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_comms.h"
  66 #include "xenbus_probe.h"
  67
  68
  69 int xen_store_evtchn;
  70 EXPORT_SYMBOL_GPL(xen_store_evtchn);
  71
  72 struct xenstore_domain_interface *xen_store_interface;
  73 EXPORT_SYMBOL_GPL(xen_store_interface);
  74
  75 enum xenstore_init xen_store_domain_type;
  76 EXPORT_SYMBOL_GPL(xen_store_domain_type);
  77
  78 static unsigned long xen_store_gfn;
  79
  80 static BLOCKING_NOTIFIER_HEAD(xenstore_chain);
  81
  82 /* If something in array of ids matches this device, return it. */
  83 static const struct xenbus_device_id *
  84 match_device(const struct xenbus_device_id *arr, struct xenbus_device *dev)
  85 {
  86         for (; *arr->devicetype != '\0'; arr++) {
  87                 if (!strcmp(arr->devicetype, dev->devicetype))
  88                         return arr;
  89         }
  90         return NULL;
  91 }
  92
  93 int xenbus_match(struct device *_dev, struct device_driver *_drv)
  94 {
  95         struct xenbus_driver *drv = to_xenbus_driver(_drv);
  96
  97         if (!drv->ids)
  98                 return 0;
  99
 100         return match_device(drv->ids, to_xenbus_device(_dev)) != NULL;
 101 }
 102 EXPORT_SYMBOL_GPL(xenbus_match);
 103
 104
 105 static void free_otherend_details(struct xenbus_device *dev)
 106 {
 107         kfree(dev->otherend);
 108         dev->otherend = NULL;
 109 }
 110
 111
 112 static void free_otherend_watch(struct xenbus_device *dev)
 113 {
 114         if (dev->otherend_watch.node) {
 115                 unregister_xenbus_watch(&dev->otherend_watch);
 116                 kfree(dev->otherend_watch.node);
 117                 dev->otherend_watch.node = NULL;
 118         }
 119 }
 120
 121
 122 static int talk_to_otherend(struct xenbus_device *dev)
 123 {
 124         struct xenbus_driver *drv = to_xenbus_driver(dev->dev.driver);
 125
 126         free_otherend_watch(dev);
 127         free_otherend_details(dev);
 128
 129         return drv->read_otherend_details(dev);
 130 }
 131
 132
 133
 134 static int watch_otherend(struct xenbus_device *dev)
 135 {
 136         struct xen_bus_type *bus =
 137                 container_of(dev->dev.bus, struct xen_bus_type, bus);
 138
 139         return xenbus_watch_pathfmt(dev, &dev->otherend_watch,
 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 **vec, unsigned int len,
 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, vec[XS_WATCH_PATH],
 185                     strlen(dev->otherend))) {
 186                 dev_dbg(&dev->dev, "Ignoring watch at %s\n",
 187                         vec[XS_WATCH_PATH]);
 188                 return;
 189         }
 190
 191         state = xenbus_read_driver_state(dev->otherend);
 192
 193         dev_dbg(&dev->dev, "state is %d, (%s), %s, %s\n",
 194                 state, xenbus_strstate(state), dev->otherend_watch.node,
 195                 vec[XS_WATCH_PATH]);
 196
 197         /*
 198          * Ignore xenbus transitions during shutdown. This prevents us doing
 199          * work that can fail e.g., when the rootfs is gone.
 200          */
 201         if (system_state > SYSTEM_RUNNING) {
 202                 if (ignore_on_shutdown && (state == XenbusStateClosing))
 203                         xenbus_frontend_closed(dev);
 204                 return;
 205         }
 206
 207         if (drv->otherend_changed)
 208                 drv->otherend_changed(dev, state);
 209 }
 210 EXPORT_SYMBOL_GPL(xenbus_otherend_changed);
 211
 212 int xenbus_dev_probe(struct device *_dev)
 213 {
 214         struct xenbus_device *dev = to_xenbus_device(_dev);
 215         struct xenbus_driver *drv = to_xenbus_driver(_dev->driver);
 216         const struct xenbus_device_id *id;
 217         int err;
 218
 219         DPRINTK("%s", dev->nodename);
 220
 221         if (!drv->probe) {
 222                 err = -ENODEV;
 223                 goto fail;
 224         }
 225
 226         id = match_device(drv->ids, dev);
 227         if (!id) {
 228                 err = -ENODEV;
 229                 goto fail;
 230         }
 231
 232         err = talk_to_otherend(dev);
 233         if (err) {
 234                 dev_warn(&dev->dev, "talk_to_otherend on %s failed.\n",
 235                          dev->nodename);
 236                 return err;
 237         }
 238
 239         err = drv->probe(dev, id);
 240         if (err)
 241                 goto fail;
 242
 243         err = watch_otherend(dev);
 244         if (err) {
 245                 dev_warn(&dev->dev, "watch_otherend on %s failed.\n",
 246                        dev->nodename);
 247                 return err;
 248         }
 249
 250         return 0;
 251 fail:
 252         xenbus_dev_error(dev, err, "xenbus_dev_probe on %s", dev->nodename);
 253         xenbus_switch_state(dev, XenbusStateClosed);
 254         return err;
 255 }
 256 EXPORT_SYMBOL_GPL(xenbus_dev_probe);
 257
 258 int xenbus_dev_remove(struct device *_dev)
 259 {
 260         struct xenbus_device *dev = to_xenbus_device(_dev);
 261         struct xenbus_driver *drv = to_xenbus_driver(_dev->driver);
 262
 263         DPRINTK("%s", dev->nodename);
 264
 265         free_otherend_watch(dev);
 266
 267         if (drv->remove)
 268                 drv->remove(dev);
 269
 270         free_otherend_details(dev);
 271
 272         xenbus_switch_state(dev, XenbusStateClosed);
 273         return 0;
 274 }
 275 EXPORT_SYMBOL_GPL(xenbus_dev_remove);
 276
 277 void xenbus_dev_shutdown(struct device *_dev)
 278 {
 279         struct xenbus_device *dev = to_xenbus_device(_dev);
 280         unsigned long timeout = 5*HZ;
 281
 282         DPRINTK("%s", dev->nodename);
 283
 284         get_device(&dev->dev);
 285         if (dev->state != XenbusStateConnected) {
 286                 pr_info("%s: %s: %s != Connected, skipping\n",
 287                         __func__, dev->nodename, xenbus_strstate(dev->state));
 288                 goto out;
 289         }
 290         xenbus_switch_state(dev, XenbusStateClosing);
 291         timeout = wait_for_completion_timeout(&dev->down, timeout);
 292         if (!timeout)
 293                 pr_info("%s: %s timeout closing device\n",
 294                         __func__, dev->nodename);
 295  out:
 296         put_device(&dev->dev);
 297 }
 298 EXPORT_SYMBOL_GPL(xenbus_dev_shutdown);
 299
 300 int xenbus_register_driver_common(struct xenbus_driver *drv,
 301                                   struct xen_bus_type *bus,
 302                                   struct module *owner, const char *mod_name)
 303 {
 304         drv->driver.name = drv->name ? drv->name : drv->ids[0].devicetype;
 305         drv->driver.bus = &bus->bus;
 306         drv->driver.owner = owner;
 307         drv->driver.mod_name = mod_name;
 308
 309         return driver_register(&drv->driver);
 310 }
 311 EXPORT_SYMBOL_GPL(xenbus_register_driver_common);
 312
 313 void xenbus_unregister_driver(struct xenbus_driver *drv)
 314 {
 315         driver_unregister(&drv->driver);
 316 }
 317 EXPORT_SYMBOL_GPL(xenbus_unregister_driver);
 318
 319 struct xb_find_info {
 320         struct xenbus_device *dev;
 321         const char *nodename;
 322 };
 323
 324 static int cmp_dev(struct device *dev, void *data)
 325 {
 326         struct xenbus_device *xendev = to_xenbus_device(dev);
 327         struct xb_find_info *info = data;
 328
 329         if (!strcmp(xendev->nodename, info->nodename)) {
 330                 info->dev = xendev;
 331                 get_device(dev);
 332                 return 1;
 333         }
 334         return 0;
 335 }
 336
 337 static struct xenbus_device *xenbus_device_find(const char *nodename,
 338                                                 struct bus_type *bus)
 339 {
 340         struct xb_find_info info = { .dev = NULL, .nodename = nodename };
 341
 342         bus_for_each_dev(bus, NULL, &info, cmp_dev);
 343         return info.dev;
 344 }
 345
 346 static int cleanup_dev(struct device *dev, void *data)
 347 {
 348         struct xenbus_device *xendev = to_xenbus_device(dev);
 349         struct xb_find_info *info = data;
 350         int len = strlen(info->nodename);
 351
 352         DPRINTK("%s", info->nodename);
 353
 354         /* Match the info->nodename path, or any subdirectory of that path. */
 355         if (strncmp(xendev->nodename, info->nodename, len))
 356                 return 0;
 357
 358         /* If the node name is longer, ensure it really is a subdirectory. */
 359         if ((strlen(xendev->nodename) > len) && (xendev->nodename[len] != '/'))
 360                 return 0;
 361
 362         info->dev = xendev;
 363         get_device(dev);
 364         return 1;
 365 }
 366
 367 static void xenbus_cleanup_devices(const char *path, struct bus_type *bus)
 368 {
 369         struct xb_find_info info = { .nodename = path };
 370
 371         do {
 372                 info.dev = NULL;
 373                 bus_for_each_dev(bus, NULL, &info, cleanup_dev);
 374                 if (info.dev) {
 375                         device_unregister(&info.dev->dev);
 376                         put_device(&info.dev->dev);
 377                 }
 378         } while (info.dev);
 379 }
 380
 381 static void xenbus_dev_release(struct device *dev)
 382 {
 383         if (dev)
 384                 kfree(to_xenbus_device(dev));
 385 }
 386
 387 static ssize_t nodename_show(struct device *dev,
 388                              struct device_attribute *attr, char *buf)
 389 {
 390         return sprintf(buf, "%s\n", to_xenbus_device(dev)->nodename);
 391 }
 392 static DEVICE_ATTR_RO(nodename);
 393
 394 static ssize_t devtype_show(struct device *dev,
 395                             struct device_attribute *attr, char *buf)
 396 {
 397         return sprintf(buf, "%s\n", to_xenbus_device(dev)->devicetype);
 398 }
 399 static DEVICE_ATTR_RO(devtype);
 400
 401 static ssize_t modalias_show(struct device *dev,
 402                              struct device_attribute *attr, char *buf)
 403 {
 404         return sprintf(buf, "%s:%s\n", dev->bus->name,
 405                        to_xenbus_device(dev)->devicetype);
 406 }
 407 static DEVICE_ATTR_RO(modalias);
 408
 409 static struct attribute *xenbus_dev_attrs[] = {
 410         &dev_attr_nodename.attr,
 411         &dev_attr_devtype.attr,
 412         &dev_attr_modalias.attr,
 413         NULL,
 414 };
 415
 416 static const struct attribute_group xenbus_dev_group = {
 417         .attrs = xenbus_dev_attrs,
 418 };
 419
 420 const struct attribute_group *xenbus_dev_groups[] = {
 421         &xenbus_dev_group,
 422         NULL,
 423 };
 424 EXPORT_SYMBOL_GPL(xenbus_dev_groups);
 425
 426 int xenbus_probe_node(struct xen_bus_type *bus,
 427                       const char *type,
 428                       const char *nodename)
 429 {
 430         char devname[XEN_BUS_ID_SIZE];
 431         int err;
 432         struct xenbus_device *xendev;
 433         size_t stringlen;
 434         char *tmpstring;
 435
 436         enum xenbus_state state = xenbus_read_driver_state(nodename);
 437
 438         if (state != XenbusStateInitialising) {
 439                 /* Device is not new, so ignore it.  This can happen if a
 440                    device is going away after switching to Closed.  */
 441                 return 0;
 442         }
 443
 444         stringlen = strlen(nodename) + 1 + strlen(type) + 1;
 445         xendev = kzalloc(sizeof(*xendev) + stringlen, GFP_KERNEL);
 446         if (!xendev)
 447                 return -ENOMEM;
 448
 449         xendev->state = XenbusStateInitialising;
 450
 451         /* Copy the strings into the extra space. */
 452
 453         tmpstring = (char *)(xendev + 1);
 454         strcpy(tmpstring, nodename);
 455         xendev->nodename = tmpstring;
 456
 457         tmpstring += strlen(tmpstring) + 1;
 458         strcpy(tmpstring, type);
 459         xendev->devicetype = tmpstring;
 460         init_completion(&xendev->down);
 461
 462         xendev->dev.bus = &bus->bus;
 463         xendev->dev.release = xenbus_dev_release;
 464
 465         err = bus->get_bus_id(devname, xendev->nodename);
 466         if (err)
 467                 goto fail;
 468
 469         dev_set_name(&xendev->dev, "%s", devname);
 470
 471         /* Register with generic device framework. */
 472         err = device_register(&xendev->dev);
 473         if (err)
 474                 goto fail;
 475
 476         return 0;
 477 fail:
 478         kfree(xendev);
 479         return err;
 480 }
 481 EXPORT_SYMBOL_GPL(xenbus_probe_node);
 482
 483 static int xenbus_probe_device_type(struct xen_bus_type *bus, const char *type)
 484 {
 485         int err = 0;
 486         char **dir;
 487         unsigned int dir_n = 0;
 488         int i;
 489
 490         dir = xenbus_directory(XBT_NIL, bus->root, type, &dir_n);
 491         if (IS_ERR(dir))
 492                 return PTR_ERR(dir);
 493
 494         for (i = 0; i < dir_n; i++) {
 495                 err = bus->probe(bus, type, dir[i]);
 496                 if (err)
 497                         break;
 498         }
 499
 500         kfree(dir);
 501         return err;
 502 }
 503
 504 int xenbus_probe_devices(struct xen_bus_type *bus)
 505 {
 506         int err = 0;
 507         char **dir;
 508         unsigned int i, dir_n;
 509
 510         dir = xenbus_directory(XBT_NIL, bus->root, "", &dir_n);
 511         if (IS_ERR(dir))
 512                 return PTR_ERR(dir);
 513
 514         for (i = 0; i < dir_n; i++) {
 515                 err = xenbus_probe_device_type(bus, dir[i]);
 516                 if (err)
 517                         break;
 518         }
 519
 520         kfree(dir);
 521         return err;
 522 }
 523 EXPORT_SYMBOL_GPL(xenbus_probe_devices);
 524
 525 static unsigned int char_count(const char *str, char c)
 526 {
 527         unsigned int i, ret = 0;
 528
 529         for (i = 0; str[i]; i++)
 530                 if (str[i] == c)
 531                         ret++;
 532         return ret;
 533 }
 534
 535 static int strsep_len(const char *str, char c, unsigned int len)
 536 {
 537         unsigned int i;
 538
 539         for (i = 0; str[i]; i++)
 540                 if (str[i] == c) {
 541                         if (len == 0)
 542                                 return i;
 543                         len--;
 544                 }
 545         return (len == 0) ? i : -ERANGE;
 546 }
 547
 548 void xenbus_dev_changed(const char *node, struct xen_bus_type *bus)
 549 {
 550         int exists, rootlen;
 551         struct xenbus_device *dev;
 552         char type[XEN_BUS_ID_SIZE];
 553         const char *p, *root;
 554
 555         if (char_count(node, '/') < 2)
 556                 return;
 557
 558         exists = xenbus_exists(XBT_NIL, node, "");
 559         if (!exists) {
 560                 xenbus_cleanup_devices(node, &bus->bus);
 561                 return;
 562         }
 563
 564         /* backend/<type>/... or device/<type>/... */
 565         p = strchr(node, '/') + 1;
 566         snprintf(type, XEN_BUS_ID_SIZE, "%.*s", (int)strcspn(p, "/"), p);
 567         type[XEN_BUS_ID_SIZE-1] = '\0';
 568
 569         rootlen = strsep_len(node, '/', bus->levels);
 570         if (rootlen < 0)
 571                 return;
 572         root = kasprintf(GFP_KERNEL, "%.*s", rootlen, node);
 573         if (!root)
 574                 return;
 575
 576         dev = xenbus_device_find(root, &bus->bus);
 577         if (!dev)
 578                 xenbus_probe_node(bus, type, root);
 579         else
 580                 put_device(&dev->dev);
 581
 582         kfree(root);
 583 }
 584 EXPORT_SYMBOL_GPL(xenbus_dev_changed);
 585
 586 int xenbus_dev_suspend(struct device *dev)
 587 {
 588         int err = 0;
 589         struct xenbus_driver *drv;
 590         struct xenbus_device *xdev
 591                 = container_of(dev, struct xenbus_device, dev);
 592
 593         DPRINTK("%s", xdev->nodename);
 594
 595         if (dev->driver == NULL)
 596                 return 0;
 597         drv = to_xenbus_driver(dev->driver);
 598         if (drv->suspend)
 599                 err = drv->suspend(xdev);
 600         if (err)
 601                 pr_warn("suspend %s failed: %i\n", dev_name(dev), err);
 602         return 0;
 603 }
 604 EXPORT_SYMBOL_GPL(xenbus_dev_suspend);
 605
 606 int xenbus_dev_resume(struct device *dev)
 607 {
 608         int err;
 609         struct xenbus_driver *drv;
 610         struct xenbus_device *xdev
 611                 = container_of(dev, struct xenbus_device, dev);
 612
 613         DPRINTK("%s", xdev->nodename);
 614
 615         if (dev->driver == NULL)
 616                 return 0;
 617         drv = to_xenbus_driver(dev->driver);
 618         err = talk_to_otherend(xdev);
 619         if (err) {
 620                 pr_warn("resume (talk_to_otherend) %s failed: %i\n",
 621                         dev_name(dev), err);
 622                 return err;
 623         }
 624
 625         xdev->state = XenbusStateInitialising;
 626
 627         if (drv->resume) {
 628                 err = drv->resume(xdev);
 629                 if (err) {
 630                         pr_warn("resume %s failed: %i\n", dev_name(dev), err);
 631                         return err;
 632                 }
 633         }
 634
 635         err = watch_otherend(xdev);
 636         if (err) {
 637                 pr_warn("resume (watch_otherend) %s failed: %d.\n",
 638                         dev_name(dev), err);
 639                 return err;
 640         }
 641
 642         return 0;
 643 }
 644 EXPORT_SYMBOL_GPL(xenbus_dev_resume);
 645
 646 int xenbus_dev_cancel(struct device *dev)
 647 {
 648         /* Do nothing */
 649         DPRINTK("cancel");
 650         return 0;
 651 }
 652 EXPORT_SYMBOL_GPL(xenbus_dev_cancel);
 653
 654 /* A flag to determine if xenstored is 'ready' (i.e. has started) */
 655 int xenstored_ready;
 656
 657
 658 int register_xenstore_notifier(struct notifier_block *nb)
 659 {
 660         int ret = 0;
 661
 662         if (xenstored_ready > 0)
 663                 ret = nb->notifier_call(nb, 0, NULL);
 664         else
 665                 blocking_notifier_chain_register(&xenstore_chain, nb);
 666
 667         return ret;
 668 }
 669 EXPORT_SYMBOL_GPL(register_xenstore_notifier);
 670
 671 void unregister_xenstore_notifier(struct notifier_block *nb)
 672 {
 673         blocking_notifier_chain_unregister(&xenstore_chain, nb);
 674 }
 675 EXPORT_SYMBOL_GPL(unregister_xenstore_notifier);
 676
 677 void xenbus_probe(struct work_struct *unused)
 678 {
 679         xenstored_ready = 1;
 680
 681         /* Notify others that xenstore is up */
 682         blocking_notifier_call_chain(&xenstore_chain, 0, NULL);
 683 }
 684 EXPORT_SYMBOL_GPL(xenbus_probe);
 685
 686 static int __init xenbus_probe_initcall(void)
 687 {
 688         if (!xen_domain())
 689                 return -ENODEV;
 690
 691         if (xen_initial_domain() || xen_hvm_domain())
 692                 return 0;
 693
 694         xenbus_probe(NULL);
 695         return 0;
 696 }
 697
 698 device_initcall(xenbus_probe_initcall);
 699
 700 /* Set up event channel for xenstored which is run as a local process
 701  * (this is normally used only in dom0)
 702  */
 703 static int __init xenstored_local_init(void)
 704 {
 705         int err = -ENOMEM;
 706         unsigned long page = 0;
 707         struct evtchn_alloc_unbound alloc_unbound;
 708
 709         /* Allocate Xenstore page */
 710         page = get_zeroed_page(GFP_KERNEL);
 711         if (!page)
 712                 goto out_err;
 713
 714         xen_store_gfn = xen_start_info->store_mfn = virt_to_gfn((void *)page);
 715
 716         /* Next allocate a local port which xenstored can bind to */
 717         alloc_unbound.dom        = DOMID_SELF;
 718         alloc_unbound.remote_dom = DOMID_SELF;
 719
 720         err = HYPERVISOR_event_channel_op(EVTCHNOP_alloc_unbound,
 721                                           &alloc_unbound);
 722         if (err == -ENOSYS)
 723                 goto out_err;
 724
 725         BUG_ON(err);
 726         xen_store_evtchn = xen_start_info->store_evtchn =
 727                 alloc_unbound.port;
 728
 729         return 0;
 730
 731  out_err:
 732         if (page != 0)
 733                 free_page(page);
 734         return err;
 735 }
 736
 737 static int xenbus_resume_cb(struct notifier_block *nb,
 738                             unsigned long action, void *data)
 739 {
 740         int err = 0;
 741
 742         if (xen_hvm_domain()) {
 743                 uint64_t v = 0;
 744
 745                 err = hvm_get_parameter(HVM_PARAM_STORE_EVTCHN, &v);
 746                 if (!err && v)
 747                         xen_store_evtchn = v;
 748                 else
 749                         pr_warn("Cannot update xenstore event channel: %d\n",
 750                                 err);
 751         } else
 752                 xen_store_evtchn = xen_start_info->store_evtchn;
 753
 754         return err;
 755 }
 756
 757 static struct notifier_block xenbus_resume_nb = {
 758         .notifier_call = xenbus_resume_cb,
 759 };
 760
 761 static int __init xenbus_init(void)
 762 {
 763         int err = 0;
 764         uint64_t v = 0;
 765         xen_store_domain_type = XS_UNKNOWN;
 766
 767         if (!xen_domain())
 768                 return -ENODEV;
 769
 770         xenbus_ring_ops_init();
 771
 772         if (xen_pv_domain())
 773                 xen_store_domain_type = XS_PV;
 774         if (xen_hvm_domain())
 775                 xen_store_domain_type = XS_HVM;
 776         if (xen_hvm_domain() && xen_initial_domain())
 777                 xen_store_domain_type = XS_LOCAL;
 778         if (xen_pv_domain() && !xen_start_info->store_evtchn)
 779                 xen_store_domain_type = XS_LOCAL;
 780         if (xen_pv_domain() && xen_start_info->store_evtchn)
 781                 xenstored_ready = 1;
 782
 783         switch (xen_store_domain_type) {
 784         case XS_LOCAL:
 785                 err = xenstored_local_init();
 786                 if (err)
 787                         goto out_error;
 788                 xen_store_interface = gfn_to_virt(xen_store_gfn);
 789                 break;
 790         case XS_PV:
 791                 xen_store_evtchn = xen_start_info->store_evtchn;
 792                 xen_store_gfn = xen_start_info->store_mfn;
 793                 xen_store_interface = gfn_to_virt(xen_store_gfn);
 794                 break;
 795         case XS_HVM:
 796                 err = hvm_get_parameter(HVM_PARAM_STORE_EVTCHN, &v);
 797                 if (err)
 798                         goto out_error;
 799                 xen_store_evtchn = (int)v;
 800                 err = hvm_get_parameter(HVM_PARAM_STORE_PFN, &v);
 801                 if (err)
 802                         goto out_error;
 803                 xen_store_gfn = (unsigned long)v;
 804                 xen_store_interface =
 805                         xen_remap(xen_store_gfn << XEN_PAGE_SHIFT,
 806                                   XEN_PAGE_SIZE);
 807                 break;
 808         default:
 809                 pr_warn("Xenstore state unknown\n");
 810                 break;
 811         }
 812
 813         /* Initialize the interface to xenstore. */
 814         err = xs_init();
 815         if (err) {
 816                 pr_warn("Error initializing xenstore comms: %i\n", err);
 817                 goto out_error;
 818         }
 819
 820         if ((xen_store_domain_type != XS_LOCAL) &&
 821             (xen_store_domain_type != XS_UNKNOWN))
 822                 xen_resume_notifier_register(&xenbus_resume_nb);
 823
 824 #ifdef CONFIG_XEN_COMPAT_XENFS
 825         /*
 826          * Create xenfs mountpoint in /proc for compatibility with
 827          * utilities that expect to find "xenbus" under "/proc/xen".
 828          */
 829         proc_create_mount_point("xen");
 830 #endif
 831
 832 out_error:
 833         return err;
 834 }
 835
 836 postcore_initcall(xenbus_init);
 837
 838 MODULE_LICENSE("GPL");