1 /******************************************************************************
2  * Talks to Xen Store to figure out what devices we have.
3  *
4  * Copyright (C) 2005 Rusty Russell, IBM Corporation
5  * Copyright (C) 2005 Mike Wray, Hewlett-Packard
6  * Copyright (C) 2005, 2006 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 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
34 
35 #define DPRINTK(fmt, args...)				\
36 	pr_debug("xenbus_probe (%s:%d) " fmt ".\n",	\
37 		 __func__, __LINE__, ##args)
38 
39 #include <linux/kernel.h>
40 #include <linux/err.h>
41 #include <linux/string.h>
42 #include <linux/ctype.h>
43 #include <linux/fcntl.h>
44 #include <linux/mm.h>
45 #include <linux/proc_fs.h>
46 #include <linux/notifier.h>
47 #include <linux/kthread.h>
48 #include <linux/mutex.h>
49 #include <linux/io.h>
50 #include <linux/slab.h>
51 #include <linux/module.h>
52 
53 #include <asm/page.h>
54 #include <asm/pgtable.h>
55 #include <asm/xen/hypervisor.h>
56 
57 #include <xen/xen.h>
58 #include <xen/xenbus.h>
59 #include <xen/events.h>
60 #include <xen/page.h>
61 
62 #include <xen/hvm.h>
63 
64 #include "xenbus_comms.h"
65 #include "xenbus_probe.h"
66 
67 
68 int xen_store_evtchn;
69 EXPORT_SYMBOL_GPL(xen_store_evtchn);
70 
71 struct xenstore_domain_interface *xen_store_interface;
72 EXPORT_SYMBOL_GPL(xen_store_interface);
73 
74 enum xenstore_init xen_store_domain_type;
75 EXPORT_SYMBOL_GPL(xen_store_domain_type);
76 
77 static unsigned long xen_store_mfn;
78 
79 static BLOCKING_NOTIFIER_HEAD(xenstore_chain);
80 
81 /* If something in array of ids matches this device, return it. */
82 static const struct xenbus_device_id *
83 match_device(const struct xenbus_device_id *arr, struct xenbus_device *dev)
84 {
85 	for (; *arr->devicetype != '\0'; arr++) {
86 		if (!strcmp(arr->devicetype, dev->devicetype))
87 			return arr;
88 	}
89 	return NULL;
90 }
91 
92 int xenbus_match(struct device *_dev, struct device_driver *_drv)
93 {
94 	struct xenbus_driver *drv = to_xenbus_driver(_drv);
95 
96 	if (!drv->ids)
97 		return 0;
98 
99 	return match_device(drv->ids, to_xenbus_device(_dev)) != NULL;
100 }
101 EXPORT_SYMBOL_GPL(xenbus_match);
102 
103 
104 static void free_otherend_details(struct xenbus_device *dev)
105 {
106 	kfree(dev->otherend);
107 	dev->otherend = NULL;
108 }
109 
110 
111 static void free_otherend_watch(struct xenbus_device *dev)
112 {
113 	if (dev->otherend_watch.node) {
114 		unregister_xenbus_watch(&dev->otherend_watch);
115 		kfree(dev->otherend_watch.node);
116 		dev->otherend_watch.node = NULL;
117 	}
118 }
119 
120 
121 static int talk_to_otherend(struct xenbus_device *dev)
122 {
123 	struct xenbus_driver *drv = to_xenbus_driver(dev->dev.driver);
124 
125 	free_otherend_watch(dev);
126 	free_otherend_details(dev);
127 
128 	return drv->read_otherend_details(dev);
129 }
130 
131 
132 
133 static int watch_otherend(struct xenbus_device *dev)
134 {
135 	struct xen_bus_type *bus =
136 		container_of(dev->dev.bus, struct xen_bus_type, bus);
137 
138 	return xenbus_watch_pathfmt(dev, &dev->otherend_watch,
139 				    bus->otherend_changed,
140 				    "%s/%s", dev->otherend, "state");
141 }
142 
143 
144 int xenbus_read_otherend_details(struct xenbus_device *xendev,
145 				 char *id_node, char *path_node)
146 {
147 	int err = xenbus_gather(XBT_NIL, xendev->nodename,
148 				id_node, "%i", &xendev->otherend_id,
149 				path_node, NULL, &xendev->otherend,
150 				NULL);
151 	if (err) {
152 		xenbus_dev_fatal(xendev, err,
153 				 "reading other end details from %s",
154 				 xendev->nodename);
155 		return err;
156 	}
157 	if (strlen(xendev->otherend) == 0 ||
158 	    !xenbus_exists(XBT_NIL, xendev->otherend, "")) {
159 		xenbus_dev_fatal(xendev, -ENOENT,
160 				 "unable to read other end from %s.  "
161 				 "missing or inaccessible.",
162 				 xendev->nodename);
163 		free_otherend_details(xendev);
164 		return -ENOENT;
165 	}
166 
167 	return 0;
168 }
169 EXPORT_SYMBOL_GPL(xenbus_read_otherend_details);
170 
171 void xenbus_otherend_changed(struct xenbus_watch *watch,
172 			     const char **vec, unsigned int len,
173 			     int ignore_on_shutdown)
174 {
175 	struct xenbus_device *dev =
176 		container_of(watch, struct xenbus_device, otherend_watch);
177 	struct xenbus_driver *drv = to_xenbus_driver(dev->dev.driver);
178 	enum xenbus_state state;
179 
180 	/* Protect us against watches firing on old details when the otherend
181 	   details change, say immediately after a resume. */
182 	if (!dev->otherend ||
183 	    strncmp(dev->otherend, vec[XS_WATCH_PATH],
184 		    strlen(dev->otherend))) {
185 		dev_dbg(&dev->dev, "Ignoring watch at %s\n",
186 			vec[XS_WATCH_PATH]);
187 		return;
188 	}
189 
190 	state = xenbus_read_driver_state(dev->otherend);
191 
192 	dev_dbg(&dev->dev, "state is %d, (%s), %s, %s\n",
193 		state, xenbus_strstate(state), dev->otherend_watch.node,
194 		vec[XS_WATCH_PATH]);
195 
196 	/*
197 	 * Ignore xenbus transitions during shutdown. This prevents us doing
198 	 * work that can fail e.g., when the rootfs is gone.
199 	 */
200 	if (system_state > SYSTEM_RUNNING) {
201 		if (ignore_on_shutdown && (state == XenbusStateClosing))
202 			xenbus_frontend_closed(dev);
203 		return;
204 	}
205 
206 	if (drv->otherend_changed)
207 		drv->otherend_changed(dev, state);
208 }
209 EXPORT_SYMBOL_GPL(xenbus_otherend_changed);
210 
211 int xenbus_dev_probe(struct device *_dev)
212 {
213 	struct xenbus_device *dev = to_xenbus_device(_dev);
214 	struct xenbus_driver *drv = to_xenbus_driver(_dev->driver);
215 	const struct xenbus_device_id *id;
216 	int err;
217 
218 	DPRINTK("%s", dev->nodename);
219 
220 	if (!drv->probe) {
221 		err = -ENODEV;
222 		goto fail;
223 	}
224 
225 	id = match_device(drv->ids, dev);
226 	if (!id) {
227 		err = -ENODEV;
228 		goto fail;
229 	}
230 
231 	err = talk_to_otherend(dev);
232 	if (err) {
233 		dev_warn(&dev->dev, "talk_to_otherend on %s failed.\n",
234 			 dev->nodename);
235 		return err;
236 	}
237 
238 	err = drv->probe(dev, id);
239 	if (err)
240 		goto fail;
241 
242 	err = watch_otherend(dev);
243 	if (err) {
244 		dev_warn(&dev->dev, "watch_otherend on %s failed.\n",
245 		       dev->nodename);
246 		return err;
247 	}
248 
249 	return 0;
250 fail:
251 	xenbus_dev_error(dev, err, "xenbus_dev_probe on %s", dev->nodename);
252 	xenbus_switch_state(dev, XenbusStateClosed);
253 	return err;
254 }
255 EXPORT_SYMBOL_GPL(xenbus_dev_probe);
256 
257 int xenbus_dev_remove(struct device *_dev)
258 {
259 	struct xenbus_device *dev = to_xenbus_device(_dev);
260 	struct xenbus_driver *drv = to_xenbus_driver(_dev->driver);
261 
262 	DPRINTK("%s", dev->nodename);
263 
264 	free_otherend_watch(dev);
265 
266 	if (drv->remove)
267 		drv->remove(dev);
268 
269 	free_otherend_details(dev);
270 
271 	xenbus_switch_state(dev, XenbusStateClosed);
272 	return 0;
273 }
274 EXPORT_SYMBOL_GPL(xenbus_dev_remove);
275 
276 void xenbus_dev_shutdown(struct device *_dev)
277 {
278 	struct xenbus_device *dev = to_xenbus_device(_dev);
279 	unsigned long timeout = 5*HZ;
280 
281 	DPRINTK("%s", dev->nodename);
282 
283 	get_device(&dev->dev);
284 	if (dev->state != XenbusStateConnected) {
285 		pr_info("%s: %s: %s != Connected, skipping\n",
286 			__func__, dev->nodename, xenbus_strstate(dev->state));
287 		goto out;
288 	}
289 	xenbus_switch_state(dev, XenbusStateClosing);
290 	timeout = wait_for_completion_timeout(&dev->down, timeout);
291 	if (!timeout)
292 		pr_info("%s: %s timeout closing device\n",
293 			__func__, dev->nodename);
294  out:
295 	put_device(&dev->dev);
296 }
297 EXPORT_SYMBOL_GPL(xenbus_dev_shutdown);
298 
299 int xenbus_register_driver_common(struct xenbus_driver *drv,
300 				  struct xen_bus_type *bus)
301 {
302 	drv->driver.bus = &bus->bus;
303 
304 	return driver_register(&drv->driver);
305 }
306 EXPORT_SYMBOL_GPL(xenbus_register_driver_common);
307 
308 void xenbus_unregister_driver(struct xenbus_driver *drv)
309 {
310 	driver_unregister(&drv->driver);
311 }
312 EXPORT_SYMBOL_GPL(xenbus_unregister_driver);
313 
314 struct xb_find_info {
315 	struct xenbus_device *dev;
316 	const char *nodename;
317 };
318 
319 static int cmp_dev(struct device *dev, void *data)
320 {
321 	struct xenbus_device *xendev = to_xenbus_device(dev);
322 	struct xb_find_info *info = data;
323 
324 	if (!strcmp(xendev->nodename, info->nodename)) {
325 		info->dev = xendev;
326 		get_device(dev);
327 		return 1;
328 	}
329 	return 0;
330 }
331 
332 static struct xenbus_device *xenbus_device_find(const char *nodename,
333 						struct bus_type *bus)
334 {
335 	struct xb_find_info info = { .dev = NULL, .nodename = nodename };
336 
337 	bus_for_each_dev(bus, NULL, &info, cmp_dev);
338 	return info.dev;
339 }
340 
341 static int cleanup_dev(struct device *dev, void *data)
342 {
343 	struct xenbus_device *xendev = to_xenbus_device(dev);
344 	struct xb_find_info *info = data;
345 	int len = strlen(info->nodename);
346 
347 	DPRINTK("%s", info->nodename);
348 
349 	/* Match the info->nodename path, or any subdirectory of that path. */
350 	if (strncmp(xendev->nodename, info->nodename, len))
351 		return 0;
352 
353 	/* If the node name is longer, ensure it really is a subdirectory. */
354 	if ((strlen(xendev->nodename) > len) && (xendev->nodename[len] != '/'))
355 		return 0;
356 
357 	info->dev = xendev;
358 	get_device(dev);
359 	return 1;
360 }
361 
362 static void xenbus_cleanup_devices(const char *path, struct bus_type *bus)
363 {
364 	struct xb_find_info info = { .nodename = path };
365 
366 	do {
367 		info.dev = NULL;
368 		bus_for_each_dev(bus, NULL, &info, cleanup_dev);
369 		if (info.dev) {
370 			device_unregister(&info.dev->dev);
371 			put_device(&info.dev->dev);
372 		}
373 	} while (info.dev);
374 }
375 
376 static void xenbus_dev_release(struct device *dev)
377 {
378 	if (dev)
379 		kfree(to_xenbus_device(dev));
380 }
381 
382 static ssize_t nodename_show(struct device *dev,
383 			     struct device_attribute *attr, char *buf)
384 {
385 	return sprintf(buf, "%s\n", to_xenbus_device(dev)->nodename);
386 }
387 
388 static ssize_t devtype_show(struct device *dev,
389 			    struct device_attribute *attr, char *buf)
390 {
391 	return sprintf(buf, "%s\n", to_xenbus_device(dev)->devicetype);
392 }
393 
394 static ssize_t modalias_show(struct device *dev,
395 			     struct device_attribute *attr, char *buf)
396 {
397 	return sprintf(buf, "%s:%s\n", dev->bus->name,
398 		       to_xenbus_device(dev)->devicetype);
399 }
400 
401 struct device_attribute xenbus_dev_attrs[] = {
402 	__ATTR_RO(nodename),
403 	__ATTR_RO(devtype),
404 	__ATTR_RO(modalias),
405 	__ATTR_NULL
406 };
407 EXPORT_SYMBOL_GPL(xenbus_dev_attrs);
408 
409 int xenbus_probe_node(struct xen_bus_type *bus,
410 		      const char *type,
411 		      const char *nodename)
412 {
413 	char devname[XEN_BUS_ID_SIZE];
414 	int err;
415 	struct xenbus_device *xendev;
416 	size_t stringlen;
417 	char *tmpstring;
418 
419 	enum xenbus_state state = xenbus_read_driver_state(nodename);
420 
421 	if (state != XenbusStateInitialising) {
422 		/* Device is not new, so ignore it.  This can happen if a
423 		   device is going away after switching to Closed.  */
424 		return 0;
425 	}
426 
427 	stringlen = strlen(nodename) + 1 + strlen(type) + 1;
428 	xendev = kzalloc(sizeof(*xendev) + stringlen, GFP_KERNEL);
429 	if (!xendev)
430 		return -ENOMEM;
431 
432 	xendev->state = XenbusStateInitialising;
433 
434 	/* Copy the strings into the extra space. */
435 
436 	tmpstring = (char *)(xendev + 1);
437 	strcpy(tmpstring, nodename);
438 	xendev->nodename = tmpstring;
439 
440 	tmpstring += strlen(tmpstring) + 1;
441 	strcpy(tmpstring, type);
442 	xendev->devicetype = tmpstring;
443 	init_completion(&xendev->down);
444 
445 	xendev->dev.bus = &bus->bus;
446 	xendev->dev.release = xenbus_dev_release;
447 
448 	err = bus->get_bus_id(devname, xendev->nodename);
449 	if (err)
450 		goto fail;
451 
452 	dev_set_name(&xendev->dev, "%s", devname);
453 
454 	/* Register with generic device framework. */
455 	err = device_register(&xendev->dev);
456 	if (err)
457 		goto fail;
458 
459 	return 0;
460 fail:
461 	kfree(xendev);
462 	return err;
463 }
464 EXPORT_SYMBOL_GPL(xenbus_probe_node);
465 
466 static int xenbus_probe_device_type(struct xen_bus_type *bus, const char *type)
467 {
468 	int err = 0;
469 	char **dir;
470 	unsigned int dir_n = 0;
471 	int i;
472 
473 	dir = xenbus_directory(XBT_NIL, bus->root, type, &dir_n);
474 	if (IS_ERR(dir))
475 		return PTR_ERR(dir);
476 
477 	for (i = 0; i < dir_n; i++) {
478 		err = bus->probe(bus, type, dir[i]);
479 		if (err)
480 			break;
481 	}
482 
483 	kfree(dir);
484 	return err;
485 }
486 
487 int xenbus_probe_devices(struct xen_bus_type *bus)
488 {
489 	int err = 0;
490 	char **dir;
491 	unsigned int i, dir_n;
492 
493 	dir = xenbus_directory(XBT_NIL, bus->root, "", &dir_n);
494 	if (IS_ERR(dir))
495 		return PTR_ERR(dir);
496 
497 	for (i = 0; i < dir_n; i++) {
498 		err = xenbus_probe_device_type(bus, dir[i]);
499 		if (err)
500 			break;
501 	}
502 
503 	kfree(dir);
504 	return err;
505 }
506 EXPORT_SYMBOL_GPL(xenbus_probe_devices);
507 
508 static unsigned int char_count(const char *str, char c)
509 {
510 	unsigned int i, ret = 0;
511 
512 	for (i = 0; str[i]; i++)
513 		if (str[i] == c)
514 			ret++;
515 	return ret;
516 }
517 
518 static int strsep_len(const char *str, char c, unsigned int len)
519 {
520 	unsigned int i;
521 
522 	for (i = 0; str[i]; i++)
523 		if (str[i] == c) {
524 			if (len == 0)
525 				return i;
526 			len--;
527 		}
528 	return (len == 0) ? i : -ERANGE;
529 }
530 
531 void xenbus_dev_changed(const char *node, struct xen_bus_type *bus)
532 {
533 	int exists, rootlen;
534 	struct xenbus_device *dev;
535 	char type[XEN_BUS_ID_SIZE];
536 	const char *p, *root;
537 
538 	if (char_count(node, '/') < 2)
539 		return;
540 
541 	exists = xenbus_exists(XBT_NIL, node, "");
542 	if (!exists) {
543 		xenbus_cleanup_devices(node, &bus->bus);
544 		return;
545 	}
546 
547 	/* backend/<type>/... or device/<type>/... */
548 	p = strchr(node, '/') + 1;
549 	snprintf(type, XEN_BUS_ID_SIZE, "%.*s", (int)strcspn(p, "/"), p);
550 	type[XEN_BUS_ID_SIZE-1] = '\0';
551 
552 	rootlen = strsep_len(node, '/', bus->levels);
553 	if (rootlen < 0)
554 		return;
555 	root = kasprintf(GFP_KERNEL, "%.*s", rootlen, node);
556 	if (!root)
557 		return;
558 
559 	dev = xenbus_device_find(root, &bus->bus);
560 	if (!dev)
561 		xenbus_probe_node(bus, type, root);
562 	else
563 		put_device(&dev->dev);
564 
565 	kfree(root);
566 }
567 EXPORT_SYMBOL_GPL(xenbus_dev_changed);
568 
569 int xenbus_dev_suspend(struct device *dev)
570 {
571 	int err = 0;
572 	struct xenbus_driver *drv;
573 	struct xenbus_device *xdev
574 		= container_of(dev, struct xenbus_device, dev);
575 
576 	DPRINTK("%s", xdev->nodename);
577 
578 	if (dev->driver == NULL)
579 		return 0;
580 	drv = to_xenbus_driver(dev->driver);
581 	if (drv->suspend)
582 		err = drv->suspend(xdev);
583 	if (err)
584 		pr_warn("suspend %s failed: %i\n", dev_name(dev), err);
585 	return 0;
586 }
587 EXPORT_SYMBOL_GPL(xenbus_dev_suspend);
588 
589 int xenbus_dev_resume(struct device *dev)
590 {
591 	int err;
592 	struct xenbus_driver *drv;
593 	struct xenbus_device *xdev
594 		= container_of(dev, struct xenbus_device, dev);
595 
596 	DPRINTK("%s", xdev->nodename);
597 
598 	if (dev->driver == NULL)
599 		return 0;
600 	drv = to_xenbus_driver(dev->driver);
601 	err = talk_to_otherend(xdev);
602 	if (err) {
603 		pr_warn("resume (talk_to_otherend) %s failed: %i\n",
604 			dev_name(dev), err);
605 		return err;
606 	}
607 
608 	xdev->state = XenbusStateInitialising;
609 
610 	if (drv->resume) {
611 		err = drv->resume(xdev);
612 		if (err) {
613 			pr_warn("resume %s failed: %i\n", dev_name(dev), err);
614 			return err;
615 		}
616 	}
617 
618 	err = watch_otherend(xdev);
619 	if (err) {
620 		pr_warn("resume (watch_otherend) %s failed: %d.\n",
621 			dev_name(dev), err);
622 		return err;
623 	}
624 
625 	return 0;
626 }
627 EXPORT_SYMBOL_GPL(xenbus_dev_resume);
628 
629 int xenbus_dev_cancel(struct device *dev)
630 {
631 	/* Do nothing */
632 	DPRINTK("cancel");
633 	return 0;
634 }
635 EXPORT_SYMBOL_GPL(xenbus_dev_cancel);
636 
637 /* A flag to determine if xenstored is 'ready' (i.e. has started) */
638 int xenstored_ready;
639 
640 
641 int register_xenstore_notifier(struct notifier_block *nb)
642 {
643 	int ret = 0;
644 
645 	if (xenstored_ready > 0)
646 		ret = nb->notifier_call(nb, 0, NULL);
647 	else
648 		blocking_notifier_chain_register(&xenstore_chain, nb);
649 
650 	return ret;
651 }
652 EXPORT_SYMBOL_GPL(register_xenstore_notifier);
653 
654 void unregister_xenstore_notifier(struct notifier_block *nb)
655 {
656 	blocking_notifier_chain_unregister(&xenstore_chain, nb);
657 }
658 EXPORT_SYMBOL_GPL(unregister_xenstore_notifier);
659 
660 void xenbus_probe(struct work_struct *unused)
661 {
662 	xenstored_ready = 1;
663 
664 	/* Notify others that xenstore is up */
665 	blocking_notifier_call_chain(&xenstore_chain, 0, NULL);
666 }
667 EXPORT_SYMBOL_GPL(xenbus_probe);
668 
669 static int __init xenbus_probe_initcall(void)
670 {
671 	if (!xen_domain())
672 		return -ENODEV;
673 
674 	if (xen_initial_domain() || xen_hvm_domain())
675 		return 0;
676 
677 	xenbus_probe(NULL);
678 	return 0;
679 }
680 
681 device_initcall(xenbus_probe_initcall);
682 
683 /* Set up event channel for xenstored which is run as a local process
684  * (this is normally used only in dom0)
685  */
686 static int __init xenstored_local_init(void)
687 {
688 	int err = 0;
689 	unsigned long page = 0;
690 	struct evtchn_alloc_unbound alloc_unbound;
691 
692 	/* Allocate Xenstore page */
693 	page = get_zeroed_page(GFP_KERNEL);
694 	if (!page)
695 		goto out_err;
696 
697 	xen_store_mfn = xen_start_info->store_mfn =
698 		pfn_to_mfn(virt_to_phys((void *)page) >>
699 			   PAGE_SHIFT);
700 
701 	/* Next allocate a local port which xenstored can bind to */
702 	alloc_unbound.dom        = DOMID_SELF;
703 	alloc_unbound.remote_dom = DOMID_SELF;
704 
705 	err = HYPERVISOR_event_channel_op(EVTCHNOP_alloc_unbound,
706 					  &alloc_unbound);
707 	if (err == -ENOSYS)
708 		goto out_err;
709 
710 	BUG_ON(err);
711 	xen_store_evtchn = xen_start_info->store_evtchn =
712 		alloc_unbound.port;
713 
714 	return 0;
715 
716  out_err:
717 	if (page != 0)
718 		free_page(page);
719 	return err;
720 }
721 
722 static int __init xenbus_init(void)
723 {
724 	int err = 0;
725 	uint64_t v = 0;
726 	xen_store_domain_type = XS_UNKNOWN;
727 
728 	if (!xen_domain())
729 		return -ENODEV;
730 
731 	xenbus_ring_ops_init();
732 
733 	if (xen_pv_domain())
734 		xen_store_domain_type = XS_PV;
735 	if (xen_hvm_domain())
736 		xen_store_domain_type = XS_HVM;
737 	if (xen_hvm_domain() && xen_initial_domain())
738 		xen_store_domain_type = XS_LOCAL;
739 	if (xen_pv_domain() && !xen_start_info->store_evtchn)
740 		xen_store_domain_type = XS_LOCAL;
741 	if (xen_pv_domain() && xen_start_info->store_evtchn)
742 		xenstored_ready = 1;
743 
744 	switch (xen_store_domain_type) {
745 	case XS_LOCAL:
746 		err = xenstored_local_init();
747 		if (err)
748 			goto out_error;
749 		xen_store_interface = mfn_to_virt(xen_store_mfn);
750 		break;
751 	case XS_PV:
752 		xen_store_evtchn = xen_start_info->store_evtchn;
753 		xen_store_mfn = xen_start_info->store_mfn;
754 		xen_store_interface = mfn_to_virt(xen_store_mfn);
755 		break;
756 	case XS_HVM:
757 		err = hvm_get_parameter(HVM_PARAM_STORE_EVTCHN, &v);
758 		if (err)
759 			goto out_error;
760 		xen_store_evtchn = (int)v;
761 		err = hvm_get_parameter(HVM_PARAM_STORE_PFN, &v);
762 		if (err)
763 			goto out_error;
764 		xen_store_mfn = (unsigned long)v;
765 		xen_store_interface =
766 			xen_remap(xen_store_mfn << PAGE_SHIFT, PAGE_SIZE);
767 		break;
768 	default:
769 		pr_warn("Xenstore state unknown\n");
770 		break;
771 	}
772 
773 	/* Initialize the interface to xenstore. */
774 	err = xs_init();
775 	if (err) {
776 		pr_warn("Error initializing xenstore comms: %i\n", err);
777 		goto out_error;
778 	}
779 
780 #ifdef CONFIG_XEN_COMPAT_XENFS
781 	/*
782 	 * Create xenfs mountpoint in /proc for compatibility with
783 	 * utilities that expect to find "xenbus" under "/proc/xen".
784 	 */
785 	proc_mkdir("xen", NULL);
786 #endif
787 
788 out_error:
789 	return err;
790 }
791 
792 postcore_initcall(xenbus_init);
793 
794 MODULE_LICENSE("GPL");
795