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 #define dev_fmt pr_fmt
  35
  36 #define DPRINTK(fmt, args...)                           \
  37         pr_debug("xenbus_probe (%s:%d) " fmt ".\n",     \
  38                  __func__, __LINE__, ##args)
  39
  40 #include <linux/kernel.h>
  41 #include <linux/err.h>
  42 #include <linux/string.h>
  43 #include <linux/ctype.h>
  44 #include <linux/fcntl.h>
  45 #include <linux/mm.h>
  46 #include <linux/proc_fs.h>
  47 #include <linux/notifier.h>
  48 #include <linux/kthread.h>
  49 #include <linux/mutex.h>
  50 #include <linux/io.h>
  51 #include <linux/slab.h>
  52 #include <linux/module.h>
  53
  54 #include <asm/page.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_will_handle,
 140                                     bus->otherend_changed,
 141                                     "%s/%s", dev->otherend, "state");
 142 }
 143
 144
 145 int xenbus_read_otherend_details(struct xenbus_device *xendev,
 146                                  char *id_node, char *path_node)
 147 {
 148         int err = xenbus_gather(XBT_NIL, xendev->nodename,
 149                                 id_node, "%i", &xendev->otherend_id,
 150                                 path_node, NULL, &xendev->otherend,
 151                                 NULL);
 152         if (err) {
 153                 xenbus_dev_fatal(xendev, err,
 154                                  "reading other end details from %s",
 155                                  xendev->nodename);
 156                 return err;
 157         }
 158         if (strlen(xendev->otherend) == 0 ||
 159             !xenbus_exists(XBT_NIL, xendev->otherend, "")) {
 160                 xenbus_dev_fatal(xendev, -ENOENT,
 161                                  "unable to read other end from %s.  "
 162                                  "missing or inaccessible.",
 163                                  xendev->nodename);
 164                 free_otherend_details(xendev);
 165                 return -ENOENT;
 166         }
 167
 168         return 0;
 169 }
 170 EXPORT_SYMBOL_GPL(xenbus_read_otherend_details);
 171
 172 void xenbus_otherend_changed(struct xenbus_watch *watch,
 173                              const char *path, const char *token,
 174                              int ignore_on_shutdown)
 175 {
 176         struct xenbus_device *dev =
 177                 container_of(watch, struct xenbus_device, otherend_watch);
 178         struct xenbus_driver *drv = to_xenbus_driver(dev->dev.driver);
 179         enum xenbus_state state;
 180
 181         /* Protect us against watches firing on old details when the otherend
 182            details change, say immediately after a resume. */
 183         if (!dev->otherend ||
 184             strncmp(dev->otherend, path, strlen(dev->otherend))) {
 185                 dev_dbg(&dev->dev, "Ignoring watch at %s\n", path);
 186                 return;
 187         }
 188
 189         state = xenbus_read_driver_state(dev->otherend);
 190
 191         dev_dbg(&dev->dev, "state is %d, (%s), %s, %s\n",
 192                 state, xenbus_strstate(state), dev->otherend_watch.node, path);
 193
 194         /*
 195          * Ignore xenbus transitions during shutdown. This prevents us doing
 196          * work that can fail e.g., when the rootfs is gone.
 197          */
 198         if (system_state > SYSTEM_RUNNING) {
 199                 if (ignore_on_shutdown && (state == XenbusStateClosing))
 200                         xenbus_frontend_closed(dev);
 201                 return;
 202         }
 203
 204         if (drv->otherend_changed)
 205                 drv->otherend_changed(dev, state);
 206 }
 207 EXPORT_SYMBOL_GPL(xenbus_otherend_changed);
 208
 209 int xenbus_dev_probe(struct device *_dev)
 210 {
 211         struct xenbus_device *dev = to_xenbus_device(_dev);
 212         struct xenbus_driver *drv = to_xenbus_driver(_dev->driver);
 213         const struct xenbus_device_id *id;
 214         int err;
 215
 216         DPRINTK("%s", dev->nodename);
 217
 218         if (!drv->probe) {
 219                 err = -ENODEV;
 220                 goto fail;
 221         }
 222
 223         id = match_device(drv->ids, dev);
 224         if (!id) {
 225                 err = -ENODEV;
 226                 goto fail;
 227         }
 228
 229         err = talk_to_otherend(dev);
 230         if (err) {
 231                 dev_warn(&dev->dev, "talk_to_otherend on %s failed.\n",
 232                          dev->nodename);
 233                 return err;
 234         }
 235
 236         if (!try_module_get(drv->driver.owner)) {
 237                 dev_warn(&dev->dev, "failed to acquire module reference on '%s'\n",
 238                          drv->driver.name);
 239                 err = -ESRCH;
 240                 goto fail;
 241         }
 242
 243         down(&dev->reclaim_sem);
 244         err = drv->probe(dev, id);
 245         up(&dev->reclaim_sem);
 246         if (err)
 247                 goto fail_put;
 248
 249         err = watch_otherend(dev);
 250         if (err) {
 251                 dev_warn(&dev->dev, "watch_otherend on %s failed.\n",
 252                        dev->nodename);
 253                 return err;
 254         }
 255
 256         return 0;
 257 fail_put:
 258         module_put(drv->driver.owner);
 259 fail:
 260         xenbus_dev_error(dev, err, "xenbus_dev_probe on %s", dev->nodename);
 261         return err;
 262 }
 263 EXPORT_SYMBOL_GPL(xenbus_dev_probe);
 264
 265 int xenbus_dev_remove(struct device *_dev)
 266 {
 267         struct xenbus_device *dev = to_xenbus_device(_dev);
 268         struct xenbus_driver *drv = to_xenbus_driver(_dev->driver);
 269
 270         DPRINTK("%s", dev->nodename);
 271
 272         free_otherend_watch(dev);
 273
 274         if (drv->remove) {
 275                 down(&dev->reclaim_sem);
 276                 drv->remove(dev);
 277                 up(&dev->reclaim_sem);
 278         }
 279
 280         module_put(drv->driver.owner);
 281
 282         free_otherend_details(dev);
 283
 284         /*
 285          * If the toolstack has forced the device state to closing then set
 286          * the state to closed now to allow it to be cleaned up.
 287          * Similarly, if the driver does not support re-bind, set the
 288          * closed.
 289          */
 290         if (!drv->allow_rebind ||
 291             xenbus_read_driver_state(dev->nodename) == XenbusStateClosing)
 292                 xenbus_switch_state(dev, XenbusStateClosed);
 293
 294         return 0;
 295 }
 296 EXPORT_SYMBOL_GPL(xenbus_dev_remove);
 297
 298 int xenbus_register_driver_common(struct xenbus_driver *drv,
 299                                   struct xen_bus_type *bus,
 300                                   struct module *owner, const char *mod_name)
 301 {
 302         drv->driver.name = drv->name ? drv->name : drv->ids[0].devicetype;
 303         drv->driver.bus = &bus->bus;
 304         drv->driver.owner = owner;
 305         drv->driver.mod_name = mod_name;
 306
 307         return driver_register(&drv->driver);
 308 }
 309 EXPORT_SYMBOL_GPL(xenbus_register_driver_common);
 310
 311 void xenbus_unregister_driver(struct xenbus_driver *drv)
 312 {
 313         driver_unregister(&drv->driver);
 314 }
 315 EXPORT_SYMBOL_GPL(xenbus_unregister_driver);
 316
 317 struct xb_find_info {
 318         struct xenbus_device *dev;
 319         const char *nodename;
 320 };
 321
 322 static int cmp_dev(struct device *dev, void *data)
 323 {
 324         struct xenbus_device *xendev = to_xenbus_device(dev);
 325         struct xb_find_info *info = data;
 326
 327         if (!strcmp(xendev->nodename, info->nodename)) {
 328                 info->dev = xendev;
 329                 get_device(dev);
 330                 return 1;
 331         }
 332         return 0;
 333 }
 334
 335 static struct xenbus_device *xenbus_device_find(const char *nodename,
 336                                                 struct bus_type *bus)
 337 {
 338         struct xb_find_info info = { .dev = NULL, .nodename = nodename };
 339
 340         bus_for_each_dev(bus, NULL, &info, cmp_dev);
 341         return info.dev;
 342 }
 343
 344 static int cleanup_dev(struct device *dev, void *data)
 345 {
 346         struct xenbus_device *xendev = to_xenbus_device(dev);
 347         struct xb_find_info *info = data;
 348         int len = strlen(info->nodename);
 349
 350         DPRINTK("%s", info->nodename);
 351
 352         /* Match the info->nodename path, or any subdirectory of that path. */
 353         if (strncmp(xendev->nodename, info->nodename, len))
 354                 return 0;
 355
 356         /* If the node name is longer, ensure it really is a subdirectory. */
 357         if ((strlen(xendev->nodename) > len) && (xendev->nodename[len] != '/'))
 358                 return 0;
 359
 360         info->dev = xendev;
 361         get_device(dev);
 362         return 1;
 363 }
 364
 365 static void xenbus_cleanup_devices(const char *path, struct bus_type *bus)
 366 {
 367         struct xb_find_info info = { .nodename = path };
 368
 369         do {
 370                 info.dev = NULL;
 371                 bus_for_each_dev(bus, NULL, &info, cleanup_dev);
 372                 if (info.dev) {
 373                         device_unregister(&info.dev->dev);
 374                         put_device(&info.dev->dev);
 375                 }
 376         } while (info.dev);
 377 }
 378
 379 static void xenbus_dev_release(struct device *dev)
 380 {
 381         if (dev)
 382                 kfree(to_xenbus_device(dev));
 383 }
 384
 385 static ssize_t nodename_show(struct device *dev,
 386                              struct device_attribute *attr, char *buf)
 387 {
 388         return sprintf(buf, "%s\n", to_xenbus_device(dev)->nodename);
 389 }
 390 static DEVICE_ATTR_RO(nodename);
 391
 392 static ssize_t devtype_show(struct device *dev,
 393                             struct device_attribute *attr, char *buf)
 394 {
 395         return sprintf(buf, "%s\n", to_xenbus_device(dev)->devicetype);
 396 }
 397 static DEVICE_ATTR_RO(devtype);
 398
 399 static ssize_t modalias_show(struct device *dev,
 400                              struct device_attribute *attr, char *buf)
 401 {
 402         return sprintf(buf, "%s:%s\n", dev->bus->name,
 403                        to_xenbus_device(dev)->devicetype);
 404 }
 405 static DEVICE_ATTR_RO(modalias);
 406
 407 static ssize_t state_show(struct device *dev,
 408                             struct device_attribute *attr, char *buf)
 409 {
 410         return sprintf(buf, "%s\n",
 411                         xenbus_strstate(to_xenbus_device(dev)->state));
 412 }
 413 static DEVICE_ATTR_RO(state);
 414
 415 static struct attribute *xenbus_dev_attrs[] = {
 416         &dev_attr_nodename.attr,
 417         &dev_attr_devtype.attr,
 418         &dev_attr_modalias.attr,
 419         &dev_attr_state.attr,
 420         NULL,
 421 };
 422
 423 static const struct attribute_group xenbus_dev_group = {
 424         .attrs = xenbus_dev_attrs,
 425 };
 426
 427 const struct attribute_group *xenbus_dev_groups[] = {
 428         &xenbus_dev_group,
 429         NULL,
 430 };
 431 EXPORT_SYMBOL_GPL(xenbus_dev_groups);
 432
 433 int xenbus_probe_node(struct xen_bus_type *bus,
 434                       const char *type,
 435                       const char *nodename)
 436 {
 437         char devname[XEN_BUS_ID_SIZE];
 438         int err;
 439         struct xenbus_device *xendev;
 440         size_t stringlen;
 441         char *tmpstring;
 442
 443         enum xenbus_state state = xenbus_read_driver_state(nodename);
 444
 445         if (state != XenbusStateInitialising) {
 446                 /* Device is not new, so ignore it.  This can happen if a
 447                    device is going away after switching to Closed.  */
 448                 return 0;
 449         }
 450
 451         stringlen = strlen(nodename) + 1 + strlen(type) + 1;
 452         xendev = kzalloc(sizeof(*xendev) + stringlen, GFP_KERNEL);
 453         if (!xendev)
 454                 return -ENOMEM;
 455
 456         xendev->state = XenbusStateInitialising;
 457
 458         /* Copy the strings into the extra space. */
 459
 460         tmpstring = (char *)(xendev + 1);
 461         strcpy(tmpstring, nodename);
 462         xendev->nodename = tmpstring;
 463
 464         tmpstring += strlen(tmpstring) + 1;
 465         strcpy(tmpstring, type);
 466         xendev->devicetype = tmpstring;
 467         init_completion(&xendev->down);
 468
 469         xendev->dev.bus = &bus->bus;
 470         xendev->dev.release = xenbus_dev_release;
 471
 472         err = bus->get_bus_id(devname, xendev->nodename);
 473         if (err)
 474                 goto fail;
 475
 476         dev_set_name(&xendev->dev, "%s", devname);
 477         sema_init(&xendev->reclaim_sem, 1);
 478
 479         /* Register with generic device framework. */
 480         err = device_register(&xendev->dev);
 481         if (err) {
 482                 put_device(&xendev->dev);
 483                 xendev = NULL;
 484                 goto fail;
 485         }
 486
 487         return 0;
 488 fail:
 489         kfree(xendev);
 490         return err;
 491 }
 492 EXPORT_SYMBOL_GPL(xenbus_probe_node);
 493
 494 static int xenbus_probe_device_type(struct xen_bus_type *bus, const char *type)
 495 {
 496         int err = 0;
 497         char **dir;
 498         unsigned int dir_n = 0;
 499         int i;
 500
 501         dir = xenbus_directory(XBT_NIL, bus->root, type, &dir_n);
 502         if (IS_ERR(dir))
 503                 return PTR_ERR(dir);
 504
 505         for (i = 0; i < dir_n; i++) {
 506                 err = bus->probe(bus, type, dir[i]);
 507                 if (err)
 508                         break;
 509         }
 510
 511         kfree(dir);
 512         return err;
 513 }
 514
 515 int xenbus_probe_devices(struct xen_bus_type *bus)
 516 {
 517         int err = 0;
 518         char **dir;
 519         unsigned int i, dir_n;
 520
 521         dir = xenbus_directory(XBT_NIL, bus->root, "", &dir_n);
 522         if (IS_ERR(dir))
 523                 return PTR_ERR(dir);
 524
 525         for (i = 0; i < dir_n; i++) {
 526                 err = xenbus_probe_device_type(bus, dir[i]);
 527                 if (err)
 528                         break;
 529         }
 530
 531         kfree(dir);
 532         return err;
 533 }
 534 EXPORT_SYMBOL_GPL(xenbus_probe_devices);
 535
 536 static unsigned int char_count(const char *str, char c)
 537 {
 538         unsigned int i, ret = 0;
 539
 540         for (i = 0; str[i]; i++)
 541                 if (str[i] == c)
 542                         ret++;
 543         return ret;
 544 }
 545
 546 static int strsep_len(const char *str, char c, unsigned int len)
 547 {
 548         unsigned int i;
 549
 550         for (i = 0; str[i]; i++)
 551                 if (str[i] == c) {
 552                         if (len == 0)
 553                                 return i;
 554                         len--;
 555                 }
 556         return (len == 0) ? i : -ERANGE;
 557 }
 558
 559 void xenbus_dev_changed(const char *node, struct xen_bus_type *bus)
 560 {
 561         int exists, rootlen;
 562         struct xenbus_device *dev;
 563         char type[XEN_BUS_ID_SIZE];
 564         const char *p, *root;
 565
 566         if (char_count(node, '/') < 2)
 567                 return;
 568
 569         exists = xenbus_exists(XBT_NIL, node, "");
 570         if (!exists) {
 571                 xenbus_cleanup_devices(node, &bus->bus);
 572                 return;
 573         }
 574
 575         /* backend/<type>/... or device/<type>/... */
 576         p = strchr(node, '/') + 1;
 577         snprintf(type, XEN_BUS_ID_SIZE, "%.*s", (int)strcspn(p, "/"), p);
 578         type[XEN_BUS_ID_SIZE-1] = '\0';
 579
 580         rootlen = strsep_len(node, '/', bus->levels);
 581         if (rootlen < 0)
 582                 return;
 583         root = kasprintf(GFP_KERNEL, "%.*s", rootlen, node);
 584         if (!root)
 585                 return;
 586
 587         dev = xenbus_device_find(root, &bus->bus);
 588         if (!dev)
 589                 xenbus_probe_node(bus, type, root);
 590         else
 591                 put_device(&dev->dev);
 592
 593         kfree(root);
 594 }
 595 EXPORT_SYMBOL_GPL(xenbus_dev_changed);
 596
 597 int xenbus_dev_suspend(struct device *dev)
 598 {
 599         int err = 0;
 600         struct xenbus_driver *drv;
 601         struct xenbus_device *xdev
 602                 = container_of(dev, struct xenbus_device, dev);
 603
 604         DPRINTK("%s", xdev->nodename);
 605
 606         if (dev->driver == NULL)
 607                 return 0;
 608         drv = to_xenbus_driver(dev->driver);
 609         if (drv->suspend)
 610                 err = drv->suspend(xdev);
 611         if (err)
 612                 dev_warn(dev, "suspend failed: %i\n", err);
 613         return 0;
 614 }
 615 EXPORT_SYMBOL_GPL(xenbus_dev_suspend);
 616
 617 int xenbus_dev_resume(struct device *dev)
 618 {
 619         int err;
 620         struct xenbus_driver *drv;
 621         struct xenbus_device *xdev
 622                 = container_of(dev, struct xenbus_device, dev);
 623
 624         DPRINTK("%s", xdev->nodename);
 625
 626         if (dev->driver == NULL)
 627                 return 0;
 628         drv = to_xenbus_driver(dev->driver);
 629         err = talk_to_otherend(xdev);
 630         if (err) {
 631                 dev_warn(dev, "resume (talk_to_otherend) failed: %i\n", err);
 632                 return err;
 633         }
 634
 635         xdev->state = XenbusStateInitialising;
 636
 637         if (drv->resume) {
 638                 err = drv->resume(xdev);
 639                 if (err) {
 640                         dev_warn(dev, "resume failed: %i\n", err);
 641                         return err;
 642                 }
 643         }
 644
 645         err = watch_otherend(xdev);
 646         if (err) {
 647                 dev_warn(dev, "resume (watch_otherend) failed: %d\n", err);
 648                 return err;
 649         }
 650
 651         return 0;
 652 }
 653 EXPORT_SYMBOL_GPL(xenbus_dev_resume);
 654
 655 int xenbus_dev_cancel(struct device *dev)
 656 {
 657         /* Do nothing */
 658         DPRINTK("cancel");
 659         return 0;
 660 }
 661 EXPORT_SYMBOL_GPL(xenbus_dev_cancel);
 662
 663 /* A flag to determine if xenstored is 'ready' (i.e. has started) */
 664 int xenstored_ready;
 665
 666
 667 int register_xenstore_notifier(struct notifier_block *nb)
 668 {
 669         int ret = 0;
 670
 671         if (xenstored_ready > 0)
 672                 ret = nb->notifier_call(nb, 0, NULL);
 673         else
 674                 blocking_notifier_chain_register(&xenstore_chain, nb);
 675
 676         return ret;
 677 }
 678 EXPORT_SYMBOL_GPL(register_xenstore_notifier);
 679
 680 void unregister_xenstore_notifier(struct notifier_block *nb)
 681 {
 682         blocking_notifier_chain_unregister(&xenstore_chain, nb);
 683 }
 684 EXPORT_SYMBOL_GPL(unregister_xenstore_notifier);
 685
 686 void xenbus_probe(struct work_struct *unused)
 687 {
 688         xenstored_ready = 1;
 689
 690         /* Notify others that xenstore is up */
 691         blocking_notifier_call_chain(&xenstore_chain, 0, NULL);
 692 }
 693 EXPORT_SYMBOL_GPL(xenbus_probe);
 694
 695 static int __init xenbus_probe_initcall(void)
 696 {
 697         if (!xen_domain())
 698                 return -ENODEV;
 699
 700         if (xen_initial_domain() || xen_hvm_domain())
 701                 return 0;
 702
 703         xenbus_probe(NULL);
 704         return 0;
 705 }
 706
 707 device_initcall(xenbus_probe_initcall);
 708
 709 /* Set up event channel for xenstored which is run as a local process
 710  * (this is normally used only in dom0)
 711  */
 712 static int __init xenstored_local_init(void)
 713 {
 714         int err = -ENOMEM;
 715         unsigned long page = 0;
 716         struct evtchn_alloc_unbound alloc_unbound;
 717
 718         /* Allocate Xenstore page */
 719         page = get_zeroed_page(GFP_KERNEL);
 720         if (!page)
 721                 goto out_err;
 722
 723         xen_store_gfn = virt_to_gfn((void *)page);
 724
 725         /* Next allocate a local port which xenstored can bind to */
 726         alloc_unbound.dom        = DOMID_SELF;
 727         alloc_unbound.remote_dom = DOMID_SELF;
 728
 729         err = HYPERVISOR_event_channel_op(EVTCHNOP_alloc_unbound,
 730                                           &alloc_unbound);
 731         if (err == -ENOSYS)
 732                 goto out_err;
 733
 734         BUG_ON(err);
 735         xen_store_evtchn = alloc_unbound.port;
 736
 737         return 0;
 738
 739  out_err:
 740         if (page != 0)
 741                 free_page(page);
 742         return err;
 743 }
 744
 745 static int xenbus_resume_cb(struct notifier_block *nb,
 746                             unsigned long action, void *data)
 747 {
 748         int err = 0;
 749
 750         if (xen_hvm_domain()) {
 751                 uint64_t v = 0;
 752
 753                 err = hvm_get_parameter(HVM_PARAM_STORE_EVTCHN, &v);
 754                 if (!err && v)
 755                         xen_store_evtchn = v;
 756                 else
 757                         pr_warn("Cannot update xenstore event channel: %d\n",
 758                                 err);
 759         } else
 760                 xen_store_evtchn = xen_start_info->store_evtchn;
 761
 762         return err;
 763 }
 764
 765 static struct notifier_block xenbus_resume_nb = {
 766         .notifier_call = xenbus_resume_cb,
 767 };
 768
 769 static int __init xenbus_init(void)
 770 {
 771         int err = 0;
 772         uint64_t v = 0;
 773         xen_store_domain_type = XS_UNKNOWN;
 774
 775         if (!xen_domain())
 776                 return -ENODEV;
 777
 778         xenbus_ring_ops_init();
 779
 780         if (xen_pv_domain())
 781                 xen_store_domain_type = XS_PV;
 782         if (xen_hvm_domain())
 783                 xen_store_domain_type = XS_HVM;
 784         if (xen_hvm_domain() && xen_initial_domain())
 785                 xen_store_domain_type = XS_LOCAL;
 786         if (xen_pv_domain() && !xen_start_info->store_evtchn)
 787                 xen_store_domain_type = XS_LOCAL;
 788         if (xen_pv_domain() && xen_start_info->store_evtchn)
 789                 xenstored_ready = 1;
 790
 791         switch (xen_store_domain_type) {
 792         case XS_LOCAL:
 793                 err = xenstored_local_init();
 794                 if (err)
 795                         goto out_error;
 796                 xen_store_interface = gfn_to_virt(xen_store_gfn);
 797                 break;
 798         case XS_PV:
 799                 xen_store_evtchn = xen_start_info->store_evtchn;
 800                 xen_store_gfn = xen_start_info->store_mfn;
 801                 xen_store_interface = gfn_to_virt(xen_store_gfn);
 802                 break;
 803         case XS_HVM:
 804                 err = hvm_get_parameter(HVM_PARAM_STORE_EVTCHN, &v);
 805                 if (err)
 806                         goto out_error;
 807                 xen_store_evtchn = (int)v;
 808                 err = hvm_get_parameter(HVM_PARAM_STORE_PFN, &v);
 809                 if (err)
 810                         goto out_error;
 811                 xen_store_gfn = (unsigned long)v;
 812                 xen_store_interface =
 813                         xen_remap(xen_store_gfn << XEN_PAGE_SHIFT,
 814                                   XEN_PAGE_SIZE);
 815                 break;
 816         default:
 817                 pr_warn("Xenstore state unknown\n");
 818                 break;
 819         }
 820
 821         /* Initialize the interface to xenstore. */
 822         err = xs_init();
 823         if (err) {
 824                 pr_warn("Error initializing xenstore comms: %i\n", err);
 825                 goto out_error;
 826         }
 827
 828         if ((xen_store_domain_type != XS_LOCAL) &&
 829             (xen_store_domain_type != XS_UNKNOWN))
 830                 xen_resume_notifier_register(&xenbus_resume_nb);
 831
 832 #ifdef CONFIG_XEN_COMPAT_XENFS
 833         /*
 834          * Create xenfs mountpoint in /proc for compatibility with
 835          * utilities that expect to find "xenbus" under "/proc/xen".
 836          */
 837         proc_create_mount_point("xen");
 838 #endif
 839
 840 out_error:
 841         return err;
 842 }
 843
 844 postcore_initcall(xenbus_init);
 845
 846 MODULE_LICENSE("GPL");