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/xen-ops.h>
61 #include <xen/page.h>
62 
63 #include <xen/hvm.h>
64 
65 #include "xenbus_comms.h"
66 #include "xenbus_probe.h"
67 
68 
69 int xen_store_evtchn;
70 EXPORT_SYMBOL_GPL(xen_store_evtchn);
71 
72 struct xenstore_domain_interface *xen_store_interface;
73 EXPORT_SYMBOL_GPL(xen_store_interface);
74 
75 enum xenstore_init xen_store_domain_type;
76 EXPORT_SYMBOL_GPL(xen_store_domain_type);
77 
78 static unsigned long xen_store_gfn;
79 
80 static BLOCKING_NOTIFIER_HEAD(xenstore_chain);
81 
82 /* If something in array of ids matches this device, return it. */
83 static const struct xenbus_device_id *
84 match_device(const struct xenbus_device_id *arr, struct xenbus_device *dev)
85 {
86 	for (; *arr->devicetype != '\0'; arr++) {
87 		if (!strcmp(arr->devicetype, dev->devicetype))
88 			return arr;
89 	}
90 	return NULL;
91 }
92 
93 int xenbus_match(struct device *_dev, struct device_driver *_drv)
94 {
95 	struct xenbus_driver *drv = to_xenbus_driver(_drv);
96 
97 	if (!drv->ids)
98 		return 0;
99 
100 	return match_device(drv->ids, to_xenbus_device(_dev)) != NULL;
101 }
102 EXPORT_SYMBOL_GPL(xenbus_match);
103 
104 
105 static void free_otherend_details(struct xenbus_device *dev)
106 {
107 	kfree(dev->otherend);
108 	dev->otherend = NULL;
109 }
110 
111 
112 static void free_otherend_watch(struct xenbus_device *dev)
113 {
114 	if (dev->otherend_watch.node) {
115 		unregister_xenbus_watch(&dev->otherend_watch);
116 		kfree(dev->otherend_watch.node);
117 		dev->otherend_watch.node = NULL;
118 	}
119 }
120 
121 
122 static int talk_to_otherend(struct xenbus_device *dev)
123 {
124 	struct xenbus_driver *drv = to_xenbus_driver(dev->dev.driver);
125 
126 	free_otherend_watch(dev);
127 	free_otherend_details(dev);
128 
129 	return drv->read_otherend_details(dev);
130 }
131 
132 
133 
134 static int watch_otherend(struct xenbus_device *dev)
135 {
136 	struct xen_bus_type *bus =
137 		container_of(dev->dev.bus, struct xen_bus_type, bus);
138 
139 	return xenbus_watch_pathfmt(dev, &dev->otherend_watch,
140 				    bus->otherend_changed,
141 				    "%s/%s", dev->otherend, "state");
142 }
143 
144 
145 int xenbus_read_otherend_details(struct xenbus_device *xendev,
146 				 char *id_node, char *path_node)
147 {
148 	int err = xenbus_gather(XBT_NIL, xendev->nodename,
149 				id_node, "%i", &xendev->otherend_id,
150 				path_node, NULL, &xendev->otherend,
151 				NULL);
152 	if (err) {
153 		xenbus_dev_fatal(xendev, err,
154 				 "reading other end details from %s",
155 				 xendev->nodename);
156 		return err;
157 	}
158 	if (strlen(xendev->otherend) == 0 ||
159 	    !xenbus_exists(XBT_NIL, xendev->otherend, "")) {
160 		xenbus_dev_fatal(xendev, -ENOENT,
161 				 "unable to read other end from %s.  "
162 				 "missing or inaccessible.",
163 				 xendev->nodename);
164 		free_otherend_details(xendev);
165 		return -ENOENT;
166 	}
167 
168 	return 0;
169 }
170 EXPORT_SYMBOL_GPL(xenbus_read_otherend_details);
171 
172 void xenbus_otherend_changed(struct xenbus_watch *watch,
173 			     const char **vec, unsigned int len,
174 			     int ignore_on_shutdown)
175 {
176 	struct xenbus_device *dev =
177 		container_of(watch, struct xenbus_device, otherend_watch);
178 	struct xenbus_driver *drv = to_xenbus_driver(dev->dev.driver);
179 	enum xenbus_state state;
180 
181 	/* Protect us against watches firing on old details when the otherend
182 	   details change, say immediately after a resume. */
183 	if (!dev->otherend ||
184 	    strncmp(dev->otherend, vec[XS_WATCH_PATH],
185 		    strlen(dev->otherend))) {
186 		dev_dbg(&dev->dev, "Ignoring watch at %s\n",
187 			vec[XS_WATCH_PATH]);
188 		return;
189 	}
190 
191 	state = xenbus_read_driver_state(dev->otherend);
192 
193 	dev_dbg(&dev->dev, "state is %d, (%s), %s, %s\n",
194 		state, xenbus_strstate(state), dev->otherend_watch.node,
195 		vec[XS_WATCH_PATH]);
196 
197 	/*
198 	 * Ignore xenbus transitions during shutdown. This prevents us doing
199 	 * work that can fail e.g., when the rootfs is gone.
200 	 */
201 	if (system_state > SYSTEM_RUNNING) {
202 		if (ignore_on_shutdown && (state == XenbusStateClosing))
203 			xenbus_frontend_closed(dev);
204 		return;
205 	}
206 
207 	if (drv->otherend_changed)
208 		drv->otherend_changed(dev, state);
209 }
210 EXPORT_SYMBOL_GPL(xenbus_otherend_changed);
211 
212 int xenbus_dev_probe(struct device *_dev)
213 {
214 	struct xenbus_device *dev = to_xenbus_device(_dev);
215 	struct xenbus_driver *drv = to_xenbus_driver(_dev->driver);
216 	const struct xenbus_device_id *id;
217 	int err;
218 
219 	DPRINTK("%s", dev->nodename);
220 
221 	if (!drv->probe) {
222 		err = -ENODEV;
223 		goto fail;
224 	}
225 
226 	id = match_device(drv->ids, dev);
227 	if (!id) {
228 		err = -ENODEV;
229 		goto fail;
230 	}
231 
232 	err = talk_to_otherend(dev);
233 	if (err) {
234 		dev_warn(&dev->dev, "talk_to_otherend on %s failed.\n",
235 			 dev->nodename);
236 		return err;
237 	}
238 
239 	err = drv->probe(dev, id);
240 	if (err)
241 		goto fail;
242 
243 	err = watch_otherend(dev);
244 	if (err) {
245 		dev_warn(&dev->dev, "watch_otherend on %s failed.\n",
246 		       dev->nodename);
247 		return err;
248 	}
249 
250 	return 0;
251 fail:
252 	xenbus_dev_error(dev, err, "xenbus_dev_probe on %s", dev->nodename);
253 	xenbus_switch_state(dev, XenbusStateClosed);
254 	return err;
255 }
256 EXPORT_SYMBOL_GPL(xenbus_dev_probe);
257 
258 int xenbus_dev_remove(struct device *_dev)
259 {
260 	struct xenbus_device *dev = to_xenbus_device(_dev);
261 	struct xenbus_driver *drv = to_xenbus_driver(_dev->driver);
262 
263 	DPRINTK("%s", dev->nodename);
264 
265 	free_otherend_watch(dev);
266 
267 	if (drv->remove)
268 		drv->remove(dev);
269 
270 	free_otherend_details(dev);
271 
272 	xenbus_switch_state(dev, XenbusStateClosed);
273 	return 0;
274 }
275 EXPORT_SYMBOL_GPL(xenbus_dev_remove);
276 
277 void xenbus_dev_shutdown(struct device *_dev)
278 {
279 	struct xenbus_device *dev = to_xenbus_device(_dev);
280 	unsigned long timeout = 5*HZ;
281 
282 	DPRINTK("%s", dev->nodename);
283 
284 	get_device(&dev->dev);
285 	if (dev->state != XenbusStateConnected) {
286 		pr_info("%s: %s: %s != Connected, skipping\n",
287 			__func__, dev->nodename, xenbus_strstate(dev->state));
288 		goto out;
289 	}
290 	xenbus_switch_state(dev, XenbusStateClosing);
291 	timeout = wait_for_completion_timeout(&dev->down, timeout);
292 	if (!timeout)
293 		pr_info("%s: %s timeout closing device\n",
294 			__func__, dev->nodename);
295  out:
296 	put_device(&dev->dev);
297 }
298 EXPORT_SYMBOL_GPL(xenbus_dev_shutdown);
299 
300 int xenbus_register_driver_common(struct xenbus_driver *drv,
301 				  struct xen_bus_type *bus,
302 				  struct module *owner, const char *mod_name)
303 {
304 	drv->driver.name = drv->name ? drv->name : drv->ids[0].devicetype;
305 	drv->driver.bus = &bus->bus;
306 	drv->driver.owner = owner;
307 	drv->driver.mod_name = mod_name;
308 
309 	return driver_register(&drv->driver);
310 }
311 EXPORT_SYMBOL_GPL(xenbus_register_driver_common);
312 
313 void xenbus_unregister_driver(struct xenbus_driver *drv)
314 {
315 	driver_unregister(&drv->driver);
316 }
317 EXPORT_SYMBOL_GPL(xenbus_unregister_driver);
318 
319 struct xb_find_info {
320 	struct xenbus_device *dev;
321 	const char *nodename;
322 };
323 
324 static int cmp_dev(struct device *dev, void *data)
325 {
326 	struct xenbus_device *xendev = to_xenbus_device(dev);
327 	struct xb_find_info *info = data;
328 
329 	if (!strcmp(xendev->nodename, info->nodename)) {
330 		info->dev = xendev;
331 		get_device(dev);
332 		return 1;
333 	}
334 	return 0;
335 }
336 
337 static struct xenbus_device *xenbus_device_find(const char *nodename,
338 						struct bus_type *bus)
339 {
340 	struct xb_find_info info = { .dev = NULL, .nodename = nodename };
341 
342 	bus_for_each_dev(bus, NULL, &info, cmp_dev);
343 	return info.dev;
344 }
345 
346 static int cleanup_dev(struct device *dev, void *data)
347 {
348 	struct xenbus_device *xendev = to_xenbus_device(dev);
349 	struct xb_find_info *info = data;
350 	int len = strlen(info->nodename);
351 
352 	DPRINTK("%s", info->nodename);
353 
354 	/* Match the info->nodename path, or any subdirectory of that path. */
355 	if (strncmp(xendev->nodename, info->nodename, len))
356 		return 0;
357 
358 	/* If the node name is longer, ensure it really is a subdirectory. */
359 	if ((strlen(xendev->nodename) > len) && (xendev->nodename[len] != '/'))
360 		return 0;
361 
362 	info->dev = xendev;
363 	get_device(dev);
364 	return 1;
365 }
366 
367 static void xenbus_cleanup_devices(const char *path, struct bus_type *bus)
368 {
369 	struct xb_find_info info = { .nodename = path };
370 
371 	do {
372 		info.dev = NULL;
373 		bus_for_each_dev(bus, NULL, &info, cleanup_dev);
374 		if (info.dev) {
375 			device_unregister(&info.dev->dev);
376 			put_device(&info.dev->dev);
377 		}
378 	} while (info.dev);
379 }
380 
381 static void xenbus_dev_release(struct device *dev)
382 {
383 	if (dev)
384 		kfree(to_xenbus_device(dev));
385 }
386 
387 static ssize_t nodename_show(struct device *dev,
388 			     struct device_attribute *attr, char *buf)
389 {
390 	return sprintf(buf, "%s\n", to_xenbus_device(dev)->nodename);
391 }
392 static DEVICE_ATTR_RO(nodename);
393 
394 static ssize_t devtype_show(struct device *dev,
395 			    struct device_attribute *attr, char *buf)
396 {
397 	return sprintf(buf, "%s\n", to_xenbus_device(dev)->devicetype);
398 }
399 static DEVICE_ATTR_RO(devtype);
400 
401 static ssize_t modalias_show(struct device *dev,
402 			     struct device_attribute *attr, char *buf)
403 {
404 	return sprintf(buf, "%s:%s\n", dev->bus->name,
405 		       to_xenbus_device(dev)->devicetype);
406 }
407 static DEVICE_ATTR_RO(modalias);
408 
409 static struct attribute *xenbus_dev_attrs[] = {
410 	&dev_attr_nodename.attr,
411 	&dev_attr_devtype.attr,
412 	&dev_attr_modalias.attr,
413 	NULL,
414 };
415 
416 static const struct attribute_group xenbus_dev_group = {
417 	.attrs = xenbus_dev_attrs,
418 };
419 
420 const struct attribute_group *xenbus_dev_groups[] = {
421 	&xenbus_dev_group,
422 	NULL,
423 };
424 EXPORT_SYMBOL_GPL(xenbus_dev_groups);
425 
426 int xenbus_probe_node(struct xen_bus_type *bus,
427 		      const char *type,
428 		      const char *nodename)
429 {
430 	char devname[XEN_BUS_ID_SIZE];
431 	int err;
432 	struct xenbus_device *xendev;
433 	size_t stringlen;
434 	char *tmpstring;
435 
436 	enum xenbus_state state = xenbus_read_driver_state(nodename);
437 
438 	if (state != XenbusStateInitialising) {
439 		/* Device is not new, so ignore it.  This can happen if a
440 		   device is going away after switching to Closed.  */
441 		return 0;
442 	}
443 
444 	stringlen = strlen(nodename) + 1 + strlen(type) + 1;
445 	xendev = kzalloc(sizeof(*xendev) + stringlen, GFP_KERNEL);
446 	if (!xendev)
447 		return -ENOMEM;
448 
449 	xendev->state = XenbusStateInitialising;
450 
451 	/* Copy the strings into the extra space. */
452 
453 	tmpstring = (char *)(xendev + 1);
454 	strcpy(tmpstring, nodename);
455 	xendev->nodename = tmpstring;
456 
457 	tmpstring += strlen(tmpstring) + 1;
458 	strcpy(tmpstring, type);
459 	xendev->devicetype = tmpstring;
460 	init_completion(&xendev->down);
461 
462 	xendev->dev.bus = &bus->bus;
463 	xendev->dev.release = xenbus_dev_release;
464 
465 	err = bus->get_bus_id(devname, xendev->nodename);
466 	if (err)
467 		goto fail;
468 
469 	dev_set_name(&xendev->dev, "%s", devname);
470 
471 	/* Register with generic device framework. */
472 	err = device_register(&xendev->dev);
473 	if (err)
474 		goto fail;
475 
476 	return 0;
477 fail:
478 	kfree(xendev);
479 	return err;
480 }
481 EXPORT_SYMBOL_GPL(xenbus_probe_node);
482 
483 static int xenbus_probe_device_type(struct xen_bus_type *bus, const char *type)
484 {
485 	int err = 0;
486 	char **dir;
487 	unsigned int dir_n = 0;
488 	int i;
489 
490 	dir = xenbus_directory(XBT_NIL, bus->root, type, &dir_n);
491 	if (IS_ERR(dir))
492 		return PTR_ERR(dir);
493 
494 	for (i = 0; i < dir_n; i++) {
495 		err = bus->probe(bus, type, dir[i]);
496 		if (err)
497 			break;
498 	}
499 
500 	kfree(dir);
501 	return err;
502 }
503 
504 int xenbus_probe_devices(struct xen_bus_type *bus)
505 {
506 	int err = 0;
507 	char **dir;
508 	unsigned int i, dir_n;
509 
510 	dir = xenbus_directory(XBT_NIL, bus->root, "", &dir_n);
511 	if (IS_ERR(dir))
512 		return PTR_ERR(dir);
513 
514 	for (i = 0; i < dir_n; i++) {
515 		err = xenbus_probe_device_type(bus, dir[i]);
516 		if (err)
517 			break;
518 	}
519 
520 	kfree(dir);
521 	return err;
522 }
523 EXPORT_SYMBOL_GPL(xenbus_probe_devices);
524 
525 static unsigned int char_count(const char *str, char c)
526 {
527 	unsigned int i, ret = 0;
528 
529 	for (i = 0; str[i]; i++)
530 		if (str[i] == c)
531 			ret++;
532 	return ret;
533 }
534 
535 static int strsep_len(const char *str, char c, unsigned int len)
536 {
537 	unsigned int i;
538 
539 	for (i = 0; str[i]; i++)
540 		if (str[i] == c) {
541 			if (len == 0)
542 				return i;
543 			len--;
544 		}
545 	return (len == 0) ? i : -ERANGE;
546 }
547 
548 void xenbus_dev_changed(const char *node, struct xen_bus_type *bus)
549 {
550 	int exists, rootlen;
551 	struct xenbus_device *dev;
552 	char type[XEN_BUS_ID_SIZE];
553 	const char *p, *root;
554 
555 	if (char_count(node, '/') < 2)
556 		return;
557 
558 	exists = xenbus_exists(XBT_NIL, node, "");
559 	if (!exists) {
560 		xenbus_cleanup_devices(node, &bus->bus);
561 		return;
562 	}
563 
564 	/* backend/<type>/... or device/<type>/... */
565 	p = strchr(node, '/') + 1;
566 	snprintf(type, XEN_BUS_ID_SIZE, "%.*s", (int)strcspn(p, "/"), p);
567 	type[XEN_BUS_ID_SIZE-1] = '\0';
568 
569 	rootlen = strsep_len(node, '/', bus->levels);
570 	if (rootlen < 0)
571 		return;
572 	root = kasprintf(GFP_KERNEL, "%.*s", rootlen, node);
573 	if (!root)
574 		return;
575 
576 	dev = xenbus_device_find(root, &bus->bus);
577 	if (!dev)
578 		xenbus_probe_node(bus, type, root);
579 	else
580 		put_device(&dev->dev);
581 
582 	kfree(root);
583 }
584 EXPORT_SYMBOL_GPL(xenbus_dev_changed);
585 
586 int xenbus_dev_suspend(struct device *dev)
587 {
588 	int err = 0;
589 	struct xenbus_driver *drv;
590 	struct xenbus_device *xdev
591 		= container_of(dev, struct xenbus_device, dev);
592 
593 	DPRINTK("%s", xdev->nodename);
594 
595 	if (dev->driver == NULL)
596 		return 0;
597 	drv = to_xenbus_driver(dev->driver);
598 	if (drv->suspend)
599 		err = drv->suspend(xdev);
600 	if (err)
601 		pr_warn("suspend %s failed: %i\n", dev_name(dev), err);
602 	return 0;
603 }
604 EXPORT_SYMBOL_GPL(xenbus_dev_suspend);
605 
606 int xenbus_dev_resume(struct device *dev)
607 {
608 	int err;
609 	struct xenbus_driver *drv;
610 	struct xenbus_device *xdev
611 		= container_of(dev, struct xenbus_device, dev);
612 
613 	DPRINTK("%s", xdev->nodename);
614 
615 	if (dev->driver == NULL)
616 		return 0;
617 	drv = to_xenbus_driver(dev->driver);
618 	err = talk_to_otherend(xdev);
619 	if (err) {
620 		pr_warn("resume (talk_to_otherend) %s failed: %i\n",
621 			dev_name(dev), err);
622 		return err;
623 	}
624 
625 	xdev->state = XenbusStateInitialising;
626 
627 	if (drv->resume) {
628 		err = drv->resume(xdev);
629 		if (err) {
630 			pr_warn("resume %s failed: %i\n", dev_name(dev), err);
631 			return err;
632 		}
633 	}
634 
635 	err = watch_otherend(xdev);
636 	if (err) {
637 		pr_warn("resume (watch_otherend) %s failed: %d.\n",
638 			dev_name(dev), err);
639 		return err;
640 	}
641 
642 	return 0;
643 }
644 EXPORT_SYMBOL_GPL(xenbus_dev_resume);
645 
646 int xenbus_dev_cancel(struct device *dev)
647 {
648 	/* Do nothing */
649 	DPRINTK("cancel");
650 	return 0;
651 }
652 EXPORT_SYMBOL_GPL(xenbus_dev_cancel);
653 
654 /* A flag to determine if xenstored is 'ready' (i.e. has started) */
655 int xenstored_ready;
656 
657 
658 int register_xenstore_notifier(struct notifier_block *nb)
659 {
660 	int ret = 0;
661 
662 	if (xenstored_ready > 0)
663 		ret = nb->notifier_call(nb, 0, NULL);
664 	else
665 		blocking_notifier_chain_register(&xenstore_chain, nb);
666 
667 	return ret;
668 }
669 EXPORT_SYMBOL_GPL(register_xenstore_notifier);
670 
671 void unregister_xenstore_notifier(struct notifier_block *nb)
672 {
673 	blocking_notifier_chain_unregister(&xenstore_chain, nb);
674 }
675 EXPORT_SYMBOL_GPL(unregister_xenstore_notifier);
676 
677 void xenbus_probe(struct work_struct *unused)
678 {
679 	xenstored_ready = 1;
680 
681 	/* Notify others that xenstore is up */
682 	blocking_notifier_call_chain(&xenstore_chain, 0, NULL);
683 }
684 EXPORT_SYMBOL_GPL(xenbus_probe);
685 
686 static int __init xenbus_probe_initcall(void)
687 {
688 	if (!xen_domain())
689 		return -ENODEV;
690 
691 	if (xen_initial_domain() || xen_hvm_domain())
692 		return 0;
693 
694 	xenbus_probe(NULL);
695 	return 0;
696 }
697 
698 device_initcall(xenbus_probe_initcall);
699 
700 /* Set up event channel for xenstored which is run as a local process
701  * (this is normally used only in dom0)
702  */
703 static int __init xenstored_local_init(void)
704 {
705 	int err = 0;
706 	unsigned long page = 0;
707 	struct evtchn_alloc_unbound alloc_unbound;
708 
709 	/* Allocate Xenstore page */
710 	page = get_zeroed_page(GFP_KERNEL);
711 	if (!page)
712 		goto out_err;
713 
714 	xen_store_gfn = xen_start_info->store_mfn = virt_to_gfn((void *)page);
715 
716 	/* Next allocate a local port which xenstored can bind to */
717 	alloc_unbound.dom        = DOMID_SELF;
718 	alloc_unbound.remote_dom = DOMID_SELF;
719 
720 	err = HYPERVISOR_event_channel_op(EVTCHNOP_alloc_unbound,
721 					  &alloc_unbound);
722 	if (err == -ENOSYS)
723 		goto out_err;
724 
725 	BUG_ON(err);
726 	xen_store_evtchn = xen_start_info->store_evtchn =
727 		alloc_unbound.port;
728 
729 	return 0;
730 
731  out_err:
732 	if (page != 0)
733 		free_page(page);
734 	return err;
735 }
736 
737 static int xenbus_resume_cb(struct notifier_block *nb,
738 			    unsigned long action, void *data)
739 {
740 	int err = 0;
741 
742 	if (xen_hvm_domain()) {
743 		uint64_t v = 0;
744 
745 		err = hvm_get_parameter(HVM_PARAM_STORE_EVTCHN, &v);
746 		if (!err && v)
747 			xen_store_evtchn = v;
748 		else
749 			pr_warn("Cannot update xenstore event channel: %d\n",
750 				err);
751 	} else
752 		xen_store_evtchn = xen_start_info->store_evtchn;
753 
754 	return err;
755 }
756 
757 static struct notifier_block xenbus_resume_nb = {
758 	.notifier_call = xenbus_resume_cb,
759 };
760 
761 static int __init xenbus_init(void)
762 {
763 	int err = 0;
764 	uint64_t v = 0;
765 	xen_store_domain_type = XS_UNKNOWN;
766 
767 	if (!xen_domain())
768 		return -ENODEV;
769 
770 	xenbus_ring_ops_init();
771 
772 	if (xen_pv_domain())
773 		xen_store_domain_type = XS_PV;
774 	if (xen_hvm_domain())
775 		xen_store_domain_type = XS_HVM;
776 	if (xen_hvm_domain() && xen_initial_domain())
777 		xen_store_domain_type = XS_LOCAL;
778 	if (xen_pv_domain() && !xen_start_info->store_evtchn)
779 		xen_store_domain_type = XS_LOCAL;
780 	if (xen_pv_domain() && xen_start_info->store_evtchn)
781 		xenstored_ready = 1;
782 
783 	switch (xen_store_domain_type) {
784 	case XS_LOCAL:
785 		err = xenstored_local_init();
786 		if (err)
787 			goto out_error;
788 		xen_store_interface = gfn_to_virt(xen_store_gfn);
789 		break;
790 	case XS_PV:
791 		xen_store_evtchn = xen_start_info->store_evtchn;
792 		xen_store_gfn = xen_start_info->store_mfn;
793 		xen_store_interface = gfn_to_virt(xen_store_gfn);
794 		break;
795 	case XS_HVM:
796 		err = hvm_get_parameter(HVM_PARAM_STORE_EVTCHN, &v);
797 		if (err)
798 			goto out_error;
799 		xen_store_evtchn = (int)v;
800 		err = hvm_get_parameter(HVM_PARAM_STORE_PFN, &v);
801 		if (err)
802 			goto out_error;
803 		xen_store_gfn = (unsigned long)v;
804 		xen_store_interface =
805 			xen_remap(xen_store_gfn << XEN_PAGE_SHIFT,
806 				  XEN_PAGE_SIZE);
807 		break;
808 	default:
809 		pr_warn("Xenstore state unknown\n");
810 		break;
811 	}
812 
813 	/* Initialize the interface to xenstore. */
814 	err = xs_init();
815 	if (err) {
816 		pr_warn("Error initializing xenstore comms: %i\n", err);
817 		goto out_error;
818 	}
819 
820 	if ((xen_store_domain_type != XS_LOCAL) &&
821 	    (xen_store_domain_type != XS_UNKNOWN))
822 		xen_resume_notifier_register(&xenbus_resume_nb);
823 
824 #ifdef CONFIG_XEN_COMPAT_XENFS
825 	/*
826 	 * Create xenfs mountpoint in /proc for compatibility with
827 	 * utilities that expect to find "xenbus" under "/proc/xen".
828 	 */
829 	proc_mkdir("xen", NULL);
830 #endif
831 
832 out_error:
833 	return err;
834 }
835 
836 postcore_initcall(xenbus_init);
837 
838 MODULE_LICENSE("GPL");
839