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 DPRINTK(fmt, args...)				\
34 	pr_debug("xenbus_probe (%s:%d) " fmt ".\n",	\
35 		 __func__, __LINE__, ##args)
36 
37 #include <linux/kernel.h>
38 #include <linux/err.h>
39 #include <linux/string.h>
40 #include <linux/ctype.h>
41 #include <linux/fcntl.h>
42 #include <linux/mm.h>
43 #include <linux/proc_fs.h>
44 #include <linux/notifier.h>
45 #include <linux/kthread.h>
46 #include <linux/mutex.h>
47 #include <linux/io.h>
48 #include <linux/slab.h>
49 
50 #include <asm/page.h>
51 #include <asm/pgtable.h>
52 #include <asm/xen/hypervisor.h>
53 
54 #include <xen/xen.h>
55 #include <xen/xenbus.h>
56 #include <xen/events.h>
57 #include <xen/page.h>
58 
59 #include <xen/hvm.h>
60 
61 #include "xenbus_comms.h"
62 #include "xenbus_probe.h"
63 
64 
65 int xen_store_evtchn;
66 EXPORT_SYMBOL_GPL(xen_store_evtchn);
67 
68 struct xenstore_domain_interface *xen_store_interface;
69 EXPORT_SYMBOL_GPL(xen_store_interface);
70 
71 static unsigned long xen_store_mfn;
72 
73 static BLOCKING_NOTIFIER_HEAD(xenstore_chain);
74 
75 /* If something in array of ids matches this device, return it. */
76 static const struct xenbus_device_id *
77 match_device(const struct xenbus_device_id *arr, struct xenbus_device *dev)
78 {
79 	for (; *arr->devicetype != '\0'; arr++) {
80 		if (!strcmp(arr->devicetype, dev->devicetype))
81 			return arr;
82 	}
83 	return NULL;
84 }
85 
86 int xenbus_match(struct device *_dev, struct device_driver *_drv)
87 {
88 	struct xenbus_driver *drv = to_xenbus_driver(_drv);
89 
90 	if (!drv->ids)
91 		return 0;
92 
93 	return match_device(drv->ids, to_xenbus_device(_dev)) != NULL;
94 }
95 EXPORT_SYMBOL_GPL(xenbus_match);
96 
97 
98 static void free_otherend_details(struct xenbus_device *dev)
99 {
100 	kfree(dev->otherend);
101 	dev->otherend = NULL;
102 }
103 
104 
105 static void free_otherend_watch(struct xenbus_device *dev)
106 {
107 	if (dev->otherend_watch.node) {
108 		unregister_xenbus_watch(&dev->otherend_watch);
109 		kfree(dev->otherend_watch.node);
110 		dev->otherend_watch.node = NULL;
111 	}
112 }
113 
114 
115 static int talk_to_otherend(struct xenbus_device *dev)
116 {
117 	struct xenbus_driver *drv = to_xenbus_driver(dev->dev.driver);
118 
119 	free_otherend_watch(dev);
120 	free_otherend_details(dev);
121 
122 	return drv->read_otherend_details(dev);
123 }
124 
125 
126 
127 static int watch_otherend(struct xenbus_device *dev)
128 {
129 	struct xen_bus_type *bus =
130 		container_of(dev->dev.bus, struct xen_bus_type, bus);
131 
132 	return xenbus_watch_pathfmt(dev, &dev->otherend_watch,
133 				    bus->otherend_changed,
134 				    "%s/%s", dev->otherend, "state");
135 }
136 
137 
138 int xenbus_read_otherend_details(struct xenbus_device *xendev,
139 				 char *id_node, char *path_node)
140 {
141 	int err = xenbus_gather(XBT_NIL, xendev->nodename,
142 				id_node, "%i", &xendev->otherend_id,
143 				path_node, NULL, &xendev->otherend,
144 				NULL);
145 	if (err) {
146 		xenbus_dev_fatal(xendev, err,
147 				 "reading other end details from %s",
148 				 xendev->nodename);
149 		return err;
150 	}
151 	if (strlen(xendev->otherend) == 0 ||
152 	    !xenbus_exists(XBT_NIL, xendev->otherend, "")) {
153 		xenbus_dev_fatal(xendev, -ENOENT,
154 				 "unable to read other end from %s.  "
155 				 "missing or inaccessible.",
156 				 xendev->nodename);
157 		free_otherend_details(xendev);
158 		return -ENOENT;
159 	}
160 
161 	return 0;
162 }
163 EXPORT_SYMBOL_GPL(xenbus_read_otherend_details);
164 
165 void xenbus_otherend_changed(struct xenbus_watch *watch,
166 			     const char **vec, unsigned int len,
167 			     int ignore_on_shutdown)
168 {
169 	struct xenbus_device *dev =
170 		container_of(watch, struct xenbus_device, otherend_watch);
171 	struct xenbus_driver *drv = to_xenbus_driver(dev->dev.driver);
172 	enum xenbus_state state;
173 
174 	/* Protect us against watches firing on old details when the otherend
175 	   details change, say immediately after a resume. */
176 	if (!dev->otherend ||
177 	    strncmp(dev->otherend, vec[XS_WATCH_PATH],
178 		    strlen(dev->otherend))) {
179 		dev_dbg(&dev->dev, "Ignoring watch at %s\n",
180 			vec[XS_WATCH_PATH]);
181 		return;
182 	}
183 
184 	state = xenbus_read_driver_state(dev->otherend);
185 
186 	dev_dbg(&dev->dev, "state is %d, (%s), %s, %s\n",
187 		state, xenbus_strstate(state), dev->otherend_watch.node,
188 		vec[XS_WATCH_PATH]);
189 
190 	/*
191 	 * Ignore xenbus transitions during shutdown. This prevents us doing
192 	 * work that can fail e.g., when the rootfs is gone.
193 	 */
194 	if (system_state > SYSTEM_RUNNING) {
195 		if (ignore_on_shutdown && (state == XenbusStateClosing))
196 			xenbus_frontend_closed(dev);
197 		return;
198 	}
199 
200 	if (drv->otherend_changed)
201 		drv->otherend_changed(dev, state);
202 }
203 EXPORT_SYMBOL_GPL(xenbus_otherend_changed);
204 
205 int xenbus_dev_probe(struct device *_dev)
206 {
207 	struct xenbus_device *dev = to_xenbus_device(_dev);
208 	struct xenbus_driver *drv = to_xenbus_driver(_dev->driver);
209 	const struct xenbus_device_id *id;
210 	int err;
211 
212 	DPRINTK("%s", dev->nodename);
213 
214 	if (!drv->probe) {
215 		err = -ENODEV;
216 		goto fail;
217 	}
218 
219 	id = match_device(drv->ids, dev);
220 	if (!id) {
221 		err = -ENODEV;
222 		goto fail;
223 	}
224 
225 	err = talk_to_otherend(dev);
226 	if (err) {
227 		dev_warn(&dev->dev, "talk_to_otherend on %s failed.\n",
228 			 dev->nodename);
229 		return err;
230 	}
231 
232 	err = drv->probe(dev, id);
233 	if (err)
234 		goto fail;
235 
236 	err = watch_otherend(dev);
237 	if (err) {
238 		dev_warn(&dev->dev, "watch_otherend on %s failed.\n",
239 		       dev->nodename);
240 		return err;
241 	}
242 
243 	return 0;
244 fail:
245 	xenbus_dev_error(dev, err, "xenbus_dev_probe on %s", dev->nodename);
246 	xenbus_switch_state(dev, XenbusStateClosed);
247 	return err;
248 }
249 EXPORT_SYMBOL_GPL(xenbus_dev_probe);
250 
251 int xenbus_dev_remove(struct device *_dev)
252 {
253 	struct xenbus_device *dev = to_xenbus_device(_dev);
254 	struct xenbus_driver *drv = to_xenbus_driver(_dev->driver);
255 
256 	DPRINTK("%s", dev->nodename);
257 
258 	free_otherend_watch(dev);
259 	free_otherend_details(dev);
260 
261 	if (drv->remove)
262 		drv->remove(dev);
263 
264 	xenbus_switch_state(dev, XenbusStateClosed);
265 	return 0;
266 }
267 EXPORT_SYMBOL_GPL(xenbus_dev_remove);
268 
269 void xenbus_dev_shutdown(struct device *_dev)
270 {
271 	struct xenbus_device *dev = to_xenbus_device(_dev);
272 	unsigned long timeout = 5*HZ;
273 
274 	DPRINTK("%s", dev->nodename);
275 
276 	get_device(&dev->dev);
277 	if (dev->state != XenbusStateConnected) {
278 		printk(KERN_INFO "%s: %s: %s != Connected, skipping\n", __func__,
279 		       dev->nodename, xenbus_strstate(dev->state));
280 		goto out;
281 	}
282 	xenbus_switch_state(dev, XenbusStateClosing);
283 	timeout = wait_for_completion_timeout(&dev->down, timeout);
284 	if (!timeout)
285 		printk(KERN_INFO "%s: %s timeout closing device\n",
286 		       __func__, dev->nodename);
287  out:
288 	put_device(&dev->dev);
289 }
290 EXPORT_SYMBOL_GPL(xenbus_dev_shutdown);
291 
292 int xenbus_register_driver_common(struct xenbus_driver *drv,
293 				  struct xen_bus_type *bus,
294 				  struct module *owner,
295 				  const char *mod_name)
296 {
297 	drv->driver.name = drv->name;
298 	drv->driver.bus = &bus->bus;
299 	drv->driver.owner = owner;
300 	drv->driver.mod_name = mod_name;
301 
302 	return driver_register(&drv->driver);
303 }
304 EXPORT_SYMBOL_GPL(xenbus_register_driver_common);
305 
306 void xenbus_unregister_driver(struct xenbus_driver *drv)
307 {
308 	driver_unregister(&drv->driver);
309 }
310 EXPORT_SYMBOL_GPL(xenbus_unregister_driver);
311 
312 struct xb_find_info
313 {
314 	struct xenbus_device *dev;
315 	const char *nodename;
316 };
317 
318 static int cmp_dev(struct device *dev, void *data)
319 {
320 	struct xenbus_device *xendev = to_xenbus_device(dev);
321 	struct xb_find_info *info = data;
322 
323 	if (!strcmp(xendev->nodename, info->nodename)) {
324 		info->dev = xendev;
325 		get_device(dev);
326 		return 1;
327 	}
328 	return 0;
329 }
330 
331 struct xenbus_device *xenbus_device_find(const char *nodename,
332 					 struct bus_type *bus)
333 {
334 	struct xb_find_info info = { .dev = NULL, .nodename = nodename };
335 
336 	bus_for_each_dev(bus, NULL, &info, cmp_dev);
337 	return info.dev;
338 }
339 
340 static int cleanup_dev(struct device *dev, void *data)
341 {
342 	struct xenbus_device *xendev = to_xenbus_device(dev);
343 	struct xb_find_info *info = data;
344 	int len = strlen(info->nodename);
345 
346 	DPRINTK("%s", info->nodename);
347 
348 	/* Match the info->nodename path, or any subdirectory of that path. */
349 	if (strncmp(xendev->nodename, info->nodename, len))
350 		return 0;
351 
352 	/* If the node name is longer, ensure it really is a subdirectory. */
353 	if ((strlen(xendev->nodename) > len) && (xendev->nodename[len] != '/'))
354 		return 0;
355 
356 	info->dev = xendev;
357 	get_device(dev);
358 	return 1;
359 }
360 
361 static void xenbus_cleanup_devices(const char *path, struct bus_type *bus)
362 {
363 	struct xb_find_info info = { .nodename = path };
364 
365 	do {
366 		info.dev = NULL;
367 		bus_for_each_dev(bus, NULL, &info, cleanup_dev);
368 		if (info.dev) {
369 			device_unregister(&info.dev->dev);
370 			put_device(&info.dev->dev);
371 		}
372 	} while (info.dev);
373 }
374 
375 static void xenbus_dev_release(struct device *dev)
376 {
377 	if (dev)
378 		kfree(to_xenbus_device(dev));
379 }
380 
381 static ssize_t xendev_show_nodename(struct device *dev,
382 				    struct device_attribute *attr, char *buf)
383 {
384 	return sprintf(buf, "%s\n", to_xenbus_device(dev)->nodename);
385 }
386 static DEVICE_ATTR(nodename, S_IRUSR | S_IRGRP | S_IROTH, xendev_show_nodename, NULL);
387 
388 static ssize_t xendev_show_devtype(struct device *dev,
389 				   struct device_attribute *attr, char *buf)
390 {
391 	return sprintf(buf, "%s\n", to_xenbus_device(dev)->devicetype);
392 }
393 static DEVICE_ATTR(devtype, S_IRUSR | S_IRGRP | S_IROTH, xendev_show_devtype, NULL);
394 
395 static ssize_t xendev_show_modalias(struct device *dev,
396 				    struct device_attribute *attr, char *buf)
397 {
398 	return sprintf(buf, "xen:%s\n", to_xenbus_device(dev)->devicetype);
399 }
400 static DEVICE_ATTR(modalias, S_IRUSR | S_IRGRP | S_IROTH, xendev_show_modalias, NULL);
401 
402 int xenbus_probe_node(struct xen_bus_type *bus,
403 		      const char *type,
404 		      const char *nodename)
405 {
406 	char devname[XEN_BUS_ID_SIZE];
407 	int err;
408 	struct xenbus_device *xendev;
409 	size_t stringlen;
410 	char *tmpstring;
411 
412 	enum xenbus_state state = xenbus_read_driver_state(nodename);
413 
414 	if (state != XenbusStateInitialising) {
415 		/* Device is not new, so ignore it.  This can happen if a
416 		   device is going away after switching to Closed.  */
417 		return 0;
418 	}
419 
420 	stringlen = strlen(nodename) + 1 + strlen(type) + 1;
421 	xendev = kzalloc(sizeof(*xendev) + stringlen, GFP_KERNEL);
422 	if (!xendev)
423 		return -ENOMEM;
424 
425 	xendev->state = XenbusStateInitialising;
426 
427 	/* Copy the strings into the extra space. */
428 
429 	tmpstring = (char *)(xendev + 1);
430 	strcpy(tmpstring, nodename);
431 	xendev->nodename = tmpstring;
432 
433 	tmpstring += strlen(tmpstring) + 1;
434 	strcpy(tmpstring, type);
435 	xendev->devicetype = tmpstring;
436 	init_completion(&xendev->down);
437 
438 	xendev->dev.bus = &bus->bus;
439 	xendev->dev.release = xenbus_dev_release;
440 
441 	err = bus->get_bus_id(devname, xendev->nodename);
442 	if (err)
443 		goto fail;
444 
445 	dev_set_name(&xendev->dev, devname);
446 
447 	/* Register with generic device framework. */
448 	err = device_register(&xendev->dev);
449 	if (err)
450 		goto fail;
451 
452 	err = device_create_file(&xendev->dev, &dev_attr_nodename);
453 	if (err)
454 		goto fail_unregister;
455 
456 	err = device_create_file(&xendev->dev, &dev_attr_devtype);
457 	if (err)
458 		goto fail_remove_nodename;
459 
460 	err = device_create_file(&xendev->dev, &dev_attr_modalias);
461 	if (err)
462 		goto fail_remove_devtype;
463 
464 	return 0;
465 fail_remove_devtype:
466 	device_remove_file(&xendev->dev, &dev_attr_devtype);
467 fail_remove_nodename:
468 	device_remove_file(&xendev->dev, &dev_attr_nodename);
469 fail_unregister:
470 	device_unregister(&xendev->dev);
471 fail:
472 	kfree(xendev);
473 	return err;
474 }
475 EXPORT_SYMBOL_GPL(xenbus_probe_node);
476 
477 static int xenbus_probe_device_type(struct xen_bus_type *bus, const char *type)
478 {
479 	int err = 0;
480 	char **dir;
481 	unsigned int dir_n = 0;
482 	int i;
483 
484 	dir = xenbus_directory(XBT_NIL, bus->root, type, &dir_n);
485 	if (IS_ERR(dir))
486 		return PTR_ERR(dir);
487 
488 	for (i = 0; i < dir_n; i++) {
489 		err = bus->probe(bus, type, dir[i]);
490 		if (err)
491 			break;
492 	}
493 
494 	kfree(dir);
495 	return err;
496 }
497 
498 int xenbus_probe_devices(struct xen_bus_type *bus)
499 {
500 	int err = 0;
501 	char **dir;
502 	unsigned int i, dir_n;
503 
504 	dir = xenbus_directory(XBT_NIL, bus->root, "", &dir_n);
505 	if (IS_ERR(dir))
506 		return PTR_ERR(dir);
507 
508 	for (i = 0; i < dir_n; i++) {
509 		err = xenbus_probe_device_type(bus, dir[i]);
510 		if (err)
511 			break;
512 	}
513 
514 	kfree(dir);
515 	return err;
516 }
517 EXPORT_SYMBOL_GPL(xenbus_probe_devices);
518 
519 static unsigned int char_count(const char *str, char c)
520 {
521 	unsigned int i, ret = 0;
522 
523 	for (i = 0; str[i]; i++)
524 		if (str[i] == c)
525 			ret++;
526 	return ret;
527 }
528 
529 static int strsep_len(const char *str, char c, unsigned int len)
530 {
531 	unsigned int i;
532 
533 	for (i = 0; str[i]; i++)
534 		if (str[i] == c) {
535 			if (len == 0)
536 				return i;
537 			len--;
538 		}
539 	return (len == 0) ? i : -ERANGE;
540 }
541 
542 void xenbus_dev_changed(const char *node, struct xen_bus_type *bus)
543 {
544 	int exists, rootlen;
545 	struct xenbus_device *dev;
546 	char type[XEN_BUS_ID_SIZE];
547 	const char *p, *root;
548 
549 	if (char_count(node, '/') < 2)
550 		return;
551 
552 	exists = xenbus_exists(XBT_NIL, node, "");
553 	if (!exists) {
554 		xenbus_cleanup_devices(node, &bus->bus);
555 		return;
556 	}
557 
558 	/* backend/<type>/... or device/<type>/... */
559 	p = strchr(node, '/') + 1;
560 	snprintf(type, XEN_BUS_ID_SIZE, "%.*s", (int)strcspn(p, "/"), p);
561 	type[XEN_BUS_ID_SIZE-1] = '\0';
562 
563 	rootlen = strsep_len(node, '/', bus->levels);
564 	if (rootlen < 0)
565 		return;
566 	root = kasprintf(GFP_KERNEL, "%.*s", rootlen, node);
567 	if (!root)
568 		return;
569 
570 	dev = xenbus_device_find(root, &bus->bus);
571 	if (!dev)
572 		xenbus_probe_node(bus, type, root);
573 	else
574 		put_device(&dev->dev);
575 
576 	kfree(root);
577 }
578 EXPORT_SYMBOL_GPL(xenbus_dev_changed);
579 
580 int xenbus_dev_suspend(struct device *dev)
581 {
582 	int err = 0;
583 	struct xenbus_driver *drv;
584 	struct xenbus_device *xdev
585 		= container_of(dev, struct xenbus_device, dev);
586 
587 	DPRINTK("%s", xdev->nodename);
588 
589 	if (dev->driver == NULL)
590 		return 0;
591 	drv = to_xenbus_driver(dev->driver);
592 	if (drv->suspend)
593 		err = drv->suspend(xdev);
594 	if (err)
595 		printk(KERN_WARNING
596 		       "xenbus: suspend %s failed: %i\n", dev_name(dev), err);
597 	return 0;
598 }
599 EXPORT_SYMBOL_GPL(xenbus_dev_suspend);
600 
601 int xenbus_dev_resume(struct device *dev)
602 {
603 	int err;
604 	struct xenbus_driver *drv;
605 	struct xenbus_device *xdev
606 		= container_of(dev, struct xenbus_device, dev);
607 
608 	DPRINTK("%s", xdev->nodename);
609 
610 	if (dev->driver == NULL)
611 		return 0;
612 	drv = to_xenbus_driver(dev->driver);
613 	err = talk_to_otherend(xdev);
614 	if (err) {
615 		printk(KERN_WARNING
616 		       "xenbus: resume (talk_to_otherend) %s failed: %i\n",
617 		       dev_name(dev), err);
618 		return err;
619 	}
620 
621 	xdev->state = XenbusStateInitialising;
622 
623 	if (drv->resume) {
624 		err = drv->resume(xdev);
625 		if (err) {
626 			printk(KERN_WARNING
627 			       "xenbus: resume %s failed: %i\n",
628 			       dev_name(dev), err);
629 			return err;
630 		}
631 	}
632 
633 	err = watch_otherend(xdev);
634 	if (err) {
635 		printk(KERN_WARNING
636 		       "xenbus_probe: resume (watch_otherend) %s failed: "
637 		       "%d.\n", dev_name(dev), err);
638 		return err;
639 	}
640 
641 	return 0;
642 }
643 EXPORT_SYMBOL_GPL(xenbus_dev_resume);
644 
645 int xenbus_dev_cancel(struct device *dev)
646 {
647 	/* Do nothing */
648 	DPRINTK("cancel");
649 	return 0;
650 }
651 EXPORT_SYMBOL_GPL(xenbus_dev_cancel);
652 
653 /* A flag to determine if xenstored is 'ready' (i.e. has started) */
654 int xenstored_ready = 0;
655 
656 
657 int register_xenstore_notifier(struct notifier_block *nb)
658 {
659 	int ret = 0;
660 
661 	if (xenstored_ready > 0)
662 		ret = nb->notifier_call(nb, 0, NULL);
663 	else
664 		blocking_notifier_chain_register(&xenstore_chain, nb);
665 
666 	return ret;
667 }
668 EXPORT_SYMBOL_GPL(register_xenstore_notifier);
669 
670 void unregister_xenstore_notifier(struct notifier_block *nb)
671 {
672 	blocking_notifier_chain_unregister(&xenstore_chain, nb);
673 }
674 EXPORT_SYMBOL_GPL(unregister_xenstore_notifier);
675 
676 void xenbus_probe(struct work_struct *unused)
677 {
678 	xenstored_ready = 1;
679 
680 	/* Notify others that xenstore is up */
681 	blocking_notifier_call_chain(&xenstore_chain, 0, NULL);
682 }
683 EXPORT_SYMBOL_GPL(xenbus_probe);
684 
685 static int __init xenbus_probe_initcall(void)
686 {
687 	if (!xen_domain())
688 		return -ENODEV;
689 
690 	if (xen_initial_domain() || xen_hvm_domain())
691 		return 0;
692 
693 	xenbus_probe(NULL);
694 	return 0;
695 }
696 
697 device_initcall(xenbus_probe_initcall);
698 
699 static int __init xenbus_init(void)
700 {
701 	int err = 0;
702 	unsigned long page = 0;
703 
704 	DPRINTK("");
705 
706 	err = -ENODEV;
707 	if (!xen_domain())
708 		return err;
709 
710 	/*
711 	 * Domain0 doesn't have a store_evtchn or store_mfn yet.
712 	 */
713 	if (xen_initial_domain()) {
714 		struct evtchn_alloc_unbound alloc_unbound;
715 
716 		/* Allocate Xenstore page */
717 		page = get_zeroed_page(GFP_KERNEL);
718 		if (!page)
719 			goto out_error;
720 
721 		xen_store_mfn = xen_start_info->store_mfn =
722 			pfn_to_mfn(virt_to_phys((void *)page) >>
723 				   PAGE_SHIFT);
724 
725 		/* Next allocate a local port which xenstored can bind to */
726 		alloc_unbound.dom        = DOMID_SELF;
727 		alloc_unbound.remote_dom = 0;
728 
729 		err = HYPERVISOR_event_channel_op(EVTCHNOP_alloc_unbound,
730 						  &alloc_unbound);
731 		if (err == -ENOSYS)
732 			goto out_error;
733 
734 		BUG_ON(err);
735 		xen_store_evtchn = xen_start_info->store_evtchn =
736 			alloc_unbound.port;
737 
738 		xen_store_interface = mfn_to_virt(xen_store_mfn);
739 	} else {
740 		if (xen_hvm_domain()) {
741 			uint64_t v = 0;
742 			err = hvm_get_parameter(HVM_PARAM_STORE_EVTCHN, &v);
743 			if (err)
744 				goto out_error;
745 			xen_store_evtchn = (int)v;
746 			err = hvm_get_parameter(HVM_PARAM_STORE_PFN, &v);
747 			if (err)
748 				goto out_error;
749 			xen_store_mfn = (unsigned long)v;
750 			xen_store_interface = ioremap(xen_store_mfn << PAGE_SHIFT, PAGE_SIZE);
751 		} else {
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 			xenstored_ready = 1;
756 		}
757 	}
758 
759 	/* Initialize the interface to xenstore. */
760 	err = xs_init();
761 	if (err) {
762 		printk(KERN_WARNING
763 		       "XENBUS: Error initializing xenstore comms: %i\n", err);
764 		goto out_error;
765 	}
766 
767 #ifdef CONFIG_XEN_COMPAT_XENFS
768 	/*
769 	 * Create xenfs mountpoint in /proc for compatibility with
770 	 * utilities that expect to find "xenbus" under "/proc/xen".
771 	 */
772 	proc_mkdir("xen", NULL);
773 #endif
774 
775 	return 0;
776 
777   out_error:
778 	if (page != 0)
779 		free_page(page);
780 
781 	return err;
782 }
783 
784 postcore_initcall(xenbus_init);
785 
786 MODULE_LICENSE("GPL");
787