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
 261         if (drv->remove)
 262                 drv->remove(dev);
 263
 264         free_otherend_details(dev);
 265
 266         xenbus_switch_state(dev, XenbusStateClosed);
 267         return 0;
 268 }
 269 EXPORT_SYMBOL_GPL(xenbus_dev_remove);
 270
 271 void xenbus_dev_shutdown(struct device *_dev)
 272 {
 273         struct xenbus_device *dev = to_xenbus_device(_dev);
 274         unsigned long timeout = 5*HZ;
 275
 276         DPRINTK("%s", dev->nodename);
 277
 278         get_device(&dev->dev);
 279         if (dev->state != XenbusStateConnected) {
 280                 printk(KERN_INFO "%s: %s: %s != Connected, skipping\n", __func__,
 281                        dev->nodename, xenbus_strstate(dev->state));
 282                 goto out;
 283         }
 284         xenbus_switch_state(dev, XenbusStateClosing);
 285         timeout = wait_for_completion_timeout(&dev->down, timeout);
 286         if (!timeout)
 287                 printk(KERN_INFO "%s: %s timeout closing device\n",
 288                        __func__, dev->nodename);
 289  out:
 290         put_device(&dev->dev);
 291 }
 292 EXPORT_SYMBOL_GPL(xenbus_dev_shutdown);
 293
 294 int xenbus_register_driver_common(struct xenbus_driver *drv,
 295                                   struct xen_bus_type *bus)
 296 {
 297         drv->driver.bus = &bus->bus;
 298
 299         return driver_register(&drv->driver);
 300 }
 301 EXPORT_SYMBOL_GPL(xenbus_register_driver_common);
 302
 303 void xenbus_unregister_driver(struct xenbus_driver *drv)
 304 {
 305         driver_unregister(&drv->driver);
 306 }
 307 EXPORT_SYMBOL_GPL(xenbus_unregister_driver);
 308
 309 struct xb_find_info {
 310         struct xenbus_device *dev;
 311         const char *nodename;
 312 };
 313
 314 static int cmp_dev(struct device *dev, void *data)
 315 {
 316         struct xenbus_device *xendev = to_xenbus_device(dev);
 317         struct xb_find_info *info = data;
 318
 319         if (!strcmp(xendev->nodename, info->nodename)) {
 320                 info->dev = xendev;
 321                 get_device(dev);
 322                 return 1;
 323         }
 324         return 0;
 325 }
 326
 327 static struct xenbus_device *xenbus_device_find(const char *nodename,
 328                                                 struct bus_type *bus)
 329 {
 330         struct xb_find_info info = { .dev = NULL, .nodename = nodename };
 331
 332         bus_for_each_dev(bus, NULL, &info, cmp_dev);
 333         return info.dev;
 334 }
 335
 336 static int cleanup_dev(struct device *dev, void *data)
 337 {
 338         struct xenbus_device *xendev = to_xenbus_device(dev);
 339         struct xb_find_info *info = data;
 340         int len = strlen(info->nodename);
 341
 342         DPRINTK("%s", info->nodename);
 343
 344         /* Match the info->nodename path, or any subdirectory of that path. */
 345         if (strncmp(xendev->nodename, info->nodename, len))
 346                 return 0;
 347
 348         /* If the node name is longer, ensure it really is a subdirectory. */
 349         if ((strlen(xendev->nodename) > len) && (xendev->nodename[len] != '/'))
 350                 return 0;
 351
 352         info->dev = xendev;
 353         get_device(dev);
 354         return 1;
 355 }
 356
 357 static void xenbus_cleanup_devices(const char *path, struct bus_type *bus)
 358 {
 359         struct xb_find_info info = { .nodename = path };
 360
 361         do {
 362                 info.dev = NULL;
 363                 bus_for_each_dev(bus, NULL, &info, cleanup_dev);
 364                 if (info.dev) {
 365                         device_unregister(&info.dev->dev);
 366                         put_device(&info.dev->dev);
 367                 }
 368         } while (info.dev);
 369 }
 370
 371 static void xenbus_dev_release(struct device *dev)
 372 {
 373         if (dev)
 374                 kfree(to_xenbus_device(dev));
 375 }
 376
 377 static ssize_t nodename_show(struct device *dev,
 378                              struct device_attribute *attr, char *buf)
 379 {
 380         return sprintf(buf, "%s\n", to_xenbus_device(dev)->nodename);
 381 }
 382
 383 static ssize_t devtype_show(struct device *dev,
 384                             struct device_attribute *attr, char *buf)
 385 {
 386         return sprintf(buf, "%s\n", to_xenbus_device(dev)->devicetype);
 387 }
 388
 389 static ssize_t modalias_show(struct device *dev,
 390                              struct device_attribute *attr, char *buf)
 391 {
 392         return sprintf(buf, "%s:%s\n", dev->bus->name,
 393                        to_xenbus_device(dev)->devicetype);
 394 }
 395
 396 struct device_attribute xenbus_dev_attrs[] = {
 397         __ATTR_RO(nodename),
 398         __ATTR_RO(devtype),
 399         __ATTR_RO(modalias),
 400         __ATTR_NULL
 401 };
 402 EXPORT_SYMBOL_GPL(xenbus_dev_attrs);
 403
 404 int xenbus_probe_node(struct xen_bus_type *bus,
 405                       const char *type,
 406                       const char *nodename)
 407 {
 408         char devname[XEN_BUS_ID_SIZE];
 409         int err;
 410         struct xenbus_device *xendev;
 411         size_t stringlen;
 412         char *tmpstring;
 413
 414         enum xenbus_state state = xenbus_read_driver_state(nodename);
 415
 416         if (state != XenbusStateInitialising) {
 417                 /* Device is not new, so ignore it.  This can happen if a
 418                    device is going away after switching to Closed.  */
 419                 return 0;
 420         }
 421
 422         stringlen = strlen(nodename) + 1 + strlen(type) + 1;
 423         xendev = kzalloc(sizeof(*xendev) + stringlen, GFP_KERNEL);
 424         if (!xendev)
 425                 return -ENOMEM;
 426
 427         xendev->state = XenbusStateInitialising;
 428
 429         /* Copy the strings into the extra space. */
 430
 431         tmpstring = (char *)(xendev + 1);
 432         strcpy(tmpstring, nodename);
 433         xendev->nodename = tmpstring;
 434
 435         tmpstring += strlen(tmpstring) + 1;
 436         strcpy(tmpstring, type);
 437         xendev->devicetype = tmpstring;
 438         init_completion(&xendev->down);
 439
 440         xendev->dev.bus = &bus->bus;
 441         xendev->dev.release = xenbus_dev_release;
 442
 443         err = bus->get_bus_id(devname, xendev->nodename);
 444         if (err)
 445                 goto fail;
 446
 447         dev_set_name(&xendev->dev, devname);
 448
 449         /* Register with generic device framework. */
 450         err = device_register(&xendev->dev);
 451         if (err)
 452                 goto fail;
 453
 454         return 0;
 455 fail:
 456         kfree(xendev);
 457         return err;
 458 }
 459 EXPORT_SYMBOL_GPL(xenbus_probe_node);
 460
 461 static int xenbus_probe_device_type(struct xen_bus_type *bus, const char *type)
 462 {
 463         int err = 0;
 464         char **dir;
 465         unsigned int dir_n = 0;
 466         int i;
 467
 468         dir = xenbus_directory(XBT_NIL, bus->root, type, &dir_n);
 469         if (IS_ERR(dir))
 470                 return PTR_ERR(dir);
 471
 472         for (i = 0; i < dir_n; i++) {
 473                 err = bus->probe(bus, type, dir[i]);
 474                 if (err)
 475                         break;
 476         }
 477
 478         kfree(dir);
 479         return err;
 480 }
 481
 482 int xenbus_probe_devices(struct xen_bus_type *bus)
 483 {
 484         int err = 0;
 485         char **dir;
 486         unsigned int i, dir_n;
 487
 488         dir = xenbus_directory(XBT_NIL, bus->root, "", &dir_n);
 489         if (IS_ERR(dir))
 490                 return PTR_ERR(dir);
 491
 492         for (i = 0; i < dir_n; i++) {
 493                 err = xenbus_probe_device_type(bus, dir[i]);
 494                 if (err)
 495                         break;
 496         }
 497
 498         kfree(dir);
 499         return err;
 500 }
 501 EXPORT_SYMBOL_GPL(xenbus_probe_devices);
 502
 503 static unsigned int char_count(const char *str, char c)
 504 {
 505         unsigned int i, ret = 0;
 506
 507         for (i = 0; str[i]; i++)
 508                 if (str[i] == c)
 509                         ret++;
 510         return ret;
 511 }
 512
 513 static int strsep_len(const char *str, char c, unsigned int len)
 514 {
 515         unsigned int i;
 516
 517         for (i = 0; str[i]; i++)
 518                 if (str[i] == c) {
 519                         if (len == 0)
 520                                 return i;
 521                         len--;
 522                 }
 523         return (len == 0) ? i : -ERANGE;
 524 }
 525
 526 void xenbus_dev_changed(const char *node, struct xen_bus_type *bus)
 527 {
 528         int exists, rootlen;
 529         struct xenbus_device *dev;
 530         char type[XEN_BUS_ID_SIZE];
 531         const char *p, *root;
 532
 533         if (char_count(node, '/') < 2)
 534                 return;
 535
 536         exists = xenbus_exists(XBT_NIL, node, "");
 537         if (!exists) {
 538                 xenbus_cleanup_devices(node, &bus->bus);
 539                 return;
 540         }
 541
 542         /* backend/<type>/... or device/<type>/... */
 543         p = strchr(node, '/') + 1;
 544         snprintf(type, XEN_BUS_ID_SIZE, "%.*s", (int)strcspn(p, "/"), p);
 545         type[XEN_BUS_ID_SIZE-1] = '\0';
 546
 547         rootlen = strsep_len(node, '/', bus->levels);
 548         if (rootlen < 0)
 549                 return;
 550         root = kasprintf(GFP_KERNEL, "%.*s", rootlen, node);
 551         if (!root)
 552                 return;
 553
 554         dev = xenbus_device_find(root, &bus->bus);
 555         if (!dev)
 556                 xenbus_probe_node(bus, type, root);
 557         else
 558                 put_device(&dev->dev);
 559
 560         kfree(root);
 561 }
 562 EXPORT_SYMBOL_GPL(xenbus_dev_changed);
 563
 564 int xenbus_dev_suspend(struct device *dev)
 565 {
 566         int err = 0;
 567         struct xenbus_driver *drv;
 568         struct xenbus_device *xdev
 569                 = container_of(dev, struct xenbus_device, dev);
 570
 571         DPRINTK("%s", xdev->nodename);
 572
 573         if (dev->driver == NULL)
 574                 return 0;
 575         drv = to_xenbus_driver(dev->driver);
 576         if (drv->suspend)
 577                 err = drv->suspend(xdev);
 578         if (err)
 579                 printk(KERN_WARNING
 580                        "xenbus: suspend %s failed: %i\n", dev_name(dev), err);
 581         return 0;
 582 }
 583 EXPORT_SYMBOL_GPL(xenbus_dev_suspend);
 584
 585 int xenbus_dev_resume(struct device *dev)
 586 {
 587         int err;
 588         struct xenbus_driver *drv;
 589         struct xenbus_device *xdev
 590                 = container_of(dev, struct xenbus_device, dev);
 591
 592         DPRINTK("%s", xdev->nodename);
 593
 594         if (dev->driver == NULL)
 595                 return 0;
 596         drv = to_xenbus_driver(dev->driver);
 597         err = talk_to_otherend(xdev);
 598         if (err) {
 599                 printk(KERN_WARNING
 600                        "xenbus: resume (talk_to_otherend) %s failed: %i\n",
 601                        dev_name(dev), err);
 602                 return err;
 603         }
 604
 605         xdev->state = XenbusStateInitialising;
 606
 607         if (drv->resume) {
 608                 err = drv->resume(xdev);
 609                 if (err) {
 610                         printk(KERN_WARNING
 611                                "xenbus: resume %s failed: %i\n",
 612                                dev_name(dev), err);
 613                         return err;
 614                 }
 615         }
 616
 617         err = watch_otherend(xdev);
 618         if (err) {
 619                 printk(KERN_WARNING
 620                        "xenbus_probe: resume (watch_otherend) %s failed: "
 621                        "%d.\n", 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 enum xenstore_init {
 723         UNKNOWN,
 724         PV,
 725         HVM,
 726         LOCAL,
 727 };
 728 static int __init xenbus_init(void)
 729 {
 730         int err = 0;
 731         enum xenstore_init usage = UNKNOWN;
 732         uint64_t v = 0;
 733
 734         if (!xen_domain())
 735                 return -ENODEV;
 736
 737         xenbus_ring_ops_init();
 738
 739         if (xen_pv_domain())
 740                 usage = PV;
 741         if (xen_hvm_domain())
 742                 usage = HVM;
 743         if (xen_hvm_domain() && xen_initial_domain())
 744                 usage = LOCAL;
 745         if (xen_pv_domain() && !xen_start_info->store_evtchn)
 746                 usage = LOCAL;
 747         if (xen_pv_domain() && xen_start_info->store_evtchn)
 748                 xenstored_ready = 1;
 749
 750         switch (usage) {
 751         case LOCAL:
 752                 err = xenstored_local_init();
 753                 if (err)
 754                         goto out_error;
 755                 xen_store_interface = mfn_to_virt(xen_store_mfn);
 756                 break;
 757         case PV:
 758                 xen_store_evtchn = xen_start_info->store_evtchn;
 759                 xen_store_mfn = xen_start_info->store_mfn;
 760                 xen_store_interface = mfn_to_virt(xen_store_mfn);
 761                 break;
 762         case HVM:
 763                 err = hvm_get_parameter(HVM_PARAM_STORE_EVTCHN, &v);
 764                 if (err)
 765                         goto out_error;
 766                 xen_store_evtchn = (int)v;
 767                 err = hvm_get_parameter(HVM_PARAM_STORE_PFN, &v);
 768                 if (err)
 769                         goto out_error;
 770                 xen_store_mfn = (unsigned long)v;
 771                 xen_store_interface =
 772                         xen_remap(xen_store_mfn << PAGE_SHIFT, PAGE_SIZE);
 773                 break;
 774         default:
 775                 pr_warn("Xenstore state unknown\n");
 776                 break;
 777         }
 778
 779         /* Initialize the interface to xenstore. */
 780         err = xs_init();
 781         if (err) {
 782                 printk(KERN_WARNING
 783                        "XENBUS: Error initializing xenstore comms: %i\n", err);
 784                 goto out_error;
 785         }
 786
 787 #ifdef CONFIG_XEN_COMPAT_XENFS
 788         /*
 789          * Create xenfs mountpoint in /proc for compatibility with
 790          * utilities that expect to find "xenbus" under "/proc/xen".
 791          */
 792         proc_mkdir("xen", NULL);
 793 #endif
 794
 795 out_error:
 796         return err;
 797 }
 798
 799 postcore_initcall(xenbus_init);
 800
 801 MODULE_LICENSE("GPL");