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 #define dev_fmt pr_fmt
35 
36 #define DPRINTK(fmt, args...)				\
37 	pr_debug("xenbus_probe (%s:%d) " fmt ".\n",	\
38 		 __func__, __LINE__, ##args)
39 
40 #include <linux/kernel.h>
41 #include <linux/err.h>
42 #include <linux/string.h>
43 #include <linux/ctype.h>
44 #include <linux/fcntl.h>
45 #include <linux/mm.h>
46 #include <linux/proc_fs.h>
47 #include <linux/notifier.h>
48 #include <linux/kthread.h>
49 #include <linux/mutex.h>
50 #include <linux/io.h>
51 #include <linux/slab.h>
52 #include <linux/module.h>
53 
54 #include <asm/page.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.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_gfn;
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_will_handle,
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 *path, const char *token,
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, path, strlen(dev->otherend))) {
185 		dev_dbg(&dev->dev, "Ignoring watch at %s\n", path);
186 		return;
187 	}
188 
189 	state = xenbus_read_driver_state(dev->otherend);
190 
191 	dev_dbg(&dev->dev, "state is %d, (%s), %s, %s\n",
192 		state, xenbus_strstate(state), dev->otherend_watch.node, path);
193 
194 	/*
195 	 * Ignore xenbus transitions during shutdown. This prevents us doing
196 	 * work that can fail e.g., when the rootfs is gone.
197 	 */
198 	if (system_state > SYSTEM_RUNNING) {
199 		if (ignore_on_shutdown && (state == XenbusStateClosing))
200 			xenbus_frontend_closed(dev);
201 		return;
202 	}
203 
204 	if (drv->otherend_changed)
205 		drv->otherend_changed(dev, state);
206 }
207 EXPORT_SYMBOL_GPL(xenbus_otherend_changed);
208 
209 int xenbus_dev_probe(struct device *_dev)
210 {
211 	struct xenbus_device *dev = to_xenbus_device(_dev);
212 	struct xenbus_driver *drv = to_xenbus_driver(_dev->driver);
213 	const struct xenbus_device_id *id;
214 	int err;
215 
216 	DPRINTK("%s", dev->nodename);
217 
218 	if (!drv->probe) {
219 		err = -ENODEV;
220 		goto fail;
221 	}
222 
223 	id = match_device(drv->ids, dev);
224 	if (!id) {
225 		err = -ENODEV;
226 		goto fail;
227 	}
228 
229 	err = talk_to_otherend(dev);
230 	if (err) {
231 		dev_warn(&dev->dev, "talk_to_otherend on %s failed.\n",
232 			 dev->nodename);
233 		return err;
234 	}
235 
236 	if (!try_module_get(drv->driver.owner)) {
237 		dev_warn(&dev->dev, "failed to acquire module reference on '%s'\n",
238 			 drv->driver.name);
239 		err = -ESRCH;
240 		goto fail;
241 	}
242 
243 	down(&dev->reclaim_sem);
244 	err = drv->probe(dev, id);
245 	up(&dev->reclaim_sem);
246 	if (err)
247 		goto fail_put;
248 
249 	err = watch_otherend(dev);
250 	if (err) {
251 		dev_warn(&dev->dev, "watch_otherend on %s failed.\n",
252 		       dev->nodename);
253 		return err;
254 	}
255 
256 	return 0;
257 fail_put:
258 	module_put(drv->driver.owner);
259 fail:
260 	xenbus_dev_error(dev, err, "xenbus_dev_probe on %s", dev->nodename);
261 	return err;
262 }
263 EXPORT_SYMBOL_GPL(xenbus_dev_probe);
264 
265 int xenbus_dev_remove(struct device *_dev)
266 {
267 	struct xenbus_device *dev = to_xenbus_device(_dev);
268 	struct xenbus_driver *drv = to_xenbus_driver(_dev->driver);
269 
270 	DPRINTK("%s", dev->nodename);
271 
272 	free_otherend_watch(dev);
273 
274 	if (drv->remove) {
275 		down(&dev->reclaim_sem);
276 		drv->remove(dev);
277 		up(&dev->reclaim_sem);
278 	}
279 
280 	module_put(drv->driver.owner);
281 
282 	free_otherend_details(dev);
283 
284 	/*
285 	 * If the toolstack has forced the device state to closing then set
286 	 * the state to closed now to allow it to be cleaned up.
287 	 * Similarly, if the driver does not support re-bind, set the
288 	 * closed.
289 	 */
290 	if (!drv->allow_rebind ||
291 	    xenbus_read_driver_state(dev->nodename) == XenbusStateClosing)
292 		xenbus_switch_state(dev, XenbusStateClosed);
293 
294 	return 0;
295 }
296 EXPORT_SYMBOL_GPL(xenbus_dev_remove);
297 
298 int xenbus_register_driver_common(struct xenbus_driver *drv,
299 				  struct xen_bus_type *bus,
300 				  struct module *owner, const char *mod_name)
301 {
302 	drv->driver.name = drv->name ? drv->name : drv->ids[0].devicetype;
303 	drv->driver.bus = &bus->bus;
304 	drv->driver.owner = owner;
305 	drv->driver.mod_name = mod_name;
306 
307 	return driver_register(&drv->driver);
308 }
309 EXPORT_SYMBOL_GPL(xenbus_register_driver_common);
310 
311 void xenbus_unregister_driver(struct xenbus_driver *drv)
312 {
313 	driver_unregister(&drv->driver);
314 }
315 EXPORT_SYMBOL_GPL(xenbus_unregister_driver);
316 
317 struct xb_find_info {
318 	struct xenbus_device *dev;
319 	const char *nodename;
320 };
321 
322 static int cmp_dev(struct device *dev, void *data)
323 {
324 	struct xenbus_device *xendev = to_xenbus_device(dev);
325 	struct xb_find_info *info = data;
326 
327 	if (!strcmp(xendev->nodename, info->nodename)) {
328 		info->dev = xendev;
329 		get_device(dev);
330 		return 1;
331 	}
332 	return 0;
333 }
334 
335 static struct xenbus_device *xenbus_device_find(const char *nodename,
336 						struct bus_type *bus)
337 {
338 	struct xb_find_info info = { .dev = NULL, .nodename = nodename };
339 
340 	bus_for_each_dev(bus, NULL, &info, cmp_dev);
341 	return info.dev;
342 }
343 
344 static int cleanup_dev(struct device *dev, void *data)
345 {
346 	struct xenbus_device *xendev = to_xenbus_device(dev);
347 	struct xb_find_info *info = data;
348 	int len = strlen(info->nodename);
349 
350 	DPRINTK("%s", info->nodename);
351 
352 	/* Match the info->nodename path, or any subdirectory of that path. */
353 	if (strncmp(xendev->nodename, info->nodename, len))
354 		return 0;
355 
356 	/* If the node name is longer, ensure it really is a subdirectory. */
357 	if ((strlen(xendev->nodename) > len) && (xendev->nodename[len] != '/'))
358 		return 0;
359 
360 	info->dev = xendev;
361 	get_device(dev);
362 	return 1;
363 }
364 
365 static void xenbus_cleanup_devices(const char *path, struct bus_type *bus)
366 {
367 	struct xb_find_info info = { .nodename = path };
368 
369 	do {
370 		info.dev = NULL;
371 		bus_for_each_dev(bus, NULL, &info, cleanup_dev);
372 		if (info.dev) {
373 			device_unregister(&info.dev->dev);
374 			put_device(&info.dev->dev);
375 		}
376 	} while (info.dev);
377 }
378 
379 static void xenbus_dev_release(struct device *dev)
380 {
381 	if (dev)
382 		kfree(to_xenbus_device(dev));
383 }
384 
385 static ssize_t nodename_show(struct device *dev,
386 			     struct device_attribute *attr, char *buf)
387 {
388 	return sprintf(buf, "%s\n", to_xenbus_device(dev)->nodename);
389 }
390 static DEVICE_ATTR_RO(nodename);
391 
392 static ssize_t devtype_show(struct device *dev,
393 			    struct device_attribute *attr, char *buf)
394 {
395 	return sprintf(buf, "%s\n", to_xenbus_device(dev)->devicetype);
396 }
397 static DEVICE_ATTR_RO(devtype);
398 
399 static ssize_t modalias_show(struct device *dev,
400 			     struct device_attribute *attr, char *buf)
401 {
402 	return sprintf(buf, "%s:%s\n", dev->bus->name,
403 		       to_xenbus_device(dev)->devicetype);
404 }
405 static DEVICE_ATTR_RO(modalias);
406 
407 static ssize_t state_show(struct device *dev,
408 			    struct device_attribute *attr, char *buf)
409 {
410 	return sprintf(buf, "%s\n",
411 			xenbus_strstate(to_xenbus_device(dev)->state));
412 }
413 static DEVICE_ATTR_RO(state);
414 
415 static struct attribute *xenbus_dev_attrs[] = {
416 	&dev_attr_nodename.attr,
417 	&dev_attr_devtype.attr,
418 	&dev_attr_modalias.attr,
419 	&dev_attr_state.attr,
420 	NULL,
421 };
422 
423 static const struct attribute_group xenbus_dev_group = {
424 	.attrs = xenbus_dev_attrs,
425 };
426 
427 const struct attribute_group *xenbus_dev_groups[] = {
428 	&xenbus_dev_group,
429 	NULL,
430 };
431 EXPORT_SYMBOL_GPL(xenbus_dev_groups);
432 
433 int xenbus_probe_node(struct xen_bus_type *bus,
434 		      const char *type,
435 		      const char *nodename)
436 {
437 	char devname[XEN_BUS_ID_SIZE];
438 	int err;
439 	struct xenbus_device *xendev;
440 	size_t stringlen;
441 	char *tmpstring;
442 
443 	enum xenbus_state state = xenbus_read_driver_state(nodename);
444 
445 	if (state != XenbusStateInitialising) {
446 		/* Device is not new, so ignore it.  This can happen if a
447 		   device is going away after switching to Closed.  */
448 		return 0;
449 	}
450 
451 	stringlen = strlen(nodename) + 1 + strlen(type) + 1;
452 	xendev = kzalloc(sizeof(*xendev) + stringlen, GFP_KERNEL);
453 	if (!xendev)
454 		return -ENOMEM;
455 
456 	xendev->state = XenbusStateInitialising;
457 
458 	/* Copy the strings into the extra space. */
459 
460 	tmpstring = (char *)(xendev + 1);
461 	strcpy(tmpstring, nodename);
462 	xendev->nodename = tmpstring;
463 
464 	tmpstring += strlen(tmpstring) + 1;
465 	strcpy(tmpstring, type);
466 	xendev->devicetype = tmpstring;
467 	init_completion(&xendev->down);
468 
469 	xendev->dev.bus = &bus->bus;
470 	xendev->dev.release = xenbus_dev_release;
471 
472 	err = bus->get_bus_id(devname, xendev->nodename);
473 	if (err)
474 		goto fail;
475 
476 	dev_set_name(&xendev->dev, "%s", devname);
477 	sema_init(&xendev->reclaim_sem, 1);
478 
479 	/* Register with generic device framework. */
480 	err = device_register(&xendev->dev);
481 	if (err) {
482 		put_device(&xendev->dev);
483 		xendev = NULL;
484 		goto fail;
485 	}
486 
487 	return 0;
488 fail:
489 	kfree(xendev);
490 	return err;
491 }
492 EXPORT_SYMBOL_GPL(xenbus_probe_node);
493 
494 static int xenbus_probe_device_type(struct xen_bus_type *bus, const char *type)
495 {
496 	int err = 0;
497 	char **dir;
498 	unsigned int dir_n = 0;
499 	int i;
500 
501 	dir = xenbus_directory(XBT_NIL, bus->root, type, &dir_n);
502 	if (IS_ERR(dir))
503 		return PTR_ERR(dir);
504 
505 	for (i = 0; i < dir_n; i++) {
506 		err = bus->probe(bus, type, dir[i]);
507 		if (err)
508 			break;
509 	}
510 
511 	kfree(dir);
512 	return err;
513 }
514 
515 int xenbus_probe_devices(struct xen_bus_type *bus)
516 {
517 	int err = 0;
518 	char **dir;
519 	unsigned int i, dir_n;
520 
521 	dir = xenbus_directory(XBT_NIL, bus->root, "", &dir_n);
522 	if (IS_ERR(dir))
523 		return PTR_ERR(dir);
524 
525 	for (i = 0; i < dir_n; i++) {
526 		err = xenbus_probe_device_type(bus, dir[i]);
527 		if (err)
528 			break;
529 	}
530 
531 	kfree(dir);
532 	return err;
533 }
534 EXPORT_SYMBOL_GPL(xenbus_probe_devices);
535 
536 static unsigned int char_count(const char *str, char c)
537 {
538 	unsigned int i, ret = 0;
539 
540 	for (i = 0; str[i]; i++)
541 		if (str[i] == c)
542 			ret++;
543 	return ret;
544 }
545 
546 static int strsep_len(const char *str, char c, unsigned int len)
547 {
548 	unsigned int i;
549 
550 	for (i = 0; str[i]; i++)
551 		if (str[i] == c) {
552 			if (len == 0)
553 				return i;
554 			len--;
555 		}
556 	return (len == 0) ? i : -ERANGE;
557 }
558 
559 void xenbus_dev_changed(const char *node, struct xen_bus_type *bus)
560 {
561 	int exists, rootlen;
562 	struct xenbus_device *dev;
563 	char type[XEN_BUS_ID_SIZE];
564 	const char *p, *root;
565 
566 	if (char_count(node, '/') < 2)
567 		return;
568 
569 	exists = xenbus_exists(XBT_NIL, node, "");
570 	if (!exists) {
571 		xenbus_cleanup_devices(node, &bus->bus);
572 		return;
573 	}
574 
575 	/* backend/<type>/... or device/<type>/... */
576 	p = strchr(node, '/') + 1;
577 	snprintf(type, XEN_BUS_ID_SIZE, "%.*s", (int)strcspn(p, "/"), p);
578 	type[XEN_BUS_ID_SIZE-1] = '\0';
579 
580 	rootlen = strsep_len(node, '/', bus->levels);
581 	if (rootlen < 0)
582 		return;
583 	root = kasprintf(GFP_KERNEL, "%.*s", rootlen, node);
584 	if (!root)
585 		return;
586 
587 	dev = xenbus_device_find(root, &bus->bus);
588 	if (!dev)
589 		xenbus_probe_node(bus, type, root);
590 	else
591 		put_device(&dev->dev);
592 
593 	kfree(root);
594 }
595 EXPORT_SYMBOL_GPL(xenbus_dev_changed);
596 
597 int xenbus_dev_suspend(struct device *dev)
598 {
599 	int err = 0;
600 	struct xenbus_driver *drv;
601 	struct xenbus_device *xdev
602 		= container_of(dev, struct xenbus_device, dev);
603 
604 	DPRINTK("%s", xdev->nodename);
605 
606 	if (dev->driver == NULL)
607 		return 0;
608 	drv = to_xenbus_driver(dev->driver);
609 	if (drv->suspend)
610 		err = drv->suspend(xdev);
611 	if (err)
612 		dev_warn(dev, "suspend failed: %i\n", err);
613 	return 0;
614 }
615 EXPORT_SYMBOL_GPL(xenbus_dev_suspend);
616 
617 int xenbus_dev_resume(struct device *dev)
618 {
619 	int err;
620 	struct xenbus_driver *drv;
621 	struct xenbus_device *xdev
622 		= container_of(dev, struct xenbus_device, dev);
623 
624 	DPRINTK("%s", xdev->nodename);
625 
626 	if (dev->driver == NULL)
627 		return 0;
628 	drv = to_xenbus_driver(dev->driver);
629 	err = talk_to_otherend(xdev);
630 	if (err) {
631 		dev_warn(dev, "resume (talk_to_otherend) failed: %i\n", err);
632 		return err;
633 	}
634 
635 	xdev->state = XenbusStateInitialising;
636 
637 	if (drv->resume) {
638 		err = drv->resume(xdev);
639 		if (err) {
640 			dev_warn(dev, "resume failed: %i\n", err);
641 			return err;
642 		}
643 	}
644 
645 	err = watch_otherend(xdev);
646 	if (err) {
647 		dev_warn(dev, "resume (watch_otherend) failed: %d\n", err);
648 		return err;
649 	}
650 
651 	return 0;
652 }
653 EXPORT_SYMBOL_GPL(xenbus_dev_resume);
654 
655 int xenbus_dev_cancel(struct device *dev)
656 {
657 	/* Do nothing */
658 	DPRINTK("cancel");
659 	return 0;
660 }
661 EXPORT_SYMBOL_GPL(xenbus_dev_cancel);
662 
663 /* A flag to determine if xenstored is 'ready' (i.e. has started) */
664 int xenstored_ready;
665 
666 
667 int register_xenstore_notifier(struct notifier_block *nb)
668 {
669 	int ret = 0;
670 
671 	if (xenstored_ready > 0)
672 		ret = nb->notifier_call(nb, 0, NULL);
673 	else
674 		blocking_notifier_chain_register(&xenstore_chain, nb);
675 
676 	return ret;
677 }
678 EXPORT_SYMBOL_GPL(register_xenstore_notifier);
679 
680 void unregister_xenstore_notifier(struct notifier_block *nb)
681 {
682 	blocking_notifier_chain_unregister(&xenstore_chain, nb);
683 }
684 EXPORT_SYMBOL_GPL(unregister_xenstore_notifier);
685 
686 void xenbus_probe(struct work_struct *unused)
687 {
688 	xenstored_ready = 1;
689 
690 	/* Notify others that xenstore is up */
691 	blocking_notifier_call_chain(&xenstore_chain, 0, NULL);
692 }
693 EXPORT_SYMBOL_GPL(xenbus_probe);
694 
695 static int __init xenbus_probe_initcall(void)
696 {
697 	if (!xen_domain())
698 		return -ENODEV;
699 
700 	if (xen_initial_domain() || xen_hvm_domain())
701 		return 0;
702 
703 	xenbus_probe(NULL);
704 	return 0;
705 }
706 
707 device_initcall(xenbus_probe_initcall);
708 
709 /* Set up event channel for xenstored which is run as a local process
710  * (this is normally used only in dom0)
711  */
712 static int __init xenstored_local_init(void)
713 {
714 	int err = -ENOMEM;
715 	unsigned long page = 0;
716 	struct evtchn_alloc_unbound alloc_unbound;
717 
718 	/* Allocate Xenstore page */
719 	page = get_zeroed_page(GFP_KERNEL);
720 	if (!page)
721 		goto out_err;
722 
723 	xen_store_gfn = virt_to_gfn((void *)page);
724 
725 	/* Next allocate a local port which xenstored can bind to */
726 	alloc_unbound.dom        = DOMID_SELF;
727 	alloc_unbound.remote_dom = DOMID_SELF;
728 
729 	err = HYPERVISOR_event_channel_op(EVTCHNOP_alloc_unbound,
730 					  &alloc_unbound);
731 	if (err == -ENOSYS)
732 		goto out_err;
733 
734 	BUG_ON(err);
735 	xen_store_evtchn = alloc_unbound.port;
736 
737 	return 0;
738 
739  out_err:
740 	if (page != 0)
741 		free_page(page);
742 	return err;
743 }
744 
745 static int xenbus_resume_cb(struct notifier_block *nb,
746 			    unsigned long action, void *data)
747 {
748 	int err = 0;
749 
750 	if (xen_hvm_domain()) {
751 		uint64_t v = 0;
752 
753 		err = hvm_get_parameter(HVM_PARAM_STORE_EVTCHN, &v);
754 		if (!err && v)
755 			xen_store_evtchn = v;
756 		else
757 			pr_warn("Cannot update xenstore event channel: %d\n",
758 				err);
759 	} else
760 		xen_store_evtchn = xen_start_info->store_evtchn;
761 
762 	return err;
763 }
764 
765 static struct notifier_block xenbus_resume_nb = {
766 	.notifier_call = xenbus_resume_cb,
767 };
768 
769 static int __init xenbus_init(void)
770 {
771 	int err = 0;
772 	uint64_t v = 0;
773 	xen_store_domain_type = XS_UNKNOWN;
774 
775 	if (!xen_domain())
776 		return -ENODEV;
777 
778 	xenbus_ring_ops_init();
779 
780 	if (xen_pv_domain())
781 		xen_store_domain_type = XS_PV;
782 	if (xen_hvm_domain())
783 		xen_store_domain_type = XS_HVM;
784 	if (xen_hvm_domain() && xen_initial_domain())
785 		xen_store_domain_type = XS_LOCAL;
786 	if (xen_pv_domain() && !xen_start_info->store_evtchn)
787 		xen_store_domain_type = XS_LOCAL;
788 	if (xen_pv_domain() && xen_start_info->store_evtchn)
789 		xenstored_ready = 1;
790 
791 	switch (xen_store_domain_type) {
792 	case XS_LOCAL:
793 		err = xenstored_local_init();
794 		if (err)
795 			goto out_error;
796 		xen_store_interface = gfn_to_virt(xen_store_gfn);
797 		break;
798 	case XS_PV:
799 		xen_store_evtchn = xen_start_info->store_evtchn;
800 		xen_store_gfn = xen_start_info->store_mfn;
801 		xen_store_interface = gfn_to_virt(xen_store_gfn);
802 		break;
803 	case XS_HVM:
804 		err = hvm_get_parameter(HVM_PARAM_STORE_EVTCHN, &v);
805 		if (err)
806 			goto out_error;
807 		xen_store_evtchn = (int)v;
808 		err = hvm_get_parameter(HVM_PARAM_STORE_PFN, &v);
809 		if (err)
810 			goto out_error;
811 		xen_store_gfn = (unsigned long)v;
812 		xen_store_interface =
813 			xen_remap(xen_store_gfn << XEN_PAGE_SHIFT,
814 				  XEN_PAGE_SIZE);
815 		break;
816 	default:
817 		pr_warn("Xenstore state unknown\n");
818 		break;
819 	}
820 
821 	/* Initialize the interface to xenstore. */
822 	err = xs_init();
823 	if (err) {
824 		pr_warn("Error initializing xenstore comms: %i\n", err);
825 		goto out_error;
826 	}
827 
828 	if ((xen_store_domain_type != XS_LOCAL) &&
829 	    (xen_store_domain_type != XS_UNKNOWN))
830 		xen_resume_notifier_register(&xenbus_resume_nb);
831 
832 #ifdef CONFIG_XEN_COMPAT_XENFS
833 	/*
834 	 * Create xenfs mountpoint in /proc for compatibility with
835 	 * utilities that expect to find "xenbus" under "/proc/xen".
836 	 */
837 	proc_create_mount_point("xen");
838 #endif
839 
840 out_error:
841 	return err;
842 }
843 
844 postcore_initcall(xenbus_init);
845 
846 MODULE_LICENSE("GPL");
847