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         err = drv->probe(dev, id);
 236         if (err)
 237                 goto fail;
 238
 239         err = watch_otherend(dev);
 240         if (err) {
 241                 dev_warn(&dev->dev, "watch_otherend on %s failed.\n",
 242                        dev->nodename);
 243                 return err;
 244         }
 245
 246         return 0;
 247 fail:
 248         xenbus_dev_error(dev, err, "xenbus_dev_probe on %s", dev->nodename);
 249         xenbus_switch_state(dev, XenbusStateClosed);
 250         return err;
 251 }
 252 EXPORT_SYMBOL_GPL(xenbus_dev_probe);
 253
 254 int xenbus_dev_remove(struct device *_dev)
 255 {
 256         struct xenbus_device *dev = to_xenbus_device(_dev);
 257         struct xenbus_driver *drv = to_xenbus_driver(_dev->driver);
 258
 259         DPRINTK("%s", dev->nodename);
 260
 261         free_otherend_watch(dev);
 262
 263         if (drv->remove)
 264                 drv->remove(dev);
 265
 266         free_otherend_details(dev);
 267
 268         xenbus_switch_state(dev, XenbusStateClosed);
 269         return 0;
 270 }
 271 EXPORT_SYMBOL_GPL(xenbus_dev_remove);
 272
 273 void xenbus_dev_shutdown(struct device *_dev)
 274 {
 275         struct xenbus_device *dev = to_xenbus_device(_dev);
 276         unsigned long timeout = 5*HZ;
 277
 278         DPRINTK("%s", dev->nodename);
 279
 280         get_device(&dev->dev);
 281         if (dev->state != XenbusStateConnected) {
 282                 pr_info("%s: %s: %s != Connected, skipping\n",
 283                         __func__, dev->nodename, xenbus_strstate(dev->state));
 284                 goto out;
 285         }
 286         xenbus_switch_state(dev, XenbusStateClosing);
 287         timeout = wait_for_completion_timeout(&dev->down, timeout);
 288         if (!timeout)
 289                 pr_info("%s: %s timeout closing device\n",
 290                         __func__, dev->nodename);
 291  out:
 292         put_device(&dev->dev);
 293 }
 294 EXPORT_SYMBOL_GPL(xenbus_dev_shutdown);
 295
 296 int xenbus_register_driver_common(struct xenbus_driver *drv,
 297                                   struct xen_bus_type *bus,
 298                                   struct module *owner, const char *mod_name)
 299 {
 300         drv->driver.name = drv->name ? drv->name : drv->ids[0].devicetype;
 301         drv->driver.bus = &bus->bus;
 302         drv->driver.owner = owner;
 303         drv->driver.mod_name = mod_name;
 304
 305         return driver_register(&drv->driver);
 306 }
 307 EXPORT_SYMBOL_GPL(xenbus_register_driver_common);
 308
 309 void xenbus_unregister_driver(struct xenbus_driver *drv)
 310 {
 311         driver_unregister(&drv->driver);
 312 }
 313 EXPORT_SYMBOL_GPL(xenbus_unregister_driver);
 314
 315 struct xb_find_info {
 316         struct xenbus_device *dev;
 317         const char *nodename;
 318 };
 319
 320 static int cmp_dev(struct device *dev, void *data)
 321 {
 322         struct xenbus_device *xendev = to_xenbus_device(dev);
 323         struct xb_find_info *info = data;
 324
 325         if (!strcmp(xendev->nodename, info->nodename)) {
 326                 info->dev = xendev;
 327                 get_device(dev);
 328                 return 1;
 329         }
 330         return 0;
 331 }
 332
 333 static struct xenbus_device *xenbus_device_find(const char *nodename,
 334                                                 struct bus_type *bus)
 335 {
 336         struct xb_find_info info = { .dev = NULL, .nodename = nodename };
 337
 338         bus_for_each_dev(bus, NULL, &info, cmp_dev);
 339         return info.dev;
 340 }
 341
 342 static int cleanup_dev(struct device *dev, void *data)
 343 {
 344         struct xenbus_device *xendev = to_xenbus_device(dev);
 345         struct xb_find_info *info = data;
 346         int len = strlen(info->nodename);
 347
 348         DPRINTK("%s", info->nodename);
 349
 350         /* Match the info->nodename path, or any subdirectory of that path. */
 351         if (strncmp(xendev->nodename, info->nodename, len))
 352                 return 0;
 353
 354         /* If the node name is longer, ensure it really is a subdirectory. */
 355         if ((strlen(xendev->nodename) > len) && (xendev->nodename[len] != '/'))
 356                 return 0;
 357
 358         info->dev = xendev;
 359         get_device(dev);
 360         return 1;
 361 }
 362
 363 static void xenbus_cleanup_devices(const char *path, struct bus_type *bus)
 364 {
 365         struct xb_find_info info = { .nodename = path };
 366
 367         do {
 368                 info.dev = NULL;
 369                 bus_for_each_dev(bus, NULL, &info, cleanup_dev);
 370                 if (info.dev) {
 371                         device_unregister(&info.dev->dev);
 372                         put_device(&info.dev->dev);
 373                 }
 374         } while (info.dev);
 375 }
 376
 377 static void xenbus_dev_release(struct device *dev)
 378 {
 379         if (dev)
 380                 kfree(to_xenbus_device(dev));
 381 }
 382
 383 static ssize_t nodename_show(struct device *dev,
 384                              struct device_attribute *attr, char *buf)
 385 {
 386         return sprintf(buf, "%s\n", to_xenbus_device(dev)->nodename);
 387 }
 388 static DEVICE_ATTR_RO(nodename);
 389
 390 static ssize_t devtype_show(struct device *dev,
 391                             struct device_attribute *attr, char *buf)
 392 {
 393         return sprintf(buf, "%s\n", to_xenbus_device(dev)->devicetype);
 394 }
 395 static DEVICE_ATTR_RO(devtype);
 396
 397 static ssize_t modalias_show(struct device *dev,
 398                              struct device_attribute *attr, char *buf)
 399 {
 400         return sprintf(buf, "%s:%s\n", dev->bus->name,
 401                        to_xenbus_device(dev)->devicetype);
 402 }
 403 static DEVICE_ATTR_RO(modalias);
 404
 405 static struct attribute *xenbus_dev_attrs[] = {
 406         &dev_attr_nodename.attr,
 407         &dev_attr_devtype.attr,
 408         &dev_attr_modalias.attr,
 409         NULL,
 410 };
 411
 412 static const struct attribute_group xenbus_dev_group = {
 413         .attrs = xenbus_dev_attrs,
 414 };
 415
 416 const struct attribute_group *xenbus_dev_groups[] = {
 417         &xenbus_dev_group,
 418         NULL,
 419 };
 420 EXPORT_SYMBOL_GPL(xenbus_dev_groups);
 421
 422 int xenbus_probe_node(struct xen_bus_type *bus,
 423                       const char *type,
 424                       const char *nodename)
 425 {
 426         char devname[XEN_BUS_ID_SIZE];
 427         int err;
 428         struct xenbus_device *xendev;
 429         size_t stringlen;
 430         char *tmpstring;
 431
 432         enum xenbus_state state = xenbus_read_driver_state(nodename);
 433
 434         if (state != XenbusStateInitialising) {
 435                 /* Device is not new, so ignore it.  This can happen if a
 436                    device is going away after switching to Closed.  */
 437                 return 0;
 438         }
 439
 440         stringlen = strlen(nodename) + 1 + strlen(type) + 1;
 441         xendev = kzalloc(sizeof(*xendev) + stringlen, GFP_KERNEL);
 442         if (!xendev)
 443                 return -ENOMEM;
 444
 445         xendev->state = XenbusStateInitialising;
 446
 447         /* Copy the strings into the extra space. */
 448
 449         tmpstring = (char *)(xendev + 1);
 450         strcpy(tmpstring, nodename);
 451         xendev->nodename = tmpstring;
 452
 453         tmpstring += strlen(tmpstring) + 1;
 454         strcpy(tmpstring, type);
 455         xendev->devicetype = tmpstring;
 456         init_completion(&xendev->down);
 457
 458         xendev->dev.bus = &bus->bus;
 459         xendev->dev.release = xenbus_dev_release;
 460
 461         err = bus->get_bus_id(devname, xendev->nodename);
 462         if (err)
 463                 goto fail;
 464
 465         dev_set_name(&xendev->dev, "%s", devname);
 466
 467         /* Register with generic device framework. */
 468         err = device_register(&xendev->dev);
 469         if (err) {
 470                 put_device(&xendev->dev);
 471                 xendev = NULL;
 472                 goto fail;
 473         }
 474
 475         return 0;
 476 fail:
 477         kfree(xendev);
 478         return err;
 479 }
 480 EXPORT_SYMBOL_GPL(xenbus_probe_node);
 481
 482 static int xenbus_probe_device_type(struct xen_bus_type *bus, const char *type)
 483 {
 484         int err = 0;
 485         char **dir;
 486         unsigned int dir_n = 0;
 487         int i;
 488
 489         dir = xenbus_directory(XBT_NIL, bus->root, type, &dir_n);
 490         if (IS_ERR(dir))
 491                 return PTR_ERR(dir);
 492
 493         for (i = 0; i < dir_n; i++) {
 494                 err = bus->probe(bus, type, dir[i]);
 495                 if (err)
 496                         break;
 497         }
 498
 499         kfree(dir);
 500         return err;
 501 }
 502
 503 int xenbus_probe_devices(struct xen_bus_type *bus)
 504 {
 505         int err = 0;
 506         char **dir;
 507         unsigned int i, dir_n;
 508
 509         dir = xenbus_directory(XBT_NIL, bus->root, "", &dir_n);
 510         if (IS_ERR(dir))
 511                 return PTR_ERR(dir);
 512
 513         for (i = 0; i < dir_n; i++) {
 514                 err = xenbus_probe_device_type(bus, dir[i]);
 515                 if (err)
 516                         break;
 517         }
 518
 519         kfree(dir);
 520         return err;
 521 }
 522 EXPORT_SYMBOL_GPL(xenbus_probe_devices);
 523
 524 static unsigned int char_count(const char *str, char c)
 525 {
 526         unsigned int i, ret = 0;
 527
 528         for (i = 0; str[i]; i++)
 529                 if (str[i] == c)
 530                         ret++;
 531         return ret;
 532 }
 533
 534 static int strsep_len(const char *str, char c, unsigned int len)
 535 {
 536         unsigned int i;
 537
 538         for (i = 0; str[i]; i++)
 539                 if (str[i] == c) {
 540                         if (len == 0)
 541                                 return i;
 542                         len--;
 543                 }
 544         return (len == 0) ? i : -ERANGE;
 545 }
 546
 547 void xenbus_dev_changed(const char *node, struct xen_bus_type *bus)
 548 {
 549         int exists, rootlen;
 550         struct xenbus_device *dev;
 551         char type[XEN_BUS_ID_SIZE];
 552         const char *p, *root;
 553
 554         if (char_count(node, '/') < 2)
 555                 return;
 556
 557         exists = xenbus_exists(XBT_NIL, node, "");
 558         if (!exists) {
 559                 xenbus_cleanup_devices(node, &bus->bus);
 560                 return;
 561         }
 562
 563         /* backend/<type>/... or device/<type>/... */
 564         p = strchr(node, '/') + 1;
 565         snprintf(type, XEN_BUS_ID_SIZE, "%.*s", (int)strcspn(p, "/"), p);
 566         type[XEN_BUS_ID_SIZE-1] = '\0';
 567
 568         rootlen = strsep_len(node, '/', bus->levels);
 569         if (rootlen < 0)
 570                 return;
 571         root = kasprintf(GFP_KERNEL, "%.*s", rootlen, node);
 572         if (!root)
 573                 return;
 574
 575         dev = xenbus_device_find(root, &bus->bus);
 576         if (!dev)
 577                 xenbus_probe_node(bus, type, root);
 578         else
 579                 put_device(&dev->dev);
 580
 581         kfree(root);
 582 }
 583 EXPORT_SYMBOL_GPL(xenbus_dev_changed);
 584
 585 int xenbus_dev_suspend(struct device *dev)
 586 {
 587         int err = 0;
 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         if (drv->suspend)
 598                 err = drv->suspend(xdev);
 599         if (err)
 600                 pr_warn("suspend %s failed: %i\n", dev_name(dev), err);
 601         return 0;
 602 }
 603 EXPORT_SYMBOL_GPL(xenbus_dev_suspend);
 604
 605 int xenbus_dev_resume(struct device *dev)
 606 {
 607         int err;
 608         struct xenbus_driver *drv;
 609         struct xenbus_device *xdev
 610                 = container_of(dev, struct xenbus_device, dev);
 611
 612         DPRINTK("%s", xdev->nodename);
 613
 614         if (dev->driver == NULL)
 615                 return 0;
 616         drv = to_xenbus_driver(dev->driver);
 617         err = talk_to_otherend(xdev);
 618         if (err) {
 619                 pr_warn("resume (talk_to_otherend) %s failed: %i\n",
 620                         dev_name(dev), err);
 621                 return err;
 622         }
 623
 624         xdev->state = XenbusStateInitialising;
 625
 626         if (drv->resume) {
 627                 err = drv->resume(xdev);
 628                 if (err) {
 629                         pr_warn("resume %s failed: %i\n", dev_name(dev), err);
 630                         return err;
 631                 }
 632         }
 633
 634         err = watch_otherend(xdev);
 635         if (err) {
 636                 pr_warn("resume (watch_otherend) %s failed: %d.\n",
 637                         dev_name(dev), err);
 638                 return err;
 639         }
 640
 641         return 0;
 642 }
 643 EXPORT_SYMBOL_GPL(xenbus_dev_resume);
 644
 645 int xenbus_dev_cancel(struct device *dev)
 646 {
 647         /* Do nothing */
 648         DPRINTK("cancel");
 649         return 0;
 650 }
 651 EXPORT_SYMBOL_GPL(xenbus_dev_cancel);
 652
 653 /* A flag to determine if xenstored is 'ready' (i.e. has started) */
 654 int xenstored_ready;
 655
 656
 657 int register_xenstore_notifier(struct notifier_block *nb)
 658 {
 659         int ret = 0;
 660
 661         if (xenstored_ready > 0)
 662                 ret = nb->notifier_call(nb, 0, NULL);
 663         else
 664                 blocking_notifier_chain_register(&xenstore_chain, nb);
 665
 666         return ret;
 667 }
 668 EXPORT_SYMBOL_GPL(register_xenstore_notifier);
 669
 670 void unregister_xenstore_notifier(struct notifier_block *nb)
 671 {
 672         blocking_notifier_chain_unregister(&xenstore_chain, nb);
 673 }
 674 EXPORT_SYMBOL_GPL(unregister_xenstore_notifier);
 675
 676 void xenbus_probe(struct work_struct *unused)
 677 {
 678         xenstored_ready = 1;
 679
 680         /* Notify others that xenstore is up */
 681         blocking_notifier_call_chain(&xenstore_chain, 0, NULL);
 682 }
 683 EXPORT_SYMBOL_GPL(xenbus_probe);
 684
 685 static int __init xenbus_probe_initcall(void)
 686 {
 687         if (!xen_domain())
 688                 return -ENODEV;
 689
 690         if (xen_initial_domain() || xen_hvm_domain())
 691                 return 0;
 692
 693         xenbus_probe(NULL);
 694         return 0;
 695 }
 696
 697 device_initcall(xenbus_probe_initcall);
 698
 699 /* Set up event channel for xenstored which is run as a local process
 700  * (this is normally used only in dom0)
 701  */
 702 static int __init xenstored_local_init(void)
 703 {
 704         int err = -ENOMEM;
 705         unsigned long page = 0;
 706         struct evtchn_alloc_unbound alloc_unbound;
 707
 708         /* Allocate Xenstore page */
 709         page = get_zeroed_page(GFP_KERNEL);
 710         if (!page)
 711                 goto out_err;
 712
 713         xen_store_gfn = xen_start_info->store_mfn = virt_to_gfn((void *)page);
 714
 715         /* Next allocate a local port which xenstored can bind to */
 716         alloc_unbound.dom        = DOMID_SELF;
 717         alloc_unbound.remote_dom = DOMID_SELF;
 718
 719         err = HYPERVISOR_event_channel_op(EVTCHNOP_alloc_unbound,
 720                                           &alloc_unbound);
 721         if (err == -ENOSYS)
 722                 goto out_err;
 723
 724         BUG_ON(err);
 725         xen_store_evtchn = xen_start_info->store_evtchn =
 726                 alloc_unbound.port;
 727
 728         return 0;
 729
 730  out_err:
 731         if (page != 0)
 732                 free_page(page);
 733         return err;
 734 }
 735
 736 static int xenbus_resume_cb(struct notifier_block *nb,
 737                             unsigned long action, void *data)
 738 {
 739         int err = 0;
 740
 741         if (xen_hvm_domain()) {
 742                 uint64_t v = 0;
 743
 744                 err = hvm_get_parameter(HVM_PARAM_STORE_EVTCHN, &v);
 745                 if (!err && v)
 746                         xen_store_evtchn = v;
 747                 else
 748                         pr_warn("Cannot update xenstore event channel: %d\n",
 749                                 err);
 750         } else
 751                 xen_store_evtchn = xen_start_info->store_evtchn;
 752
 753         return err;
 754 }
 755
 756 static struct notifier_block xenbus_resume_nb = {
 757         .notifier_call = xenbus_resume_cb,
 758 };
 759
 760 static int __init xenbus_init(void)
 761 {
 762         int err = 0;
 763         uint64_t v = 0;
 764         xen_store_domain_type = XS_UNKNOWN;
 765
 766         if (!xen_domain())
 767                 return -ENODEV;
 768
 769         xenbus_ring_ops_init();
 770
 771         if (xen_pv_domain())
 772                 xen_store_domain_type = XS_PV;
 773         if (xen_hvm_domain())
 774                 xen_store_domain_type = XS_HVM;
 775         if (xen_hvm_domain() && xen_initial_domain())
 776                 xen_store_domain_type = XS_LOCAL;
 777         if (xen_pv_domain() && !xen_start_info->store_evtchn)
 778                 xen_store_domain_type = XS_LOCAL;
 779         if (xen_pv_domain() && xen_start_info->store_evtchn)
 780                 xenstored_ready = 1;
 781
 782         switch (xen_store_domain_type) {
 783         case XS_LOCAL:
 784                 err = xenstored_local_init();
 785                 if (err)
 786                         goto out_error;
 787                 xen_store_interface = gfn_to_virt(xen_store_gfn);
 788                 break;
 789         case XS_PV:
 790                 xen_store_evtchn = xen_start_info->store_evtchn;
 791                 xen_store_gfn = xen_start_info->store_mfn;
 792                 xen_store_interface = gfn_to_virt(xen_store_gfn);
 793                 break;
 794         case XS_HVM:
 795                 err = hvm_get_parameter(HVM_PARAM_STORE_EVTCHN, &v);
 796                 if (err)
 797                         goto out_error;
 798                 xen_store_evtchn = (int)v;
 799                 err = hvm_get_parameter(HVM_PARAM_STORE_PFN, &v);
 800                 if (err)
 801                         goto out_error;
 802                 xen_store_gfn = (unsigned long)v;
 803                 xen_store_interface =
 804                         xen_remap(xen_store_gfn << XEN_PAGE_SHIFT,
 805                                   XEN_PAGE_SIZE);
 806                 break;
 807         default:
 808                 pr_warn("Xenstore state unknown\n");
 809                 break;
 810         }
 811
 812         /* Initialize the interface to xenstore. */
 813         err = xs_init();
 814         if (err) {
 815                 pr_warn("Error initializing xenstore comms: %i\n", err);
 816                 goto out_error;
 817         }
 818
 819         if ((xen_store_domain_type != XS_LOCAL) &&
 820             (xen_store_domain_type != XS_UNKNOWN))
 821                 xen_resume_notifier_register(&xenbus_resume_nb);
 822
 823 #ifdef CONFIG_XEN_COMPAT_XENFS
 824         /*
 825          * Create xenfs mountpoint in /proc for compatibility with
 826          * utilities that expect to find "xenbus" under "/proc/xen".
 827          */
 828         proc_create_mount_point("xen");
 829 #endif
 830
 831 out_error:
 832         return err;
 833 }
 834
 835 postcore_initcall(xenbus_init);
 836
 837 MODULE_LICENSE("GPL");