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 #include <linux/module.h>
50 
51 #include <asm/page.h>
52 #include <asm/pgtable.h>
53 #include <asm/xen/hypervisor.h>
54 
55 #include <xen/xen.h>
56 #include <xen/xenbus.h>
57 #include <xen/events.h>
58 #include <xen/page.h>
59 
60 #include <xen/hvm.h>
61 
62 #include "xenbus_comms.h"
63 #include "xenbus_probe.h"
64 
65 
66 int xen_store_evtchn;
67 EXPORT_SYMBOL_GPL(xen_store_evtchn);
68 
69 struct xenstore_domain_interface *xen_store_interface;
70 EXPORT_SYMBOL_GPL(xen_store_interface);
71 
72 static unsigned long xen_store_mfn;
73 
74 static BLOCKING_NOTIFIER_HEAD(xenstore_chain);
75 
76 /* If something in array of ids matches this device, return it. */
77 static const struct xenbus_device_id *
78 match_device(const struct xenbus_device_id *arr, struct xenbus_device *dev)
79 {
80 	for (; *arr->devicetype != '\0'; arr++) {
81 		if (!strcmp(arr->devicetype, dev->devicetype))
82 			return arr;
83 	}
84 	return NULL;
85 }
86 
87 int xenbus_match(struct device *_dev, struct device_driver *_drv)
88 {
89 	struct xenbus_driver *drv = to_xenbus_driver(_drv);
90 
91 	if (!drv->ids)
92 		return 0;
93 
94 	return match_device(drv->ids, to_xenbus_device(_dev)) != NULL;
95 }
96 EXPORT_SYMBOL_GPL(xenbus_match);
97 
98 
99 static void free_otherend_details(struct xenbus_device *dev)
100 {
101 	kfree(dev->otherend);
102 	dev->otherend = NULL;
103 }
104 
105 
106 static void free_otherend_watch(struct xenbus_device *dev)
107 {
108 	if (dev->otherend_watch.node) {
109 		unregister_xenbus_watch(&dev->otherend_watch);
110 		kfree(dev->otherend_watch.node);
111 		dev->otherend_watch.node = NULL;
112 	}
113 }
114 
115 
116 static int talk_to_otherend(struct xenbus_device *dev)
117 {
118 	struct xenbus_driver *drv = to_xenbus_driver(dev->dev.driver);
119 
120 	free_otherend_watch(dev);
121 	free_otherend_details(dev);
122 
123 	return drv->read_otherend_details(dev);
124 }
125 
126 
127 
128 static int watch_otherend(struct xenbus_device *dev)
129 {
130 	struct xen_bus_type *bus =
131 		container_of(dev->dev.bus, struct xen_bus_type, bus);
132 
133 	return xenbus_watch_pathfmt(dev, &dev->otherend_watch,
134 				    bus->otherend_changed,
135 				    "%s/%s", dev->otherend, "state");
136 }
137 
138 
139 int xenbus_read_otherend_details(struct xenbus_device *xendev,
140 				 char *id_node, char *path_node)
141 {
142 	int err = xenbus_gather(XBT_NIL, xendev->nodename,
143 				id_node, "%i", &xendev->otherend_id,
144 				path_node, NULL, &xendev->otherend,
145 				NULL);
146 	if (err) {
147 		xenbus_dev_fatal(xendev, err,
148 				 "reading other end details from %s",
149 				 xendev->nodename);
150 		return err;
151 	}
152 	if (strlen(xendev->otherend) == 0 ||
153 	    !xenbus_exists(XBT_NIL, xendev->otherend, "")) {
154 		xenbus_dev_fatal(xendev, -ENOENT,
155 				 "unable to read other end from %s.  "
156 				 "missing or inaccessible.",
157 				 xendev->nodename);
158 		free_otherend_details(xendev);
159 		return -ENOENT;
160 	}
161 
162 	return 0;
163 }
164 EXPORT_SYMBOL_GPL(xenbus_read_otherend_details);
165 
166 void xenbus_otherend_changed(struct xenbus_watch *watch,
167 			     const char **vec, unsigned int len,
168 			     int ignore_on_shutdown)
169 {
170 	struct xenbus_device *dev =
171 		container_of(watch, struct xenbus_device, otherend_watch);
172 	struct xenbus_driver *drv = to_xenbus_driver(dev->dev.driver);
173 	enum xenbus_state state;
174 
175 	/* Protect us against watches firing on old details when the otherend
176 	   details change, say immediately after a resume. */
177 	if (!dev->otherend ||
178 	    strncmp(dev->otherend, vec[XS_WATCH_PATH],
179 		    strlen(dev->otherend))) {
180 		dev_dbg(&dev->dev, "Ignoring watch at %s\n",
181 			vec[XS_WATCH_PATH]);
182 		return;
183 	}
184 
185 	state = xenbus_read_driver_state(dev->otherend);
186 
187 	dev_dbg(&dev->dev, "state is %d, (%s), %s, %s\n",
188 		state, xenbus_strstate(state), dev->otherend_watch.node,
189 		vec[XS_WATCH_PATH]);
190 
191 	/*
192 	 * Ignore xenbus transitions during shutdown. This prevents us doing
193 	 * work that can fail e.g., when the rootfs is gone.
194 	 */
195 	if (system_state > SYSTEM_RUNNING) {
196 		if (ignore_on_shutdown && (state == XenbusStateClosing))
197 			xenbus_frontend_closed(dev);
198 		return;
199 	}
200 
201 	if (drv->otherend_changed)
202 		drv->otherend_changed(dev, state);
203 }
204 EXPORT_SYMBOL_GPL(xenbus_otherend_changed);
205 
206 int xenbus_dev_probe(struct device *_dev)
207 {
208 	struct xenbus_device *dev = to_xenbus_device(_dev);
209 	struct xenbus_driver *drv = to_xenbus_driver(_dev->driver);
210 	const struct xenbus_device_id *id;
211 	int err;
212 
213 	DPRINTK("%s", dev->nodename);
214 
215 	if (!drv->probe) {
216 		err = -ENODEV;
217 		goto fail;
218 	}
219 
220 	id = match_device(drv->ids, dev);
221 	if (!id) {
222 		err = -ENODEV;
223 		goto fail;
224 	}
225 
226 	err = talk_to_otherend(dev);
227 	if (err) {
228 		dev_warn(&dev->dev, "talk_to_otherend on %s failed.\n",
229 			 dev->nodename);
230 		return err;
231 	}
232 
233 	err = drv->probe(dev, id);
234 	if (err)
235 		goto fail;
236 
237 	err = watch_otherend(dev);
238 	if (err) {
239 		dev_warn(&dev->dev, "watch_otherend on %s failed.\n",
240 		       dev->nodename);
241 		return err;
242 	}
243 
244 	return 0;
245 fail:
246 	xenbus_dev_error(dev, err, "xenbus_dev_probe on %s", dev->nodename);
247 	xenbus_switch_state(dev, XenbusStateClosed);
248 	return err;
249 }
250 EXPORT_SYMBOL_GPL(xenbus_dev_probe);
251 
252 int xenbus_dev_remove(struct device *_dev)
253 {
254 	struct xenbus_device *dev = to_xenbus_device(_dev);
255 	struct xenbus_driver *drv = to_xenbus_driver(_dev->driver);
256 
257 	DPRINTK("%s", dev->nodename);
258 
259 	free_otherend_watch(dev);
260 
261 	if (drv->remove)
262 		drv->remove(dev);
263 
264 	free_otherend_details(dev);
265 
266 	xenbus_switch_state(dev, XenbusStateClosed);
267 	return 0;
268 }
269 EXPORT_SYMBOL_GPL(xenbus_dev_remove);
270 
271 void xenbus_dev_shutdown(struct device *_dev)
272 {
273 	struct xenbus_device *dev = to_xenbus_device(_dev);
274 	unsigned long timeout = 5*HZ;
275 
276 	DPRINTK("%s", dev->nodename);
277 
278 	get_device(&dev->dev);
279 	if (dev->state != XenbusStateConnected) {
280 		printk(KERN_INFO "%s: %s: %s != Connected, skipping\n", __func__,
281 		       dev->nodename, xenbus_strstate(dev->state));
282 		goto out;
283 	}
284 	xenbus_switch_state(dev, XenbusStateClosing);
285 	timeout = wait_for_completion_timeout(&dev->down, timeout);
286 	if (!timeout)
287 		printk(KERN_INFO "%s: %s timeout closing device\n",
288 		       __func__, dev->nodename);
289  out:
290 	put_device(&dev->dev);
291 }
292 EXPORT_SYMBOL_GPL(xenbus_dev_shutdown);
293 
294 int xenbus_register_driver_common(struct xenbus_driver *drv,
295 				  struct xen_bus_type *bus)
296 {
297 	drv->driver.bus = &bus->bus;
298 
299 	return driver_register(&drv->driver);
300 }
301 EXPORT_SYMBOL_GPL(xenbus_register_driver_common);
302 
303 void xenbus_unregister_driver(struct xenbus_driver *drv)
304 {
305 	driver_unregister(&drv->driver);
306 }
307 EXPORT_SYMBOL_GPL(xenbus_unregister_driver);
308 
309 struct xb_find_info {
310 	struct xenbus_device *dev;
311 	const char *nodename;
312 };
313 
314 static int cmp_dev(struct device *dev, void *data)
315 {
316 	struct xenbus_device *xendev = to_xenbus_device(dev);
317 	struct xb_find_info *info = data;
318 
319 	if (!strcmp(xendev->nodename, info->nodename)) {
320 		info->dev = xendev;
321 		get_device(dev);
322 		return 1;
323 	}
324 	return 0;
325 }
326 
327 static struct xenbus_device *xenbus_device_find(const char *nodename,
328 						struct bus_type *bus)
329 {
330 	struct xb_find_info info = { .dev = NULL, .nodename = nodename };
331 
332 	bus_for_each_dev(bus, NULL, &info, cmp_dev);
333 	return info.dev;
334 }
335 
336 static int cleanup_dev(struct device *dev, void *data)
337 {
338 	struct xenbus_device *xendev = to_xenbus_device(dev);
339 	struct xb_find_info *info = data;
340 	int len = strlen(info->nodename);
341 
342 	DPRINTK("%s", info->nodename);
343 
344 	/* Match the info->nodename path, or any subdirectory of that path. */
345 	if (strncmp(xendev->nodename, info->nodename, len))
346 		return 0;
347 
348 	/* If the node name is longer, ensure it really is a subdirectory. */
349 	if ((strlen(xendev->nodename) > len) && (xendev->nodename[len] != '/'))
350 		return 0;
351 
352 	info->dev = xendev;
353 	get_device(dev);
354 	return 1;
355 }
356 
357 static void xenbus_cleanup_devices(const char *path, struct bus_type *bus)
358 {
359 	struct xb_find_info info = { .nodename = path };
360 
361 	do {
362 		info.dev = NULL;
363 		bus_for_each_dev(bus, NULL, &info, cleanup_dev);
364 		if (info.dev) {
365 			device_unregister(&info.dev->dev);
366 			put_device(&info.dev->dev);
367 		}
368 	} while (info.dev);
369 }
370 
371 static void xenbus_dev_release(struct device *dev)
372 {
373 	if (dev)
374 		kfree(to_xenbus_device(dev));
375 }
376 
377 static ssize_t nodename_show(struct device *dev,
378 			     struct device_attribute *attr, char *buf)
379 {
380 	return sprintf(buf, "%s\n", to_xenbus_device(dev)->nodename);
381 }
382 
383 static ssize_t devtype_show(struct device *dev,
384 			    struct device_attribute *attr, char *buf)
385 {
386 	return sprintf(buf, "%s\n", to_xenbus_device(dev)->devicetype);
387 }
388 
389 static ssize_t modalias_show(struct device *dev,
390 			     struct device_attribute *attr, char *buf)
391 {
392 	return sprintf(buf, "%s:%s\n", dev->bus->name,
393 		       to_xenbus_device(dev)->devicetype);
394 }
395 
396 struct device_attribute xenbus_dev_attrs[] = {
397 	__ATTR_RO(nodename),
398 	__ATTR_RO(devtype),
399 	__ATTR_RO(modalias),
400 	__ATTR_NULL
401 };
402 EXPORT_SYMBOL_GPL(xenbus_dev_attrs);
403 
404 int xenbus_probe_node(struct xen_bus_type *bus,
405 		      const char *type,
406 		      const char *nodename)
407 {
408 	char devname[XEN_BUS_ID_SIZE];
409 	int err;
410 	struct xenbus_device *xendev;
411 	size_t stringlen;
412 	char *tmpstring;
413 
414 	enum xenbus_state state = xenbus_read_driver_state(nodename);
415 
416 	if (state != XenbusStateInitialising) {
417 		/* Device is not new, so ignore it.  This can happen if a
418 		   device is going away after switching to Closed.  */
419 		return 0;
420 	}
421 
422 	stringlen = strlen(nodename) + 1 + strlen(type) + 1;
423 	xendev = kzalloc(sizeof(*xendev) + stringlen, GFP_KERNEL);
424 	if (!xendev)
425 		return -ENOMEM;
426 
427 	xendev->state = XenbusStateInitialising;
428 
429 	/* Copy the strings into the extra space. */
430 
431 	tmpstring = (char *)(xendev + 1);
432 	strcpy(tmpstring, nodename);
433 	xendev->nodename = tmpstring;
434 
435 	tmpstring += strlen(tmpstring) + 1;
436 	strcpy(tmpstring, type);
437 	xendev->devicetype = tmpstring;
438 	init_completion(&xendev->down);
439 
440 	xendev->dev.bus = &bus->bus;
441 	xendev->dev.release = xenbus_dev_release;
442 
443 	err = bus->get_bus_id(devname, xendev->nodename);
444 	if (err)
445 		goto fail;
446 
447 	dev_set_name(&xendev->dev, devname);
448 
449 	/* Register with generic device framework. */
450 	err = device_register(&xendev->dev);
451 	if (err)
452 		goto fail;
453 
454 	return 0;
455 fail:
456 	kfree(xendev);
457 	return err;
458 }
459 EXPORT_SYMBOL_GPL(xenbus_probe_node);
460 
461 static int xenbus_probe_device_type(struct xen_bus_type *bus, const char *type)
462 {
463 	int err = 0;
464 	char **dir;
465 	unsigned int dir_n = 0;
466 	int i;
467 
468 	dir = xenbus_directory(XBT_NIL, bus->root, type, &dir_n);
469 	if (IS_ERR(dir))
470 		return PTR_ERR(dir);
471 
472 	for (i = 0; i < dir_n; i++) {
473 		err = bus->probe(bus, type, dir[i]);
474 		if (err)
475 			break;
476 	}
477 
478 	kfree(dir);
479 	return err;
480 }
481 
482 int xenbus_probe_devices(struct xen_bus_type *bus)
483 {
484 	int err = 0;
485 	char **dir;
486 	unsigned int i, dir_n;
487 
488 	dir = xenbus_directory(XBT_NIL, bus->root, "", &dir_n);
489 	if (IS_ERR(dir))
490 		return PTR_ERR(dir);
491 
492 	for (i = 0; i < dir_n; i++) {
493 		err = xenbus_probe_device_type(bus, dir[i]);
494 		if (err)
495 			break;
496 	}
497 
498 	kfree(dir);
499 	return err;
500 }
501 EXPORT_SYMBOL_GPL(xenbus_probe_devices);
502 
503 static unsigned int char_count(const char *str, char c)
504 {
505 	unsigned int i, ret = 0;
506 
507 	for (i = 0; str[i]; i++)
508 		if (str[i] == c)
509 			ret++;
510 	return ret;
511 }
512 
513 static int strsep_len(const char *str, char c, unsigned int len)
514 {
515 	unsigned int i;
516 
517 	for (i = 0; str[i]; i++)
518 		if (str[i] == c) {
519 			if (len == 0)
520 				return i;
521 			len--;
522 		}
523 	return (len == 0) ? i : -ERANGE;
524 }
525 
526 void xenbus_dev_changed(const char *node, struct xen_bus_type *bus)
527 {
528 	int exists, rootlen;
529 	struct xenbus_device *dev;
530 	char type[XEN_BUS_ID_SIZE];
531 	const char *p, *root;
532 
533 	if (char_count(node, '/') < 2)
534 		return;
535 
536 	exists = xenbus_exists(XBT_NIL, node, "");
537 	if (!exists) {
538 		xenbus_cleanup_devices(node, &bus->bus);
539 		return;
540 	}
541 
542 	/* backend/<type>/... or device/<type>/... */
543 	p = strchr(node, '/') + 1;
544 	snprintf(type, XEN_BUS_ID_SIZE, "%.*s", (int)strcspn(p, "/"), p);
545 	type[XEN_BUS_ID_SIZE-1] = '\0';
546 
547 	rootlen = strsep_len(node, '/', bus->levels);
548 	if (rootlen < 0)
549 		return;
550 	root = kasprintf(GFP_KERNEL, "%.*s", rootlen, node);
551 	if (!root)
552 		return;
553 
554 	dev = xenbus_device_find(root, &bus->bus);
555 	if (!dev)
556 		xenbus_probe_node(bus, type, root);
557 	else
558 		put_device(&dev->dev);
559 
560 	kfree(root);
561 }
562 EXPORT_SYMBOL_GPL(xenbus_dev_changed);
563 
564 int xenbus_dev_suspend(struct device *dev)
565 {
566 	int err = 0;
567 	struct xenbus_driver *drv;
568 	struct xenbus_device *xdev
569 		= container_of(dev, struct xenbus_device, dev);
570 
571 	DPRINTK("%s", xdev->nodename);
572 
573 	if (dev->driver == NULL)
574 		return 0;
575 	drv = to_xenbus_driver(dev->driver);
576 	if (drv->suspend)
577 		err = drv->suspend(xdev);
578 	if (err)
579 		printk(KERN_WARNING
580 		       "xenbus: suspend %s failed: %i\n", dev_name(dev), err);
581 	return 0;
582 }
583 EXPORT_SYMBOL_GPL(xenbus_dev_suspend);
584 
585 int xenbus_dev_resume(struct device *dev)
586 {
587 	int err;
588 	struct xenbus_driver *drv;
589 	struct xenbus_device *xdev
590 		= container_of(dev, struct xenbus_device, dev);
591 
592 	DPRINTK("%s", xdev->nodename);
593 
594 	if (dev->driver == NULL)
595 		return 0;
596 	drv = to_xenbus_driver(dev->driver);
597 	err = talk_to_otherend(xdev);
598 	if (err) {
599 		printk(KERN_WARNING
600 		       "xenbus: resume (talk_to_otherend) %s failed: %i\n",
601 		       dev_name(dev), err);
602 		return err;
603 	}
604 
605 	xdev->state = XenbusStateInitialising;
606 
607 	if (drv->resume) {
608 		err = drv->resume(xdev);
609 		if (err) {
610 			printk(KERN_WARNING
611 			       "xenbus: resume %s failed: %i\n",
612 			       dev_name(dev), err);
613 			return err;
614 		}
615 	}
616 
617 	err = watch_otherend(xdev);
618 	if (err) {
619 		printk(KERN_WARNING
620 		       "xenbus_probe: resume (watch_otherend) %s failed: "
621 		       "%d.\n", 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 enum xenstore_init {
723 	UNKNOWN,
724 	PV,
725 	HVM,
726 	LOCAL,
727 };
728 static int __init xenbus_init(void)
729 {
730 	int err = 0;
731 	enum xenstore_init usage = UNKNOWN;
732 	uint64_t v = 0;
733 
734 	if (!xen_domain())
735 		return -ENODEV;
736 
737 	xenbus_ring_ops_init();
738 
739 	if (xen_pv_domain())
740 		usage = PV;
741 	if (xen_hvm_domain())
742 		usage = HVM;
743 	if (xen_hvm_domain() && xen_initial_domain())
744 		usage = LOCAL;
745 	if (xen_pv_domain() && !xen_start_info->store_evtchn)
746 		usage = LOCAL;
747 	if (xen_pv_domain() && xen_start_info->store_evtchn)
748 		xenstored_ready = 1;
749 
750 	switch (usage) {
751 	case LOCAL:
752 		err = xenstored_local_init();
753 		if (err)
754 			goto out_error;
755 		xen_store_interface = mfn_to_virt(xen_store_mfn);
756 		break;
757 	case PV:
758 		xen_store_evtchn = xen_start_info->store_evtchn;
759 		xen_store_mfn = xen_start_info->store_mfn;
760 		xen_store_interface = mfn_to_virt(xen_store_mfn);
761 		break;
762 	case HVM:
763 		err = hvm_get_parameter(HVM_PARAM_STORE_EVTCHN, &v);
764 		if (err)
765 			goto out_error;
766 		xen_store_evtchn = (int)v;
767 		err = hvm_get_parameter(HVM_PARAM_STORE_PFN, &v);
768 		if (err)
769 			goto out_error;
770 		xen_store_mfn = (unsigned long)v;
771 		xen_store_interface =
772 			ioremap(xen_store_mfn << PAGE_SHIFT, PAGE_SIZE);
773 		break;
774 	default:
775 		pr_warn("Xenstore state unknown\n");
776 		break;
777 	}
778 
779 	/* Initialize the interface to xenstore. */
780 	err = xs_init();
781 	if (err) {
782 		printk(KERN_WARNING
783 		       "XENBUS: Error initializing xenstore comms: %i\n", err);
784 		goto out_error;
785 	}
786 
787 #ifdef CONFIG_XEN_COMPAT_XENFS
788 	/*
789 	 * Create xenfs mountpoint in /proc for compatibility with
790 	 * utilities that expect to find "xenbus" under "/proc/xen".
791 	 */
792 	proc_mkdir("xen", NULL);
793 #endif
794 
795 out_error:
796 	return err;
797 }
798 
799 postcore_initcall(xenbus_init);
800 
801 MODULE_LICENSE("GPL");
802