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 <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.h"
  51
  52 #define XENBUS_PAGES(_grants)   (DIV_ROUND_UP(_grants, XEN_PFN_PER_PAGE))
  53
  54 #define XENBUS_MAX_RING_PAGES   (XENBUS_PAGES(XENBUS_MAX_RING_GRANTS))
  55
  56 struct xenbus_map_node {
  57         struct list_head next;
  58         union {
  59                 struct {
  60                         struct vm_struct *area;
  61                 } pv;
  62                 struct {
  63                         struct page *pages[XENBUS_MAX_RING_PAGES];
  64                         unsigned long addrs[XENBUS_MAX_RING_GRANTS];
  65                         void *addr;
  66                 } hvm;
  67         };
  68         grant_handle_t handles[XENBUS_MAX_RING_GRANTS];
  69         unsigned int   nr_handles;
  70 };
  71
  72 static DEFINE_SPINLOCK(xenbus_valloc_lock);
  73 static LIST_HEAD(xenbus_valloc_pages);
  74
  75 struct xenbus_ring_ops {
  76         int (*map)(struct xenbus_device *dev,
  77                    grant_ref_t *gnt_refs, unsigned int nr_grefs,
  78                    void **vaddr);
  79         int (*unmap)(struct xenbus_device *dev, void *vaddr);
  80 };
  81
  82 static const struct xenbus_ring_ops *ring_ops __read_mostly;
  83
  84 const char *xenbus_strstate(enum xenbus_state state)
  85 {
  86         static const char *const name[] = {
  87                 [ XenbusStateUnknown      ] = "Unknown",
  88                 [ XenbusStateInitialising ] = "Initialising",
  89                 [ XenbusStateInitWait     ] = "InitWait",
  90                 [ XenbusStateInitialised  ] = "Initialised",
  91                 [ XenbusStateConnected    ] = "Connected",
  92                 [ XenbusStateClosing      ] = "Closing",
  93                 [ XenbusStateClosed       ] = "Closed",
  94                 [XenbusStateReconfiguring] = "Reconfiguring",
  95                 [XenbusStateReconfigured] = "Reconfigured",
  96         };
  97         return (state < ARRAY_SIZE(name)) ? name[state] : "INVALID";
  98 }
  99 EXPORT_SYMBOL_GPL(xenbus_strstate);
 100
 101 /**
 102  * xenbus_watch_path - register a watch
 103  * @dev: xenbus device
 104  * @path: path to watch
 105  * @watch: watch to register
 106  * @callback: callback to register
 107  *
 108  * Register a @watch on the given path, using the given xenbus_watch structure
 109  * for storage, and the given @callback function as the callback.  Return 0 on
 110  * success, or -errno on error.  On success, the given @path will be saved as
 111  * @watch->node, and remains the caller's to free.  On error, @watch->node will
 112  * be NULL, the device will switch to %XenbusStateClosing, and the error will
 113  * be saved in the store.
 114  */
 115 int xenbus_watch_path(struct xenbus_device *dev, const char *path,
 116                       struct xenbus_watch *watch,
 117                       void (*callback)(struct xenbus_watch *,
 118                                        const char *, const char *))
 119 {
 120         int err;
 121
 122         watch->node = path;
 123         watch->callback = callback;
 124
 125         err = register_xenbus_watch(watch);
 126
 127         if (err) {
 128                 watch->node = NULL;
 129                 watch->callback = NULL;
 130                 xenbus_dev_fatal(dev, err, "adding watch on %s", path);
 131         }
 132
 133         return err;
 134 }
 135 EXPORT_SYMBOL_GPL(xenbus_watch_path);
 136
 137
 138 /**
 139  * xenbus_watch_pathfmt - register a watch on a sprintf-formatted path
 140  * @dev: xenbus device
 141  * @watch: watch to register
 142  * @callback: callback to register
 143  * @pathfmt: format of path to watch
 144  *
 145  * Register a watch on the given @path, using the given xenbus_watch
 146  * structure for storage, and the given @callback function as the callback.
 147  * Return 0 on success, or -errno on error.  On success, the watched path
 148  * (@path/@path2) will be saved as @watch->node, and becomes the caller's to
 149  * kfree().  On error, watch->node will be NULL, so the caller has nothing to
 150  * free, the device will switch to %XenbusStateClosing, and the error will be
 151  * saved in the store.
 152  */
 153 int xenbus_watch_pathfmt(struct xenbus_device *dev,
 154                          struct xenbus_watch *watch,
 155                          void (*callback)(struct xenbus_watch *,
 156                                           const char *, const char *),
 157                          const char *pathfmt, ...)
 158 {
 159         int err;
 160         va_list ap;
 161         char *path;
 162
 163         va_start(ap, pathfmt);
 164         path = kvasprintf(GFP_NOIO | __GFP_HIGH, pathfmt, ap);
 165         va_end(ap);
 166
 167         if (!path) {
 168                 xenbus_dev_fatal(dev, -ENOMEM, "allocating path for watch");
 169                 return -ENOMEM;
 170         }
 171         err = xenbus_watch_path(dev, path, watch, callback);
 172
 173         if (err)
 174                 kfree(path);
 175         return err;
 176 }
 177 EXPORT_SYMBOL_GPL(xenbus_watch_pathfmt);
 178
 179 static void xenbus_switch_fatal(struct xenbus_device *, int, int,
 180                                 const char *, ...);
 181
 182 static int
 183 __xenbus_switch_state(struct xenbus_device *dev,
 184                       enum xenbus_state state, int depth)
 185 {
 186         /* We check whether the state is currently set to the given value, and
 187            if not, then the state is set.  We don't want to unconditionally
 188            write the given state, because we don't want to fire watches
 189            unnecessarily.  Furthermore, if the node has gone, we don't write
 190            to it, as the device will be tearing down, and we don't want to
 191            resurrect that directory.
 192
 193            Note that, because of this cached value of our state, this
 194            function will not take a caller's Xenstore transaction
 195            (something it was trying to in the past) because dev->state
 196            would not get reset if the transaction was aborted.
 197          */
 198
 199         struct xenbus_transaction xbt;
 200         int current_state;
 201         int err, abort;
 202
 203         if (state == dev->state)
 204                 return 0;
 205
 206 again:
 207         abort = 1;
 208
 209         err = xenbus_transaction_start(&xbt);
 210         if (err) {
 211                 xenbus_switch_fatal(dev, depth, err, "starting transaction");
 212                 return 0;
 213         }
 214
 215         err = xenbus_scanf(xbt, dev->nodename, "state", "%d", &current_state);
 216         if (err != 1)
 217                 goto abort;
 218
 219         err = xenbus_printf(xbt, dev->nodename, "state", "%d", state);
 220         if (err) {
 221                 xenbus_switch_fatal(dev, depth, err, "writing new state");
 222                 goto abort;
 223         }
 224
 225         abort = 0;
 226 abort:
 227         err = xenbus_transaction_end(xbt, abort);
 228         if (err) {
 229                 if (err == -EAGAIN && !abort)
 230                         goto again;
 231                 xenbus_switch_fatal(dev, depth, err, "ending transaction");
 232         } else
 233                 dev->state = state;
 234
 235         return 0;
 236 }
 237
 238 /**
 239  * xenbus_switch_state
 240  * @dev: xenbus device
 241  * @state: new state
 242  *
 243  * Advertise in the store a change of the given driver to the given new_state.
 244  * Return 0 on success, or -errno on error.  On error, the device will switch
 245  * to XenbusStateClosing, and the error will be saved in the store.
 246  */
 247 int xenbus_switch_state(struct xenbus_device *dev, enum xenbus_state state)
 248 {
 249         return __xenbus_switch_state(dev, state, 0);
 250 }
 251
 252 EXPORT_SYMBOL_GPL(xenbus_switch_state);
 253
 254 int xenbus_frontend_closed(struct xenbus_device *dev)
 255 {
 256         xenbus_switch_state(dev, XenbusStateClosed);
 257         complete(&dev->down);
 258         return 0;
 259 }
 260 EXPORT_SYMBOL_GPL(xenbus_frontend_closed);
 261
 262 static void xenbus_va_dev_error(struct xenbus_device *dev, int err,
 263                                 const char *fmt, va_list ap)
 264 {
 265         unsigned int len;
 266         char *printf_buffer;
 267         char *path_buffer;
 268
 269 #define PRINTF_BUFFER_SIZE 4096
 270
 271         printf_buffer = kmalloc(PRINTF_BUFFER_SIZE, GFP_KERNEL);
 272         if (!printf_buffer)
 273                 return;
 274
 275         len = sprintf(printf_buffer, "%i ", -err);
 276         vsnprintf(printf_buffer + len, PRINTF_BUFFER_SIZE - len, fmt, ap);
 277
 278         dev_err(&dev->dev, "%s\n", printf_buffer);
 279
 280         path_buffer = kasprintf(GFP_KERNEL, "error/%s", dev->nodename);
 281         if (path_buffer)
 282                 xenbus_write(XBT_NIL, path_buffer, "error", printf_buffer);
 283
 284         kfree(printf_buffer);
 285         kfree(path_buffer);
 286 }
 287
 288 /**
 289  * xenbus_dev_error
 290  * @dev: xenbus device
 291  * @err: error to report
 292  * @fmt: error message format
 293  *
 294  * Report the given negative errno into the store, along with the given
 295  * formatted message.
 296  */
 297 void xenbus_dev_error(struct xenbus_device *dev, int err, const char *fmt, ...)
 298 {
 299         va_list ap;
 300
 301         va_start(ap, fmt);
 302         xenbus_va_dev_error(dev, err, fmt, ap);
 303         va_end(ap);
 304 }
 305 EXPORT_SYMBOL_GPL(xenbus_dev_error);
 306
 307 /**
 308  * xenbus_dev_fatal
 309  * @dev: xenbus device
 310  * @err: error to report
 311  * @fmt: error message format
 312  *
 313  * Equivalent to xenbus_dev_error(dev, err, fmt, args), followed by
 314  * xenbus_switch_state(dev, XenbusStateClosing) to schedule an orderly
 315  * closedown of this driver and its peer.
 316  */
 317
 318 void xenbus_dev_fatal(struct xenbus_device *dev, int err, const char *fmt, ...)
 319 {
 320         va_list ap;
 321
 322         va_start(ap, fmt);
 323         xenbus_va_dev_error(dev, err, fmt, ap);
 324         va_end(ap);
 325
 326         xenbus_switch_state(dev, XenbusStateClosing);
 327 }
 328 EXPORT_SYMBOL_GPL(xenbus_dev_fatal);
 329
 330 /**
 331  * Equivalent to xenbus_dev_fatal(dev, err, fmt, args), but helps
 332  * avoiding recursion within xenbus_switch_state.
 333  */
 334 static void xenbus_switch_fatal(struct xenbus_device *dev, int depth, int err,
 335                                 const char *fmt, ...)
 336 {
 337         va_list ap;
 338
 339         va_start(ap, fmt);
 340         xenbus_va_dev_error(dev, err, fmt, ap);
 341         va_end(ap);
 342
 343         if (!depth)
 344                 __xenbus_switch_state(dev, XenbusStateClosing, 1);
 345 }
 346
 347 /**
 348  * xenbus_grant_ring
 349  * @dev: xenbus device
 350  * @vaddr: starting virtual address of the ring
 351  * @nr_pages: number of pages to be granted
 352  * @grefs: grant reference array to be filled in
 353  *
 354  * Grant access to the given @vaddr to the peer of the given device.
 355  * Then fill in @grefs with grant references.  Return 0 on success, or
 356  * -errno on error.  On error, the device will switch to
 357  * XenbusStateClosing, and the error will be saved in the store.
 358  */
 359 int xenbus_grant_ring(struct xenbus_device *dev, void *vaddr,
 360                       unsigned int nr_pages, grant_ref_t *grefs)
 361 {
 362         int err;
 363         int i, j;
 364
 365         for (i = 0; i < nr_pages; i++) {
 366                 err = gnttab_grant_foreign_access(dev->otherend_id,
 367                                                   virt_to_gfn(vaddr), 0);
 368                 if (err < 0) {
 369                         xenbus_dev_fatal(dev, err,
 370                                          "granting access to ring page");
 371                         goto fail;
 372                 }
 373                 grefs[i] = err;
 374
 375                 vaddr = vaddr + XEN_PAGE_SIZE;
 376         }
 377
 378         return 0;
 379
 380 fail:
 381         for (j = 0; j < i; j++)
 382                 gnttab_end_foreign_access_ref(grefs[j], 0);
 383         return err;
 384 }
 385 EXPORT_SYMBOL_GPL(xenbus_grant_ring);
 386
 387
 388 /**
 389  * Allocate an event channel for the given xenbus_device, assigning the newly
 390  * created local port to *port.  Return 0 on success, or -errno on error.  On
 391  * error, the device will switch to XenbusStateClosing, and the error will be
 392  * saved in the store.
 393  */
 394 int xenbus_alloc_evtchn(struct xenbus_device *dev, evtchn_port_t *port)
 395 {
 396         struct evtchn_alloc_unbound alloc_unbound;
 397         int err;
 398
 399         alloc_unbound.dom = DOMID_SELF;
 400         alloc_unbound.remote_dom = dev->otherend_id;
 401
 402         err = HYPERVISOR_event_channel_op(EVTCHNOP_alloc_unbound,
 403                                           &alloc_unbound);
 404         if (err)
 405                 xenbus_dev_fatal(dev, err, "allocating event channel");
 406         else
 407                 *port = alloc_unbound.port;
 408
 409         return err;
 410 }
 411 EXPORT_SYMBOL_GPL(xenbus_alloc_evtchn);
 412
 413
 414 /**
 415  * Free an existing event channel. Returns 0 on success or -errno on error.
 416  */
 417 int xenbus_free_evtchn(struct xenbus_device *dev, evtchn_port_t port)
 418 {
 419         struct evtchn_close close;
 420         int err;
 421
 422         close.port = port;
 423
 424         err = HYPERVISOR_event_channel_op(EVTCHNOP_close, &close);
 425         if (err)
 426                 xenbus_dev_error(dev, err, "freeing event channel %u", port);
 427
 428         return err;
 429 }
 430 EXPORT_SYMBOL_GPL(xenbus_free_evtchn);
 431
 432
 433 /**
 434  * xenbus_map_ring_valloc
 435  * @dev: xenbus device
 436  * @gnt_refs: grant reference array
 437  * @nr_grefs: number of grant references
 438  * @vaddr: pointer to address to be filled out by mapping
 439  *
 440  * Map @nr_grefs pages of memory into this domain from another
 441  * domain's grant table.  xenbus_map_ring_valloc allocates @nr_grefs
 442  * pages of virtual address space, maps the pages to that address, and
 443  * sets *vaddr to that address.  Returns 0 on success, and GNTST_*
 444  * (see xen/include/interface/grant_table.h) or -ENOMEM / -EINVAL on
 445  * error. If an error is returned, device will switch to
 446  * XenbusStateClosing and the error message will be saved in XenStore.
 447  */
 448 int xenbus_map_ring_valloc(struct xenbus_device *dev, grant_ref_t *gnt_refs,
 449                            unsigned int nr_grefs, void **vaddr)
 450 {
 451         return ring_ops->map(dev, gnt_refs, nr_grefs, vaddr);
 452 }
 453 EXPORT_SYMBOL_GPL(xenbus_map_ring_valloc);
 454
 455 /* N.B. sizeof(phys_addr_t) doesn't always equal to sizeof(unsigned
 456  * long), e.g. 32-on-64.  Caller is responsible for preparing the
 457  * right array to feed into this function */
 458 static int __xenbus_map_ring(struct xenbus_device *dev,
 459                              grant_ref_t *gnt_refs,
 460                              unsigned int nr_grefs,
 461                              grant_handle_t *handles,
 462                              phys_addr_t *addrs,
 463                              unsigned int flags,
 464                              bool *leaked)
 465 {
 466         struct gnttab_map_grant_ref map[XENBUS_MAX_RING_GRANTS];
 467         struct gnttab_unmap_grant_ref unmap[XENBUS_MAX_RING_GRANTS];
 468         int i, j;
 469         int err = GNTST_okay;
 470
 471         if (nr_grefs > XENBUS_MAX_RING_GRANTS)
 472                 return -EINVAL;
 473
 474         for (i = 0; i < nr_grefs; i++) {
 475                 memset(&map[i], 0, sizeof(map[i]));
 476                 gnttab_set_map_op(&map[i], addrs[i], flags, gnt_refs[i],
 477                                   dev->otherend_id);
 478                 handles[i] = INVALID_GRANT_HANDLE;
 479         }
 480
 481         gnttab_batch_map(map, i);
 482
 483         for (i = 0; i < nr_grefs; i++) {
 484                 if (map[i].status != GNTST_okay) {
 485                         err = map[i].status;
 486                         xenbus_dev_fatal(dev, map[i].status,
 487                                          "mapping in shared page %d from domain %d",
 488                                          gnt_refs[i], dev->otherend_id);
 489                         goto fail;
 490                 } else
 491                         handles[i] = map[i].handle;
 492         }
 493
 494         return GNTST_okay;
 495
 496  fail:
 497         for (i = j = 0; i < nr_grefs; i++) {
 498                 if (handles[i] != INVALID_GRANT_HANDLE) {
 499                         memset(&unmap[j], 0, sizeof(unmap[j]));
 500                         gnttab_set_unmap_op(&unmap[j], (phys_addr_t)addrs[i],
 501                                             GNTMAP_host_map, handles[i]);
 502                         j++;
 503                 }
 504         }
 505
 506         if (HYPERVISOR_grant_table_op(GNTTABOP_unmap_grant_ref, unmap, j))
 507                 BUG();
 508
 509         *leaked = false;
 510         for (i = 0; i < j; i++) {
 511                 if (unmap[i].status != GNTST_okay) {
 512                         *leaked = true;
 513                         break;
 514                 }
 515         }
 516
 517         return err;
 518 }
 519
 520 /**
 521  * xenbus_unmap_ring
 522  * @dev: xenbus device
 523  * @handles: grant handle array
 524  * @nr_handles: number of handles in the array
 525  * @vaddrs: addresses to unmap
 526  *
 527  * Unmap memory in this domain that was imported from another domain.
 528  * Returns 0 on success and returns GNTST_* on error
 529  * (see xen/include/interface/grant_table.h).
 530  */
 531 static int xenbus_unmap_ring(struct xenbus_device *dev, grant_handle_t *handles,
 532                              unsigned int nr_handles, unsigned long *vaddrs)
 533 {
 534         struct gnttab_unmap_grant_ref unmap[XENBUS_MAX_RING_GRANTS];
 535         int i;
 536         int err;
 537
 538         if (nr_handles > XENBUS_MAX_RING_GRANTS)
 539                 return -EINVAL;
 540
 541         for (i = 0; i < nr_handles; i++)
 542                 gnttab_set_unmap_op(&unmap[i], vaddrs[i],
 543                                     GNTMAP_host_map, handles[i]);
 544
 545         if (HYPERVISOR_grant_table_op(GNTTABOP_unmap_grant_ref, unmap, i))
 546                 BUG();
 547
 548         err = GNTST_okay;
 549         for (i = 0; i < nr_handles; i++) {
 550                 if (unmap[i].status != GNTST_okay) {
 551                         xenbus_dev_error(dev, unmap[i].status,
 552                                          "unmapping page at handle %d error %d",
 553                                          handles[i], unmap[i].status);
 554                         err = unmap[i].status;
 555                         break;
 556                 }
 557         }
 558
 559         return err;
 560 }
 561
 562 struct map_ring_valloc_hvm
 563 {
 564         unsigned int idx;
 565
 566         /* Why do we need two arrays? See comment of __xenbus_map_ring */
 567         phys_addr_t phys_addrs[XENBUS_MAX_RING_GRANTS];
 568         unsigned long addrs[XENBUS_MAX_RING_GRANTS];
 569 };
 570
 571 static void xenbus_map_ring_setup_grant_hvm(unsigned long gfn,
 572                                             unsigned int goffset,
 573                                             unsigned int len,
 574                                             void *data)
 575 {
 576         struct map_ring_valloc_hvm *info = data;
 577         unsigned long vaddr = (unsigned long)gfn_to_virt(gfn);
 578
 579         info->phys_addrs[info->idx] = vaddr;
 580         info->addrs[info->idx] = vaddr;
 581
 582         info->idx++;
 583 }
 584
 585 static int xenbus_map_ring_valloc_hvm(struct xenbus_device *dev,
 586                                       grant_ref_t *gnt_ref,
 587                                       unsigned int nr_grefs,
 588                                       void **vaddr)
 589 {
 590         struct xenbus_map_node *node;
 591         int err;
 592         void *addr;
 593         bool leaked = false;
 594         struct map_ring_valloc_hvm info = {
 595                 .idx = 0,
 596         };
 597         unsigned int nr_pages = XENBUS_PAGES(nr_grefs);
 598
 599         if (nr_grefs > XENBUS_MAX_RING_GRANTS)
 600                 return -EINVAL;
 601
 602         *vaddr = NULL;
 603
 604         node = kzalloc(sizeof(*node), GFP_KERNEL);
 605         if (!node)
 606                 return -ENOMEM;
 607
 608         err = alloc_xenballooned_pages(nr_pages, node->hvm.pages);
 609         if (err)
 610                 goto out_err;
 611
 612         gnttab_foreach_grant(node->hvm.pages, nr_grefs,
 613                              xenbus_map_ring_setup_grant_hvm,
 614                              &info);
 615
 616         err = __xenbus_map_ring(dev, gnt_ref, nr_grefs, node->handles,
 617                                 info.phys_addrs, GNTMAP_host_map, &leaked);
 618         node->nr_handles = nr_grefs;
 619
 620         if (err)
 621                 goto out_free_ballooned_pages;
 622
 623         addr = vmap(node->hvm.pages, nr_pages, VM_MAP | VM_IOREMAP,
 624                     PAGE_KERNEL);
 625         if (!addr) {
 626                 err = -ENOMEM;
 627                 goto out_xenbus_unmap_ring;
 628         }
 629
 630         node->hvm.addr = addr;
 631
 632         spin_lock(&xenbus_valloc_lock);
 633         list_add(&node->next, &xenbus_valloc_pages);
 634         spin_unlock(&xenbus_valloc_lock);
 635
 636         *vaddr = addr;
 637         return 0;
 638
 639  out_xenbus_unmap_ring:
 640         if (!leaked)
 641                 xenbus_unmap_ring(dev, node->handles, nr_grefs, info.addrs);
 642         else
 643                 pr_alert("leaking %p size %u page(s)",
 644                          addr, nr_pages);
 645  out_free_ballooned_pages:
 646         if (!leaked)
 647                 free_xenballooned_pages(nr_pages, node->hvm.pages);
 648  out_err:
 649         kfree(node);
 650         return err;
 651 }
 652
 653 /**
 654  * xenbus_unmap_ring_vfree
 655  * @dev: xenbus device
 656  * @vaddr: addr to unmap
 657  *
 658  * Based on Rusty Russell's skeleton driver's unmap_page.
 659  * Unmap a page of memory in this domain that was imported from another domain.
 660  * Use xenbus_unmap_ring_vfree if you mapped in your memory with
 661  * xenbus_map_ring_valloc (it will free the virtual address space).
 662  * Returns 0 on success and returns GNTST_* on error
 663  * (see xen/include/interface/grant_table.h).
 664  */
 665 int xenbus_unmap_ring_vfree(struct xenbus_device *dev, void *vaddr)
 666 {
 667         return ring_ops->unmap(dev, vaddr);
 668 }
 669 EXPORT_SYMBOL_GPL(xenbus_unmap_ring_vfree);
 670
 671 #ifdef CONFIG_XEN_PV
 672 static int xenbus_map_ring_valloc_pv(struct xenbus_device *dev,
 673                                      grant_ref_t *gnt_refs,
 674                                      unsigned int nr_grefs,
 675                                      void **vaddr)
 676 {
 677         struct xenbus_map_node *node;
 678         struct vm_struct *area;
 679         pte_t *ptes[XENBUS_MAX_RING_GRANTS];
 680         phys_addr_t phys_addrs[XENBUS_MAX_RING_GRANTS];
 681         int err = GNTST_okay;
 682         int i;
 683         bool leaked;
 684
 685         *vaddr = NULL;
 686
 687         if (nr_grefs > XENBUS_MAX_RING_GRANTS)
 688                 return -EINVAL;
 689
 690         node = kzalloc(sizeof(*node), GFP_KERNEL);
 691         if (!node)
 692                 return -ENOMEM;
 693
 694         area = alloc_vm_area(XEN_PAGE_SIZE * nr_grefs, ptes);
 695         if (!area) {
 696                 kfree(node);
 697                 return -ENOMEM;
 698         }
 699
 700         for (i = 0; i < nr_grefs; i++)
 701                 phys_addrs[i] = arbitrary_virt_to_machine(ptes[i]).maddr;
 702
 703         err = __xenbus_map_ring(dev, gnt_refs, nr_grefs, node->handles,
 704                                 phys_addrs,
 705                                 GNTMAP_host_map | GNTMAP_contains_pte,
 706                                 &leaked);
 707         if (err)
 708                 goto failed;
 709
 710         node->nr_handles = nr_grefs;
 711         node->pv.area = area;
 712
 713         spin_lock(&xenbus_valloc_lock);
 714         list_add(&node->next, &xenbus_valloc_pages);
 715         spin_unlock(&xenbus_valloc_lock);
 716
 717         *vaddr = area->addr;
 718         return 0;
 719
 720 failed:
 721         if (!leaked)
 722                 free_vm_area(area);
 723         else
 724                 pr_alert("leaking VM area %p size %u page(s)", area, nr_grefs);
 725
 726         kfree(node);
 727         return err;
 728 }
 729
 730 static int xenbus_unmap_ring_vfree_pv(struct xenbus_device *dev, void *vaddr)
 731 {
 732         struct xenbus_map_node *node;
 733         struct gnttab_unmap_grant_ref unmap[XENBUS_MAX_RING_GRANTS];
 734         unsigned int level;
 735         int i;
 736         bool leaked = false;
 737         int err;
 738
 739         spin_lock(&xenbus_valloc_lock);
 740         list_for_each_entry(node, &xenbus_valloc_pages, next) {
 741                 if (node->pv.area->addr == vaddr) {
 742                         list_del(&node->next);
 743                         goto found;
 744                 }
 745         }
 746         node = NULL;
 747  found:
 748         spin_unlock(&xenbus_valloc_lock);
 749
 750         if (!node) {
 751                 xenbus_dev_error(dev, -ENOENT,
 752                                  "can't find mapped virtual address %p", vaddr);
 753                 return GNTST_bad_virt_addr;
 754         }
 755
 756         for (i = 0; i < node->nr_handles; i++) {
 757                 unsigned long addr;
 758
 759                 memset(&unmap[i], 0, sizeof(unmap[i]));
 760                 addr = (unsigned long)vaddr + (XEN_PAGE_SIZE * i);
 761                 unmap[i].host_addr = arbitrary_virt_to_machine(
 762                         lookup_address(addr, &level)).maddr;
 763                 unmap[i].dev_bus_addr = 0;
 764                 unmap[i].handle = node->handles[i];
 765         }
 766
 767         if (HYPERVISOR_grant_table_op(GNTTABOP_unmap_grant_ref, unmap, i))
 768                 BUG();
 769
 770         err = GNTST_okay;
 771         leaked = false;
 772         for (i = 0; i < node->nr_handles; i++) {
 773                 if (unmap[i].status != GNTST_okay) {
 774                         leaked = true;
 775                         xenbus_dev_error(dev, unmap[i].status,
 776                                          "unmapping page at handle %d error %d",
 777                                          node->handles[i], unmap[i].status);
 778                         err = unmap[i].status;
 779                         break;
 780                 }
 781         }
 782
 783         if (!leaked)
 784                 free_vm_area(node->pv.area);
 785         else
 786                 pr_alert("leaking VM area %p size %u page(s)",
 787                          node->pv.area, node->nr_handles);
 788
 789         kfree(node);
 790         return err;
 791 }
 792
 793 static const struct xenbus_ring_ops ring_ops_pv = {
 794         .map = xenbus_map_ring_valloc_pv,
 795         .unmap = xenbus_unmap_ring_vfree_pv,
 796 };
 797 #endif
 798
 799 struct unmap_ring_vfree_hvm
 800 {
 801         unsigned int idx;
 802         unsigned long addrs[XENBUS_MAX_RING_GRANTS];
 803 };
 804
 805 static void xenbus_unmap_ring_setup_grant_hvm(unsigned long gfn,
 806                                               unsigned int goffset,
 807                                               unsigned int len,
 808                                               void *data)
 809 {
 810         struct unmap_ring_vfree_hvm *info = data;
 811
 812         info->addrs[info->idx] = (unsigned long)gfn_to_virt(gfn);
 813
 814         info->idx++;
 815 }
 816
 817 static int xenbus_unmap_ring_vfree_hvm(struct xenbus_device *dev, void *vaddr)
 818 {
 819         int rv;
 820         struct xenbus_map_node *node;
 821         void *addr;
 822         struct unmap_ring_vfree_hvm info = {
 823                 .idx = 0,
 824         };
 825         unsigned int nr_pages;
 826
 827         spin_lock(&xenbus_valloc_lock);
 828         list_for_each_entry(node, &xenbus_valloc_pages, next) {
 829                 addr = node->hvm.addr;
 830                 if (addr == vaddr) {
 831                         list_del(&node->next);
 832                         goto found;
 833                 }
 834         }
 835         node = addr = NULL;
 836  found:
 837         spin_unlock(&xenbus_valloc_lock);
 838
 839         if (!node) {
 840                 xenbus_dev_error(dev, -ENOENT,
 841                                  "can't find mapped virtual address %p", vaddr);
 842                 return GNTST_bad_virt_addr;
 843         }
 844
 845         nr_pages = XENBUS_PAGES(node->nr_handles);
 846
 847         gnttab_foreach_grant(node->hvm.pages, node->nr_handles,
 848                              xenbus_unmap_ring_setup_grant_hvm,
 849                              &info);
 850
 851         rv = xenbus_unmap_ring(dev, node->handles, node->nr_handles,
 852                                info.addrs);
 853         if (!rv) {
 854                 vunmap(vaddr);
 855                 free_xenballooned_pages(nr_pages, node->hvm.pages);
 856         }
 857         else
 858                 WARN(1, "Leaking %p, size %u page(s)\n", vaddr, nr_pages);
 859
 860         kfree(node);
 861         return rv;
 862 }
 863
 864 /**
 865  * xenbus_read_driver_state
 866  * @path: path for driver
 867  *
 868  * Return the state of the driver rooted at the given store path, or
 869  * XenbusStateUnknown if no state can be read.
 870  */
 871 enum xenbus_state xenbus_read_driver_state(const char *path)
 872 {
 873         enum xenbus_state result;
 874         int err = xenbus_gather(XBT_NIL, path, "state", "%d", &result, NULL);
 875         if (err)
 876                 result = XenbusStateUnknown;
 877
 878         return result;
 879 }
 880 EXPORT_SYMBOL_GPL(xenbus_read_driver_state);
 881
 882 static const struct xenbus_ring_ops ring_ops_hvm = {
 883         .map = xenbus_map_ring_valloc_hvm,
 884         .unmap = xenbus_unmap_ring_vfree_hvm,
 885 };
 886
 887 void __init xenbus_ring_ops_init(void)
 888 {
 889 #ifdef CONFIG_XEN_PV
 890         if (!xen_feature(XENFEAT_auto_translated_physmap))
 891                 ring_ops = &ring_ops_pv;
 892         else
 893 #endif
 894                 ring_ops = &ring_ops_hvm;
 895 }