {
 421                 /* Device is not new, so ignore it.  This can happen if a
 422                    device is going away after switching to Closed.  */
 423                 return 0;
 424         }
 425
 426         stringlen = strlen(nodename) + 1 + strlen(type) + 1;
 427         xendev = kzalloc(sizeof(*xendev) + stringlen, GFP_KERNEL);
 428         if (!xendev)
 429                 return -ENOMEM;
 430
 431         xendev->state = XenbusStateInitialising;
 432
 433         /* Copy the strings into the extra space. */
 434
 435         tmpstring = (char *)(xendev + 1);
 436         strcpy(tmpstring, nodename);
 437         xendev->nodename = tmpstring;
 438
 439         tmpstring += strlen(tmpstring) + 1;
 440         strcpy(tmpstring, type);
 441         xendev->devicetype = tmpstring;
 442         init_completion(&xendev->down);
 443
 444         xendev->dev.bus = &bus->bus;
 445         xendev->dev.release = xenbus_dev_release;
 446
 447         err = bus->get_bus_id(devname, xendev->nodename);
 448         if (err)
 449                 goto fail;
 450
 451         dev_set_name(&xendev->dev, devname);
 452
 453         /* Register with generic device framework. */
 454         err = device_register(&xendev->dev);
 455         if (err)
 456                 goto fail;
 457
 458         return 0;
 459 fail:
 460         kfree(xendev);
 461         return err;
 462 }
 463 EXPORT_SYMBOL_GPL(xenbus_probe_node);
 464
 465 static int xenbus_probe_device_type(struct xen_bus_type *bus, const char *type)
 466 {
 467         int err = 0;
 468         char **dir;
 469         unsigned int dir_n = 0;
 470         int i;
 471
 472         dir = xenbus_directory(XBT_NIL, bus->root, type, &dir_n);
 473         if (IS_ERR(dir))
 474                 return PTR_ERR(dir);
 475
 476         for (i = 0; i < dir_n; i++) {
 477                 err = bus->probe(bus, type, dir[i]);
 478                 if (err)
 479                         break;
 480         }
 481
 482         kfree(dir);
 483         return err;
 484 }
 485
 486 int xenbus_probe_devices(struct xen_bus_type *bus)
 487 {
 488         int err = 0;
 489         char **dir;
 490         unsigned int i, dir_n;
 491
 492         dir = xenbus_directory(XBT_NIL, bus->root, "", &dir_n);
 493         if (IS_ERR(dir))
 494                 return PTR_ERR(dir);
 495
 496         for (i = 0; i < dir_n; i++) {
 497                 err = xenbus_probe_device_type(bus, dir[i]);
 498                 if (err)
 499                         break;
 500         }
 501
 502         kfree(dir);
 503         return err;
 504 }
 505 EXPORT_SYMBOL_GPL(xenbus_probe_devices);
 506
 507 static unsigned int char_count(const char *str, char c)
 508 {
 509         unsigned int i, ret = 0;
 510
 511         for (i = 0; str[i]; i++)
 512                 if (str[i] == c)
 513                         ret++;
 514         return ret;
 515 }
 516
 517 static int strsep_len(const char *str, char c, unsigned int len)
 518 {
 519         unsigned int i;
 520
 521         for (i = 0; str[i]; i++)
 522                 if (str[i] == c) {
 523                         if (len == 0)
 524                                 return i;
 525                         len--;
 526                 }
 527         return (len == 0) ? i : -ERANGE;
 528 }
 529
 530 void xenbus_dev_changed(const char *node, struct xen_bus_type *bus)
 531 {
 532         int exists, rootlen;
 533         struct xenbus_device *dev;
 534         char type[XEN_BUS_ID_SIZE];
 535         const char *p, *root;
 536
 537         if (char_count(node, '/') < 2)
 538                 return;
 539
 540         exists = xenbus_exists(XBT_NIL, node, "");
 541         if (!exists) {
 542                 xenbus_cleanup_devices(node, &bus->bus);
 543                 return;
 544         }
 545
 546         /* backend/<type>/... or device/<type>/... */
 547         p = strchr(node, '/') + 1;
 548         snprintf(type, XEN_BUS_ID_SIZE, "%.*s", (int)strcspn(p, "/"), p);
 549         type[XEN_BUS_ID_SIZE-1] = '\0';
 550
 551         rootlen = strsep_len(node, '/', bus->levels);
 552         if (rootlen < 0)
 553                 return;
 554         root = kasprintf(GFP_KERNEL, "%.*s", rootlen, node);
 555         if (!root)
 556                 return;
 557
 558         dev = xenbus_device_find(root, &bus->bus);
 559         if (!dev)
 560                 xenbus_probe_node(bus, type, root);
 561         else
 562                 put_device(&dev->dev);
 563
 564         kfree(root);
 565 }
 566 EXPORT_SYMBOL_GPL(xenbus_dev_changed);
 567
 568 int xenbus_dev_suspend(struct device *dev)
 569 {
 570         int err = 0;
 571         struct xenbus_driver *drv;
 572         struct xenbus_device *xdev
 573                 = container_of(dev, struct xenbus_device, dev);
 574
 575         DPRINTK("%s", xdev->nodename);
 576
 577         if (dev->driver == NULL)
 578                 return 0;
 579         drv = to_xenbus_driver(dev->driver);
 580         if (drv->suspend)
 581                 err = drv->suspend(xdev);
 582         if (err)
 583                 printk(KERN_WARNING
 584                        "xenbus: suspend %s failed: %i\n", dev_name(dev), err);
 585         return 0;
 586 }
 587 EXPORT_SYMBOL_GPL(xenbus_dev_suspend);
 588
 589 int xenbus_dev_resume(struct device *dev)
 590 {
 591         int err;
 592         struct xenbus_driver *drv;
 593         struct xenbus_device *xdev
 594                 = container_of(dev, struct xenbus_device, dev);
 595
 596         DPRINTK("%s", xdev->nodename);
 597
 598         if (dev->driver == NULL)
 599                 return 0;
 600         drv = to_xenbus_driver(dev->driver);
 601         err = talk_to_otherend(xdev);
 602         if (err) {
 603                 printk(KERN_WARNING
 604                        "xenbus: resume (talk_to_otherend) %s failed: %i\n",
 605                        dev_name(dev), err);
 606                 return err;
 607         }
 608
 609         xdev->state = XenbusStateInitialising;
 610
 611         if (drv->resume) {
 612                 err = drv->resume(xdev);
 613                 if (err) {
 614                         printk(KERN_WARNING
 615                                "xenbus: resume %s failed: %i\n",
 616                                dev_name(dev), err);
 617                         return err;
 618                 }
 619         }
 620
 621         err = watch_otherend(xdev);
 622         if (err) {
 623                 printk(KERN_WARNING
 624                        "xenbus_probe: resume (watch_otherend) %s failed: "
 625                        "%d.\n", dev_name(dev), err);
 626                 return err;
 627         }
 628
 629         return 0;
 630 }
 631 EXPORT_SYMBOL_GPL(xenbus_dev_resume);
 632
 633 int xenbus_dev_cancel(struct device *dev)
 634 {
 635         /* Do nothing */
 636         DPRINTK("cancel");
 637         return 0;
 638 }
 639 EXPORT_SYMBOL_GPL(xenbus_dev_cancel);
 640
 641 /* A flag to determine if xenstored is 'ready' (i.e. has started) */
 642 int xenstored_ready = 0;
 643
 644
 645 int register_xenstore_notifier(struct notifier_block *nb)
 646 {
 647         int ret = 0;
 648
 649         if (xenstored_ready > 0)
 650                 ret = nb->notifier_call(nb, 0, NULL);
 651         else
 652                 blocking_notifier_chain_register(&xenstore_chain, nb);
 653
 654         return ret;
 655 }
 656 EXPORT_SYMBOL_GPL(register_xenstore_notifier);
 657
 658 void unregister_xenstore_notifier(struct notifier_block *nb)
 659 {
 660         blocking_notifier_chain_unregister(&xenstore_chain, nb);
 661 }
 662 EXPORT_SYMBOL_GPL(unregister_xenstore_notifier);
 663
 664 void xenbus_probe(struct work_struct *unused)
 665 {
 666         xenstored_ready = 1;
 667
 668         /* Notify others that xenstore is up */
 669         blocking_notifier_call_chain(&xenstore_chain, 0, NULL);
 670 }
 671 EXPORT_SYMBOL_GPL(xenbus_probe);
 672
 673 static int __init xenbus_probe_initcall(void)
 674 {
 675         if (!xen_domain())
 676                 return -ENODEV;
 677
 678         if (xen_initial_domain() || xen_hvm_domain())
 679                 return 0;
 680
 681         xenbus_probe(NULL);
 682         return 0;
 683 }
 684
 685 device_initcall(xenbus_probe_initcall);
 686
 687 static int __init xenbus_init(void)
 688 {
 689         int err = 0;
 690         unsigned long page = 0;
 691
 692         DPRINTK("");
 693
 694         err = -ENODEV;
 695         if (!xen_domain())
 696                 return err;
 697
 698         /*
 699          * Domain0 doesn't have a store_evtchn or store_mfn yet.
 700          */
 701         if (xen_initial_domain()) {
 702                 struct evtchn_alloc_unbound alloc_unbound;
 703
 704                 /* Allocate Xenstore page */
 705                 page = get_zeroed_page(GFP_KERNEL);
 706                 if (!page)
 707                         goto out_error;
 708
 709                 xen_store_mfn = xen_start_info->store_mfn =
 710                         pfn_to_mfn(virt_to_phys((void *)page) >>
 711                                    PAGE_SHIFT);
 712
 713                 /* Next allocate a local port which xenstored can bind to */
 714                 alloc_unbound.dom        = DOMID_SELF;
 715                 alloc_unbound.remote_dom = 0;
 716
 717                 err = HYPERVISOR_event_channel_op(EVTCHNOP_alloc_unbound,
 718                                                   &alloc_unbound);
 719                 if (err == -ENOSYS)
 720                         goto out_error;
 721
 722                 BUG_ON(err);
 723                 xen_store_evtchn = xen_start_info->store_evtchn =
 724                         alloc_unbound.port;
 725
 726                 xen_store_interface = mfn_to_virt(xen_store_mfn);
 727         } else {
 728                 if (xen_hvm_domain()) {
 729                         uint64_t v = 0;
 730                         err = hvm_get_parameter(HVM_PARAM_STORE_EVTCHN, &v);
 731                         if (err)
 732                                 goto out_error;
 733                         xen_store_evtchn = (int)v;
 734                         err = hvm_get_parameter(HVM_PARAM_STORE_PFN, &v);
 735                         if (err)
 736                                 goto out_error;
 737                         xen_store_mfn = (unsigned long)v;
 738                         xen_store_interface = ioremap(xen_store_mfn << PAGE_SHIFT, PAGE_SIZE);
 739                 } else {
 740                         xen_store_evtchn = xen_start_info->store_evtchn;
 741                         xen_store_mfn = xen_start_info->store_mfn;
 742                         xen_store_interface = mfn_to_virt(xen_store_mfn);
 743                         xenstored_ready = 1;
 744                 }
 745         }
 746
 747         /* Initialize the interface to xenstore. */
 748         err = xs_init();
 749         if (err) {
 750                 printk(KERN_WARNING
 751                        "XENBUS: Error initializing xenstore comms: %i\n", err);
 752                 goto out_error;
 753         }
 754
 755 #ifdef CONFIG_XEN_COMPAT_XENFS
 756         /*
 757          * Create xenfs mountpoint in /proc for compatibility with
 758          * utilities that expect to find "xenbus" under "/proc/xen".
 759          */
 760         proc_mkdir("xen", NULL);
 761 #endif
 762
 763         return 0;
 764
 765   out_error:
 766         if (page != 0)
 767                 free_page(page);
 768
 769         return err;
 770 }
 771
 772 postcore_initcall(xenbus_init);
 773
 774 MODULE_LICENSE("GPL");