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 pr_fmt(fmt) KBUILD_MODNAME ": " fmt
  34
  35 #define DPRINTK(fmt, args...)                           \
  36         pr_debug("xenbus_probe (%s:%d) " fmt ".\n",     \
  37                  __func__, __LINE__, ##args)
  38
  39 #include <linux/kernel.h>
  40 #include <linux/err.h>
  41 #include <linux/string.h>
  42 #include <linux/ctype.h>
  43 #include <linux/fcntl.h>
  44 #include <linux/mm.h>
  45 #include <linux/proc_fs.h>
  46 #include <linux/notifier.h>
  47 #include <linux/kthread.h>
  48 #include <linux/mutex.h>
  49 #include <linux/io.h>
  50 #include <linux/slab.h>
  51 #include <linux/module.h>
  52
  53 #include <asm/page.h>
  54 #include <asm/pgtable.h>
  55 #include <asm/xen/hypervisor.h>
  56
  57 #include <xen/xen.h>
  58 #include <xen/xenbus.h>
  59 #include <xen/events.h>
  60 #include <xen/page.h>
  61
  62 #include <xen/hvm.h>
  63
  64 #include "xenbus_comms.h"
  65 #include "xenbus_probe.h"
  66
  67
  68 int xen_store_evtchn;
  69 EXPORT_SYMBOL_GPL(xen_store_evtchn);
  70
  71 struct xenstore_domain_interface *xen_store_interface;
  72 EXPORT_SYMBOL_GPL(xen_store_interface);
  73
  74 enum xenstore_init xen_store_domain_type;
  75 EXPORT_SYMBOL_GPL(xen_store_domain_type);
  76
  77 static unsigned long xen_store_mfn;
  78
  79 static BLOCKING_NOTIFIER_HEAD(xenstore_chain);
  80
  81 /* If something in array of ids matches this device, return it. */
  82 static const struct xenbus_device_id *
  83 match_device(const struct xenbus_device_id *arr, struct xenbus_device *dev)
  84 {
  85         for (; *arr->devicetype != '\0'; arr++) {
  86                 if (!strcmp(arr->devicetype, dev->devicetype))
  87                         return arr;
  88         }
  89         return NULL;
  90 }
  91
  92 int xenbus_match(struct device *_dev, struct device_driver *_drv)
  93 {
  94         struct xenbus_driver *drv = to_xenbus_driver(_drv);
  95
  96         if (!drv->ids)
  97                 return 0;
  98
  99         return match_device(drv->ids, to_xenbus_device(_dev)) != NULL;
 100 }
 101 EXPORT_SYMBOL_GPL(xenbus_match);
 102
 103
 104 static void free_otherend_details(struct xenbus_device *dev)
 105 {
 106         kfree(dev->otherend);
 107         dev->otherend = NULL;
 108 }
 109
 110
 111 static void free_otherend_watch(struct xenbus_device *dev)
 112 {
 113         if (dev->otherend_watch.node) {
 114                 unregister_xenbus_watch(&dev->otherend_watch);
 115                 kfree(dev->otherend_watch.node);
 116                 dev->otherend_watch.node = NULL;
 117         }
 118 }
 119
 120
 121 static int talk_to_otherend(struct xenbus_device *dev)
 122 {
 123         struct xenbus_driver *drv = to_xenbus_driver(dev->dev.driver);
 124
 125         free_otherend_watch(dev);
 126         free_otherend_details(dev);
 127
 128         return drv->read_otherend_details(dev);
 129 }
 130
 131
 132
 133 static int watch_otherend(struct xenbus_device *dev)
 134 {
 135         struct xen_bus_type *bus =
 136                 container_of(dev->dev.bus, struct xen_bus_type, bus);
 137
 138         return xenbus_watch_pathfmt(dev, &dev->otherend_watch,
 139                                     bus->otherend_changed,
 140                                     "%s/%s", dev->otherend, "state");
 141 }
 142
 143
 144 int xenbus_read_otherend_details(struct xenbus_device *xendev,
 145                                  char *id_node, char *path_node)
 146 {
 147         int err = xenbus_gather(XBT_NIL, xendev->nodename,
 148                                 id_node, "%i", &xendev->otherend_id,
 149                                 path_node, NULL, &xendev->otherend,
 150                                 NULL);
 151         if (err) {
 152                 xenbus_dev_fatal(xendev, err,
 153                                  "reading other end details from %s",
 154                                  xendev->nodename);
 155                 return err;
 156         }
 157         if (strlen(xendev->otherend) == 0 ||
 158             !xenbus_exists(XBT_NIL, xendev->otherend, "")) {
 159                 xenbus_dev_fatal(xendev, -ENOENT,
 160                                  "unable to read other end from %s.  "
 161                                  "missing or inaccessible.",
 162                                  xendev->nodename);
 163                 free_otherend_details(xendev);
 164                 return -ENOENT;
 165         }
 166
 167         return 0;
 168 }
 169 EXPORT_SYMBOL_GPL(xenbus_read_otherend_details);
 170
 171 void xenbus_otherend_changed(struct xenbus_watch *watch,
 172                              const char **vec, unsigned int len,
 173                              int ignore_on_shutdown)
 174 {
 175         struct xenbus_device *dev =
 176                 container_of(watch, struct xenbus_device, otherend_watch);
 177         struct xenbus_driver *drv = to_xenbus_driver(dev->dev.driver);
 178         enum xenbus_state state;
 179
 180         /* Protect us against watches firing on old details when the otherend
 181            details change, say immediately after a resume. */
 182         if (!dev->otherend ||
 183             strncmp(dev->otherend, vec[XS_WATCH_PATH],
 184                     strlen(dev->otherend))) {
 185                 dev_dbg(&dev->dev, "Ignoring watch at %s\n",
 186                         vec[XS_WATCH_PATH]);
 187                 return;
 188         }
 189
 190         state = xenbus_read_driver_state(dev->otherend);
 191
 192         dev_dbg(&dev->dev, "state is %d, (%s), %s, %s\n",
 193                 state, xenbus_strstate(state), dev->otherend_watch.node,
 194                 vec[XS_WATCH_PATH]);
 195
 196         /*
 197          * Ignore xenbus transitions during shutdown. This prevents us doing
 198          * work that can fail e.g., when the rootfs is gone.
 199          */
 200         if (system_state > SYSTEM_RUNNING) {
 201                 if (ignore_on_shutdown && (state == XenbusStateClosing))
 202                         xenbus_frontend_closed(dev);
 203                 return;
 204         }
 205
 206         if (drv->otherend_changed)
 207                 drv->otherend_changed(dev, state);
 208 }
 209 EXPORT_SYMBOL_GPL(xenbus_otherend_changed);
 210
 211 int xenbus_dev_probe(struct device *_dev)
 212 {
 213         struct xenbus_device *dev = to_xenbus_device(_dev);
 214         struct xenbus_driver *drv = to_xenbus_driver(_dev->driver);
 215         const struct xenbus_device_id *id;
 216         int err;
 217
 218         DPRINTK("%s", dev->nodename);
 219
 220         if (!drv->probe) {
 221                 err = -ENODEV;
 222                 goto fail;
 223         }
 224
 225         id = match_device(drv->ids, dev);
 226         if (!id) {
 227                 err = -ENODEV;
 228                 goto fail;
 229         }
 230
 231         err = talk_to_otherend(dev);
 232         if (err) {
 233                 dev_warn(&dev->dev, "talk_to_otherend on %s failed.\n",
 234                          dev->nodename);
 235                 return err;
 236         }
 237
 238         err = drv->probe(dev, id);
 239         if (err)
 240                 goto fail;
 241
 242         err = watch_otherend(dev);
 243         if (err) {
 244                 dev_warn(&dev->dev, "watch_otherend on %s failed.\n",
 245                        dev->nodename);
 246                 return err;
 247         }
 248
 249         return 0;
 250 fail:
 251         xenbus_dev_error(dev, err, "xenbus_dev_probe on %s", dev->nodename);
 252         xenbus_switch_state(dev, XenbusStateClosed);
 253         return err;
 254 }
 255 EXPORT_SYMBOL_GPL(xenbus_dev_probe);
 256
 257 int xenbus_dev_remove(struct device *_dev)
 258 {
 259         struct xenbus_device *dev = to_xenbus_device(_dev);
 260         struct xenbus_driver *drv = to_xenbus_driver(_dev->driver);
 261
 262         DPRINTK("%s", dev->nodename);
 263
 264         free_otherend_watch(dev);
 265
 266         if (drv->remove)
 267                 drv->remove(dev);
 268
 269         free_otherend_details(dev);
 270
 271         xenbus_switch_state(dev, XenbusStateClosed);
 272         return 0;
 273 }
 274 EXPORT_SYMBOL_GPL(xenbus_dev_remove);
 275
 276 void xenbus_dev_shutdown(struct device *_dev)
 277 {
 278         struct xenbus_device *dev = to_xenbus_device(_dev);
 279         unsigned long timeout = 5*HZ;
 280
 281         DPRINTK("%s", dev->nodename);
 282
 283         get_device(&dev->dev);
 284         if (dev->state != XenbusStateConnected) {
 285                 pr_info("%s: %s: %s != Connected, skipping\n",
 286                         __func__, dev->nodename, xenbus_strstate(dev->state));
 287                 goto out;
 288         }
 289         xenbus_switch_state(dev, XenbusStateClosing);
 290         timeout = wait_for_completion_timeout(&dev->down, timeout);
 291         if (!timeout)
 292                 pr_info("%s: %s timeout closing device\n",
 293                         __func__, dev->nodename);
 294  out:
 295         put_device(&dev->dev);
 296 }
 297 EXPORT_SYMBOL_GPL(xenbus_dev_shutdown);
 298
 299 int xenbus_register_driver_common(struct xenbus_driver *drv,
 300                                   struct xen_bus_type *bus)
 301 {
 302         drv->driver.bus = &bus->bus;
 303
 304         return driver_register(&drv->driver);
 305 }
 306 EXPORT_SYMBOL_GPL(xenbus_register_driver_common);
 307
 308 void xenbus_unregister_driver(struct xenbus_driver *drv)
 309 {
 310         driver_unregister(&drv->driver);
 311 }
 312 EXPORT_SYMBOL_GPL(xenbus_unregister_driver);
 313
 314 struct xb_find_info {
 315         struct xenbus_device *dev;
 316         const char *nodename;
 317 };
 318
 319 static int cmp_dev(struct device *dev, void *data)
 320 {
 321         struct xenbus_device *xendev = to_xenbus_device(dev);
 322         struct xb_find_info *info = data;
 323
 324         if (!strcmp(xendev->nodename, info->nodename)) {
 325                 info->dev = xendev;
 326                 get_device(dev);
 327                 return 1;
 328         }
 329         return 0;
 330 }
 331
 332 static struct xenbus_device *xenbus_device_find(const char *nodename,
 333                                                 struct bus_type *bus)
 334 {
 335         struct xb_find_info info = { .dev = NULL, .nodename = nodename };
 336
 337         bus_for_each_dev(bus, NULL, &info, cmp_dev);
 338         return info.dev;
 339 }
 340
 341 static int cleanup_dev(struct device *dev, void *data)
 342 {
 343         struct xenbus_device *xendev = to_xenbus_device(dev);
 344         struct xb_find_info *info = data;
 345         int len = strlen(info->nodename);
 346
 347         DPRINTK("%s", info->nodename);
 348
 349         /* Match the info->nodename path, or any subdirectory of that path. */
 350         if (strncmp(xendev->nodename, info->nodename, len))
 351                 return 0;
 352
 353         /* If the node name is longer, ensure it really is a subdirectory. */
 354         if ((strlen(xendev->nodename) > len) && (xendev->nodename[len] != '/'))
 355                 return 0;
 356
 357         info->dev = xendev;
 358         get_device(dev);
 359         return 1;
 360 }
 361
 362 static void xenbus_cleanup_devices(const char *path, struct bus_type *bus)
 363 {
 364         struct xb_find_info info = { .nodename = path };
 365
 366         do {
 367                 info.dev = NULL;
 368                 bus_for_each_dev(bus, NULL, &info, cleanup_dev);
 369                 if (info.dev) {
 370                         device_unregister(&info.dev->dev);
 371                         put_device(&info.dev->dev);
 372                 }
 373         } while (info.dev);
 374 }
 375
 376 static void xenbus_dev_release(struct device *dev)
 377 {
 378         if (dev)
 379                 kfree(to_xenbus_device(dev));
 380 }
 381
 382 static ssize_t nodename_show(struct device *dev,
 383                              struct device_attribute *attr, char *buf)
 384 {
 385         return sprintf(buf, "%s\n", to_xenbus_device(dev)->nodename);
 386 }
 387
 388 static ssize_t devtype_show(struct device *dev,
 389                             struct device_attribute *attr, char *buf)
 390 {
 391         return sprintf(buf, "%s\n", to_xenbus_device(dev)->devicetype);
 392 }
 393
 394 static ssize_t modalias_show(struct device *dev,
 395                              struct device_attribute *attr, char *buf)
 396 {
 397         return sprintf(buf, "%s:%s\n", dev->bus->name,
 398                        to_xenbus_device(dev)->devicetype);
 399 }
 400
 401 struct device_attribute xenbus_dev_attrs[] = {
 402         __ATTR_RO(nodename),
 403         __ATTR_RO(devtype),
 404         __ATTR_RO(modalias),
 405         __ATTR_NULL
 406 };
 407 EXPORT_SYMBOL_GPL(xenbus_dev_attrs);
 408
 409 int xenbus_probe_node(struct xen_bus_type *bus,
 410                       const char *type,
 411                       const char *nodename)
 412 {
 413         char devname[XEN_BUS_ID_SIZE];
 414         int err;
 415         struct xenbus_device *xendev;
 416         size_t stringlen;
 417         char *tmpstring;
 418
 419         enum xenbus_state state = xenbus_read_driver_state(nodename);
 420
 421         if (state != XenbusStateInitialising) {
 422                 /* Device is not new, so ignore it.  This can happen if a
 423                    device is going away after switching to Closed.  */
 424                 return 0;
 425         }
 426
 427         stringlen = strlen(nodename) + 1 + strlen(type) + 1;
 428         xendev = kzalloc(sizeof(*xendev) + stringlen, GFP_KERNEL);
 429         if (!xendev)
 430                 return -ENOMEM;
 431
 432         xendev->state = XenbusStateInitialising;
 433
 434         /* Copy the strings into the extra space. */
 435
 436         tmpstring = (char *)(xendev + 1);
 437         strcpy(tmpstring, nodename);
 438         xendev->nodename = tmpstring;
 439
 440         tmpstring += strlen(tmpstring) + 1;
 441         strcpy(tmpstring, type);
 442         xendev->devicetype = tmpstring;
 443         init_completion(&xendev->down);
 444
 445         xendev->dev.bus = &bus->bus;
 446         xendev->dev.release = xenbus_dev_release;
 447
 448         err = bus->get_bus_id(devname, xendev->nodename);
 449         if (err)
 450                 goto fail;
 451
 452         dev_set_name(&xendev->dev, "%s", devname);
 453
 454         /* Register with generic device framework. */
 455         err = device_register(&xendev->dev);
 456         if (err)
 457                 goto fail;
 458
 459         return 0;
 460 fail:
 461         kfree(xendev);
 462         return err;
 463 }
 464 EXPORT_SYMBOL_GPL(xenbus_probe_node);
 465
 466 static int xenbus_probe_device_type(struct xen_bus_type *bus, const char *type)
 467 {
 468         int err = 0;
 469         char **dir;
 470         unsigned int dir_n = 0;
 471         int i;
 472
 473         dir = xenbus_directory(XBT_NIL, bus->root, type, &dir_n);
 474         if (IS_ERR(dir))
 475                 return PTR_ERR(dir);
 476
 477         for (i = 0; i < dir_n; i++) {
 478                 err = bus->probe(bus, type, dir[i]);
 479                 if (err)
 480                         break;
 481         }
 482
 483         kfree(dir);
 484         return err;
 485 }
 486
 487 int xenbus_probe_devices(struct xen_bus_type *bus)
 488 {
 489         int err = 0;
 490         char **dir;
 491         unsigned int i, dir_n;
 492
 493         dir = xenbus_directory(XBT_NIL, bus->root, "", &dir_n);
 494         if (IS_ERR(dir))
 495                 return PTR_ERR(dir);
 496
 497         for (i = 0; i < dir_n; i++) {
 498                 err = xenbus_probe_device_type(bus, dir[i]);
 499                 if (err)
 500                         break;
 501         }
 502
 503         kfree(dir);
 504         return err;
 505 }
 506 EXPORT_SYMBOL_GPL(xenbus_probe_devices);
 507
 508 static unsigned int char_count(const char *str, char c)
 509 {
 510         unsigned int i, ret = 0;
 511
 512         for (i = 0; str[i]; i++)
 513                 if (str[i] == c)
 514                         ret++;
 515         return ret;
 516 }
 517
 518 static int strsep_len(const char *str, char c, unsigned int len)
 519 {
 520         unsigned int i;
 521
 522         for (i = 0; str[i]; i++)
 523                 if (str[i] == c) {
 524                         if (len == 0)
 525                                 return i;
 526                         len--;
 527                 }
 528         return (len == 0) ? i : -ERANGE;
 529 }
 530
 531 void xenbus_dev_changed(const char *node, struct xen_bus_type *bus)
 532 {
 533         int exists, rootlen;
 534         struct xenbus_device *dev;
 535         char type[XEN_BUS_ID_SIZE];
 536         const char *p, *root;
 537
 538         if (char_count(node, '/') < 2)
 539                 return;
 540
 541         exists = xenbus_exists(XBT_NIL, node, "");
 542         if (!exists) {
 543                 xenbus_cleanup_devices(node, &bus->bus);
 544                 return;
 545         }
 546
 547         /* backend/<type>/... or device/<type>/... */
 548         p = strchr(node, '/') + 1;
 549         snprintf(type, XEN_BUS_ID_SIZE, "%.*s", (int)strcspn(p, "/"), p);
 550         type[XEN_BUS_ID_SIZE-1] = '\0';
 551
 552         rootlen = strsep_len(node, '/', bus->levels);
 553         if (rootlen < 0)
 554                 return;
 555         root = kasprintf(GFP_KERNEL, "%.*s", rootlen, node);
 556         if (!root)
 557                 return;
 558
 559         dev = xenbus_device_find(root, &bus->bus);
 560         if (!dev)
 561                 xenbus_probe_node(bus, type, root);
 562         else
 563                 put_device(&dev->dev);
 564
 565         kfree(root);
 566 }
 567 EXPORT_SYMBOL_GPL(xenbus_dev_changed);
 568
 569 int xenbus_dev_suspend(struct device *dev)
 570 {
 571         int err = 0;
 572         struct xenbus_driver *drv;
 573         struct xenbus_device *xdev
 574                 = container_of(dev, struct xenbus_device, dev);
 575
 576         DPRINTK("%s", xdev->nodename);
 577
 578         if (dev->driver == NULL)
 579                 return 0;
 580         drv = to_xenbus_driver(dev->driver);
 581         if (drv->suspend)
 582                 err = drv->suspend(xdev);
 583         if (err)
 584                 pr_warn("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                 pr_warn("resume (talk_to_otherend) %s failed: %i\n",
 604                         dev_name(dev), err);
 605                 return err;
 606         }
 607
 608         xdev->state = XenbusStateInitialising;
 609
 610         if (drv->resume) {
 611                 err = drv->resume(xdev);
 612                 if (err) {
 613                         pr_warn("resume %s failed: %i\n", dev_name(dev), err);
 614                         return err;
 615                 }
 616         }
 617
 618         err = watch_otherend(xdev);
 619         if (err) {
 620                 pr_warn("resume (watch_otherend) %s failed: %d.\n",
 621                         dev_name(dev), err);
 622                 return err;
 623         }
 624
 625         return 0;
 626 }
 627 EXPORT_SYMBOL_GPL(xenbus_dev_resume);
 628
 629 int xenbus_dev_cancel(struct device *dev)
 630 {
 631         /* Do nothing */
 632         DPRINTK("cancel");
 633         return 0;
 634 }
 635 EXPORT_SYMBOL_GPL(xenbus_dev_cancel);
 636
 637 /* A flag to determine if xenstored is 'ready' (i.e. has started) */
 638 int xenstored_ready;
 639
 640
 641 int register_xenstore_notifier(struct notifier_block *nb)
 642 {
 643         int ret = 0;
 644
 645         if (xenstored_ready > 0)
 646                 ret = nb->notifier_call(nb, 0, NULL);
 647         else
 648                 blocking_notifier_chain_register(&xenstore_chain, nb);
 649
 650         return ret;
 651 }
 652 EXPORT_SYMBOL_GPL(register_xenstore_notifier);
 653
 654 void unregister_xenstore_notifier(struct notifier_block *nb)
 655 {
 656         blocking_notifier_chain_unregister(&xenstore_chain, nb);
 657 }
 658 EXPORT_SYMBOL_GPL(unregister_xenstore_notifier);
 659
 660 void xenbus_probe(struct work_struct *unused)
 661 {
 662         xenstored_ready = 1;
 663
 664         /* Notify others that xenstore is up */
 665         blocking_notifier_call_chain(&xenstore_chain, 0, NULL);
 666 }
 667 EXPORT_SYMBOL_GPL(xenbus_probe);
 668
 669 static int __init xenbus_probe_initcall(void)
 670 {
 671         if (!xen_domain())
 672                 return -ENODEV;
 673
 674         if (xen_initial_domain() || xen_hvm_domain())
 675                 return 0;
 676
 677         xenbus_probe(NULL);
 678         return 0;
 679 }
 680
 681 device_initcall(xenbus_probe_initcall);
 682
 683 /* Set up event channel for xenstored which is run as a local process
 684  * (this is normally used only in dom0)
 685  */
 686 static int __init xenstored_local_init(void)
 687 {
 688         int err = 0;
 689         unsigned long page = 0;
 690         struct evtchn_alloc_unbound alloc_unbound;
 691
 692         /* Allocate Xenstore page */
 693         page = get_zeroed_page(GFP_KERNEL);
 694         if (!page)
 695                 goto out_err;
 696
 697         xen_store_mfn = xen_start_info->store_mfn =
 698                 pfn_to_mfn(virt_to_phys((void *)page) >>
 699                            PAGE_SHIFT);
 700
 701         /* Next allocate a local port which xenstored can bind to */
 702         alloc_unbound.dom        = DOMID_SELF;
 703         alloc_unbound.remote_dom = DOMID_SELF;
 704
 705         err = HYPERVISOR_event_channel_op(EVTCHNOP_alloc_unbound,
 706                                           &alloc_unbound);
 707         if (err == -ENOSYS)
 708                 goto out_err;
 709
 710         BUG_ON(err);
 711         xen_store_evtchn = xen_start_info->store_evtchn =
 712                 alloc_unbound.port;
 713
 714         return 0;
 715
 716  out_err:
 717         if (page != 0)
 718                 free_page(page);
 719         return err;
 720 }
 721
 722 static int __init xenbus_init(void)
 723 {
 724         int err = 0;
 725         uint64_t v = 0;
 726         xen_store_domain_type = XS_UNKNOWN;
 727
 728         if (!xen_domain())
 729                 return -ENODEV;
 730
 731         xenbus_ring_ops_init();
 732
 733         if (xen_pv_domain())
 734                 xen_store_domain_type = XS_PV;
 735         if (xen_hvm_domain())
 736                 xen_store_domain_type = XS_HVM;
 737         if (xen_hvm_domain() && xen_initial_domain())
 738                 xen_store_domain_type = XS_LOCAL;
 739         if (xen_pv_domain() && !xen_start_info->store_evtchn)
 740                 xen_store_domain_type = XS_LOCAL;
 741         if (xen_pv_domain() && xen_start_info->store_evtchn)
 742                 xenstored_ready = 1;
 743
 744         switch (xen_store_domain_type) {
 745         case XS_LOCAL:
 746                 err = xenstored_local_init();
 747                 if (err)
 748                         goto out_error;
 749                 xen_store_interface = mfn_to_virt(xen_store_mfn);
 750                 break;
 751         case XS_PV:
 752                 xen_store_evtchn = xen_start_info->store_evtchn;
 753                 xen_store_mfn = xen_start_info->store_mfn;
 754                 xen_store_interface = mfn_to_virt(xen_store_mfn);
 755                 break;
 756         case XS_HVM:
 757                 err = hvm_get_parameter(HVM_PARAM_STORE_EVTCHN, &v);
 758                 if (err)
 759                         goto out_error;
 760                 xen_store_evtchn = (int)v;
 761                 err = hvm_get_parameter(HVM_PARAM_STORE_PFN, &v);
 762                 if (err)
 763                         goto out_error;
 764                 xen_store_mfn = (unsigned long)v;
 765                 xen_store_interface =
 766                         xen_remap(xen_store_mfn << PAGE_SHIFT, PAGE_SIZE);
 767                 break;
 768         default:
 769                 pr_warn("Xenstore state unknown\n");
 770                 break;
 771         }
 772
 773         /* Initialize the interface to xenstore. */
 774         err = xs_init();
 775         if (err) {
 776                 pr_warn("Error initializing xenstore comms: %i\n", err);
 777                 goto out_error;
 778         }
 779
 780 #ifdef CONFIG_XEN_COMPAT_XENFS
 781         /*
 782          * Create xenfs mountpoint in /proc for compatibility with
 783          * utilities that expect to find "xenbus" under "/proc/xen".
 784          */
 785         proc_mkdir("xen", NULL);
 786 #endif
 787
 788 out_error:
 789         return err;
 790 }
 791
 792 postcore_initcall(xenbus_init);
 793
 794 MODULE_LICENSE("GPL");