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 #define XENBUS_SHOW_STAT(name)						\
210 static ssize_t show_##name(struct device *_dev,				\
211 			   struct device_attribute *attr,		\
212 			   char *buf)					\
213 {									\
214 	struct xenbus_device *dev = to_xenbus_device(_dev);		\
215 									\
216 	return sprintf(buf, "%d\n", atomic_read(&dev->name));		\
217 }									\
218 static DEVICE_ATTR(name, 0444, show_##name, NULL)
219 
220 XENBUS_SHOW_STAT(event_channels);
221 XENBUS_SHOW_STAT(events);
222 XENBUS_SHOW_STAT(spurious_events);
223 XENBUS_SHOW_STAT(jiffies_eoi_delayed);
224 
225 static ssize_t show_spurious_threshold(struct device *_dev,
226 				       struct device_attribute *attr,
227 				       char *buf)
228 {
229 	struct xenbus_device *dev = to_xenbus_device(_dev);
230 
231 	return sprintf(buf, "%d\n", dev->spurious_threshold);
232 }
233 
234 static ssize_t set_spurious_threshold(struct device *_dev,
235 				      struct device_attribute *attr,
236 				      const char *buf, size_t count)
237 {
238 	struct xenbus_device *dev = to_xenbus_device(_dev);
239 	unsigned int val;
240 	ssize_t ret;
241 
242 	ret = kstrtouint(buf, 0, &val);
243 	if (ret)
244 		return ret;
245 
246 	dev->spurious_threshold = val;
247 
248 	return count;
249 }
250 
251 static DEVICE_ATTR(spurious_threshold, 0644, show_spurious_threshold,
252 		   set_spurious_threshold);
253 
254 static struct attribute *xenbus_attrs[] = {
255 	&dev_attr_event_channels.attr,
256 	&dev_attr_events.attr,
257 	&dev_attr_spurious_events.attr,
258 	&dev_attr_jiffies_eoi_delayed.attr,
259 	&dev_attr_spurious_threshold.attr,
260 	NULL
261 };
262 
263 static const struct attribute_group xenbus_group = {
264 	.name = "xenbus",
265 	.attrs = xenbus_attrs,
266 };
267 
268 int xenbus_dev_probe(struct device *_dev)
269 {
270 	struct xenbus_device *dev = to_xenbus_device(_dev);
271 	struct xenbus_driver *drv = to_xenbus_driver(_dev->driver);
272 	const struct xenbus_device_id *id;
273 	int err;
274 
275 	DPRINTK("%s", dev->nodename);
276 
277 	if (!drv->probe) {
278 		err = -ENODEV;
279 		goto fail;
280 	}
281 
282 	id = match_device(drv->ids, dev);
283 	if (!id) {
284 		err = -ENODEV;
285 		goto fail;
286 	}
287 
288 	err = talk_to_otherend(dev);
289 	if (err) {
290 		dev_warn(&dev->dev, "talk_to_otherend on %s failed.\n",
291 			 dev->nodename);
292 		return err;
293 	}
294 
295 	if (!try_module_get(drv->driver.owner)) {
296 		dev_warn(&dev->dev, "failed to acquire module reference on '%s'\n",
297 			 drv->driver.name);
298 		err = -ESRCH;
299 		goto fail;
300 	}
301 
302 	down(&dev->reclaim_sem);
303 	err = drv->probe(dev, id);
304 	up(&dev->reclaim_sem);
305 	if (err)
306 		goto fail_put;
307 
308 	err = watch_otherend(dev);
309 	if (err) {
310 		dev_warn(&dev->dev, "watch_otherend on %s failed.\n",
311 		       dev->nodename);
312 		return err;
313 	}
314 
315 	dev->spurious_threshold = 1;
316 	if (sysfs_create_group(&dev->dev.kobj, &xenbus_group))
317 		dev_warn(&dev->dev, "sysfs_create_group on %s failed.\n",
318 			 dev->nodename);
319 
320 	return 0;
321 fail_put:
322 	module_put(drv->driver.owner);
323 fail:
324 	xenbus_dev_error(dev, err, "xenbus_dev_probe on %s", dev->nodename);
325 	return err;
326 }
327 EXPORT_SYMBOL_GPL(xenbus_dev_probe);
328 
329 int xenbus_dev_remove(struct device *_dev)
330 {
331 	struct xenbus_device *dev = to_xenbus_device(_dev);
332 	struct xenbus_driver *drv = to_xenbus_driver(_dev->driver);
333 
334 	DPRINTK("%s", dev->nodename);
335 
336 	sysfs_remove_group(&dev->dev.kobj, &xenbus_group);
337 
338 	free_otherend_watch(dev);
339 
340 	if (drv->remove) {
341 		down(&dev->reclaim_sem);
342 		drv->remove(dev);
343 		up(&dev->reclaim_sem);
344 	}
345 
346 	module_put(drv->driver.owner);
347 
348 	free_otherend_details(dev);
349 
350 	/*
351 	 * If the toolstack has forced the device state to closing then set
352 	 * the state to closed now to allow it to be cleaned up.
353 	 * Similarly, if the driver does not support re-bind, set the
354 	 * closed.
355 	 */
356 	if (!drv->allow_rebind ||
357 	    xenbus_read_driver_state(dev->nodename) == XenbusStateClosing)
358 		xenbus_switch_state(dev, XenbusStateClosed);
359 
360 	return 0;
361 }
362 EXPORT_SYMBOL_GPL(xenbus_dev_remove);
363 
364 int xenbus_register_driver_common(struct xenbus_driver *drv,
365 				  struct xen_bus_type *bus,
366 				  struct module *owner, const char *mod_name)
367 {
368 	drv->driver.name = drv->name ? drv->name : drv->ids[0].devicetype;
369 	drv->driver.bus = &bus->bus;
370 	drv->driver.owner = owner;
371 	drv->driver.mod_name = mod_name;
372 
373 	return driver_register(&drv->driver);
374 }
375 EXPORT_SYMBOL_GPL(xenbus_register_driver_common);
376 
377 void xenbus_unregister_driver(struct xenbus_driver *drv)
378 {
379 	driver_unregister(&drv->driver);
380 }
381 EXPORT_SYMBOL_GPL(xenbus_unregister_driver);
382 
383 struct xb_find_info {
384 	struct xenbus_device *dev;
385 	const char *nodename;
386 };
387 
388 static int cmp_dev(struct device *dev, void *data)
389 {
390 	struct xenbus_device *xendev = to_xenbus_device(dev);
391 	struct xb_find_info *info = data;
392 
393 	if (!strcmp(xendev->nodename, info->nodename)) {
394 		info->dev = xendev;
395 		get_device(dev);
396 		return 1;
397 	}
398 	return 0;
399 }
400 
401 static struct xenbus_device *xenbus_device_find(const char *nodename,
402 						struct bus_type *bus)
403 {
404 	struct xb_find_info info = { .dev = NULL, .nodename = nodename };
405 
406 	bus_for_each_dev(bus, NULL, &info, cmp_dev);
407 	return info.dev;
408 }
409 
410 static int cleanup_dev(struct device *dev, void *data)
411 {
412 	struct xenbus_device *xendev = to_xenbus_device(dev);
413 	struct xb_find_info *info = data;
414 	int len = strlen(info->nodename);
415 
416 	DPRINTK("%s", info->nodename);
417 
418 	/* Match the info->nodename path, or any subdirectory of that path. */
419 	if (strncmp(xendev->nodename, info->nodename, len))
420 		return 0;
421 
422 	/* If the node name is longer, ensure it really is a subdirectory. */
423 	if ((strlen(xendev->nodename) > len) && (xendev->nodename[len] != '/'))
424 		return 0;
425 
426 	info->dev = xendev;
427 	get_device(dev);
428 	return 1;
429 }
430 
431 static void xenbus_cleanup_devices(const char *path, struct bus_type *bus)
432 {
433 	struct xb_find_info info = { .nodename = path };
434 
435 	do {
436 		info.dev = NULL;
437 		bus_for_each_dev(bus, NULL, &info, cleanup_dev);
438 		if (info.dev) {
439 			device_unregister(&info.dev->dev);
440 			put_device(&info.dev->dev);
441 		}
442 	} while (info.dev);
443 }
444 
445 static void xenbus_dev_release(struct device *dev)
446 {
447 	if (dev)
448 		kfree(to_xenbus_device(dev));
449 }
450 
451 static ssize_t nodename_show(struct device *dev,
452 			     struct device_attribute *attr, char *buf)
453 {
454 	return sprintf(buf, "%s\n", to_xenbus_device(dev)->nodename);
455 }
456 static DEVICE_ATTR_RO(nodename);
457 
458 static ssize_t devtype_show(struct device *dev,
459 			    struct device_attribute *attr, char *buf)
460 {
461 	return sprintf(buf, "%s\n", to_xenbus_device(dev)->devicetype);
462 }
463 static DEVICE_ATTR_RO(devtype);
464 
465 static ssize_t modalias_show(struct device *dev,
466 			     struct device_attribute *attr, char *buf)
467 {
468 	return sprintf(buf, "%s:%s\n", dev->bus->name,
469 		       to_xenbus_device(dev)->devicetype);
470 }
471 static DEVICE_ATTR_RO(modalias);
472 
473 static ssize_t state_show(struct device *dev,
474 			    struct device_attribute *attr, char *buf)
475 {
476 	return sprintf(buf, "%s\n",
477 			xenbus_strstate(to_xenbus_device(dev)->state));
478 }
479 static DEVICE_ATTR_RO(state);
480 
481 static struct attribute *xenbus_dev_attrs[] = {
482 	&dev_attr_nodename.attr,
483 	&dev_attr_devtype.attr,
484 	&dev_attr_modalias.attr,
485 	&dev_attr_state.attr,
486 	NULL,
487 };
488 
489 static const struct attribute_group xenbus_dev_group = {
490 	.attrs = xenbus_dev_attrs,
491 };
492 
493 const struct attribute_group *xenbus_dev_groups[] = {
494 	&xenbus_dev_group,
495 	NULL,
496 };
497 EXPORT_SYMBOL_GPL(xenbus_dev_groups);
498 
499 int xenbus_probe_node(struct xen_bus_type *bus,
500 		      const char *type,
501 		      const char *nodename)
502 {
503 	char devname[XEN_BUS_ID_SIZE];
504 	int err;
505 	struct xenbus_device *xendev;
506 	size_t stringlen;
507 	char *tmpstring;
508 
509 	enum xenbus_state state = xenbus_read_driver_state(nodename);
510 
511 	if (state != XenbusStateInitialising) {
512 		/* Device is not new, so ignore it.  This can happen if a
513 		   device is going away after switching to Closed.  */
514 		return 0;
515 	}
516 
517 	stringlen = strlen(nodename) + 1 + strlen(type) + 1;
518 	xendev = kzalloc(sizeof(*xendev) + stringlen, GFP_KERNEL);
519 	if (!xendev)
520 		return -ENOMEM;
521 
522 	xendev->state = XenbusStateInitialising;
523 
524 	/* Copy the strings into the extra space. */
525 
526 	tmpstring = (char *)(xendev + 1);
527 	strcpy(tmpstring, nodename);
528 	xendev->nodename = tmpstring;
529 
530 	tmpstring += strlen(tmpstring) + 1;
531 	strcpy(tmpstring, type);
532 	xendev->devicetype = tmpstring;
533 	init_completion(&xendev->down);
534 
535 	xendev->dev.bus = &bus->bus;
536 	xendev->dev.release = xenbus_dev_release;
537 
538 	err = bus->get_bus_id(devname, xendev->nodename);
539 	if (err)
540 		goto fail;
541 
542 	dev_set_name(&xendev->dev, "%s", devname);
543 	sema_init(&xendev->reclaim_sem, 1);
544 
545 	/* Register with generic device framework. */
546 	err = device_register(&xendev->dev);
547 	if (err) {
548 		put_device(&xendev->dev);
549 		xendev = NULL;
550 		goto fail;
551 	}
552 
553 	return 0;
554 fail:
555 	kfree(xendev);
556 	return err;
557 }
558 EXPORT_SYMBOL_GPL(xenbus_probe_node);
559 
560 static int xenbus_probe_device_type(struct xen_bus_type *bus, const char *type)
561 {
562 	int err = 0;
563 	char **dir;
564 	unsigned int dir_n = 0;
565 	int i;
566 
567 	dir = xenbus_directory(XBT_NIL, bus->root, type, &dir_n);
568 	if (IS_ERR(dir))
569 		return PTR_ERR(dir);
570 
571 	for (i = 0; i < dir_n; i++) {
572 		err = bus->probe(bus, type, dir[i]);
573 		if (err)
574 			break;
575 	}
576 
577 	kfree(dir);
578 	return err;
579 }
580 
581 int xenbus_probe_devices(struct xen_bus_type *bus)
582 {
583 	int err = 0;
584 	char **dir;
585 	unsigned int i, dir_n;
586 
587 	dir = xenbus_directory(XBT_NIL, bus->root, "", &dir_n);
588 	if (IS_ERR(dir))
589 		return PTR_ERR(dir);
590 
591 	for (i = 0; i < dir_n; i++) {
592 		err = xenbus_probe_device_type(bus, dir[i]);
593 		if (err)
594 			break;
595 	}
596 
597 	kfree(dir);
598 	return err;
599 }
600 EXPORT_SYMBOL_GPL(xenbus_probe_devices);
601 
602 static unsigned int char_count(const char *str, char c)
603 {
604 	unsigned int i, ret = 0;
605 
606 	for (i = 0; str[i]; i++)
607 		if (str[i] == c)
608 			ret++;
609 	return ret;
610 }
611 
612 static int strsep_len(const char *str, char c, unsigned int len)
613 {
614 	unsigned int i;
615 
616 	for (i = 0; str[i]; i++)
617 		if (str[i] == c) {
618 			if (len == 0)
619 				return i;
620 			len--;
621 		}
622 	return (len == 0) ? i : -ERANGE;
623 }
624 
625 void xenbus_dev_changed(const char *node, struct xen_bus_type *bus)
626 {
627 	int exists, rootlen;
628 	struct xenbus_device *dev;
629 	char type[XEN_BUS_ID_SIZE];
630 	const char *p, *root;
631 
632 	if (char_count(node, '/') < 2)
633 		return;
634 
635 	exists = xenbus_exists(XBT_NIL, node, "");
636 	if (!exists) {
637 		xenbus_cleanup_devices(node, &bus->bus);
638 		return;
639 	}
640 
641 	/* backend/<type>/... or device/<type>/... */
642 	p = strchr(node, '/') + 1;
643 	snprintf(type, XEN_BUS_ID_SIZE, "%.*s", (int)strcspn(p, "/"), p);
644 	type[XEN_BUS_ID_SIZE-1] = '\0';
645 
646 	rootlen = strsep_len(node, '/', bus->levels);
647 	if (rootlen < 0)
648 		return;
649 	root = kasprintf(GFP_KERNEL, "%.*s", rootlen, node);
650 	if (!root)
651 		return;
652 
653 	dev = xenbus_device_find(root, &bus->bus);
654 	if (!dev)
655 		xenbus_probe_node(bus, type, root);
656 	else
657 		put_device(&dev->dev);
658 
659 	kfree(root);
660 }
661 EXPORT_SYMBOL_GPL(xenbus_dev_changed);
662 
663 int xenbus_dev_suspend(struct device *dev)
664 {
665 	int err = 0;
666 	struct xenbus_driver *drv;
667 	struct xenbus_device *xdev
668 		= container_of(dev, struct xenbus_device, dev);
669 
670 	DPRINTK("%s", xdev->nodename);
671 
672 	if (dev->driver == NULL)
673 		return 0;
674 	drv = to_xenbus_driver(dev->driver);
675 	if (drv->suspend)
676 		err = drv->suspend(xdev);
677 	if (err)
678 		dev_warn(dev, "suspend failed: %i\n", err);
679 	return 0;
680 }
681 EXPORT_SYMBOL_GPL(xenbus_dev_suspend);
682 
683 int xenbus_dev_resume(struct device *dev)
684 {
685 	int err;
686 	struct xenbus_driver *drv;
687 	struct xenbus_device *xdev
688 		= container_of(dev, struct xenbus_device, dev);
689 
690 	DPRINTK("%s", xdev->nodename);
691 
692 	if (dev->driver == NULL)
693 		return 0;
694 	drv = to_xenbus_driver(dev->driver);
695 	err = talk_to_otherend(xdev);
696 	if (err) {
697 		dev_warn(dev, "resume (talk_to_otherend) failed: %i\n", err);
698 		return err;
699 	}
700 
701 	xdev->state = XenbusStateInitialising;
702 
703 	if (drv->resume) {
704 		err = drv->resume(xdev);
705 		if (err) {
706 			dev_warn(dev, "resume failed: %i\n", err);
707 			return err;
708 		}
709 	}
710 
711 	err = watch_otherend(xdev);
712 	if (err) {
713 		dev_warn(dev, "resume (watch_otherend) failed: %d\n", err);
714 		return err;
715 	}
716 
717 	return 0;
718 }
719 EXPORT_SYMBOL_GPL(xenbus_dev_resume);
720 
721 int xenbus_dev_cancel(struct device *dev)
722 {
723 	/* Do nothing */
724 	DPRINTK("cancel");
725 	return 0;
726 }
727 EXPORT_SYMBOL_GPL(xenbus_dev_cancel);
728 
729 /* A flag to determine if xenstored is 'ready' (i.e. has started) */
730 int xenstored_ready;
731 
732 
733 int register_xenstore_notifier(struct notifier_block *nb)
734 {
735 	int ret = 0;
736 
737 	if (xenstored_ready > 0)
738 		ret = nb->notifier_call(nb, 0, NULL);
739 	else
740 		blocking_notifier_chain_register(&xenstore_chain, nb);
741 
742 	return ret;
743 }
744 EXPORT_SYMBOL_GPL(register_xenstore_notifier);
745 
746 void unregister_xenstore_notifier(struct notifier_block *nb)
747 {
748 	blocking_notifier_chain_unregister(&xenstore_chain, nb);
749 }
750 EXPORT_SYMBOL_GPL(unregister_xenstore_notifier);
751 
752 static void xenbus_probe(void)
753 {
754 	xenstored_ready = 1;
755 
756 	/*
757 	 * In the HVM case, xenbus_init() deferred its call to
758 	 * xs_init() in case callbacks were not operational yet.
759 	 * So do it now.
760 	 */
761 	if (xen_store_domain_type == XS_HVM)
762 		xs_init();
763 
764 	/* Notify others that xenstore is up */
765 	blocking_notifier_call_chain(&xenstore_chain, 0, NULL);
766 }
767 
768 /*
769  * Returns true when XenStore init must be deferred in order to
770  * allow the PCI platform device to be initialised, before we
771  * can actually have event channel interrupts working.
772  */
773 static bool xs_hvm_defer_init_for_callback(void)
774 {
775 #ifdef CONFIG_XEN_PVHVM
776 	return xen_store_domain_type == XS_HVM &&
777 		!xen_have_vector_callback;
778 #else
779 	return false;
780 #endif
781 }
782 
783 static int xenbus_probe_thread(void *unused)
784 {
785 	DEFINE_WAIT(w);
786 
787 	/*
788 	 * We actually just want to wait for *any* trigger of xb_waitq,
789 	 * and run xenbus_probe() the moment it occurs.
790 	 */
791 	prepare_to_wait(&xb_waitq, &w, TASK_INTERRUPTIBLE);
792 	schedule();
793 	finish_wait(&xb_waitq, &w);
794 
795 	DPRINTK("probing");
796 	xenbus_probe();
797 	return 0;
798 }
799 
800 static int __init xenbus_probe_initcall(void)
801 {
802 	/*
803 	 * Probe XenBus here in the XS_PV case, and also XS_HVM unless we
804 	 * need to wait for the platform PCI device to come up.
805 	 */
806 	if (xen_store_domain_type == XS_PV ||
807 	    (xen_store_domain_type == XS_HVM &&
808 	     !xs_hvm_defer_init_for_callback()))
809 		xenbus_probe();
810 
811 	/*
812 	 * For XS_LOCAL, spawn a thread which will wait for xenstored
813 	 * or a xenstore-stubdom to be started, then probe. It will be
814 	 * triggered when communication starts happening, by waiting
815 	 * on xb_waitq.
816 	 */
817 	if (xen_store_domain_type == XS_LOCAL) {
818 		struct task_struct *probe_task;
819 
820 		probe_task = kthread_run(xenbus_probe_thread, NULL,
821 					 "xenbus_probe");
822 		if (IS_ERR(probe_task))
823 			return PTR_ERR(probe_task);
824 	}
825 	return 0;
826 }
827 device_initcall(xenbus_probe_initcall);
828 
829 int xen_set_callback_via(uint64_t via)
830 {
831 	struct xen_hvm_param a;
832 	int ret;
833 
834 	a.domid = DOMID_SELF;
835 	a.index = HVM_PARAM_CALLBACK_IRQ;
836 	a.value = via;
837 
838 	ret = HYPERVISOR_hvm_op(HVMOP_set_param, &a);
839 	if (ret)
840 		return ret;
841 
842 	/*
843 	 * If xenbus_probe_initcall() deferred the xenbus_probe()
844 	 * due to the callback not functioning yet, we can do it now.
845 	 */
846 	if (!xenstored_ready && xs_hvm_defer_init_for_callback())
847 		xenbus_probe();
848 
849 	return ret;
850 }
851 EXPORT_SYMBOL_GPL(xen_set_callback_via);
852 
853 /* Set up event channel for xenstored which is run as a local process
854  * (this is normally used only in dom0)
855  */
856 static int __init xenstored_local_init(void)
857 {
858 	int err = -ENOMEM;
859 	unsigned long page = 0;
860 	struct evtchn_alloc_unbound alloc_unbound;
861 
862 	/* Allocate Xenstore page */
863 	page = get_zeroed_page(GFP_KERNEL);
864 	if (!page)
865 		goto out_err;
866 
867 	xen_store_gfn = virt_to_gfn((void *)page);
868 
869 	/* Next allocate a local port which xenstored can bind to */
870 	alloc_unbound.dom        = DOMID_SELF;
871 	alloc_unbound.remote_dom = DOMID_SELF;
872 
873 	err = HYPERVISOR_event_channel_op(EVTCHNOP_alloc_unbound,
874 					  &alloc_unbound);
875 	if (err == -ENOSYS)
876 		goto out_err;
877 
878 	BUG_ON(err);
879 	xen_store_evtchn = alloc_unbound.port;
880 
881 	return 0;
882 
883  out_err:
884 	if (page != 0)
885 		free_page(page);
886 	return err;
887 }
888 
889 static int xenbus_resume_cb(struct notifier_block *nb,
890 			    unsigned long action, void *data)
891 {
892 	int err = 0;
893 
894 	if (xen_hvm_domain()) {
895 		uint64_t v = 0;
896 
897 		err = hvm_get_parameter(HVM_PARAM_STORE_EVTCHN, &v);
898 		if (!err && v)
899 			xen_store_evtchn = v;
900 		else
901 			pr_warn("Cannot update xenstore event channel: %d\n",
902 				err);
903 	} else
904 		xen_store_evtchn = xen_start_info->store_evtchn;
905 
906 	return err;
907 }
908 
909 static struct notifier_block xenbus_resume_nb = {
910 	.notifier_call = xenbus_resume_cb,
911 };
912 
913 static int __init xenbus_init(void)
914 {
915 	int err = 0;
916 	uint64_t v = 0;
917 	xen_store_domain_type = XS_UNKNOWN;
918 
919 	if (!xen_domain())
920 		return -ENODEV;
921 
922 	xenbus_ring_ops_init();
923 
924 	if (xen_pv_domain())
925 		xen_store_domain_type = XS_PV;
926 	if (xen_hvm_domain())
927 		xen_store_domain_type = XS_HVM;
928 	if (xen_hvm_domain() && xen_initial_domain())
929 		xen_store_domain_type = XS_LOCAL;
930 	if (xen_pv_domain() && !xen_start_info->store_evtchn)
931 		xen_store_domain_type = XS_LOCAL;
932 	if (xen_pv_domain() && xen_start_info->store_evtchn)
933 		xenstored_ready = 1;
934 
935 	switch (xen_store_domain_type) {
936 	case XS_LOCAL:
937 		err = xenstored_local_init();
938 		if (err)
939 			goto out_error;
940 		xen_store_interface = gfn_to_virt(xen_store_gfn);
941 		break;
942 	case XS_PV:
943 		xen_store_evtchn = xen_start_info->store_evtchn;
944 		xen_store_gfn = xen_start_info->store_mfn;
945 		xen_store_interface = gfn_to_virt(xen_store_gfn);
946 		break;
947 	case XS_HVM:
948 		err = hvm_get_parameter(HVM_PARAM_STORE_EVTCHN, &v);
949 		if (err)
950 			goto out_error;
951 		xen_store_evtchn = (int)v;
952 		err = hvm_get_parameter(HVM_PARAM_STORE_PFN, &v);
953 		if (err)
954 			goto out_error;
955 		xen_store_gfn = (unsigned long)v;
956 		xen_store_interface =
957 			xen_remap(xen_store_gfn << XEN_PAGE_SHIFT,
958 				  XEN_PAGE_SIZE);
959 		break;
960 	default:
961 		pr_warn("Xenstore state unknown\n");
962 		break;
963 	}
964 
965 	/*
966 	 * HVM domains may not have a functional callback yet. In that
967 	 * case let xs_init() be called from xenbus_probe(), which will
968 	 * get invoked at an appropriate time.
969 	 */
970 	if (xen_store_domain_type != XS_HVM) {
971 		err = xs_init();
972 		if (err) {
973 			pr_warn("Error initializing xenstore comms: %i\n", err);
974 			goto out_error;
975 		}
976 	}
977 
978 	if ((xen_store_domain_type != XS_LOCAL) &&
979 	    (xen_store_domain_type != XS_UNKNOWN))
980 		xen_resume_notifier_register(&xenbus_resume_nb);
981 
982 #ifdef CONFIG_XEN_COMPAT_XENFS
983 	/*
984 	 * Create xenfs mountpoint in /proc for compatibility with
985 	 * utilities that expect to find "xenbus" under "/proc/xen".
986 	 */
987 	proc_create_mount_point("xen");
988 #endif
989 
990 out_error:
991 	return err;
992 }
993 
994 postcore_initcall(xenbus_init);
995 
996 MODULE_LICENSE("GPL");
997