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                 dev_err(&dev->dev, "failed to write error node for %s (%s)\n",
 284                         dev->nodename, printf_buffer);
 285
 286         kfree(printf_buffer);
 287         kfree(path_buffer);
 288 }
 289
 290 /**
 291  * xenbus_dev_error
 292  * @dev: xenbus device
 293  * @err: error to report
 294  * @fmt: error message format
 295  *
 296  * Report the given negative errno into the store, along with the given
 297  * formatted message.
 298  */
 299 void xenbus_dev_error(struct xenbus_device *dev, int err, const char *fmt, ...)
 300 {
 301         va_list ap;
 302
 303         va_start(ap, fmt);
 304         xenbus_va_dev_error(dev, err, fmt, ap);
 305         va_end(ap);
 306 }
 307 EXPORT_SYMBOL_GPL(xenbus_dev_error);
 308
 309 /**
 310  * xenbus_dev_fatal
 311  * @dev: xenbus device
 312  * @err: error to report
 313  * @fmt: error message format
 314  *
 315  * Equivalent to xenbus_dev_error(dev, err, fmt, args), followed by
 316  * xenbus_switch_state(dev, XenbusStateClosing) to schedule an orderly
 317  * closedown of this driver and its peer.
 318  */
 319
 320 void xenbus_dev_fatal(struct xenbus_device *dev, int err, const char *fmt, ...)
 321 {
 322         va_list ap;
 323
 324         va_start(ap, fmt);
 325         xenbus_va_dev_error(dev, err, fmt, ap);
 326         va_end(ap);
 327
 328         xenbus_switch_state(dev, XenbusStateClosing);
 329 }
 330 EXPORT_SYMBOL_GPL(xenbus_dev_fatal);
 331
 332 /**
 333  * Equivalent to xenbus_dev_fatal(dev, err, fmt, args), but helps
 334  * avoiding recursion within xenbus_switch_state.
 335  */
 336 static void xenbus_switch_fatal(struct xenbus_device *dev, int depth, int err,
 337                                 const char *fmt, ...)
 338 {
 339         va_list ap;
 340
 341         va_start(ap, fmt);
 342         xenbus_va_dev_error(dev, err, fmt, ap);
 343         va_end(ap);
 344
 345         if (!depth)
 346                 __xenbus_switch_state(dev, XenbusStateClosing, 1);
 347 }
 348
 349 /**
 350  * xenbus_grant_ring
 351  * @dev: xenbus device
 352  * @vaddr: starting virtual address of the ring
 353  * @nr_pages: number of pages to be granted
 354  * @grefs: grant reference array to be filled in
 355  *
 356  * Grant access to the given @vaddr to the peer of the given device.
 357  * Then fill in @grefs with grant references.  Return 0 on success, or
 358  * -errno on error.  On error, the device will switch to
 359  * XenbusStateClosing, and the error will be saved in the store.
 360  */
 361 int xenbus_grant_ring(struct xenbus_device *dev, void *vaddr,
 362                       unsigned int nr_pages, grant_ref_t *grefs)
 363 {
 364         int err;
 365         int i, j;
 366
 367         for (i = 0; i < nr_pages; i++) {
 368                 err = gnttab_grant_foreign_access(dev->otherend_id,
 369                                                   virt_to_gfn(vaddr), 0);
 370                 if (err < 0) {
 371                         xenbus_dev_fatal(dev, err,
 372                                          "granting access to ring page");
 373                         goto fail;
 374                 }
 375                 grefs[i] = err;
 376
 377                 vaddr = vaddr + XEN_PAGE_SIZE;
 378         }
 379
 380         return 0;
 381
 382 fail:
 383         for (j = 0; j < i; j++)
 384                 gnttab_end_foreign_access_ref(grefs[j], 0);
 385         return err;
 386 }
 387 EXPORT_SYMBOL_GPL(xenbus_grant_ring);
 388
 389
 390 /**
 391  * Allocate an event channel for the given xenbus_device, assigning the newly
 392  * created local port to *port.  Return 0 on success, or -errno on error.  On
 393  * error, the device will switch to XenbusStateClosing, and the error will be
 394  * saved in the store.
 395  */
 396 int xenbus_alloc_evtchn(struct xenbus_device *dev, int *port)
 397 {
 398         struct evtchn_alloc_unbound alloc_unbound;
 399         int err;
 400
 401         alloc_unbound.dom = DOMID_SELF;
 402         alloc_unbound.remote_dom = dev->otherend_id;
 403
 404         err = HYPERVISOR_event_channel_op(EVTCHNOP_alloc_unbound,
 405                                           &alloc_unbound);
 406         if (err)
 407                 xenbus_dev_fatal(dev, err, "allocating event channel");
 408         else
 409                 *port = alloc_unbound.port;
 410
 411         return err;
 412 }
 413 EXPORT_SYMBOL_GPL(xenbus_alloc_evtchn);
 414
 415
 416 /**
 417  * Free an existing event channel. Returns 0 on success or -errno on error.
 418  */
 419 int xenbus_free_evtchn(struct xenbus_device *dev, int port)
 420 {
 421         struct evtchn_close close;
 422         int err;
 423
 424         close.port = port;
 425
 426         err = HYPERVISOR_event_channel_op(EVTCHNOP_close, &close);
 427         if (err)
 428                 xenbus_dev_error(dev, err, "freeing event channel %d", port);
 429
 430         return err;
 431 }
 432 EXPORT_SYMBOL_GPL(xenbus_free_evtchn);
 433
 434
 435 /**
 436  * xenbus_map_ring_valloc
 437  * @dev: xenbus device
 438  * @gnt_refs: grant reference array
 439  * @nr_grefs: number of grant references
 440  * @vaddr: pointer to address to be filled out by mapping
 441  *
 442  * Map @nr_grefs pages of memory into this domain from another
 443  * domain's grant table.  xenbus_map_ring_valloc allocates @nr_grefs
 444  * pages of virtual address space, maps the pages to that address, and
 445  * sets *vaddr to that address.  Returns 0 on success, and GNTST_*
 446  * (see xen/include/interface/grant_table.h) or -ENOMEM / -EINVAL on
 447  * error. If an error is returned, device will switch to
 448  * XenbusStateClosing and the error message will be saved in XenStore.
 449  */
 450 int xenbus_map_ring_valloc(struct xenbus_device *dev, grant_ref_t *gnt_refs,
 451                            unsigned int nr_grefs, void **vaddr)
 452 {
 453         return ring_ops->map(dev, gnt_refs, nr_grefs, vaddr);
 454 }
 455 EXPORT_SYMBOL_GPL(xenbus_map_ring_valloc);
 456
 457 /* N.B. sizeof(phys_addr_t) doesn't always equal to sizeof(unsigned
 458  * long), e.g. 32-on-64.  Caller is responsible for preparing the
 459  * right array to feed into this function */
 460 static int __xenbus_map_ring(struct xenbus_device *dev,
 461                              grant_ref_t *gnt_refs,
 462                              unsigned int nr_grefs,
 463                              grant_handle_t *handles,
 464                              phys_addr_t *addrs,
 465                              unsigned int flags,
 466                              bool *leaked)
 467 {
 468         struct gnttab_map_grant_ref map[XENBUS_MAX_RING_GRANTS];
 469         struct gnttab_unmap_grant_ref unmap[XENBUS_MAX_RING_GRANTS];
 470         int i, j;
 471         int err = GNTST_okay;
 472
 473         if (nr_grefs > XENBUS_MAX_RING_GRANTS)
 474                 return -EINVAL;
 475
 476         for (i = 0; i < nr_grefs; i++) {
 477                 memset(&map[i], 0, sizeof(map[i]));
 478                 gnttab_set_map_op(&map[i], addrs[i], flags, gnt_refs[i],
 479                                   dev->otherend_id);
 480                 handles[i] = INVALID_GRANT_HANDLE;
 481         }
 482
 483         gnttab_batch_map(map, i);
 484
 485         for (i = 0; i < nr_grefs; i++) {
 486                 if (map[i].status != GNTST_okay) {
 487                         err = map[i].status;
 488                         xenbus_dev_fatal(dev, map[i].status,
 489                                          "mapping in shared page %d from domain %d",
 490                                          gnt_refs[i], dev->otherend_id);
 491                         goto fail;
 492                 } else
 493                         handles[i] = map[i].handle;
 494         }
 495
 496         return GNTST_okay;
 497
 498  fail:
 499         for (i = j = 0; i < nr_grefs; i++) {
 500                 if (handles[i] != INVALID_GRANT_HANDLE) {
 501                         memset(&unmap[j], 0, sizeof(unmap[j]));
 502                         gnttab_set_unmap_op(&unmap[j], (phys_addr_t)addrs[i],
 503                                             GNTMAP_host_map, handles[i]);
 504                         j++;
 505                 }
 506         }
 507
 508         if (HYPERVISOR_grant_table_op(GNTTABOP_unmap_grant_ref, unmap, j))
 509                 BUG();
 510
 511         *leaked = false;
 512         for (i = 0; i < j; i++) {
 513                 if (unmap[i].status != GNTST_okay) {
 514                         *leaked = true;
 515                         break;
 516                 }
 517         }
 518
 519         return err;
 520 }
 521
 522 struct map_ring_valloc_hvm
 523 {
 524         unsigned int idx;
 525
 526         /* Why do we need two arrays? See comment of __xenbus_map_ring */
 527         phys_addr_t phys_addrs[XENBUS_MAX_RING_GRANTS];
 528         unsigned long addrs[XENBUS_MAX_RING_GRANTS];
 529 };
 530
 531 static void xenbus_map_ring_setup_grant_hvm(unsigned long gfn,
 532                                             unsigned int goffset,
 533                                             unsigned int len,
 534                                             void *data)
 535 {
 536         struct map_ring_valloc_hvm *info = data;
 537         unsigned long vaddr = (unsigned long)gfn_to_virt(gfn);
 538
 539         info->phys_addrs[info->idx] = vaddr;
 540         info->addrs[info->idx] = vaddr;
 541
 542         info->idx++;
 543 }
 544
 545 static int xenbus_map_ring_valloc_hvm(struct xenbus_device *dev,
 546                                       grant_ref_t *gnt_ref,
 547                                       unsigned int nr_grefs,
 548                                       void **vaddr)
 549 {
 550         struct xenbus_map_node *node;
 551         int err;
 552         void *addr;
 553         bool leaked = false;
 554         struct map_ring_valloc_hvm info = {
 555                 .idx = 0,
 556         };
 557         unsigned int nr_pages = XENBUS_PAGES(nr_grefs);
 558
 559         if (nr_grefs > XENBUS_MAX_RING_GRANTS)
 560                 return -EINVAL;
 561
 562         *vaddr = NULL;
 563
 564         node = kzalloc(sizeof(*node), GFP_KERNEL);
 565         if (!node)
 566                 return -ENOMEM;
 567
 568         err = alloc_xenballooned_pages(nr_pages, node->hvm.pages);
 569         if (err)
 570                 goto out_err;
 571
 572         gnttab_foreach_grant(node->hvm.pages, nr_grefs,
 573                              xenbus_map_ring_setup_grant_hvm,
 574                              &info);
 575
 576         err = __xenbus_map_ring(dev, gnt_ref, nr_grefs, node->handles,
 577                                 info.phys_addrs, GNTMAP_host_map, &leaked);
 578         node->nr_handles = nr_grefs;
 579
 580         if (err)
 581                 goto out_free_ballooned_pages;
 582
 583         addr = vmap(node->hvm.pages, nr_pages, VM_MAP | VM_IOREMAP,
 584                     PAGE_KERNEL);
 585         if (!addr) {
 586                 err = -ENOMEM;
 587                 goto out_xenbus_unmap_ring;
 588         }
 589
 590         node->hvm.addr = addr;
 591
 592         spin_lock(&xenbus_valloc_lock);
 593         list_add(&node->next, &xenbus_valloc_pages);
 594         spin_unlock(&xenbus_valloc_lock);
 595
 596         *vaddr = addr;
 597         return 0;
 598
 599  out_xenbus_unmap_ring:
 600         if (!leaked)
 601                 xenbus_unmap_ring(dev, node->handles, nr_grefs, info.addrs);
 602         else
 603                 pr_alert("leaking %p size %u page(s)",
 604                          addr, nr_pages);
 605  out_free_ballooned_pages:
 606         if (!leaked)
 607                 free_xenballooned_pages(nr_pages, node->hvm.pages);
 608  out_err:
 609         kfree(node);
 610         return err;
 611 }
 612
 613
 614 /**
 615  * xenbus_map_ring
 616  * @dev: xenbus device
 617  * @gnt_refs: grant reference array
 618  * @nr_grefs: number of grant reference
 619  * @handles: pointer to grant handle to be filled
 620  * @vaddrs: addresses to be mapped to
 621  * @leaked: fail to clean up a failed map, caller should not free vaddr
 622  *
 623  * Map pages of memory into this domain from another domain's grant table.
 624  * xenbus_map_ring does not allocate the virtual address space (you must do
 625  * this yourself!). It only maps in the pages to the specified address.
 626  * Returns 0 on success, and GNTST_* (see xen/include/interface/grant_table.h)
 627  * or -ENOMEM / -EINVAL on error. If an error is returned, device will switch to
 628  * XenbusStateClosing and the first error message will be saved in XenStore.
 629  * Further more if we fail to map the ring, caller should check @leaked.
 630  * If @leaked is not zero it means xenbus_map_ring fails to clean up, caller
 631  * should not free the address space of @vaddr.
 632  */
 633 int xenbus_map_ring(struct xenbus_device *dev, grant_ref_t *gnt_refs,
 634                     unsigned int nr_grefs, grant_handle_t *handles,
 635                     unsigned long *vaddrs, bool *leaked)
 636 {
 637         phys_addr_t phys_addrs[XENBUS_MAX_RING_GRANTS];
 638         int i;
 639
 640         if (nr_grefs > XENBUS_MAX_RING_GRANTS)
 641                 return -EINVAL;
 642
 643         for (i = 0; i < nr_grefs; i++)
 644                 phys_addrs[i] = (unsigned long)vaddrs[i];
 645
 646         return __xenbus_map_ring(dev, gnt_refs, nr_grefs, handles,
 647                                  phys_addrs, GNTMAP_host_map, leaked);
 648 }
 649 EXPORT_SYMBOL_GPL(xenbus_map_ring);
 650
 651
 652 /**
 653  * xenbus_unmap_ring_vfree
 654  * @dev: xenbus device
 655  * @vaddr: addr to unmap
 656  *
 657  * Based on Rusty Russell's skeleton driver's unmap_page.
 658  * Unmap a page of memory in this domain that was imported from another domain.
 659  * Use xenbus_unmap_ring_vfree if you mapped in your memory with
 660  * xenbus_map_ring_valloc (it will free the virtual address space).
 661  * Returns 0 on success and returns GNTST_* on error
 662  * (see xen/include/interface/grant_table.h).
 663  */
 664 int xenbus_unmap_ring_vfree(struct xenbus_device *dev, void *vaddr)
 665 {
 666         return ring_ops->unmap(dev, vaddr);
 667 }
 668 EXPORT_SYMBOL_GPL(xenbus_unmap_ring_vfree);
 669
 670 #ifdef CONFIG_XEN_PV
 671 static int xenbus_map_ring_valloc_pv(struct xenbus_device *dev,
 672                                      grant_ref_t *gnt_refs,
 673                                      unsigned int nr_grefs,
 674                                      void **vaddr)
 675 {
 676         struct xenbus_map_node *node;
 677         struct vm_struct *area;
 678         pte_t *ptes[XENBUS_MAX_RING_GRANTS];
 679         phys_addr_t phys_addrs[XENBUS_MAX_RING_GRANTS];
 680         int err = GNTST_okay;
 681         int i;
 682         bool leaked;
 683
 684         *vaddr = NULL;
 685
 686         if (nr_grefs > XENBUS_MAX_RING_GRANTS)
 687                 return -EINVAL;
 688
 689         node = kzalloc(sizeof(*node), GFP_KERNEL);
 690         if (!node)
 691                 return -ENOMEM;
 692
 693         area = alloc_vm_area(XEN_PAGE_SIZE * nr_grefs, ptes);
 694         if (!area) {
 695                 kfree(node);
 696                 return -ENOMEM;
 697         }
 698
 699         for (i = 0; i < nr_grefs; i++)
 700                 phys_addrs[i] = arbitrary_virt_to_machine(ptes[i]).maddr;
 701
 702         err = __xenbus_map_ring(dev, gnt_refs, nr_grefs, node->handles,
 703                                 phys_addrs,
 704                                 GNTMAP_host_map | GNTMAP_contains_pte,
 705                                 &leaked);
 706         if (err)
 707                 goto failed;
 708
 709         node->nr_handles = nr_grefs;
 710         node->pv.area = area;
 711
 712         spin_lock(&xenbus_valloc_lock);
 713         list_add(&node->next, &xenbus_valloc_pages);
 714         spin_unlock(&xenbus_valloc_lock);
 715
 716         *vaddr = area->addr;
 717         return 0;
 718
 719 failed:
 720         if (!leaked)
 721                 free_vm_area(area);
 722         else
 723                 pr_alert("leaking VM area %p size %u page(s)", area, nr_grefs);
 724
 725         kfree(node);
 726         return err;
 727 }
 728
 729 static int xenbus_unmap_ring_vfree_pv(struct xenbus_device *dev, void *vaddr)
 730 {
 731         struct xenbus_map_node *node;
 732         struct gnttab_unmap_grant_ref unmap[XENBUS_MAX_RING_GRANTS];
 733         unsigned int level;
 734         int i;
 735         bool leaked = false;
 736         int err;
 737
 738         spin_lock(&xenbus_valloc_lock);
 739         list_for_each_entry(node, &xenbus_valloc_pages, next) {
 740                 if (node->pv.area->addr == vaddr) {
 741                         list_del(&node->next);
 742                         goto found;
 743                 }
 744         }
 745         node = NULL;
 746  found:
 747         spin_unlock(&xenbus_valloc_lock);
 748
 749         if (!node) {
 750                 xenbus_dev_error(dev, -ENOENT,
 751                                  "can't find mapped virtual address %p", vaddr);
 752                 return GNTST_bad_virt_addr;
 753         }
 754
 755         for (i = 0; i < node->nr_handles; i++) {
 756                 unsigned long addr;
 757
 758                 memset(&unmap[i], 0, sizeof(unmap[i]));
 759                 addr = (unsigned long)vaddr + (XEN_PAGE_SIZE * i);
 760                 unmap[i].host_addr = arbitrary_virt_to_machine(
 761                         lookup_address(addr, &level)).maddr;
 762                 unmap[i].dev_bus_addr = 0;
 763                 unmap[i].handle = node->handles[i];
 764         }
 765
 766         if (HYPERVISOR_grant_table_op(GNTTABOP_unmap_grant_ref, unmap, i))
 767                 BUG();
 768
 769         err = GNTST_okay;
 770         leaked = false;
 771         for (i = 0; i < node->nr_handles; i++) {
 772                 if (unmap[i].status != GNTST_okay) {
 773                         leaked = true;
 774                         xenbus_dev_error(dev, unmap[i].status,
 775                                          "unmapping page at handle %d error %d",
 776                                          node->handles[i], unmap[i].status);
 777                         err = unmap[i].status;
 778                         break;
 779                 }
 780         }
 781
 782         if (!leaked)
 783                 free_vm_area(node->pv.area);
 784         else
 785                 pr_alert("leaking VM area %p size %u page(s)",
 786                          node->pv.area, node->nr_handles);
 787
 788         kfree(node);
 789         return err;
 790 }
 791
 792 static const struct xenbus_ring_ops ring_ops_pv = {
 793         .map = xenbus_map_ring_valloc_pv,
 794         .unmap = xenbus_unmap_ring_vfree_pv,
 795 };
 796 #endif
 797
 798 struct unmap_ring_vfree_hvm
 799 {
 800         unsigned int idx;
 801         unsigned long addrs[XENBUS_MAX_RING_GRANTS];
 802 };
 803
 804 static void xenbus_unmap_ring_setup_grant_hvm(unsigned long gfn,
 805                                               unsigned int goffset,
 806                                               unsigned int len,
 807                                               void *data)
 808 {
 809         struct unmap_ring_vfree_hvm *info = data;
 810
 811         info->addrs[info->idx] = (unsigned long)gfn_to_virt(gfn);
 812
 813         info->idx++;
 814 }
 815
 816 static int xenbus_unmap_ring_vfree_hvm(struct xenbus_device *dev, void *vaddr)
 817 {
 818         int rv;
 819         struct xenbus_map_node *node;
 820         void *addr;
 821         struct unmap_ring_vfree_hvm info = {
 822                 .idx = 0,
 823         };
 824         unsigned int nr_pages;
 825
 826         spin_lock(&xenbus_valloc_lock);
 827         list_for_each_entry(node, &xenbus_valloc_pages, next) {
 828                 addr = node->hvm.addr;
 829                 if (addr == vaddr) {
 830                         list_del(&node->next);
 831                         goto found;
 832                 }
 833         }
 834         node = addr = NULL;
 835  found:
 836         spin_unlock(&xenbus_valloc_lock);
 837
 838         if (!node) {
 839                 xenbus_dev_error(dev, -ENOENT,
 840                                  "can't find mapped virtual address %p", vaddr);
 841                 return GNTST_bad_virt_addr;
 842         }
 843
 844         nr_pages = XENBUS_PAGES(node->nr_handles);
 845
 846         gnttab_foreach_grant(node->hvm.pages, node->nr_handles,
 847                              xenbus_unmap_ring_setup_grant_hvm,
 848                              &info);
 849
 850         rv = xenbus_unmap_ring(dev, node->handles, node->nr_handles,
 851                                info.addrs);
 852         if (!rv) {
 853                 vunmap(vaddr);
 854                 free_xenballooned_pages(nr_pages, node->hvm.pages);
 855         }
 856         else
 857                 WARN(1, "Leaking %p, size %u page(s)\n", vaddr, nr_pages);
 858
 859         kfree(node);
 860         return rv;
 861 }
 862
 863 /**
 864  * xenbus_unmap_ring
 865  * @dev: xenbus device
 866  * @handles: grant handle array
 867  * @nr_handles: number of handles in the array
 868  * @vaddrs: addresses to unmap
 869  *
 870  * Unmap memory in this domain that was imported from another domain.
 871  * Returns 0 on success and returns GNTST_* on error
 872  * (see xen/include/interface/grant_table.h).
 873  */
 874 int xenbus_unmap_ring(struct xenbus_device *dev,
 875                       grant_handle_t *handles, unsigned int nr_handles,
 876                       unsigned long *vaddrs)
 877 {
 878         struct gnttab_unmap_grant_ref unmap[XENBUS_MAX_RING_GRANTS];
 879         int i;
 880         int err;
 881
 882         if (nr_handles > XENBUS_MAX_RING_GRANTS)
 883                 return -EINVAL;
 884
 885         for (i = 0; i < nr_handles; i++)
 886                 gnttab_set_unmap_op(&unmap[i], vaddrs[i],
 887                                     GNTMAP_host_map, handles[i]);
 888
 889         if (HYPERVISOR_grant_table_op(GNTTABOP_unmap_grant_ref, unmap, i))
 890                 BUG();
 891
 892         err = GNTST_okay;
 893         for (i = 0; i < nr_handles; i++) {
 894                 if (unmap[i].status != GNTST_okay) {
 895                         xenbus_dev_error(dev, unmap[i].status,
 896                                          "unmapping page at handle %d error %d",
 897                                          handles[i], unmap[i].status);
 898                         err = unmap[i].status;
 899                         break;
 900                 }
 901         }
 902
 903         return err;
 904 }
 905 EXPORT_SYMBOL_GPL(xenbus_unmap_ring);
 906
 907
 908 /**
 909  * xenbus_read_driver_state
 910  * @path: path for driver
 911  *
 912  * Return the state of the driver rooted at the given store path, or
 913  * XenbusStateUnknown if no state can be read.
 914  */
 915 enum xenbus_state xenbus_read_driver_state(const char *path)
 916 {
 917         enum xenbus_state result;
 918         int err = xenbus_gather(XBT_NIL, path, "state", "%d", &result, NULL);
 919         if (err)
 920                 result = XenbusStateUnknown;
 921
 922         return result;
 923 }
 924 EXPORT_SYMBOL_GPL(xenbus_read_driver_state);
 925
 926 static const struct xenbus_ring_ops ring_ops_hvm = {
 927         .map = xenbus_map_ring_valloc_hvm,
 928         .unmap = xenbus_unmap_ring_vfree_hvm,
 929 };
 930
 931 void __init xenbus_ring_ops_init(void)
 932 {
 933 #ifdef CONFIG_XEN_PV
 934         if (!xen_feature(XENFEAT_auto_translated_physmap))
 935                 ring_ops = &ring_ops_pv;
 936         else
 937 #endif
 938                 ring_ops = &ring_ops_hvm;
 939 }