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  * Bind to an existing interdomain event channel in another domain. Returns 0
 405  * on success and stores the local port in *port. On error, returns -errno,
 406  * switches the device to XenbusStateClosing, and saves the error in XenStore.
 407  */
 408 int xenbus_bind_evtchn(struct xenbus_device *dev, int remote_port, int *port)
 409 {
 410         struct evtchn_bind_interdomain bind_interdomain;
 411         int err;
 412
 413         bind_interdomain.remote_dom = dev->otherend_id;
 414         bind_interdomain.remote_port = remote_port;
 415
 416         err = HYPERVISOR_event_channel_op(EVTCHNOP_bind_interdomain,
 417                                           &bind_interdomain);
 418         if (err)
 419                 xenbus_dev_fatal(dev, err,
 420                                  "binding to event channel %d from domain %d",
 421                                  remote_port, dev->otherend_id);
 422         else
 423                 *port = bind_interdomain.local_port;
 424
 425         return err;
 426 }
 427 EXPORT_SYMBOL_GPL(xenbus_bind_evtchn);
 428
 429
 430 /**
 431  * Free an existing event channel. Returns 0 on success or -errno on error.
 432  */
 433 int xenbus_free_evtchn(struct xenbus_device *dev, int port)
 434 {
 435         struct evtchn_close close;
 436         int err;
 437
 438         close.port = port;
 439
 440         err = HYPERVISOR_event_channel_op(EVTCHNOP_close, &close);
 441         if (err)
 442                 xenbus_dev_error(dev, err, "freeing event channel %d", port);
 443
 444         return err;
 445 }
 446 EXPORT_SYMBOL_GPL(xenbus_free_evtchn);
 447
 448
 449 /**
 450  * xenbus_map_ring_valloc
 451  * @dev: xenbus device
 452  * @gnt_ref: grant reference
 453  * @vaddr: pointer to address to be filled out by mapping
 454  *
 455  * Based on Rusty Russell's skeleton driver's map_page.
 456  * Map a page of memory into this domain from another domain's grant table.
 457  * xenbus_map_ring_valloc allocates a page of virtual address space, maps the
 458  * page to that address, and sets *vaddr to that address.
 459  * Returns 0 on success, and GNTST_* (see xen/include/interface/grant_table.h)
 460  * or -ENOMEM on error. If an error is returned, device will switch to
 461  * XenbusStateClosing and the error message will be saved in XenStore.
 462  */
 463 int xenbus_map_ring_valloc(struct xenbus_device *dev, int gnt_ref, void **vaddr)
 464 {
 465         return ring_ops->map(dev, gnt_ref, vaddr);
 466 }
 467 EXPORT_SYMBOL_GPL(xenbus_map_ring_valloc);
 468
 469 static int xenbus_map_ring_valloc_pv(struct xenbus_device *dev,
 470                                      int gnt_ref, void **vaddr)
 471 {
 472         struct gnttab_map_grant_ref op = {
 473                 .flags = GNTMAP_host_map | GNTMAP_contains_pte,
 474                 .ref   = gnt_ref,
 475                 .dom   = dev->otherend_id,
 476         };
 477         struct xenbus_map_node *node;
 478         struct vm_struct *area;
 479         pte_t *pte;
 480
 481         *vaddr = NULL;
 482
 483         node = kzalloc(sizeof(*node), GFP_KERNEL);
 484         if (!node)
 485                 return -ENOMEM;
 486
 487         area = alloc_vm_area(PAGE_SIZE, &pte);
 488         if (!area) {
 489                 kfree(node);
 490                 return -ENOMEM;
 491         }
 492
 493         op.host_addr = arbitrary_virt_to_machine(pte).maddr;
 494
 495         gnttab_batch_map(&op, 1);
 496
 497         if (op.status != GNTST_okay) {
 498                 free_vm_area(area);
 499                 kfree(node);
 500                 xenbus_dev_fatal(dev, op.status,
 501                                  "mapping in shared page %d from domain %d",
 502                                  gnt_ref, dev->otherend_id);
 503                 return op.status;
 504         }
 505
 506         node->handle = op.handle;
 507         node->area = area;
 508
 509         spin_lock(&xenbus_valloc_lock);
 510         list_add(&node->next, &xenbus_valloc_pages);
 511         spin_unlock(&xenbus_valloc_lock);
 512
 513         *vaddr = area->addr;
 514         return 0;
 515 }
 516
 517 static int xenbus_map_ring_valloc_hvm(struct xenbus_device *dev,
 518                                       int gnt_ref, void **vaddr)
 519 {
 520         struct xenbus_map_node *node;
 521         int err;
 522         void *addr;
 523
 524         *vaddr = NULL;
 525
 526         node = kzalloc(sizeof(*node), GFP_KERNEL);
 527         if (!node)
 528                 return -ENOMEM;
 529
 530         err = alloc_xenballooned_pages(1, &node->page, false /* lowmem */);
 531         if (err)
 532                 goto out_err;
 533
 534         addr = pfn_to_kaddr(page_to_pfn(node->page));
 535
 536         err = xenbus_map_ring(dev, gnt_ref, &node->handle, addr);
 537         if (err)
 538                 goto out_err_free_ballooned_pages;
 539
 540         spin_lock(&xenbus_valloc_lock);
 541         list_add(&node->next, &xenbus_valloc_pages);
 542         spin_unlock(&xenbus_valloc_lock);
 543
 544         *vaddr = addr;
 545         return 0;
 546
 547  out_err_free_ballooned_pages:
 548         free_xenballooned_pages(1, &node->page);
 549  out_err:
 550         kfree(node);
 551         return err;
 552 }
 553
 554
 555 /**
 556  * xenbus_map_ring
 557  * @dev: xenbus device
 558  * @gnt_ref: grant reference
 559  * @handle: pointer to grant handle to be filled
 560  * @vaddr: address to be mapped to
 561  *
 562  * Map a page of memory into this domain from another domain's grant table.
 563  * xenbus_map_ring does not allocate the virtual address space (you must do
 564  * this yourself!). It only maps in the page to the specified address.
 565  * Returns 0 on success, and GNTST_* (see xen/include/interface/grant_table.h)
 566  * or -ENOMEM on error. If an error is returned, device will switch to
 567  * XenbusStateClosing and the error message will be saved in XenStore.
 568  */
 569 int xenbus_map_ring(struct xenbus_device *dev, int gnt_ref,
 570                     grant_handle_t *handle, void *vaddr)
 571 {
 572         struct gnttab_map_grant_ref op;
 573
 574         gnttab_set_map_op(&op, (unsigned long)vaddr, GNTMAP_host_map, gnt_ref,
 575                           dev->otherend_id);
 576
 577         gnttab_batch_map(&op, 1);
 578
 579         if (op.status != GNTST_okay) {
 580                 xenbus_dev_fatal(dev, op.status,
 581                                  "mapping in shared page %d from domain %d",
 582                                  gnt_ref, dev->otherend_id);
 583         } else
 584                 *handle = op.handle;
 585
 586         return op.status;
 587 }
 588 EXPORT_SYMBOL_GPL(xenbus_map_ring);
 589
 590
 591 /**
 592  * xenbus_unmap_ring_vfree
 593  * @dev: xenbus device
 594  * @vaddr: addr to unmap
 595  *
 596  * Based on Rusty Russell's skeleton driver's unmap_page.
 597  * Unmap a page of memory in this domain that was imported from another domain.
 598  * Use xenbus_unmap_ring_vfree if you mapped in your memory with
 599  * xenbus_map_ring_valloc (it will free the virtual address space).
 600  * Returns 0 on success and returns GNTST_* on error
 601  * (see xen/include/interface/grant_table.h).
 602  */
 603 int xenbus_unmap_ring_vfree(struct xenbus_device *dev, void *vaddr)
 604 {
 605         return ring_ops->unmap(dev, vaddr);
 606 }
 607 EXPORT_SYMBOL_GPL(xenbus_unmap_ring_vfree);
 608
 609 static int xenbus_unmap_ring_vfree_pv(struct xenbus_device *dev, void *vaddr)
 610 {
 611         struct xenbus_map_node *node;
 612         struct gnttab_unmap_grant_ref op = {
 613                 .host_addr = (unsigned long)vaddr,
 614         };
 615         unsigned int level;
 616
 617         spin_lock(&xenbus_valloc_lock);
 618         list_for_each_entry(node, &xenbus_valloc_pages, next) {
 619                 if (node->area->addr == vaddr) {
 620                         list_del(&node->next);
 621                         goto found;
 622                 }
 623         }
 624         node = NULL;
 625  found:
 626         spin_unlock(&xenbus_valloc_lock);
 627
 628         if (!node) {
 629                 xenbus_dev_error(dev, -ENOENT,
 630                                  "can't find mapped virtual address %p", vaddr);
 631                 return GNTST_bad_virt_addr;
 632         }
 633
 634         op.handle = node->handle;
 635         op.host_addr = arbitrary_virt_to_machine(
 636                 lookup_address((unsigned long)vaddr, &level)).maddr;
 637
 638         if (HYPERVISOR_grant_table_op(GNTTABOP_unmap_grant_ref, &op, 1))
 639                 BUG();
 640
 641         if (op.status == GNTST_okay)
 642                 free_vm_area(node->area);
 643         else
 644                 xenbus_dev_error(dev, op.status,
 645                                  "unmapping page at handle %d error %d",
 646                                  node->handle, op.status);
 647
 648         kfree(node);
 649         return op.status;
 650 }
 651
 652 static int xenbus_unmap_ring_vfree_hvm(struct xenbus_device *dev, void *vaddr)
 653 {
 654         int rv;
 655         struct xenbus_map_node *node;
 656         void *addr;
 657
 658         spin_lock(&xenbus_valloc_lock);
 659         list_for_each_entry(node, &xenbus_valloc_pages, next) {
 660                 addr = pfn_to_kaddr(page_to_pfn(node->page));
 661                 if (addr == vaddr) {
 662                         list_del(&node->next);
 663                         goto found;
 664                 }
 665         }
 666         node = addr = NULL;
 667  found:
 668         spin_unlock(&xenbus_valloc_lock);
 669
 670         if (!node) {
 671                 xenbus_dev_error(dev, -ENOENT,
 672                                  "can't find mapped virtual address %p", vaddr);
 673                 return GNTST_bad_virt_addr;
 674         }
 675
 676         rv = xenbus_unmap_ring(dev, node->handle, addr);
 677
 678         if (!rv)
 679                 free_xenballooned_pages(1, &node->page);
 680         else
 681                 WARN(1, "Leaking %p\n", vaddr);
 682
 683         kfree(node);
 684         return rv;
 685 }
 686
 687 /**
 688  * xenbus_unmap_ring
 689  * @dev: xenbus device
 690  * @handle: grant handle
 691  * @vaddr: addr to unmap
 692  *
 693  * Unmap a page of memory in this domain that was imported from another domain.
 694  * Returns 0 on success and returns GNTST_* on error
 695  * (see xen/include/interface/grant_table.h).
 696  */
 697 int xenbus_unmap_ring(struct xenbus_device *dev,
 698                       grant_handle_t handle, void *vaddr)
 699 {
 700         struct gnttab_unmap_grant_ref op;
 701
 702         gnttab_set_unmap_op(&op, (unsigned long)vaddr, GNTMAP_host_map, handle);
 703
 704         if (HYPERVISOR_grant_table_op(GNTTABOP_unmap_grant_ref, &op, 1))
 705                 BUG();
 706
 707         if (op.status != GNTST_okay)
 708                 xenbus_dev_error(dev, op.status,
 709                                  "unmapping page at handle %d error %d",
 710                                  handle, op.status);
 711
 712         return op.status;
 713 }
 714 EXPORT_SYMBOL_GPL(xenbus_unmap_ring);
 715
 716
 717 /**
 718  * xenbus_read_driver_state
 719  * @path: path for driver
 720  *
 721  * Return the state of the driver rooted at the given store path, or
 722  * XenbusStateUnknown if no state can be read.
 723  */
 724 enum xenbus_state xenbus_read_driver_state(const char *path)
 725 {
 726         enum xenbus_state result;
 727         int err = xenbus_gather(XBT_NIL, path, "state", "%d", &result, NULL);
 728         if (err)
 729                 result = XenbusStateUnknown;
 730
 731         return result;
 732 }
 733 EXPORT_SYMBOL_GPL(xenbus_read_driver_state);
 734
 735 static const struct xenbus_ring_ops ring_ops_pv = {
 736         .map = xenbus_map_ring_valloc_pv,
 737         .unmap = xenbus_unmap_ring_vfree_pv,
 738 };
 739
 740 static const struct xenbus_ring_ops ring_ops_hvm = {
 741         .map = xenbus_map_ring_valloc_hvm,
 742         .unmap = xenbus_unmap_ring_vfree_hvm,
 743 };
 744
 745 void __init xenbus_ring_ops_init(void)
 746 {
 747         if (!xen_feature(XENFEAT_auto_translated_physmap))
 748                 ring_ops = &ring_ops_pv;
 749         else
 750                 ring_ops = &ring_ops_hvm;
 751 }