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