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/slab.h> 34 #include <linux/types.h> 35 #include <linux/spinlock.h> 36 #include <linux/vmalloc.h> 37 #include <linux/export.h> 38 #include <asm/xen/hypervisor.h> 39 #include <asm/xen/page.h> 40 #include <xen/interface/xen.h> 41 #include <xen/interface/event_channel.h> 42 #include <xen/balloon.h> 43 #include <xen/events.h> 44 #include <xen/grant_table.h> 45 #include <xen/xenbus.h> 46 #include <xen/xen.h> 47 48 #include "xenbus_probe.h" 49 50 struct xenbus_map_node { 51 struct list_head next; 52 union { 53 struct vm_struct *area; /* PV */ 54 struct page *page; /* HVM */ 55 }; 56 grant_handle_t handle; 57 }; 58 59 static DEFINE_SPINLOCK(xenbus_valloc_lock); 60 static LIST_HEAD(xenbus_valloc_pages); 61 62 struct xenbus_ring_ops { 63 int (*map)(struct xenbus_device *dev, int gnt, void **vaddr); 64 int (*unmap)(struct xenbus_device *dev, void *vaddr); 65 }; 66 67 static const struct xenbus_ring_ops *ring_ops __read_mostly; 68 69 const char *xenbus_strstate(enum xenbus_state state) 70 { 71 static const char *const name[] = { 72 [ XenbusStateUnknown ] = "Unknown", 73 [ XenbusStateInitialising ] = "Initialising", 74 [ XenbusStateInitWait ] = "InitWait", 75 [ XenbusStateInitialised ] = "Initialised", 76 [ XenbusStateConnected ] = "Connected", 77 [ XenbusStateClosing ] = "Closing", 78 [ XenbusStateClosed ] = "Closed", 79 [XenbusStateReconfiguring] = "Reconfiguring", 80 [XenbusStateReconfigured] = "Reconfigured", 81 }; 82 return (state < ARRAY_SIZE(name)) ? name[state] : "INVALID"; 83 } 84 EXPORT_SYMBOL_GPL(xenbus_strstate); 85 86 /** 87 * xenbus_watch_path - register a watch 88 * @dev: xenbus device 89 * @path: path to watch 90 * @watch: watch to register 91 * @callback: callback to register 92 * 93 * Register a @watch on the given path, using the given xenbus_watch structure 94 * for storage, and the given @callback function as the callback. Return 0 on 95 * success, or -errno on error. On success, the given @path will be saved as 96 * @watch->node, and remains the caller's to free. On error, @watch->node will 97 * be NULL, the device will switch to %XenbusStateClosing, and the error will 98 * be saved in the store. 99 */ 100 int xenbus_watch_path(struct xenbus_device *dev, const char *path, 101 struct xenbus_watch *watch, 102 void (*callback)(struct xenbus_watch *, 103 const char **, unsigned int)) 104 { 105 int err; 106 107 watch->node = path; 108 watch->callback = callback; 109 110 err = register_xenbus_watch(watch); 111 112 if (err) { 113 watch->node = NULL; 114 watch->callback = NULL; 115 xenbus_dev_fatal(dev, err, "adding watch on %s", path); 116 } 117 118 return err; 119 } 120 EXPORT_SYMBOL_GPL(xenbus_watch_path); 121 122 123 /** 124 * xenbus_watch_pathfmt - register a watch on a sprintf-formatted path 125 * @dev: xenbus device 126 * @watch: watch to register 127 * @callback: callback to register 128 * @pathfmt: format of path to watch 129 * 130 * Register a watch on the given @path, using the given xenbus_watch 131 * structure for storage, and the given @callback function as the callback. 132 * Return 0 on success, or -errno on error. On success, the watched path 133 * (@path/@path2) will be saved as @watch->node, and becomes the caller's to 134 * kfree(). On error, watch->node will be NULL, so the caller has nothing to 135 * free, the device will switch to %XenbusStateClosing, and the error will be 136 * saved in the store. 137 */ 138 int xenbus_watch_pathfmt(struct xenbus_device *dev, 139 struct xenbus_watch *watch, 140 void (*callback)(struct xenbus_watch *, 141 const char **, unsigned int), 142 const char *pathfmt, ...) 143 { 144 int err; 145 va_list ap; 146 char *path; 147 148 va_start(ap, pathfmt); 149 path = kvasprintf(GFP_NOIO | __GFP_HIGH, pathfmt, ap); 150 va_end(ap); 151 152 if (!path) { 153 xenbus_dev_fatal(dev, -ENOMEM, "allocating path for watch"); 154 return -ENOMEM; 155 } 156 err = xenbus_watch_path(dev, path, watch, callback); 157 158 if (err) 159 kfree(path); 160 return err; 161 } 162 EXPORT_SYMBOL_GPL(xenbus_watch_pathfmt); 163 164 static void xenbus_switch_fatal(struct xenbus_device *, int, int, 165 const char *, ...); 166 167 static int 168 __xenbus_switch_state(struct xenbus_device *dev, 169 enum xenbus_state state, int depth) 170 { 171 /* We check whether the state is currently set to the given value, and 172 if not, then the state is set. We don't want to unconditionally 173 write the given state, because we don't want to fire watches 174 unnecessarily. Furthermore, if the node has gone, we don't write 175 to it, as the device will be tearing down, and we don't want to 176 resurrect that directory. 177 178 Note that, because of this cached value of our state, this 179 function will not take a caller's Xenstore transaction 180 (something it was trying to in the past) because dev->state 181 would not get reset if the transaction was aborted. 182 */ 183 184 struct xenbus_transaction xbt; 185 int current_state; 186 int err, abort; 187 188 if (state == dev->state) 189 return 0; 190 191 again: 192 abort = 1; 193 194 err = xenbus_transaction_start(&xbt); 195 if (err) { 196 xenbus_switch_fatal(dev, depth, err, "starting transaction"); 197 return 0; 198 } 199 200 err = xenbus_scanf(xbt, dev->nodename, "state", "%d", ¤t_state); 201 if (err != 1) 202 goto abort; 203 204 err = xenbus_printf(xbt, dev->nodename, "state", "%d", state); 205 if (err) { 206 xenbus_switch_fatal(dev, depth, err, "writing new state"); 207 goto abort; 208 } 209 210 abort = 0; 211 abort: 212 err = xenbus_transaction_end(xbt, abort); 213 if (err) { 214 if (err == -EAGAIN && !abort) 215 goto again; 216 xenbus_switch_fatal(dev, depth, err, "ending transaction"); 217 } else 218 dev->state = state; 219 220 return 0; 221 } 222 223 /** 224 * xenbus_switch_state 225 * @dev: xenbus device 226 * @state: new state 227 * 228 * Advertise in the store a change of the given driver to the given new_state. 229 * Return 0 on success, or -errno on error. On error, the device will switch 230 * to XenbusStateClosing, and the error will be saved in the store. 231 */ 232 int xenbus_switch_state(struct xenbus_device *dev, enum xenbus_state state) 233 { 234 return __xenbus_switch_state(dev, state, 0); 235 } 236 237 EXPORT_SYMBOL_GPL(xenbus_switch_state); 238 239 int xenbus_frontend_closed(struct xenbus_device *dev) 240 { 241 xenbus_switch_state(dev, XenbusStateClosed); 242 complete(&dev->down); 243 return 0; 244 } 245 EXPORT_SYMBOL_GPL(xenbus_frontend_closed); 246 247 /** 248 * Return the path to the error node for the given device, or NULL on failure. 249 * If the value returned is non-NULL, then it is the caller's to kfree. 250 */ 251 static char *error_path(struct xenbus_device *dev) 252 { 253 return kasprintf(GFP_KERNEL, "error/%s", dev->nodename); 254 } 255 256 257 static void xenbus_va_dev_error(struct xenbus_device *dev, int err, 258 const char *fmt, va_list ap) 259 { 260 int ret; 261 unsigned int len; 262 char *printf_buffer = NULL; 263 char *path_buffer = NULL; 264 265 #define PRINTF_BUFFER_SIZE 4096 266 printf_buffer = kmalloc(PRINTF_BUFFER_SIZE, GFP_KERNEL); 267 if (printf_buffer == NULL) 268 goto fail; 269 270 len = sprintf(printf_buffer, "%i ", -err); 271 ret = vsnprintf(printf_buffer+len, PRINTF_BUFFER_SIZE-len, fmt, ap); 272 273 BUG_ON(len + ret > PRINTF_BUFFER_SIZE-1); 274 275 dev_err(&dev->dev, "%s\n", printf_buffer); 276 277 path_buffer = error_path(dev); 278 279 if (path_buffer == NULL) { 280 dev_err(&dev->dev, "failed to write error node for %s (%s)\n", 281 dev->nodename, printf_buffer); 282 goto fail; 283 } 284 285 if (xenbus_write(XBT_NIL, path_buffer, "error", printf_buffer) != 0) { 286 dev_err(&dev->dev, "failed to write error node for %s (%s)\n", 287 dev->nodename, printf_buffer); 288 goto fail; 289 } 290 291 fail: 292 kfree(printf_buffer); 293 kfree(path_buffer); 294 } 295 296 297 /** 298 * xenbus_dev_error 299 * @dev: xenbus device 300 * @err: error to report 301 * @fmt: error message format 302 * 303 * Report the given negative errno into the store, along with the given 304 * formatted message. 305 */ 306 void xenbus_dev_error(struct xenbus_device *dev, int err, const char *fmt, ...) 307 { 308 va_list ap; 309 310 va_start(ap, fmt); 311 xenbus_va_dev_error(dev, err, fmt, ap); 312 va_end(ap); 313 } 314 EXPORT_SYMBOL_GPL(xenbus_dev_error); 315 316 /** 317 * xenbus_dev_fatal 318 * @dev: xenbus device 319 * @err: error to report 320 * @fmt: error message format 321 * 322 * Equivalent to xenbus_dev_error(dev, err, fmt, args), followed by 323 * xenbus_switch_state(dev, XenbusStateClosing) to schedule an orderly 324 * closedown of this driver and its peer. 325 */ 326 327 void xenbus_dev_fatal(struct xenbus_device *dev, int err, const char *fmt, ...) 328 { 329 va_list ap; 330 331 va_start(ap, fmt); 332 xenbus_va_dev_error(dev, err, fmt, ap); 333 va_end(ap); 334 335 xenbus_switch_state(dev, XenbusStateClosing); 336 } 337 EXPORT_SYMBOL_GPL(xenbus_dev_fatal); 338 339 /** 340 * Equivalent to xenbus_dev_fatal(dev, err, fmt, args), but helps 341 * avoiding recursion within xenbus_switch_state. 342 */ 343 static void xenbus_switch_fatal(struct xenbus_device *dev, int depth, int err, 344 const char *fmt, ...) 345 { 346 va_list ap; 347 348 va_start(ap, fmt); 349 xenbus_va_dev_error(dev, err, fmt, ap); 350 va_end(ap); 351 352 if (!depth) 353 __xenbus_switch_state(dev, XenbusStateClosing, 1); 354 } 355 356 /** 357 * xenbus_grant_ring 358 * @dev: xenbus device 359 * @ring_mfn: mfn of ring to grant 360 361 * Grant access to the given @ring_mfn to the peer of the given device. Return 362 * 0 on success, or -errno on error. On error, the device will switch to 363 * XenbusStateClosing, and the error will be saved in the store. 364 */ 365 int xenbus_grant_ring(struct xenbus_device *dev, unsigned long ring_mfn) 366 { 367 int err = gnttab_grant_foreign_access(dev->otherend_id, ring_mfn, 0); 368 if (err < 0) 369 xenbus_dev_fatal(dev, err, "granting access to ring page"); 370 return err; 371 } 372 EXPORT_SYMBOL_GPL(xenbus_grant_ring); 373 374 375 /** 376 * Allocate an event channel for the given xenbus_device, assigning the newly 377 * created local port to *port. Return 0 on success, or -errno on error. On 378 * error, the device will switch to XenbusStateClosing, and the error will be 379 * saved in the store. 380 */ 381 int xenbus_alloc_evtchn(struct xenbus_device *dev, int *port) 382 { 383 struct evtchn_alloc_unbound alloc_unbound; 384 int err; 385 386 alloc_unbound.dom = DOMID_SELF; 387 alloc_unbound.remote_dom = dev->otherend_id; 388 389 err = HYPERVISOR_event_channel_op(EVTCHNOP_alloc_unbound, 390 &alloc_unbound); 391 if (err) 392 xenbus_dev_fatal(dev, err, "allocating event channel"); 393 else 394 *port = alloc_unbound.port; 395 396 return err; 397 } 398 EXPORT_SYMBOL_GPL(xenbus_alloc_evtchn); 399 400 401 /** 402 * Bind to an existing interdomain event channel in another domain. Returns 0 403 * on success and stores the local port in *port. On error, returns -errno, 404 * switches the device to XenbusStateClosing, and saves the error in XenStore. 405 */ 406 int xenbus_bind_evtchn(struct xenbus_device *dev, int remote_port, int *port) 407 { 408 struct evtchn_bind_interdomain bind_interdomain; 409 int err; 410 411 bind_interdomain.remote_dom = dev->otherend_id; 412 bind_interdomain.remote_port = remote_port; 413 414 err = HYPERVISOR_event_channel_op(EVTCHNOP_bind_interdomain, 415 &bind_interdomain); 416 if (err) 417 xenbus_dev_fatal(dev, err, 418 "binding to event channel %d from domain %d", 419 remote_port, dev->otherend_id); 420 else 421 *port = bind_interdomain.local_port; 422 423 return err; 424 } 425 EXPORT_SYMBOL_GPL(xenbus_bind_evtchn); 426 427 428 /** 429 * Free an existing event channel. Returns 0 on success or -errno on error. 430 */ 431 int xenbus_free_evtchn(struct xenbus_device *dev, int port) 432 { 433 struct evtchn_close close; 434 int err; 435 436 close.port = port; 437 438 err = HYPERVISOR_event_channel_op(EVTCHNOP_close, &close); 439 if (err) 440 xenbus_dev_error(dev, err, "freeing event channel %d", port); 441 442 return err; 443 } 444 EXPORT_SYMBOL_GPL(xenbus_free_evtchn); 445 446 447 /** 448 * xenbus_map_ring_valloc 449 * @dev: xenbus device 450 * @gnt_ref: grant reference 451 * @vaddr: pointer to address to be filled out by mapping 452 * 453 * Based on Rusty Russell's skeleton driver's map_page. 454 * Map a page of memory into this domain from another domain's grant table. 455 * xenbus_map_ring_valloc allocates a page of virtual address space, maps the 456 * page to that address, and sets *vaddr to that address. 457 * Returns 0 on success, and GNTST_* (see xen/include/interface/grant_table.h) 458 * or -ENOMEM on error. If an error is returned, device will switch to 459 * XenbusStateClosing and the error message will be saved in XenStore. 460 */ 461 int xenbus_map_ring_valloc(struct xenbus_device *dev, int gnt_ref, void **vaddr) 462 { 463 return ring_ops->map(dev, gnt_ref, vaddr); 464 } 465 EXPORT_SYMBOL_GPL(xenbus_map_ring_valloc); 466 467 static int xenbus_map_ring_valloc_pv(struct xenbus_device *dev, 468 int gnt_ref, void **vaddr) 469 { 470 struct gnttab_map_grant_ref op = { 471 .flags = GNTMAP_host_map | GNTMAP_contains_pte, 472 .ref = gnt_ref, 473 .dom = dev->otherend_id, 474 }; 475 struct xenbus_map_node *node; 476 struct vm_struct *area; 477 pte_t *pte; 478 479 *vaddr = NULL; 480 481 node = kzalloc(sizeof(*node), GFP_KERNEL); 482 if (!node) 483 return -ENOMEM; 484 485 area = alloc_vm_area(PAGE_SIZE, &pte); 486 if (!area) { 487 kfree(node); 488 return -ENOMEM; 489 } 490 491 op.host_addr = arbitrary_virt_to_machine(pte).maddr; 492 493 gnttab_batch_map(&op, 1); 494 495 if (op.status != GNTST_okay) { 496 free_vm_area(area); 497 kfree(node); 498 xenbus_dev_fatal(dev, op.status, 499 "mapping in shared page %d from domain %d", 500 gnt_ref, dev->otherend_id); 501 return op.status; 502 } 503 504 node->handle = op.handle; 505 node->area = area; 506 507 spin_lock(&xenbus_valloc_lock); 508 list_add(&node->next, &xenbus_valloc_pages); 509 spin_unlock(&xenbus_valloc_lock); 510 511 *vaddr = area->addr; 512 return 0; 513 } 514 515 static int xenbus_map_ring_valloc_hvm(struct xenbus_device *dev, 516 int gnt_ref, void **vaddr) 517 { 518 struct xenbus_map_node *node; 519 int err; 520 void *addr; 521 522 *vaddr = NULL; 523 524 node = kzalloc(sizeof(*node), GFP_KERNEL); 525 if (!node) 526 return -ENOMEM; 527 528 err = alloc_xenballooned_pages(1, &node->page, false /* lowmem */); 529 if (err) 530 goto out_err; 531 532 addr = pfn_to_kaddr(page_to_pfn(node->page)); 533 534 err = xenbus_map_ring(dev, gnt_ref, &node->handle, addr); 535 if (err) 536 goto out_err; 537 538 spin_lock(&xenbus_valloc_lock); 539 list_add(&node->next, &xenbus_valloc_pages); 540 spin_unlock(&xenbus_valloc_lock); 541 542 *vaddr = addr; 543 return 0; 544 545 out_err: 546 free_xenballooned_pages(1, &node->page); 547 kfree(node); 548 return err; 549 } 550 551 552 /** 553 * xenbus_map_ring 554 * @dev: xenbus device 555 * @gnt_ref: grant reference 556 * @handle: pointer to grant handle to be filled 557 * @vaddr: address to be mapped to 558 * 559 * Map a page of memory into this domain from another domain's grant table. 560 * xenbus_map_ring does not allocate the virtual address space (you must do 561 * this yourself!). It only maps in the page to the specified address. 562 * Returns 0 on success, and GNTST_* (see xen/include/interface/grant_table.h) 563 * or -ENOMEM on error. If an error is returned, device will switch to 564 * XenbusStateClosing and the error message will be saved in XenStore. 565 */ 566 int xenbus_map_ring(struct xenbus_device *dev, int gnt_ref, 567 grant_handle_t *handle, void *vaddr) 568 { 569 struct gnttab_map_grant_ref op; 570 571 gnttab_set_map_op(&op, (unsigned long)vaddr, GNTMAP_host_map, gnt_ref, 572 dev->otherend_id); 573 574 gnttab_batch_map(&op, 1); 575 576 if (op.status != GNTST_okay) { 577 xenbus_dev_fatal(dev, op.status, 578 "mapping in shared page %d from domain %d", 579 gnt_ref, dev->otherend_id); 580 } else 581 *handle = op.handle; 582 583 return op.status; 584 } 585 EXPORT_SYMBOL_GPL(xenbus_map_ring); 586 587 588 /** 589 * xenbus_unmap_ring_vfree 590 * @dev: xenbus device 591 * @vaddr: addr to unmap 592 * 593 * Based on Rusty Russell's skeleton driver's unmap_page. 594 * Unmap a page of memory in this domain that was imported from another domain. 595 * Use xenbus_unmap_ring_vfree if you mapped in your memory with 596 * xenbus_map_ring_valloc (it will free the virtual address space). 597 * Returns 0 on success and returns GNTST_* on error 598 * (see xen/include/interface/grant_table.h). 599 */ 600 int xenbus_unmap_ring_vfree(struct xenbus_device *dev, void *vaddr) 601 { 602 return ring_ops->unmap(dev, vaddr); 603 } 604 EXPORT_SYMBOL_GPL(xenbus_unmap_ring_vfree); 605 606 static int xenbus_unmap_ring_vfree_pv(struct xenbus_device *dev, void *vaddr) 607 { 608 struct xenbus_map_node *node; 609 struct gnttab_unmap_grant_ref op = { 610 .host_addr = (unsigned long)vaddr, 611 }; 612 unsigned int level; 613 614 spin_lock(&xenbus_valloc_lock); 615 list_for_each_entry(node, &xenbus_valloc_pages, next) { 616 if (node->area->addr == vaddr) { 617 list_del(&node->next); 618 goto found; 619 } 620 } 621 node = NULL; 622 found: 623 spin_unlock(&xenbus_valloc_lock); 624 625 if (!node) { 626 xenbus_dev_error(dev, -ENOENT, 627 "can't find mapped virtual address %p", vaddr); 628 return GNTST_bad_virt_addr; 629 } 630 631 op.handle = node->handle; 632 op.host_addr = arbitrary_virt_to_machine( 633 lookup_address((unsigned long)vaddr, &level)).maddr; 634 635 if (HYPERVISOR_grant_table_op(GNTTABOP_unmap_grant_ref, &op, 1)) 636 BUG(); 637 638 if (op.status == GNTST_okay) 639 free_vm_area(node->area); 640 else 641 xenbus_dev_error(dev, op.status, 642 "unmapping page at handle %d error %d", 643 node->handle, op.status); 644 645 kfree(node); 646 return op.status; 647 } 648 649 static int xenbus_unmap_ring_vfree_hvm(struct xenbus_device *dev, void *vaddr) 650 { 651 int rv; 652 struct xenbus_map_node *node; 653 void *addr; 654 655 spin_lock(&xenbus_valloc_lock); 656 list_for_each_entry(node, &xenbus_valloc_pages, next) { 657 addr = pfn_to_kaddr(page_to_pfn(node->page)); 658 if (addr == vaddr) { 659 list_del(&node->next); 660 goto found; 661 } 662 } 663 node = addr = NULL; 664 found: 665 spin_unlock(&xenbus_valloc_lock); 666 667 if (!node) { 668 xenbus_dev_error(dev, -ENOENT, 669 "can't find mapped virtual address %p", vaddr); 670 return GNTST_bad_virt_addr; 671 } 672 673 rv = xenbus_unmap_ring(dev, node->handle, addr); 674 675 if (!rv) 676 free_xenballooned_pages(1, &node->page); 677 else 678 WARN(1, "Leaking %p\n", vaddr); 679 680 kfree(node); 681 return rv; 682 } 683 684 /** 685 * xenbus_unmap_ring 686 * @dev: xenbus device 687 * @handle: grant handle 688 * @vaddr: addr to unmap 689 * 690 * Unmap a page of memory in this domain that was imported from another domain. 691 * Returns 0 on success and returns GNTST_* on error 692 * (see xen/include/interface/grant_table.h). 693 */ 694 int xenbus_unmap_ring(struct xenbus_device *dev, 695 grant_handle_t handle, void *vaddr) 696 { 697 struct gnttab_unmap_grant_ref op; 698 699 gnttab_set_unmap_op(&op, (unsigned long)vaddr, GNTMAP_host_map, handle); 700 701 if (HYPERVISOR_grant_table_op(GNTTABOP_unmap_grant_ref, &op, 1)) 702 BUG(); 703 704 if (op.status != GNTST_okay) 705 xenbus_dev_error(dev, op.status, 706 "unmapping page at handle %d error %d", 707 handle, op.status); 708 709 return op.status; 710 } 711 EXPORT_SYMBOL_GPL(xenbus_unmap_ring); 712 713 714 /** 715 * xenbus_read_driver_state 716 * @path: path for driver 717 * 718 * Return the state of the driver rooted at the given store path, or 719 * XenbusStateUnknown if no state can be read. 720 */ 721 enum xenbus_state xenbus_read_driver_state(const char *path) 722 { 723 enum xenbus_state result; 724 int err = xenbus_gather(XBT_NIL, path, "state", "%d", &result, NULL); 725 if (err) 726 result = XenbusStateUnknown; 727 728 return result; 729 } 730 EXPORT_SYMBOL_GPL(xenbus_read_driver_state); 731 732 static const struct xenbus_ring_ops ring_ops_pv = { 733 .map = xenbus_map_ring_valloc_pv, 734 .unmap = xenbus_unmap_ring_vfree_pv, 735 }; 736 737 static const struct xenbus_ring_ops ring_ops_hvm = { 738 .map = xenbus_map_ring_valloc_hvm, 739 .unmap = xenbus_unmap_ring_vfree_hvm, 740 }; 741 742 void __init xenbus_ring_ops_init(void) 743 { 744 if (xen_pv_domain()) 745 ring_ops = &ring_ops_pv; 746 else 747 ring_ops = &ring_ops_hvm; 748 } 749