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.
6 * Copyright (C) 2005 XenSource Ltd
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:
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:
21 * The above copyright notice and this permission notice shall be included in
22 * all copies or substantial portions of the Software.
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
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>
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>
48 #include <xen/features.h>
52 #define XENBUS_PAGES(_grants) (DIV_ROUND_UP(_grants, XEN_PFN_PER_PAGE))
54 #define XENBUS_MAX_RING_PAGES (XENBUS_PAGES(XENBUS_MAX_RING_GRANTS))
56 struct xenbus_map_node {
57 struct list_head next;
60 struct vm_struct *area;
63 struct page *pages[XENBUS_MAX_RING_PAGES];
64 unsigned long addrs[XENBUS_MAX_RING_GRANTS];
68 grant_handle_t handles[XENBUS_MAX_RING_GRANTS];
69 unsigned int nr_handles;
72 struct map_ring_valloc {
73 struct xenbus_map_node *node;
75 /* Why do we need two arrays? See comment of __xenbus_map_ring */
76 unsigned long addrs[XENBUS_MAX_RING_GRANTS];
77 phys_addr_t phys_addrs[XENBUS_MAX_RING_GRANTS];
79 struct gnttab_map_grant_ref map[XENBUS_MAX_RING_GRANTS];
80 struct gnttab_unmap_grant_ref unmap[XENBUS_MAX_RING_GRANTS];
85 static DEFINE_SPINLOCK(xenbus_valloc_lock);
86 static LIST_HEAD(xenbus_valloc_pages);
88 struct xenbus_ring_ops {
89 int (*map)(struct xenbus_device *dev, struct map_ring_valloc *info,
90 grant_ref_t *gnt_refs, unsigned int nr_grefs,
92 int (*unmap)(struct xenbus_device *dev, void *vaddr);
95 static const struct xenbus_ring_ops *ring_ops __read_mostly;
97 const char *xenbus_strstate(enum xenbus_state state)
99 static const char *const name[] = {
100 [ XenbusStateUnknown ] = "Unknown",
101 [ XenbusStateInitialising ] = "Initialising",
102 [ XenbusStateInitWait ] = "InitWait",
103 [ XenbusStateInitialised ] = "Initialised",
104 [ XenbusStateConnected ] = "Connected",
105 [ XenbusStateClosing ] = "Closing",
106 [ XenbusStateClosed ] = "Closed",
107 [XenbusStateReconfiguring] = "Reconfiguring",
108 [XenbusStateReconfigured] = "Reconfigured",
110 return (state < ARRAY_SIZE(name)) ? name[state] : "INVALID";
112 EXPORT_SYMBOL_GPL(xenbus_strstate);
115 * xenbus_watch_path - register a watch
116 * @dev: xenbus device
117 * @path: path to watch
118 * @watch: watch to register
119 * @callback: callback to register
121 * Register a @watch on the given path, using the given xenbus_watch structure
122 * for storage, and the given @callback function as the callback. Return 0 on
123 * success, or -errno on error. On success, the given @path will be saved as
124 * @watch->node, and remains the caller's to free. On error, @watch->node will
125 * be NULL, the device will switch to %XenbusStateClosing, and the error will
126 * be saved in the store.
128 int xenbus_watch_path(struct xenbus_device *dev, const char *path,
129 struct xenbus_watch *watch,
130 bool (*will_handle)(struct xenbus_watch *,
131 const char *, const char *),
132 void (*callback)(struct xenbus_watch *,
133 const char *, const char *))
138 watch->will_handle = will_handle;
139 watch->callback = callback;
141 err = register_xenbus_watch(watch);
145 watch->will_handle = NULL;
146 watch->callback = NULL;
147 xenbus_dev_fatal(dev, err, "adding watch on %s", path);
152 EXPORT_SYMBOL_GPL(xenbus_watch_path);
156 * xenbus_watch_pathfmt - register a watch on a sprintf-formatted path
157 * @dev: xenbus device
158 * @watch: watch to register
159 * @callback: callback to register
160 * @pathfmt: format of path to watch
162 * Register a watch on the given @path, using the given xenbus_watch
163 * structure for storage, and the given @callback function as the callback.
164 * Return 0 on success, or -errno on error. On success, the watched path
165 * (@path/@path2) will be saved as @watch->node, and becomes the caller's to
166 * kfree(). On error, watch->node will be NULL, so the caller has nothing to
167 * free, the device will switch to %XenbusStateClosing, and the error will be
168 * saved in the store.
170 int xenbus_watch_pathfmt(struct xenbus_device *dev,
171 struct xenbus_watch *watch,
172 bool (*will_handle)(struct xenbus_watch *,
173 const char *, const char *),
174 void (*callback)(struct xenbus_watch *,
175 const char *, const char *),
176 const char *pathfmt, ...)
182 va_start(ap, pathfmt);
183 path = kvasprintf(GFP_NOIO | __GFP_HIGH, pathfmt, ap);
187 xenbus_dev_fatal(dev, -ENOMEM, "allocating path for watch");
190 err = xenbus_watch_path(dev, path, watch, will_handle, callback);
196 EXPORT_SYMBOL_GPL(xenbus_watch_pathfmt);
198 static void xenbus_switch_fatal(struct xenbus_device *, int, int,
202 __xenbus_switch_state(struct xenbus_device *dev,
203 enum xenbus_state state, int depth)
205 /* We check whether the state is currently set to the given value, and
206 if not, then the state is set. We don't want to unconditionally
207 write the given state, because we don't want to fire watches
208 unnecessarily. Furthermore, if the node has gone, we don't write
209 to it, as the device will be tearing down, and we don't want to
210 resurrect that directory.
212 Note that, because of this cached value of our state, this
213 function will not take a caller's Xenstore transaction
214 (something it was trying to in the past) because dev->state
215 would not get reset if the transaction was aborted.
218 struct xenbus_transaction xbt;
222 if (state == dev->state)
228 err = xenbus_transaction_start(&xbt);
230 xenbus_switch_fatal(dev, depth, err, "starting transaction");
234 err = xenbus_scanf(xbt, dev->nodename, "state", "%d", ¤t_state);
238 err = xenbus_printf(xbt, dev->nodename, "state", "%d", state);
240 xenbus_switch_fatal(dev, depth, err, "writing new state");
246 err = xenbus_transaction_end(xbt, abort);
248 if (err == -EAGAIN && !abort)
250 xenbus_switch_fatal(dev, depth, err, "ending transaction");
258 * xenbus_switch_state
259 * @dev: xenbus device
262 * Advertise in the store a change of the given driver to the given new_state.
263 * Return 0 on success, or -errno on error. On error, the device will switch
264 * to XenbusStateClosing, and the error will be saved in the store.
266 int xenbus_switch_state(struct xenbus_device *dev, enum xenbus_state state)
268 return __xenbus_switch_state(dev, state, 0);
271 EXPORT_SYMBOL_GPL(xenbus_switch_state);
273 int xenbus_frontend_closed(struct xenbus_device *dev)
275 xenbus_switch_state(dev, XenbusStateClosed);
276 complete(&dev->down);
279 EXPORT_SYMBOL_GPL(xenbus_frontend_closed);
281 static void xenbus_va_dev_error(struct xenbus_device *dev, int err,
282 const char *fmt, va_list ap)
288 #define PRINTF_BUFFER_SIZE 4096
290 printf_buffer = kmalloc(PRINTF_BUFFER_SIZE, GFP_KERNEL);
294 len = sprintf(printf_buffer, "%i ", -err);
295 vsnprintf(printf_buffer + len, PRINTF_BUFFER_SIZE - len, fmt, ap);
297 dev_err(&dev->dev, "%s\n", printf_buffer);
299 path_buffer = kasprintf(GFP_KERNEL, "error/%s", dev->nodename);
301 xenbus_write(XBT_NIL, path_buffer, "error", printf_buffer);
303 kfree(printf_buffer);
309 * @dev: xenbus device
310 * @err: error to report
311 * @fmt: error message format
313 * Report the given negative errno into the store, along with the given
316 void xenbus_dev_error(struct xenbus_device *dev, int err, const char *fmt, ...)
321 xenbus_va_dev_error(dev, err, fmt, ap);
324 EXPORT_SYMBOL_GPL(xenbus_dev_error);
328 * @dev: xenbus device
329 * @err: error to report
330 * @fmt: error message format
332 * Equivalent to xenbus_dev_error(dev, err, fmt, args), followed by
333 * xenbus_switch_state(dev, XenbusStateClosing) to schedule an orderly
334 * closedown of this driver and its peer.
337 void xenbus_dev_fatal(struct xenbus_device *dev, int err, const char *fmt, ...)
342 xenbus_va_dev_error(dev, err, fmt, ap);
345 xenbus_switch_state(dev, XenbusStateClosing);
347 EXPORT_SYMBOL_GPL(xenbus_dev_fatal);
350 * Equivalent to xenbus_dev_fatal(dev, err, fmt, args), but helps
351 * avoiding recursion within xenbus_switch_state.
353 static void xenbus_switch_fatal(struct xenbus_device *dev, int depth, int err,
354 const char *fmt, ...)
359 xenbus_va_dev_error(dev, err, fmt, ap);
363 __xenbus_switch_state(dev, XenbusStateClosing, 1);
368 * @dev: xenbus device
369 * @vaddr: starting virtual address of the ring
370 * @nr_pages: number of pages to be granted
371 * @grefs: grant reference array to be filled in
373 * Grant access to the given @vaddr to the peer of the given device.
374 * Then fill in @grefs with grant references. Return 0 on success, or
375 * -errno on error. On error, the device will switch to
376 * XenbusStateClosing, and the error will be saved in the store.
378 int xenbus_grant_ring(struct xenbus_device *dev, void *vaddr,
379 unsigned int nr_pages, grant_ref_t *grefs)
384 for (i = 0; i < nr_pages; i++) {
387 if (is_vmalloc_addr(vaddr))
388 gfn = pfn_to_gfn(vmalloc_to_pfn(vaddr));
390 gfn = virt_to_gfn(vaddr);
392 err = gnttab_grant_foreign_access(dev->otherend_id, gfn, 0);
394 xenbus_dev_fatal(dev, err,
395 "granting access to ring page");
400 vaddr = vaddr + XEN_PAGE_SIZE;
406 for (j = 0; j < i; j++)
407 gnttab_end_foreign_access_ref(grefs[j], 0);
410 EXPORT_SYMBOL_GPL(xenbus_grant_ring);
414 * Allocate an event channel for the given xenbus_device, assigning the newly
415 * created local port to *port. Return 0 on success, or -errno on error. On
416 * error, the device will switch to XenbusStateClosing, and the error will be
417 * saved in the store.
419 int xenbus_alloc_evtchn(struct xenbus_device *dev, evtchn_port_t *port)
421 struct evtchn_alloc_unbound alloc_unbound;
424 alloc_unbound.dom = DOMID_SELF;
425 alloc_unbound.remote_dom = dev->otherend_id;
427 err = HYPERVISOR_event_channel_op(EVTCHNOP_alloc_unbound,
430 xenbus_dev_fatal(dev, err, "allocating event channel");
432 *port = alloc_unbound.port;
436 EXPORT_SYMBOL_GPL(xenbus_alloc_evtchn);
440 * Free an existing event channel. Returns 0 on success or -errno on error.
442 int xenbus_free_evtchn(struct xenbus_device *dev, evtchn_port_t port)
444 struct evtchn_close close;
449 err = HYPERVISOR_event_channel_op(EVTCHNOP_close, &close);
451 xenbus_dev_error(dev, err, "freeing event channel %u", port);
455 EXPORT_SYMBOL_GPL(xenbus_free_evtchn);
459 * xenbus_map_ring_valloc
460 * @dev: xenbus device
461 * @gnt_refs: grant reference array
462 * @nr_grefs: number of grant references
463 * @vaddr: pointer to address to be filled out by mapping
465 * Map @nr_grefs pages of memory into this domain from another
466 * domain's grant table. xenbus_map_ring_valloc allocates @nr_grefs
467 * pages of virtual address space, maps the pages to that address, and
468 * sets *vaddr to that address. Returns 0 on success, and -errno on
469 * error. If an error is returned, device will switch to
470 * XenbusStateClosing and the error message will be saved in XenStore.
472 int xenbus_map_ring_valloc(struct xenbus_device *dev, grant_ref_t *gnt_refs,
473 unsigned int nr_grefs, void **vaddr)
476 struct map_ring_valloc *info;
480 if (nr_grefs > XENBUS_MAX_RING_GRANTS)
483 info = kzalloc(sizeof(*info), GFP_KERNEL);
487 info->node = kzalloc(sizeof(*info->node), GFP_KERNEL);
491 err = ring_ops->map(dev, info, gnt_refs, nr_grefs, vaddr);
497 EXPORT_SYMBOL_GPL(xenbus_map_ring_valloc);
499 /* N.B. sizeof(phys_addr_t) doesn't always equal to sizeof(unsigned
500 * long), e.g. 32-on-64. Caller is responsible for preparing the
501 * right array to feed into this function */
502 static int __xenbus_map_ring(struct xenbus_device *dev,
503 grant_ref_t *gnt_refs,
504 unsigned int nr_grefs,
505 grant_handle_t *handles,
506 struct map_ring_valloc *info,
512 if (nr_grefs > XENBUS_MAX_RING_GRANTS)
515 for (i = 0; i < nr_grefs; i++) {
516 gnttab_set_map_op(&info->map[i], info->phys_addrs[i], flags,
517 gnt_refs[i], dev->otherend_id);
518 handles[i] = INVALID_GRANT_HANDLE;
521 gnttab_batch_map(info->map, i);
523 for (i = 0; i < nr_grefs; i++) {
524 if (info->map[i].status != GNTST_okay) {
525 xenbus_dev_fatal(dev, info->map[i].status,
526 "mapping in shared page %d from domain %d",
527 gnt_refs[i], dev->otherend_id);
530 handles[i] = info->map[i].handle;
536 for (i = j = 0; i < nr_grefs; i++) {
537 if (handles[i] != INVALID_GRANT_HANDLE) {
538 gnttab_set_unmap_op(&info->unmap[j],
540 GNTMAP_host_map, handles[i]);
545 if (HYPERVISOR_grant_table_op(GNTTABOP_unmap_grant_ref, info->unmap, j))
549 for (i = 0; i < j; i++) {
550 if (info->unmap[i].status != GNTST_okay) {
561 * @dev: xenbus device
562 * @handles: grant handle array
563 * @nr_handles: number of handles in the array
564 * @vaddrs: addresses to unmap
566 * Unmap memory in this domain that was imported from another domain.
567 * Returns 0 on success and returns GNTST_* on error
568 * (see xen/include/interface/grant_table.h).
570 static int xenbus_unmap_ring(struct xenbus_device *dev, grant_handle_t *handles,
571 unsigned int nr_handles, unsigned long *vaddrs)
573 struct gnttab_unmap_grant_ref unmap[XENBUS_MAX_RING_GRANTS];
577 if (nr_handles > XENBUS_MAX_RING_GRANTS)
580 for (i = 0; i < nr_handles; i++)
581 gnttab_set_unmap_op(&unmap[i], vaddrs[i],
582 GNTMAP_host_map, handles[i]);
584 if (HYPERVISOR_grant_table_op(GNTTABOP_unmap_grant_ref, unmap, i))
588 for (i = 0; i < nr_handles; i++) {
589 if (unmap[i].status != GNTST_okay) {
590 xenbus_dev_error(dev, unmap[i].status,
591 "unmapping page at handle %d error %d",
592 handles[i], unmap[i].status);
593 err = unmap[i].status;
601 static void xenbus_map_ring_setup_grant_hvm(unsigned long gfn,
602 unsigned int goffset,
606 struct map_ring_valloc *info = data;
607 unsigned long vaddr = (unsigned long)gfn_to_virt(gfn);
609 info->phys_addrs[info->idx] = vaddr;
610 info->addrs[info->idx] = vaddr;
615 static int xenbus_map_ring_hvm(struct xenbus_device *dev,
616 struct map_ring_valloc *info,
617 grant_ref_t *gnt_ref,
618 unsigned int nr_grefs,
621 struct xenbus_map_node *node = info->node;
625 unsigned int nr_pages = XENBUS_PAGES(nr_grefs);
627 err = xen_alloc_unpopulated_pages(nr_pages, node->hvm.pages);
631 gnttab_foreach_grant(node->hvm.pages, nr_grefs,
632 xenbus_map_ring_setup_grant_hvm,
635 err = __xenbus_map_ring(dev, gnt_ref, nr_grefs, node->handles,
636 info, GNTMAP_host_map, &leaked);
637 node->nr_handles = nr_grefs;
640 goto out_free_ballooned_pages;
642 addr = vmap(node->hvm.pages, nr_pages, VM_MAP | VM_IOREMAP,
646 goto out_xenbus_unmap_ring;
649 node->hvm.addr = addr;
651 spin_lock(&xenbus_valloc_lock);
652 list_add(&node->next, &xenbus_valloc_pages);
653 spin_unlock(&xenbus_valloc_lock);
660 out_xenbus_unmap_ring:
662 xenbus_unmap_ring(dev, node->handles, nr_grefs, info->addrs);
664 pr_alert("leaking %p size %u page(s)",
666 out_free_ballooned_pages:
668 xen_free_unpopulated_pages(nr_pages, node->hvm.pages);
674 * xenbus_unmap_ring_vfree
675 * @dev: xenbus device
676 * @vaddr: addr to unmap
678 * Based on Rusty Russell's skeleton driver's unmap_page.
679 * Unmap a page of memory in this domain that was imported from another domain.
680 * Use xenbus_unmap_ring_vfree if you mapped in your memory with
681 * xenbus_map_ring_valloc (it will free the virtual address space).
682 * Returns 0 on success and returns GNTST_* on error
683 * (see xen/include/interface/grant_table.h).
685 int xenbus_unmap_ring_vfree(struct xenbus_device *dev, void *vaddr)
687 return ring_ops->unmap(dev, vaddr);
689 EXPORT_SYMBOL_GPL(xenbus_unmap_ring_vfree);
692 static int map_ring_apply(pte_t *pte, unsigned long addr, void *data)
694 struct map_ring_valloc *info = data;
696 info->phys_addrs[info->idx++] = arbitrary_virt_to_machine(pte).maddr;
700 static int xenbus_map_ring_pv(struct xenbus_device *dev,
701 struct map_ring_valloc *info,
702 grant_ref_t *gnt_refs,
703 unsigned int nr_grefs,
706 struct xenbus_map_node *node = info->node;
707 struct vm_struct *area;
711 area = get_vm_area(XEN_PAGE_SIZE * nr_grefs, VM_IOREMAP);
714 if (apply_to_page_range(&init_mm, (unsigned long)area->addr,
715 XEN_PAGE_SIZE * nr_grefs, map_ring_apply, info))
717 err = __xenbus_map_ring(dev, gnt_refs, nr_grefs, node->handles,
718 info, GNTMAP_host_map | GNTMAP_contains_pte,
723 node->nr_handles = nr_grefs;
724 node->pv.area = area;
726 spin_lock(&xenbus_valloc_lock);
727 list_add(&node->next, &xenbus_valloc_pages);
728 spin_unlock(&xenbus_valloc_lock);
739 pr_alert("leaking VM area %p size %u page(s)", area, nr_grefs);
744 static int xenbus_unmap_ring_pv(struct xenbus_device *dev, void *vaddr)
746 struct xenbus_map_node *node;
747 struct gnttab_unmap_grant_ref unmap[XENBUS_MAX_RING_GRANTS];
753 spin_lock(&xenbus_valloc_lock);
754 list_for_each_entry(node, &xenbus_valloc_pages, next) {
755 if (node->pv.area->addr == vaddr) {
756 list_del(&node->next);
762 spin_unlock(&xenbus_valloc_lock);
765 xenbus_dev_error(dev, -ENOENT,
766 "can't find mapped virtual address %p", vaddr);
767 return GNTST_bad_virt_addr;
770 for (i = 0; i < node->nr_handles; i++) {
773 memset(&unmap[i], 0, sizeof(unmap[i]));
774 addr = (unsigned long)vaddr + (XEN_PAGE_SIZE * i);
775 unmap[i].host_addr = arbitrary_virt_to_machine(
776 lookup_address(addr, &level)).maddr;
777 unmap[i].dev_bus_addr = 0;
778 unmap[i].handle = node->handles[i];
781 if (HYPERVISOR_grant_table_op(GNTTABOP_unmap_grant_ref, unmap, i))
786 for (i = 0; i < node->nr_handles; i++) {
787 if (unmap[i].status != GNTST_okay) {
789 xenbus_dev_error(dev, unmap[i].status,
790 "unmapping page at handle %d error %d",
791 node->handles[i], unmap[i].status);
792 err = unmap[i].status;
798 free_vm_area(node->pv.area);
800 pr_alert("leaking VM area %p size %u page(s)",
801 node->pv.area, node->nr_handles);
807 static const struct xenbus_ring_ops ring_ops_pv = {
808 .map = xenbus_map_ring_pv,
809 .unmap = xenbus_unmap_ring_pv,
813 struct unmap_ring_hvm
816 unsigned long addrs[XENBUS_MAX_RING_GRANTS];
819 static void xenbus_unmap_ring_setup_grant_hvm(unsigned long gfn,
820 unsigned int goffset,
824 struct unmap_ring_hvm *info = data;
826 info->addrs[info->idx] = (unsigned long)gfn_to_virt(gfn);
831 static int xenbus_unmap_ring_hvm(struct xenbus_device *dev, void *vaddr)
834 struct xenbus_map_node *node;
836 struct unmap_ring_hvm info = {
839 unsigned int nr_pages;
841 spin_lock(&xenbus_valloc_lock);
842 list_for_each_entry(node, &xenbus_valloc_pages, next) {
843 addr = node->hvm.addr;
845 list_del(&node->next);
851 spin_unlock(&xenbus_valloc_lock);
854 xenbus_dev_error(dev, -ENOENT,
855 "can't find mapped virtual address %p", vaddr);
856 return GNTST_bad_virt_addr;
859 nr_pages = XENBUS_PAGES(node->nr_handles);
861 gnttab_foreach_grant(node->hvm.pages, node->nr_handles,
862 xenbus_unmap_ring_setup_grant_hvm,
865 rv = xenbus_unmap_ring(dev, node->handles, node->nr_handles,
869 xen_free_unpopulated_pages(nr_pages, node->hvm.pages);
872 WARN(1, "Leaking %p, size %u page(s)\n", vaddr, nr_pages);
879 * xenbus_read_driver_state
880 * @path: path for driver
882 * Return the state of the driver rooted at the given store path, or
883 * XenbusStateUnknown if no state can be read.
885 enum xenbus_state xenbus_read_driver_state(const char *path)
887 enum xenbus_state result;
888 int err = xenbus_gather(XBT_NIL, path, "state", "%d", &result, NULL);
890 result = XenbusStateUnknown;
894 EXPORT_SYMBOL_GPL(xenbus_read_driver_state);
896 static const struct xenbus_ring_ops ring_ops_hvm = {
897 .map = xenbus_map_ring_hvm,
898 .unmap = xenbus_unmap_ring_hvm,
901 void __init xenbus_ring_ops_init(void)
904 if (!xen_feature(XENFEAT_auto_translated_physmap))
905 ring_ops = &ring_ops_pv;
908 ring_ops = &ring_ops_hvm;