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/xen-ops.h>
  61 #include <xen/page.h>
  62
  63 #include <xen/hvm.h>
  64
  65 #include "xenbus.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_gfn;
  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 *path, const char *token,
 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, path, strlen(dev->otherend))) {
 184                 dev_dbg(&dev->dev, "Ignoring watch at %s\n", path);
 185                 return;
 186         }
 187
 188         state = xenbus_read_driver_state(dev->otherend);
 189
 190         dev_dbg(&dev->dev, "state is %d, (%s), %s, %s\n",
 191                 state, xenbus_strstate(state), dev->otherend_watch.node, path);
 192
 193         /*
 194          * Ignore xenbus transitions during shutdown. This prevents us doing
 195          * work that can fail e.g., when the rootfs is gone.
 196          */
 197         if (system_state > SYSTEM_RUNNING) {
 198                 if (ignore_on_shutdown && (state == XenbusStateClosing))
 199                         xenbus_frontend_closed(dev);
 200                 return;
 201         }
 202
 203         if (drv->otherend_changed)
 204                 drv->otherend_changed(dev, state);
 205 }
 206 EXPORT_SYMBOL_GPL(xenbus_otherend_changed);
 207
 208 int xenbus_dev_probe(struct device *_dev)
 209 {
 210         struct xenbus_device *dev = to_xenbus_device(_dev);
 211         struct xenbus_driver *drv = to_xenbus_driver(_dev->driver);
 212         const struct xenbus_device_id *id;
 213         int err;
 214
 215         DPRINTK("%s", dev->nodename);
 216
 217         if (!drv->probe) {
 218                 err = -ENODEV;
 219                 goto fail;
 220         }
 221
 222         id = match_device(drv->ids, dev);
 223         if (!id) {
 224                 err = -ENODEV;
 225                 goto fail;
 226         }
 227
 228         err = talk_to_otherend(dev);
 229         if (err) {
 230                 dev_warn(&dev->dev, "talk_to_otherend on %s failed.\n",
 231                          dev->nodename);
 232                 return err;
 233         }
 234
 235         if (!try_module_get(drv->driver.owner)) {
 236                 dev_warn(&dev->dev, "failed to acquire module reference on '%s'\n",
 237                          drv->driver.name);
 238                 err = -ESRCH;
 239                 goto fail;
 240         }
 241
 242         down(&dev->reclaim_sem);
 243         err = drv->probe(dev, id);
 244         up(&dev->reclaim_sem);
 245         if (err)
 246                 goto fail_put;
 247
 248         err = watch_otherend(dev);
 249         if (err) {
 250                 dev_warn(&dev->dev, "watch_otherend on %s failed.\n",
 251                        dev->nodename);
 252                 return err;
 253         }
 254
 255         return 0;
 256 fail_put:
 257         module_put(drv->driver.owner);
 258 fail:
 259         xenbus_dev_error(dev, err, "xenbus_dev_probe on %s", dev->nodename);
 260         return err;
 261 }
 262 EXPORT_SYMBOL_GPL(xenbus_dev_probe);
 263
 264 int xenbus_dev_remove(struct device *_dev)
 265 {
 266         struct xenbus_device *dev = to_xenbus_device(_dev);
 267         struct xenbus_driver *drv = to_xenbus_driver(_dev->driver);
 268
 269         DPRINTK("%s", dev->nodename);
 270
 271         free_otherend_watch(dev);
 272
 273         if (drv->remove) {
 274                 down(&dev->reclaim_sem);
 275                 drv->remove(dev);
 276                 up(&dev->reclaim_sem);
 277         }
 278
 279         module_put(drv->driver.owner);
 280
 281         free_otherend_details(dev);
 282
 283         /*
 284          * If the toolstack has forced the device state to closing then set
 285          * the state to closed now to allow it to be cleaned up.
 286          * Similarly, if the driver does not support re-bind, set the
 287          * closed.
 288          */
 289         if (!drv->allow_rebind ||
 290             xenbus_read_driver_state(dev->nodename) == XenbusStateClosing)
 291                 xenbus_switch_state(dev, XenbusStateClosed);
 292
 293         return 0;
 294 }
 295 EXPORT_SYMBOL_GPL(xenbus_dev_remove);
 296
 297 int xenbus_register_driver_common(struct xenbus_driver *drv,
 298                                   struct xen_bus_type *bus,
 299                                   struct module *owner, const char *mod_name)
 300 {
 301         drv->driver.name = drv->name ? drv->name : drv->ids[0].devicetype;
 302         drv->driver.bus = &bus->bus;
 303         drv->driver.owner = owner;
 304         drv->driver.mod_name = mod_name;
 305
 306         return driver_register(&drv->driver);
 307 }
 308 EXPORT_SYMBOL_GPL(xenbus_register_driver_common);
 309
 310 void xenbus_unregister_driver(struct xenbus_driver *drv)
 311 {
 312         driver_unregister(&drv->driver);
 313 }
 314 EXPORT_SYMBOL_GPL(xenbus_unregister_driver);
 315
 316 struct xb_find_info {
 317         struct xenbus_device *dev;
 318         const char *nodename;
 319 };
 320
 321 static int cmp_dev(struct device *dev, void *data)
 322 {
 323         struct xenbus_device *xendev = to_xenbus_device(dev);
 324         struct xb_find_info *info = data;
 325
 326         if (!strcmp(xendev->nodename, info->nodename)) {
 327                 info->dev = xendev;
 328                 get_device(dev);
 329                 return 1;
 330         }
 331         return 0;
 332 }
 333
 334 static struct xenbus_device *xenbus_device_find(const char *nodename,
 335                                                 struct bus_type *bus)
 336 {
 337         struct xb_find_info info = { .dev = NULL, .nodename = nodename };
 338
 339         bus_for_each_dev(bus, NULL, &info, cmp_dev);
 340         return info.dev;
 341 }
 342
 343 static int cleanup_dev(struct device *dev, void *data)
 344 {
 345         struct xenbus_device *xendev = to_xenbus_device(dev);
 346         struct xb_find_info *info = data;
 347         int len = strlen(info->nodename);
 348
 349         DPRINTK("%s", info->nodename);
 350
 351         /* Match the info->nodename path, or any subdirectory of that path. */
 352         if (strncmp(xendev->nodename, info->nodename, len))
 353                 return 0;
 354
 355         /* If the node name is longer, ensure it really is a subdirectory. */
 356         if ((strlen(xendev->nodename) > len) && (xendev->nodename[len] != '/'))
 357                 return 0;
 358
 359         info->dev = xendev;
 360         get_device(dev);
 361         return 1;
 362 }
 363
 364 static void xenbus_cleanup_devices(const char *path, struct bus_type *bus)
 365 {
 366         struct xb_find_info info = { .nodename = path };
 367
 368         do {
 369                 info.dev = NULL;
 370                 bus_for_each_dev(bus, NULL, &info, cleanup_dev);
 371                 if (info.dev) {
 372                         device_unregister(&info.dev->dev);
 373                         put_device(&info.dev->dev);
 374                 }
 375         } while (info.dev);
 376 }
 377
 378 static void xenbus_dev_release(struct device *dev)
 379 {
 380         if (dev)
 381                 kfree(to_xenbus_device(dev));
 382 }
 383
 384 static ssize_t nodename_show(struct device *dev,
 385                              struct device_attribute *attr, char *buf)
 386 {
 387         return sprintf(buf, "%s\n", to_xenbus_device(dev)->nodename);
 388 }
 389 static DEVICE_ATTR_RO(nodename);
 390
 391 static ssize_t devtype_show(struct device *dev,
 392                             struct device_attribute *attr, char *buf)
 393 {
 394         return sprintf(buf, "%s\n", to_xenbus_device(dev)->devicetype);
 395 }
 396 static DEVICE_ATTR_RO(devtype);
 397
 398 static ssize_t modalias_show(struct device *dev,
 399                              struct device_attribute *attr, char *buf)
 400 {
 401         return sprintf(buf, "%s:%s\n", dev->bus->name,
 402                        to_xenbus_device(dev)->devicetype);
 403 }
 404 static DEVICE_ATTR_RO(modalias);
 405
 406 static ssize_t state_show(struct device *dev,
 407                             struct device_attribute *attr, char *buf)
 408 {
 409         return sprintf(buf, "%s\n",
 410                         xenbus_strstate(to_xenbus_device(dev)->state));
 411 }
 412 static DEVICE_ATTR_RO(state);
 413
 414 static struct attribute *xenbus_dev_attrs[] = {
 415         &dev_attr_nodename.attr,
 416         &dev_attr_devtype.attr,
 417         &dev_attr_modalias.attr,
 418         &dev_attr_state.attr,
 419         NULL,
 420 };
 421
 422 static const struct attribute_group xenbus_dev_group = {
 423         .attrs = xenbus_dev_attrs,
 424 };
 425
 426 const struct attribute_group *xenbus_dev_groups[] = {
 427         &xenbus_dev_group,
 428         NULL,
 429 };
 430 EXPORT_SYMBOL_GPL(xenbus_dev_groups);
 431
 432 int xenbus_probe_node(struct xen_bus_type *bus,
 433                       const char *type,
 434                       const char *nodename)
 435 {
 436         char devname[XEN_BUS_ID_SIZE];
 437         int err;
 438         struct xenbus_device *xendev;
 439         size_t stringlen;
 440         char *tmpstring;
 441
 442         enum xenbus_state state = xenbus_read_driver_state(nodename);
 443
 444         if (state != XenbusStateInitialising) {
 445                 /* Device is not new, so ignore it.  This can happen if a
 446                    device is going away after switching to Closed.  */
 447                 return 0;
 448         }
 449
 450         stringlen = strlen(nodename) + 1 + strlen(type) + 1;
 451         xendev = kzalloc(sizeof(*xendev) + stringlen, GFP_KERNEL);
 452         if (!xendev)
 453                 return -ENOMEM;
 454
 455         xendev->state = XenbusStateInitialising;
 456
 457         /* Copy the strings into the extra space. */
 458
 459         tmpstring = (char *)(xendev + 1);
 460         strcpy(tmpstring, nodename);
 461         xendev->nodename = tmpstring;
 462
 463         tmpstring += strlen(tmpstring) + 1;
 464         strcpy(tmpstring, type);
 465         xendev->devicetype = tmpstring;
 466         init_completion(&xendev->down);
 467
 468         xendev->dev.bus = &bus->bus;
 469         xendev->dev.release = xenbus_dev_release;
 470
 471         err = bus->get_bus_id(devname, xendev->nodename);
 472         if (err)
 473                 goto fail;
 474
 475         dev_set_name(&xendev->dev, "%s", devname);
 476         sema_init(&xendev->reclaim_sem, 1);
 477
 478         /* Register with generic device framework. */
 479         err = device_register(&xendev->dev);
 480         if (err) {
 481                 put_device(&xendev->dev);
 482                 xendev = NULL;
 483                 goto fail;
 484         }
 485
 486         return 0;
 487 fail:
 488         kfree(xendev);
 489         return err;
 490 }
 491 EXPORT_SYMBOL_GPL(xenbus_probe_node);
 492
 493 static int xenbus_probe_device_type(struct xen_bus_type *bus, const char *type)
 494 {
 495         int err = 0;
 496         char **dir;
 497         unsigned int dir_n = 0;
 498         int i;
 499
 500         dir = xenbus_directory(XBT_NIL, bus->root, type, &dir_n);
 501         if (IS_ERR(dir))
 502                 return PTR_ERR(dir);
 503
 504         for (i = 0; i < dir_n; i++) {
 505                 err = bus->probe(bus, type, dir[i]);
 506                 if (err)
 507                         break;
 508         }
 509
 510         kfree(dir);
 511         return err;
 512 }
 513
 514 int xenbus_probe_devices(struct xen_bus_type *bus)
 515 {
 516         int err = 0;
 517         char **dir;
 518         unsigned int i, dir_n;
 519
 520         dir = xenbus_directory(XBT_NIL, bus->root, "", &dir_n);
 521         if (IS_ERR(dir))
 522                 return PTR_ERR(dir);
 523
 524         for (i = 0; i < dir_n; i++) {
 525                 err = xenbus_probe_device_type(bus, dir[i]);
 526                 if (err)
 527                         break;
 528         }
 529
 530         kfree(dir);
 531         return err;
 532 }
 533 EXPORT_SYMBOL_GPL(xenbus_probe_devices);
 534
 535 static unsigned int char_count(const char *str, char c)
 536 {
 537         unsigned int i, ret = 0;
 538
 539         for (i = 0; str[i]; i++)
 540                 if (str[i] == c)
 541                         ret++;
 542         return ret;
 543 }
 544
 545 static int strsep_len(const char *str, char c, unsigned int len)
 546 {
 547         unsigned int i;
 548
 549         for (i = 0; str[i]; i++)
 550                 if (str[i] == c) {
 551                         if (len == 0)
 552                                 return i;
 553                         len--;
 554                 }
 555         return (len == 0) ? i : -ERANGE;
 556 }
 557
 558 void xenbus_dev_changed(const char *node, struct xen_bus_type *bus)
 559 {
 560         int exists, rootlen;
 561         struct xenbus_device *dev;
 562         char type[XEN_BUS_ID_SIZE];
 563         const char *p, *root;
 564
 565         if (char_count(node, '/') < 2)
 566                 return;
 567
 568         exists = xenbus_exists(XBT_NIL, node, "");
 569         if (!exists) {
 570                 xenbus_cleanup_devices(node, &bus->bus);
 571                 return;
 572         }
 573
 574         /* backend/<type>/... or device/<type>/... */
 575         p = strchr(node, '/') + 1;
 576         snprintf(type, XEN_BUS_ID_SIZE, "%.*s", (int)strcspn(p, "/"), p);
 577         type[XEN_BUS_ID_SIZE-1] = '\0';
 578
 579         rootlen = strsep_len(node, '/', bus->levels);
 580         if (rootlen < 0)
 581                 return;
 582         root = kasprintf(GFP_KERNEL, "%.*s", rootlen, node);
 583         if (!root)
 584                 return;
 585
 586         dev = xenbus_device_find(root, &bus->bus);
 587         if (!dev)
 588                 xenbus_probe_node(bus, type, root);
 589         else
 590                 put_device(&dev->dev);
 591
 592         kfree(root);
 593 }
 594 EXPORT_SYMBOL_GPL(xenbus_dev_changed);
 595
 596 int xenbus_dev_suspend(struct device *dev)
 597 {
 598         int err = 0;
 599         struct xenbus_driver *drv;
 600         struct xenbus_device *xdev
 601                 = container_of(dev, struct xenbus_device, dev);
 602
 603         DPRINTK("%s", xdev->nodename);
 604
 605         if (dev->driver == NULL)
 606                 return 0;
 607         drv = to_xenbus_driver(dev->driver);
 608         if (drv->suspend)
 609                 err = drv->suspend(xdev);
 610         if (err)
 611                 pr_warn("suspend %s failed: %i\n", dev_name(dev), err);
 612         return 0;
 613 }
 614 EXPORT_SYMBOL_GPL(xenbus_dev_suspend);
 615
 616 int xenbus_dev_resume(struct device *dev)
 617 {
 618         int err;
 619         struct xenbus_driver *drv;
 620         struct xenbus_device *xdev
 621                 = container_of(dev, struct xenbus_device, dev);
 622
 623         DPRINTK("%s", xdev->nodename);
 624
 625         if (dev->driver == NULL)
 626                 return 0;
 627         drv = to_xenbus_driver(dev->driver);
 628         err = talk_to_otherend(xdev);
 629         if (err) {
 630                 pr_warn("resume (talk_to_otherend) %s failed: %i\n",
 631                         dev_name(dev), err);
 632                 return err;
 633         }
 634
 635         xdev->state = XenbusStateInitialising;
 636
 637         if (drv->resume) {
 638                 err = drv->resume(xdev);
 639                 if (err) {
 640                         pr_warn("resume %s failed: %i\n", dev_name(dev), err);
 641                         return err;
 642                 }
 643         }
 644
 645         err = watch_otherend(xdev);
 646         if (err) {
 647                 pr_warn("resume (watch_otherend) %s failed: %d.\n",
 648                         dev_name(dev), err);
 649                 return err;
 650         }
 651
 652         return 0;
 653 }
 654 EXPORT_SYMBOL_GPL(xenbus_dev_resume);
 655
 656 int xenbus_dev_cancel(struct device *dev)
 657 {
 658         /* Do nothing */
 659         DPRINTK("cancel");
 660         return 0;
 661 }
 662 EXPORT_SYMBOL_GPL(xenbus_dev_cancel);
 663
 664 /* A flag to determine if xenstored is 'ready' (i.e. has started) */
 665 int xenstored_ready;
 666
 667
 668 int register_xenstore_notifier(struct notifier_block *nb)
 669 {
 670         int ret = 0;
 671
 672         if (xenstored_ready > 0)
 673                 ret = nb->notifier_call(nb, 0, NULL);
 674         else
 675                 blocking_notifier_chain_register(&xenstore_chain, nb);
 676
 677         return ret;
 678 }
 679 EXPORT_SYMBOL_GPL(register_xenstore_notifier);
 680
 681 void unregister_xenstore_notifier(struct notifier_block *nb)
 682 {
 683         blocking_notifier_chain_unregister(&xenstore_chain, nb);
 684 }
 685 EXPORT_SYMBOL_GPL(unregister_xenstore_notifier);
 686
 687 void xenbus_probe(struct work_struct *unused)
 688 {
 689         xenstored_ready = 1;
 690
 691         /* Notify others that xenstore is up */
 692         blocking_notifier_call_chain(&xenstore_chain, 0, NULL);
 693 }
 694 EXPORT_SYMBOL_GPL(xenbus_probe);
 695
 696 static int __init xenbus_probe_initcall(void)
 697 {
 698         if (!xen_domain())
 699                 return -ENODEV;
 700
 701         if (xen_initial_domain() || xen_hvm_domain())
 702                 return 0;
 703
 704         xenbus_probe(NULL);
 705         return 0;
 706 }
 707
 708 device_initcall(xenbus_probe_initcall);
 709
 710 /* Set up event channel for xenstored which is run as a local process
 711  * (this is normally used only in dom0)
 712  */
 713 static int __init xenstored_local_init(void)
 714 {
 715         int err = -ENOMEM;
 716         unsigned long page = 0;
 717         struct evtchn_alloc_unbound alloc_unbound;
 718
 719         /* Allocate Xenstore page */
 720         page = get_zeroed_page(GFP_KERNEL);
 721         if (!page)
 722                 goto out_err;
 723
 724         xen_store_gfn = virt_to_gfn((void *)page);
 725
 726         /* Next allocate a local port which xenstored can bind to */
 727         alloc_unbound.dom        = DOMID_SELF;
 728         alloc_unbound.remote_dom = DOMID_SELF;
 729
 730         err = HYPERVISOR_event_channel_op(EVTCHNOP_alloc_unbound,
 731                                           &alloc_unbound);
 732         if (err == -ENOSYS)
 733                 goto out_err;
 734
 735         BUG_ON(err);
 736         xen_store_evtchn = alloc_unbound.port;
 737
 738         return 0;
 739
 740  out_err:
 741         if (page != 0)
 742                 free_page(page);
 743         return err;
 744 }
 745
 746 static int xenbus_resume_cb(struct notifier_block *nb,
 747                             unsigned long action, void *data)
 748 {
 749         int err = 0;
 750
 751         if (xen_hvm_domain()) {
 752                 uint64_t v = 0;
 753
 754                 err = hvm_get_parameter(HVM_PARAM_STORE_EVTCHN, &v);
 755                 if (!err && v)
 756                         xen_store_evtchn = v;
 757                 else
 758                         pr_warn("Cannot update xenstore event channel: %d\n",
 759                                 err);
 760         } else
 761                 xen_store_evtchn = xen_start_info->store_evtchn;
 762
 763         return err;
 764 }
 765
 766 static struct notifier_block xenbus_resume_nb = {
 767         .notifier_call = xenbus_resume_cb,
 768 };
 769
 770 static int __init xenbus_init(void)
 771 {
 772         int err = 0;
 773         uint64_t v = 0;
 774         xen_store_domain_type = XS_UNKNOWN;
 775
 776         if (!xen_domain())
 777                 return -ENODEV;
 778
 779         xenbus_ring_ops_init();
 780
 781         if (xen_pv_domain())
 782                 xen_store_domain_type = XS_PV;
 783         if (xen_hvm_domain())
 784                 xen_store_domain_type = XS_HVM;
 785         if (xen_hvm_domain() && xen_initial_domain())
 786                 xen_store_domain_type = XS_LOCAL;
 787         if (xen_pv_domain() && !xen_start_info->store_evtchn)
 788                 xen_store_domain_type = XS_LOCAL;
 789         if (xen_pv_domain() && xen_start_info->store_evtchn)
 790                 xenstored_ready = 1;
 791
 792         switch (xen_store_domain_type) {
 793         case XS_LOCAL:
 794                 err = xenstored_local_init();
 795                 if (err)
 796                         goto out_error;
 797                 xen_store_interface = gfn_to_virt(xen_store_gfn);
 798                 break;
 799         case XS_PV:
 800                 xen_store_evtchn = xen_start_info->store_evtchn;
 801                 xen_store_gfn = xen_start_info->store_mfn;
 802                 xen_store_interface = gfn_to_virt(xen_store_gfn);
 803                 break;
 804         case XS_HVM:
 805                 err = hvm_get_parameter(HVM_PARAM_STORE_EVTCHN, &v);
 806                 if (err)
 807                         goto out_error;
 808                 xen_store_evtchn = (int)v;
 809                 err = hvm_get_parameter(HVM_PARAM_STORE_PFN, &v);
 810                 if (err)
 811                         goto out_error;
 812                 xen_store_gfn = (unsigned long)v;
 813                 xen_store_interface =
 814                         xen_remap(xen_store_gfn << XEN_PAGE_SHIFT,
 815                                   XEN_PAGE_SIZE);
 816                 break;
 817         default:
 818                 pr_warn("Xenstore state unknown\n");
 819                 break;
 820         }
 821
 822         /* Initialize the interface to xenstore. */
 823         err = xs_init();
 824         if (err) {
 825                 pr_warn("Error initializing xenstore comms: %i\n", err);
 826                 goto out_error;
 827         }
 828
 829         if ((xen_store_domain_type != XS_LOCAL) &&
 830             (xen_store_domain_type != XS_UNKNOWN))
 831                 xen_resume_notifier_register(&xenbus_resume_nb);
 832
 833 #ifdef CONFIG_XEN_COMPAT_XENFS
 834         /*
 835          * Create xenfs mountpoint in /proc for compatibility with
 836          * utilities that expect to find "xenbus" under "/proc/xen".
 837          */
 838         proc_create_mount_point("xen");
 839 #endif
 840
 841 out_error:
 842         return err;
 843 }
 844
 845 postcore_initcall(xenbus_init);
 846
 847 MODULE_LICENSE("GPL");