drivers/xen/xenbus/xenbus_client.c

   1 /******************************************************************************
   2  * Client-facing interface for the Xenbus driver.  In other words, the
   3  * interface between the Xenbus and the device-specific code, be it the
   4  * frontend or the backend of that driver.
   5  *
   6  * Copyright (C) 2005 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 #include <linux/mm.h>
  34 #include <linux/slab.h>
  35 #include <linux/types.h>
  36 #include <linux/spinlock.h>
  37 #include <linux/vmalloc.h>
  38 #include <linux/export.h>
  39 #include <asm/xen/hypervisor.h>
  40 #include <asm/xen/page.h>
  41 #include <xen/interface/xen.h>
  42 #include <xen/interface/event_channel.h>
  43 #include <xen/balloon.h>
  44 #include <xen/events.h>
  45 #include <xen/grant_table.h>
  46 #include <xen/xenbus.h>
  47 #include <xen/xen.h>
  48 #include <xen/features.h>
  49
  50 #include "xenbus_probe.h"
  51
  52 struct xenbus_map_node {
  53         struct list_head next;
  54         union {
  55                 struct vm_struct *area; /* PV */
  56                 struct page *page;     /* HVM */
  57         };
  58         grant_handle_t handle;
  59 };
  60
  61 static DEFINE_SPINLOCK(xenbus_valloc_lock);
  62 static LIST_HEAD(xenbus_valloc_pages);
  63
  64 struct xenbus_ring_ops {
  65         int (*map)(struct xenbus_device *dev, int gnt, void **vaddr);
  66         int (*unmap)(struct xenbus_device *dev, void *vaddr);
  67 };
  68
  69 static const struct xenbus_ring_ops *ring_ops __read_mostly;
  70
  71 const char *xenbus_strstate(enum xenbus_state state)
  72 {
  73         static const char *const name[] = {
  74                 [ XenbusStateUnknown      ] = "Unknown",
  75                 [ XenbusStateInitialising ] = "Initialising",
  76                 [ XenbusStateInitWait     ] = "InitWait",
  77                 [ XenbusStateInitialised  ] = "Initialised",
  78                 [ XenbusStateConnected    ] = "Connected",
  79                 [ XenbusStateClosing      ] = "Closing",
  80                 [ XenbusStateClosed       ] = "Closed",
  81                 [XenbusStateReconfiguring] = "Reconfiguring",
  82                 [XenbusStateReconfigured] = "Reconfigured",
  83         };
  84         return (state < ARRAY_SIZE(name)) ? name[state] : "INVALID";
  85 }
  86 EXPORT_SYMBOL_GPL(xenbus_strstate);
  87
  88 /**
  89  * xenbus_watch_path - register a watch
  90  * @dev: xenbus device
  91  * @path: path to watch
  92  * @watch: watch to register
  93  * @callback: callback to register
  94  *
  95  * Register a @watch on the given path, using the given xenbus_watch structure
  96  * for storage, and the given @callback function as the callback.  Return 0 on
  97  * success, or -errno on error.  On success, the given @path will be saved as
  98  * @watch->node, and remains the caller's to free.  On error, @watch->node will
  99  * be NULL, the device will switch to %XenbusStateClosing, and the error will
 100  * be saved in the store.
 101  */
 102 int xenbus_watch_path(struct xenbus_device *dev, const char *path,
 103                       struct xenbus_watch *watch,
 104                       void (*callback)(struct xenbus_watch *,
 105                                        const char **, unsigned int))
 106 {
 107         int err;
 108
 109         watch->node = path;
 110         watch->callback = callback;
 111
 112         err = register_xenbus_watch(watch);
 113
 114         if (err) {
 115                 watch->node = NULL;
 116                 watch->callback = NULL;
 117                 xenbus_dev_fatal(dev, err, "adding watch on %s", path);
 118         }
 119
 120         return err;
 121 }
 122 EXPORT_SYMBOL_GPL(xenbus_watch_path);
 123
 124
 125 /**
 126  * xenbus_watch_pathfmt - register a watch on a sprintf-formatted path
 127  * @dev: xenbus device
 128  * @watch: watch to register
 129  * @callback: callback to register
 130  * @pathfmt: format of path to watch
 131  *
 132  * Register a watch on the given @path, using the given xenbus_watch
 133  * structure for storage, and the given @callback function as the callback.
 134  * Return 0 on success, or -errno on error.  On success, the watched path
 135  * (@path/@path2) will be saved as @watch->node, and becomes the caller's to
 136  * kfree().  On error, watch->node will be NULL, so the caller has nothing to
 137  * free, the device will switch to %XenbusStateClosing, and the error will be
 138  * saved in the store.
 139  */
 140 int xenbus_watch_pathfmt(struct xenbus_device *dev,
 141                          struct xenbus_watch *watch,
 142                          void (*callback)(struct xenbus_watch *,
 143                                         const char **, unsigned int),
 144                          const char *pathfmt, ...)
 145 {
 146         int err;
 147         va_list ap;
 148         char *path;
 149
 150         va_start(ap, pathfmt);
 151         path = kvasprintf(GFP_NOIO | __GFP_HIGH, pathfmt, ap);
 152         va_end(ap);
 153
 154         if (!path) {
 155                 xenbus_dev_fatal(dev, -ENOMEM, "allocating path for watch");
 156                 return -ENOMEM;
 157         }
 158         err = xenbus_watch_path(dev, path, watch, callback);
 159
 160         if (err)
 161                 kfree(path);
 162         return err;
 163 }
 164 EXPORT_SYMBOL_GPL(xenbus_watch_pathfmt);
 165
 166 static void xenbus_switch_fatal(struct xenbus_device *, int, int,
 167                                 const char *, ...);
 168
 169 static int
 170 __xenbus_switch_state(struct xenbus_device *dev,
 171                       enum xenbus_state state, int depth)
 172 {
 173         /* We check whether the state is currently set to the given value, and
 174            if not, then the state is set.  We don't want to unconditionally
 175            write the given state, because we don't want to fire watches
 176            unnecessarily.  Furthermore, if the node has gone, we don't write
 177            to it, as the device will be tearing down, and we don't want to
 178            resurrect that directory.
 179
 180            Note that, because of this cached value of our state, this
 181            function will not take a caller's Xenstore transaction
 182            (something it was trying to in the past) because dev->state
 183            would not get reset if the transaction was aborted.
 184          */
 185
 186         struct xenbus_transaction xbt;
 187         int current_state;
 188         int err, abort;
 189
 190         if (state == dev->state)
 191                 return 0;
 192
 193 again:
 194         abort = 1;
 195
 196         err = xenbus_transaction_start(&xbt);
 197         if (err) {
 198                 xenbus_switch_fatal(dev, depth, err, "starting transaction");
 199                 return 0;
 200         }
 201
 202         err = xenbus_scanf(xbt, dev->nodename, "state", "%d", &current_state);
 203         if (err != 1)
 204                 goto abort;
 205
 206         err = xenbus_printf(xbt, dev->nodename, "state", "%d", state);
 207         if (err) {
 208                 xenbus_switch_fatal(dev, depth, err, "writing new state");
 209                 goto abort;
 210         }
 211
 212         abort = 0;
 213 abort:
 214         err = xenbus_transaction_end(xbt, abort);
 215         if (err) {
 216                 if (err == -EAGAIN && !abort)
 217                         goto again;
 218                 xenbus_switch_fatal(dev, depth, err, "ending transaction");
 219         } else
 220                 dev->state = state;
 221
 222         return 0;
 223 }
 224
 225 /**
 226  * xenbus_switch_state
 227  * @dev: xenbus device
 228  * @state: new state
 229  *
 230  * Advertise in the store a change of the given driver to the given new_state.
 231  * Return 0 on success, or -errno on error.  On error, the device will switch
 232  * to XenbusStateClosing, and the error will be saved in the store.
 233  */
 234 int xenbus_switch_state(struct xenbus_device *dev, enum xenbus_state state)
 235 {
 236         return __xenbus_switch_state(dev, state, 0);
 237 }
 238
 239 EXPORT_SYMBOL_GPL(xenbus_switch_state);
 240
 241 int xenbus_frontend_closed(struct xenbus_device *dev)
 242 {
 243         xenbus_switch_state(dev, XenbusStateClosed);
 244         complete(&dev->down);
 245         return 0;
 246 }
 247 EXPORT_SYMBOL_GPL(xenbus_frontend_closed);
 248
 249 /**
 250  * Return the path to the error node for the given device, or NULL on failure.
 251  * If the value returned is non-NULL, then it is the caller's to kfree.
 252  */
 253 static char *error_path(struct xenbus_device *dev)
 254 {
 255         return kasprintf(GFP_KERNEL, "error/%s", dev->nodename);
 256 }
 257
 258
 259 static void xenbus_va_dev_error(struct xenbus_device *dev, int err,
 260                                 const char *fmt, va_list ap)
 261 {
 262         int ret;
 263         unsigned int len;
 264         char *printf_buffer = NULL;
 265         char *path_buffer = NULL;
 266
 267 #define PRINTF_BUFFER_SIZE 4096
 268         printf_buffer = kmalloc(PRINTF_BUFFER_SIZE, GFP_KERNEL);
 269         if (printf_buffer == NULL)
 270                 goto fail;
 271
 272         len = sprintf(printf_buffer, "%i ", -err);
 273         ret = vsnprintf(printf_buffer+len, PRINTF_BUFFER_SIZE-len, fmt, ap);
 274
 275         BUG_ON(len + ret > PRINTF_BUFFER_SIZE-1);
 276
 277         dev_err(&dev->dev, "%s\n", printf_buffer);
 278
 279         path_buffer = error_path(dev);
 280
 281         if (path_buffer == NULL) {
 282                 dev_err(&dev->dev, "failed to write error node for %s (%s)\n",
 283                        dev->nodename, printf_buffer);
 284                 goto fail;
 285         }
 286
 287         if (xenbus_write(XBT_NIL, path_buffer, "error", printf_buffer) != 0) {
 288                 dev_err(&dev->dev, "failed to write error node for %s (%s)\n",
 289                        dev->nodename, printf_buffer);
 290                 goto fail;
 291         }
 292
 293 fail:
 294         kfree(printf_buffer);
 295         kfree(path_buffer);
 296 }
 297
 298
 299 /**
 300  * xenbus_dev_error
 301  * @dev: xenbus device
 302  * @err: error to report
 303  * @fmt: error message format
 304  *
 305  * Report the given negative errno into the store, along with the given
 306  * formatted message.
 307  */
 308 void xenbus_dev_error(struct xenbus_device *dev, int err, const char *fmt, ...)
 309 {
 310         va_list ap;
 311
 312         va_start(ap, fmt);
 313         xenbus_va_dev_error(dev, err, fmt, ap);
 314         va_end(ap);
 315 }
 316 EXPORT_SYMBOL_GPL(xenbus_dev_error);
 317
 318 /**
 319  * xenbus_dev_fatal
 320  * @dev: xenbus device
 321  * @err: error to report
 322  * @fmt: error message format
 323  *
 324  * Equivalent to xenbus_dev_error(dev, err, fmt, args), followed by
 325  * xenbus_switch_state(dev, XenbusStateClosing) to schedule an orderly
 326  * closedown of this driver and its peer.
 327  */
 328
 329 void xenbus_dev_fatal(struct xenbus_device *dev, int err, const char *fmt, ...)
 330 {
 331         va_list ap;
 332
 333         va_start(ap, fmt);
 334         xenbus_va_dev_error(dev, err, fmt, ap);
 335         va_end(ap);
 336
 337         xenbus_switch_state(dev, XenbusStateClosing);
 338 }
 339 EXPORT_SYMBOL_GPL(xenbus_dev_fatal);
 340
 341 /**
 342  * Equivalent to xenbus_dev_fatal(dev, err, fmt, args), but helps
 343  * avoiding recursion within xenbus_switch_state.
 344  */
 345 static void xenbus_switch_fatal(struct xenbus_device *dev, int depth, int err,
 346                                 const char *fmt, ...)
 347 {
 348         va_list ap;
 349
 350         va_start(ap, fmt);
 351         xenbus_va_dev_error(dev, err, fmt, ap);
 352         va_end(ap);
 353
 354         if (!depth)
 355                 __xenbus_switch_state(dev, XenbusStateClosing, 1);
 356 }
 357
 358 /**
 359  * xenbus_grant_ring
 360  * @dev: xenbus device
 361  * @ring_mfn: mfn of ring to grant
 362
 363  * Grant access to the given @ring_mfn to the peer of the given device.  Return
 364  * 0 on success, or -errno on error.  On error, the device will switch to
 365  * XenbusStateClosing, and the error will be saved in the store.
 366  */
 367 int xenbus_grant_ring(struct xenbus_device *dev, unsigned long ring_mfn)
 368 {
 369         int err = gnttab_grant_foreign_access(dev->otherend_id, ring_mfn, 0);
 370         if (err < 0)
 371                 xenbus_dev_fatal(dev, err, "granting access to ring page");
 372         return err;
 373 }
 374 EXPORT_SYMBOL_GPL(xenbus_grant_ring);
 375
 376
 377 /**
 378  * Allocate an event channel for the given xenbus_device, assigning the newly
 379  * created local port to *port.  Return 0 on success, or -errno on error.  On
 380  * error, the device will switch to XenbusStateClosing, and the error will be
 381  * saved in the store.
 382  */
 383 int xenbus_alloc_evtchn(struct xenbus_device *dev, int *port)
 384 {
 385         struct evtchn_alloc_unbound alloc_unbound;
 386         int err;
 387
 388         alloc_unbound.dom = DOMID_SELF;
 389         alloc_unbound.remote_dom = dev->otherend_id;
 390
 391         err = HYPERVISOR_event_channel_op(EVTCHNOP_alloc_unbound,
 392                                           &alloc_unbound);
 393         if (err)
 394                 xenbus_dev_fatal(dev, err, "allocating event channel");
 395         else
 396                 *port = alloc_unbound.port;
 397
 398         return err;
 399 }
 400 EXPORT_SYMBOL_GPL(xenbus_alloc_evtchn);
 401
 402
 403 /**
 404  * Free an existing event channel. Returns 0 on success or -errno on error.
 405  */
 406 int xenbus_free_evtchn(struct xenbus_device *dev, int port)
 407 {
 408         struct evtchn_close close;
 409         int err;
 410
 411         close.port = port;
 412
 413         err = HYPERVISOR_event_channel_op(EVTCHNOP_close, &close);
 414         if (err)
 415                 xenbus_dev_error(dev, err, "freeing event channel %d", port);
 416
 417         return err;
 418 }
 419 EXPORT_SYMBOL_GPL(xenbus_free_evtchn);
 420
 421
 422 /**
 423  * xenbus_map_ring_valloc
 424  * @dev: xenbus device
 425  * @gnt_ref: grant reference
 426  * @vaddr: pointer to address to be filled out by mapping
 427  *
 428  * Based on Rusty Russell's skeleton driver's map_page.
 429  * Map a page of memory into this domain from another domain's grant table.
 430  * xenbus_map_ring_valloc allocates a page of virtual address space, maps the
 431  * page to that address, and sets *vaddr to that address.
 432  * Returns 0 on success, and GNTST_* (see xen/include/interface/grant_table.h)
 433  * or -ENOMEM on error. If an error is returned, device will switch to
 434  * XenbusStateClosing and the error message will be saved in XenStore.
 435  */
 436 int xenbus_map_ring_valloc(struct xenbus_device *dev, int gnt_ref, void **vaddr)
 437 {
 438         return ring_ops->map(dev, gnt_ref, vaddr);
 439 }
 440 EXPORT_SYMBOL_GPL(xenbus_map_ring_valloc);
 441
 442 static int xenbus_map_ring_valloc_pv(struct xenbus_device *dev,
 443                                      int gnt_ref, void **vaddr)
 444 {
 445         struct gnttab_map_grant_ref op = {
 446                 .flags = GNTMAP_host_map | GNTMAP_contains_pte,
 447                 .ref   = gnt_ref,
 448                 .dom   = dev->otherend_id,
 449         };
 450         struct xenbus_map_node *node;
 451         struct vm_struct *area;
 452         pte_t *pte;
 453
 454         *vaddr = NULL;
 455
 456         node = kzalloc(sizeof(*node), GFP_KERNEL);
 457         if (!node)
 458                 return -ENOMEM;
 459
 460         area = alloc_vm_area(PAGE_SIZE, &pte);
 461         if (!area) {
 462                 kfree(node);
 463                 return -ENOMEM;
 464         }
 465
 466         op.host_addr = arbitrary_virt_to_machine(pte).maddr;
 467
 468         gnttab_batch_map(&op, 1);
 469
 470         if (op.status != GNTST_okay) {
 471                 free_vm_area(area);
 472                 kfree(node);
 473                 xenbus_dev_fatal(dev, op.status,
 474                                  "mapping in shared page %d from domain %d",
 475                                  gnt_ref, dev->otherend_id);
 476                 return op.status;
 477         }
 478
 479         node->handle = op.handle;
 480         node->area = area;
 481
 482         spin_lock(&xenbus_valloc_lock);
 483         list_add(&node->next, &xenbus_valloc_pages);
 484         spin_unlock(&xenbus_valloc_lock);
 485
 486         *vaddr = area->addr;
 487         return 0;
 488 }
 489
 490 static int xenbus_map_ring_valloc_hvm(struct xenbus_device *dev,
 491                                       int gnt_ref, void **vaddr)
 492 {
 493         struct xenbus_map_node *node;
 494         int err;
 495         void *addr;
 496
 497         *vaddr = NULL;
 498
 499         node = kzalloc(sizeof(*node), GFP_KERNEL);
 500         if (!node)
 501                 return -ENOMEM;
 502
 503         err = alloc_xenballooned_pages(1, &node->page, false /* lowmem */);
 504         if (err)
 505                 goto out_err;
 506
 507         addr = pfn_to_kaddr(page_to_pfn(node->page));
 508
 509         err = xenbus_map_ring(dev, gnt_ref, &node->handle, addr);
 510         if (err)
 511                 goto out_err_free_ballooned_pages;
 512
 513         spin_lock(&xenbus_valloc_lock);
 514         list_add(&node->next, &xenbus_valloc_pages);
 515         spin_unlock(&xenbus_valloc_lock);
 516
 517         *vaddr = addr;
 518         return 0;
 519
 520  out_err_free_ballooned_pages:
 521         free_xenballooned_pages(1, &node->page);
 522  out_err:
 523         kfree(node);
 524         return err;
 525 }
 526
 527
 528 /**
 529  * xenbus_map_ring
 530  * @dev: xenbus device
 531  * @gnt_ref: grant reference
 532  * @handle: pointer to grant handle to be filled
 533  * @vaddr: address to be mapped to
 534  *
 535  * Map a page of memory into this domain from another domain's grant table.
 536  * xenbus_map_ring does not allocate the virtual address space (you must do
 537  * this yourself!). It only maps in the page to the specified address.
 538  * Returns 0 on success, and GNTST_* (see xen/include/interface/grant_table.h)
 539  * or -ENOMEM on error. If an error is returned, device will switch to
 540  * XenbusStateClosing and the error message will be saved in XenStore.
 541  */
 542 int xenbus_map_ring(struct xenbus_device *dev, int gnt_ref,
 543                     grant_handle_t *handle, void *vaddr)
 544 {
 545         struct gnttab_map_grant_ref op;
 546
 547         gnttab_set_map_op(&op, (unsigned long)vaddr, GNTMAP_host_map, gnt_ref,
 548                           dev->otherend_id);
 549
 550         gnttab_batch_map(&op, 1);
 551
 552         if (op.status != GNTST_okay) {
 553                 xenbus_dev_fatal(dev, op.status,
 554                                  "mapping in shared page %d from domain %d",
 555                                  gnt_ref, dev->otherend_id);
 556         } else
 557                 *handle = op.handle;
 558
 559         return op.status;
 560 }
 561 EXPORT_SYMBOL_GPL(xenbus_map_ring);
 562
 563
 564 /**
 565  * xenbus_unmap_ring_vfree
 566  * @dev: xenbus device
 567  * @vaddr: addr to unmap
 568  *
 569  * Based on Rusty Russell's skeleton driver's unmap_page.
 570  * Unmap a page of memory in this domain that was imported from another domain.
 571  * Use xenbus_unmap_ring_vfree if you mapped in your memory with
 572  * xenbus_map_ring_valloc (it will free the virtual address space).
 573  * Returns 0 on success and returns GNTST_* on error
 574  * (see xen/include/interface/grant_table.h).
 575  */
 576 int xenbus_unmap_ring_vfree(struct xenbus_device *dev, void *vaddr)
 577 {
 578         return ring_ops->unmap(dev, vaddr);
 579 }
 580 EXPORT_SYMBOL_GPL(xenbus_unmap_ring_vfree);
 581
 582 static int xenbus_unmap_ring_vfree_pv(struct xenbus_device *dev, void *vaddr)
 583 {
 584         struct xenbus_map_node *node;
 585         struct gnttab_unmap_grant_ref op = {
 586                 .host_addr = (unsigned long)vaddr,
 587         };
 588         unsigned int level;
 589
 590         spin_lock(&xenbus_valloc_lock);
 591         list_for_each_entry(node, &xenbus_valloc_pages, next) {
 592                 if (node->area->addr == vaddr) {
 593                         list_del(&node->next);
 594                         goto found;
 595                 }
 596         }
 597         node = NULL;
 598  found:
 599         spin_unlock(&xenbus_valloc_lock);
 600
 601         if (!node) {
 602                 xenbus_dev_error(dev, -ENOENT,
 603                                  "can't find mapped virtual address %p", vaddr);
 604                 return GNTST_bad_virt_addr;
 605         }
 606
 607         op.handle = node->handle;
 608         op.host_addr = arbitrary_virt_to_machine(
 609                 lookup_address((unsigned long)vaddr, &level)).maddr;
 610
 611         if (HYPERVISOR_grant_table_op(GNTTABOP_unmap_grant_ref, &op, 1))
 612                 BUG();
 613
 614         if (op.status == GNTST_okay)
 615                 free_vm_area(node->area);
 616         else
 617                 xenbus_dev_error(dev, op.status,
 618                                  "unmapping page at handle %d error %d",
 619                                  node->handle, op.status);
 620
 621         kfree(node);
 622         return op.status;
 623 }
 624
 625 static int xenbus_unmap_ring_vfree_hvm(struct xenbus_device *dev, void *vaddr)
 626 {
 627         int rv;
 628         struct xenbus_map_node *node;
 629         void *addr;
 630
 631         spin_lock(&xenbus_valloc_lock);
 632         list_for_each_entry(node, &xenbus_valloc_pages, next) {
 633                 addr = pfn_to_kaddr(page_to_pfn(node->page));
 634                 if (addr == vaddr) {
 635                         list_del(&node->next);
 636                         goto found;
 637                 }
 638         }
 639         node = addr = NULL;
 640  found:
 641         spin_unlock(&xenbus_valloc_lock);
 642
 643         if (!node) {
 644                 xenbus_dev_error(dev, -ENOENT,
 645                                  "can't find mapped virtual address %p", vaddr);
 646                 return GNTST_bad_virt_addr;
 647         }
 648
 649         rv = xenbus_unmap_ring(dev, node->handle, addr);
 650
 651         if (!rv)
 652                 free_xenballooned_pages(1, &node->page);
 653         else
 654                 WARN(1, "Leaking %p\n", vaddr);
 655
 656         kfree(node);
 657         return rv;
 658 }
 659
 660 /**
 661  * xenbus_unmap_ring
 662  * @dev: xenbus device
 663  * @handle: grant handle
 664  * @vaddr: addr to unmap
 665  *
 666  * Unmap a page of memory in this domain that was imported from another domain.
 667  * Returns 0 on success and returns GNTST_* on error
 668  * (see xen/include/interface/grant_table.h).
 669  */
 670 int xenbus_unmap_ring(struct xenbus_device *dev,
 671                       grant_handle_t handle, void *vaddr)
 672 {
 673         struct gnttab_unmap_grant_ref op;
 674
 675         gnttab_set_unmap_op(&op, (unsigned long)vaddr, GNTMAP_host_map, handle);
 676
 677         if (HYPERVISOR_grant_table_op(GNTTABOP_unmap_grant_ref, &op, 1))
 678                 BUG();
 679
 680         if (op.status != GNTST_okay)
 681                 xenbus_dev_error(dev, op.status,
 682                                  "unmapping page at handle %d error %d",
 683                                  handle, op.status);
 684
 685         return op.status;
 686 }
 687 EXPORT_SYMBOL_GPL(xenbus_unmap_ring);
 688
 689
 690 /**
 691  * xenbus_read_driver_state
 692  * @path: path for driver
 693  *
 694  * Return the state of the driver rooted at the given store path, or
 695  * XenbusStateUnknown if no state can be read.
 696  */
 697 enum xenbus_state xenbus_read_driver_state(const char *path)
 698 {
 699         enum xenbus_state result;
 700         int err = xenbus_gather(XBT_NIL, path, "state", "%d", &result, NULL);
 701         if (err)
 702                 result = XenbusStateUnknown;
 703
 704         return result;
 705 }
 706 EXPORT_SYMBOL_GPL(xenbus_read_driver_state);
 707
 708 static const struct xenbus_ring_ops ring_ops_pv = {
 709         .map = xenbus_map_ring_valloc_pv,
 710         .unmap = xenbus_unmap_ring_vfree_pv,
 711 };
 712
 713 static const struct xenbus_ring_ops ring_ops_hvm = {
 714         .map = xenbus_map_ring_valloc_hvm,
 715         .unmap = xenbus_unmap_ring_vfree_hvm,
 716 };
 717
 718 void __init xenbus_ring_ops_init(void)
 719 {
 720         if (!xen_feature(XENFEAT_auto_translated_physmap))
 721                 ring_ops = &ring_ops_pv;
 722         else
 723                 ring_ops = &ring_ops_hvm;
 724 }