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
68static int xs_init_irq;
69int xen_store_evtchn;
70EXPORT_SYMBOL_GPL(xen_store_evtchn);
71
72struct xenstore_domain_interface *xen_store_interface;
73EXPORT_SYMBOL_GPL(xen_store_interface);
74
75enum xenstore_init xen_store_domain_type;
76EXPORT_SYMBOL_GPL(xen_store_domain_type);
77
78static unsigned long xen_store_gfn;
79
80static BLOCKING_NOTIFIER_HEAD(xenstore_chain);
81
82/* If something in array of ids matches this device, return it. */
83static const struct xenbus_device_id *
84match_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
93int 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}
102EXPORT_SYMBOL_GPL(xenbus_match);
103
104
105static void free_otherend_details(struct xenbus_device *dev)
106{
107	kfree(dev->otherend);
108	dev->otherend = NULL;
109}
110
111
112static 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
122static 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
134static 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_will_handle,
141				    bus->otherend_changed,
142				    "%s/%s", dev->otherend, "state");
143}
144
145
146int xenbus_read_otherend_details(struct xenbus_device *xendev,
147				 char *id_node, char *path_node)
148{
149	int err = xenbus_gather(XBT_NIL, xendev->nodename,
150				id_node, "%i", &xendev->otherend_id,
151				path_node, NULL, &xendev->otherend,
152				NULL);
153	if (err) {
154		xenbus_dev_fatal(xendev, err,
155				 "reading other end details from %s",
156				 xendev->nodename);
157		return err;
158	}
159	if (strlen(xendev->otherend) == 0 ||
160	    !xenbus_exists(XBT_NIL, xendev->otherend, "")) {
161		xenbus_dev_fatal(xendev, -ENOENT,
162				 "unable to read other end from %s.  "
163				 "missing or inaccessible.",
164				 xendev->nodename);
165		free_otherend_details(xendev);
166		return -ENOENT;
167	}
168
169	return 0;
170}
171EXPORT_SYMBOL_GPL(xenbus_read_otherend_details);
172
173void xenbus_otherend_changed(struct xenbus_watch *watch,
174			     const char *path, const char *token,
175			     int ignore_on_shutdown)
176{
177	struct xenbus_device *dev =
178		container_of(watch, struct xenbus_device, otherend_watch);
179	struct xenbus_driver *drv = to_xenbus_driver(dev->dev.driver);
180	enum xenbus_state state;
181
182	/* Protect us against watches firing on old details when the otherend
183	   details change, say immediately after a resume. */
184	if (!dev->otherend ||
185	    strncmp(dev->otherend, path, strlen(dev->otherend))) {
186		dev_dbg(&dev->dev, "Ignoring watch at %s\n", path);
187		return;
188	}
189
190	state = xenbus_read_driver_state(dev->otherend);
191
192	dev_dbg(&dev->dev, "state is %d, (%s), %s, %s\n",
193		state, xenbus_strstate(state), dev->otherend_watch.node, path);
194
195	/*
196	 * Ignore xenbus transitions during shutdown. This prevents us doing
197	 * work that can fail e.g., when the rootfs is gone.
198	 */
199	if (system_state > SYSTEM_RUNNING) {
200		if (ignore_on_shutdown && (state == XenbusStateClosing))
201			xenbus_frontend_closed(dev);
202		return;
203	}
204
205	if (drv->otherend_changed)
206		drv->otherend_changed(dev, state);
207}
208EXPORT_SYMBOL_GPL(xenbus_otherend_changed);
209
210#define XENBUS_SHOW_STAT(name)						\
211static ssize_t name##_show(struct device *_dev,				\
212			   struct device_attribute *attr,		\
213			   char *buf)					\
214{									\
215	struct xenbus_device *dev = to_xenbus_device(_dev);		\
216									\
217	return sprintf(buf, "%d\n", atomic_read(&dev->name));		\
218}									\
219static DEVICE_ATTR_RO(name)
220
221XENBUS_SHOW_STAT(event_channels);
222XENBUS_SHOW_STAT(events);
223XENBUS_SHOW_STAT(spurious_events);
224XENBUS_SHOW_STAT(jiffies_eoi_delayed);
225
226static ssize_t spurious_threshold_show(struct device *_dev,
227				       struct device_attribute *attr,
228				       char *buf)
229{
230	struct xenbus_device *dev = to_xenbus_device(_dev);
231
232	return sprintf(buf, "%d\n", dev->spurious_threshold);
233}
234
235static ssize_t spurious_threshold_store(struct device *_dev,
236					struct device_attribute *attr,
237					const char *buf, size_t count)
238{
239	struct xenbus_device *dev = to_xenbus_device(_dev);
240	unsigned int val;
241	ssize_t ret;
242
243	ret = kstrtouint(buf, 0, &val);
244	if (ret)
245		return ret;
246
247	dev->spurious_threshold = val;
248
249	return count;
250}
251
252static DEVICE_ATTR_RW(spurious_threshold);
253
254static 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
263static const struct attribute_group xenbus_group = {
264	.name = "xenbus",
265	.attrs = xenbus_attrs,
266};
267
268int 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;
321fail_put:
322	module_put(drv->driver.owner);
323fail:
324	xenbus_dev_error(dev, err, "xenbus_dev_probe on %s", dev->nodename);
325	return err;
326}
327EXPORT_SYMBOL_GPL(xenbus_dev_probe);
328
329void 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}
360EXPORT_SYMBOL_GPL(xenbus_dev_remove);
361
362int xenbus_register_driver_common(struct xenbus_driver *drv,
363				  struct xen_bus_type *bus,
364				  struct module *owner, const char *mod_name)
365{
366	drv->driver.name = drv->name ? drv->name : drv->ids[0].devicetype;
367	drv->driver.bus = &bus->bus;
368	drv->driver.owner = owner;
369	drv->driver.mod_name = mod_name;
370
371	return driver_register(&drv->driver);
372}
373EXPORT_SYMBOL_GPL(xenbus_register_driver_common);
374
375void xenbus_unregister_driver(struct xenbus_driver *drv)
376{
377	driver_unregister(&drv->driver);
378}
379EXPORT_SYMBOL_GPL(xenbus_unregister_driver);
380
381struct xb_find_info {
382	struct xenbus_device *dev;
383	const char *nodename;
384};
385
386static int cmp_dev(struct device *dev, void *data)
387{
388	struct xenbus_device *xendev = to_xenbus_device(dev);
389	struct xb_find_info *info = data;
390
391	if (!strcmp(xendev->nodename, info->nodename)) {
392		info->dev = xendev;
393		get_device(dev);
394		return 1;
395	}
396	return 0;
397}
398
399static struct xenbus_device *xenbus_device_find(const char *nodename,
400						struct bus_type *bus)
401{
402	struct xb_find_info info = { .dev = NULL, .nodename = nodename };
403
404	bus_for_each_dev(bus, NULL, &info, cmp_dev);
405	return info.dev;
406}
407
408static int cleanup_dev(struct device *dev, void *data)
409{
410	struct xenbus_device *xendev = to_xenbus_device(dev);
411	struct xb_find_info *info = data;
412	int len = strlen(info->nodename);
413
414	DPRINTK("%s", info->nodename);
415
416	/* Match the info->nodename path, or any subdirectory of that path. */
417	if (strncmp(xendev->nodename, info->nodename, len))
418		return 0;
419
420	/* If the node name is longer, ensure it really is a subdirectory. */
421	if ((strlen(xendev->nodename) > len) && (xendev->nodename[len] != '/'))
422		return 0;
423
424	info->dev = xendev;
425	get_device(dev);
426	return 1;
427}
428
429static void xenbus_cleanup_devices(const char *path, struct bus_type *bus)
430{
431	struct xb_find_info info = { .nodename = path };
432
433	do {
434		info.dev = NULL;
435		bus_for_each_dev(bus, NULL, &info, cleanup_dev);
436		if (info.dev) {
437			device_unregister(&info.dev->dev);
438			put_device(&info.dev->dev);
439		}
440	} while (info.dev);
441}
442
443static void xenbus_dev_release(struct device *dev)
444{
445	if (dev)
446		kfree(to_xenbus_device(dev));
447}
448
449static ssize_t nodename_show(struct device *dev,
450			     struct device_attribute *attr, char *buf)
451{
452	return sprintf(buf, "%s\n", to_xenbus_device(dev)->nodename);
453}
454static DEVICE_ATTR_RO(nodename);
455
456static ssize_t devtype_show(struct device *dev,
457			    struct device_attribute *attr, char *buf)
458{
459	return sprintf(buf, "%s\n", to_xenbus_device(dev)->devicetype);
460}
461static DEVICE_ATTR_RO(devtype);
462
463static ssize_t modalias_show(struct device *dev,
464			     struct device_attribute *attr, char *buf)
465{
466	return sprintf(buf, "%s:%s\n", dev->bus->name,
467		       to_xenbus_device(dev)->devicetype);
468}
469static DEVICE_ATTR_RO(modalias);
470
471static ssize_t state_show(struct device *dev,
472			    struct device_attribute *attr, char *buf)
473{
474	return sprintf(buf, "%s\n",
475			xenbus_strstate(to_xenbus_device(dev)->state));
476}
477static DEVICE_ATTR_RO(state);
478
479static struct attribute *xenbus_dev_attrs[] = {
480	&dev_attr_nodename.attr,
481	&dev_attr_devtype.attr,
482	&dev_attr_modalias.attr,
483	&dev_attr_state.attr,
484	NULL,
485};
486
487static const struct attribute_group xenbus_dev_group = {
488	.attrs = xenbus_dev_attrs,
489};
490
491const struct attribute_group *xenbus_dev_groups[] = {
492	&xenbus_dev_group,
493	NULL,
494};
495EXPORT_SYMBOL_GPL(xenbus_dev_groups);
496
497int xenbus_probe_node(struct xen_bus_type *bus,
498		      const char *type,
499		      const char *nodename)
500{
501	char devname[XEN_BUS_ID_SIZE];
502	int err;
503	struct xenbus_device *xendev;
504	size_t stringlen;
505	char *tmpstring;
506
507	enum xenbus_state state = xenbus_read_driver_state(nodename);
508
509	if (state != XenbusStateInitialising) {
510		/* Device is not new, so ignore it.  This can happen if a
511		   device is going away after switching to Closed.  */
512		return 0;
513	}
514
515	stringlen = strlen(nodename) + 1 + strlen(type) + 1;
516	xendev = kzalloc(sizeof(*xendev) + stringlen, GFP_KERNEL);
517	if (!xendev)
518		return -ENOMEM;
519
520	xendev->state = XenbusStateInitialising;
521
522	/* Copy the strings into the extra space. */
523
524	tmpstring = (char *)(xendev + 1);
525	strcpy(tmpstring, nodename);
526	xendev->nodename = tmpstring;
527
528	tmpstring += strlen(tmpstring) + 1;
529	strcpy(tmpstring, type);
530	xendev->devicetype = tmpstring;
531	init_completion(&xendev->down);
532
533	xendev->dev.bus = &bus->bus;
534	xendev->dev.release = xenbus_dev_release;
535
536	err = bus->get_bus_id(devname, xendev->nodename);
537	if (err)
538		goto fail;
539
540	dev_set_name(&xendev->dev, "%s", devname);
541	sema_init(&xendev->reclaim_sem, 1);
542
543	/* Register with generic device framework. */
544	err = device_register(&xendev->dev);
545	if (err) {
546		put_device(&xendev->dev);
547		xendev = NULL;
548		goto fail;
549	}
550
551	return 0;
552fail:
553	kfree(xendev);
554	return err;
555}
556EXPORT_SYMBOL_GPL(xenbus_probe_node);
557
558static int xenbus_probe_device_type(struct xen_bus_type *bus, const char *type)
559{
560	int err = 0;
561	char **dir;
562	unsigned int dir_n = 0;
563	int i;
564
565	dir = xenbus_directory(XBT_NIL, bus->root, type, &dir_n);
566	if (IS_ERR(dir))
567		return PTR_ERR(dir);
568
569	for (i = 0; i < dir_n; i++) {
570		err = bus->probe(bus, type, dir[i]);
571		if (err)
572			break;
573	}
574
575	kfree(dir);
576	return err;
577}
578
579int xenbus_probe_devices(struct xen_bus_type *bus)
580{
581	int err = 0;
582	char **dir;
583	unsigned int i, dir_n;
584
585	dir = xenbus_directory(XBT_NIL, bus->root, "", &dir_n);
586	if (IS_ERR(dir))
587		return PTR_ERR(dir);
588
589	for (i = 0; i < dir_n; i++) {
590		err = xenbus_probe_device_type(bus, dir[i]);
591		if (err)
592			break;
593	}
594
595	kfree(dir);
596	return err;
597}
598EXPORT_SYMBOL_GPL(xenbus_probe_devices);
599
600static unsigned int char_count(const char *str, char c)
601{
602	unsigned int i, ret = 0;
603
604	for (i = 0; str[i]; i++)
605		if (str[i] == c)
606			ret++;
607	return ret;
608}
609
610static int strsep_len(const char *str, char c, unsigned int len)
611{
612	unsigned int i;
613
614	for (i = 0; str[i]; i++)
615		if (str[i] == c) {
616			if (len == 0)
617				return i;
618			len--;
619		}
620	return (len == 0) ? i : -ERANGE;
621}
622
623void xenbus_dev_changed(const char *node, struct xen_bus_type *bus)
624{
625	int exists, rootlen;
626	struct xenbus_device *dev;
627	char type[XEN_BUS_ID_SIZE];
628	const char *p, *root;
629
630	if (char_count(node, '/') < 2)
631		return;
632
633	exists = xenbus_exists(XBT_NIL, node, "");
634	if (!exists) {
635		xenbus_cleanup_devices(node, &bus->bus);
636		return;
637	}
638
639	/* backend/<type>/... or device/<type>/... */
640	p = strchr(node, '/') + 1;
641	snprintf(type, XEN_BUS_ID_SIZE, "%.*s", (int)strcspn(p, "/"), p);
642	type[XEN_BUS_ID_SIZE-1] = '\0';
643
644	rootlen = strsep_len(node, '/', bus->levels);
645	if (rootlen < 0)
646		return;
647	root = kasprintf(GFP_KERNEL, "%.*s", rootlen, node);
648	if (!root)
649		return;
650
651	dev = xenbus_device_find(root, &bus->bus);
652	if (!dev)
653		xenbus_probe_node(bus, type, root);
654	else
655		put_device(&dev->dev);
656
657	kfree(root);
658}
659EXPORT_SYMBOL_GPL(xenbus_dev_changed);
660
661int xenbus_dev_suspend(struct device *dev)
662{
663	int err = 0;
664	struct xenbus_driver *drv;
665	struct xenbus_device *xdev
666		= container_of(dev, struct xenbus_device, dev);
667
668	DPRINTK("%s", xdev->nodename);
669
670	if (dev->driver == NULL)
671		return 0;
672	drv = to_xenbus_driver(dev->driver);
673	if (drv->suspend)
674		err = drv->suspend(xdev);
675	if (err)
676		dev_warn(dev, "suspend failed: %i\n", err);
677	return 0;
678}
679EXPORT_SYMBOL_GPL(xenbus_dev_suspend);
680
681int xenbus_dev_resume(struct device *dev)
682{
683	int err;
684	struct xenbus_driver *drv;
685	struct xenbus_device *xdev
686		= container_of(dev, struct xenbus_device, dev);
687
688	DPRINTK("%s", xdev->nodename);
689
690	if (dev->driver == NULL)
691		return 0;
692	drv = to_xenbus_driver(dev->driver);
693	err = talk_to_otherend(xdev);
694	if (err) {
695		dev_warn(dev, "resume (talk_to_otherend) failed: %i\n", err);
696		return err;
697	}
698
699	xdev->state = XenbusStateInitialising;
700
701	if (drv->resume) {
702		err = drv->resume(xdev);
703		if (err) {
704			dev_warn(dev, "resume failed: %i\n", err);
705			return err;
706		}
707	}
708
709	err = watch_otherend(xdev);
710	if (err) {
711		dev_warn(dev, "resume (watch_otherend) failed: %d\n", err);
712		return err;
713	}
714
715	return 0;
716}
717EXPORT_SYMBOL_GPL(xenbus_dev_resume);
718
719int xenbus_dev_cancel(struct device *dev)
720{
721	/* Do nothing */
722	DPRINTK("cancel");
723	return 0;
724}
725EXPORT_SYMBOL_GPL(xenbus_dev_cancel);
726
727/* A flag to determine if xenstored is 'ready' (i.e. has started) */
728int xenstored_ready;
729
730
731int register_xenstore_notifier(struct notifier_block *nb)
732{
733	int ret = 0;
734
735	if (xenstored_ready > 0)
736		ret = nb->notifier_call(nb, 0, NULL);
737	else
738		blocking_notifier_chain_register(&xenstore_chain, nb);
739
740	return ret;
741}
742EXPORT_SYMBOL_GPL(register_xenstore_notifier);
743
744void unregister_xenstore_notifier(struct notifier_block *nb)
745{
746	blocking_notifier_chain_unregister(&xenstore_chain, nb);
747}
748EXPORT_SYMBOL_GPL(unregister_xenstore_notifier);
749
750static void xenbus_probe(void)
751{
752	xenstored_ready = 1;
753
754	if (!xen_store_interface) {
755		xen_store_interface = memremap(xen_store_gfn << XEN_PAGE_SHIFT,
756					       XEN_PAGE_SIZE, MEMREMAP_WB);
757		/*
758		 * Now it is safe to free the IRQ used for xenstore late
759		 * initialization. No need to unbind: it is about to be
760		 * bound again from xb_init_comms. Note that calling
761		 * unbind_from_irqhandler now would result in xen_evtchn_close()
762		 * being called and the event channel not being enabled again
763		 * afterwards, resulting in missed event notifications.
764		 */
765		free_irq(xs_init_irq, &xb_waitq);
766	}
767
768	/*
769	 * In the HVM case, xenbus_init() deferred its call to
770	 * xs_init() in case callbacks were not operational yet.
771	 * So do it now.
772	 */
773	if (xen_store_domain_type == XS_HVM)
774		xs_init();
775
776	/* Notify others that xenstore is up */
777	blocking_notifier_call_chain(&xenstore_chain, 0, NULL);
778}
779
780/*
781 * Returns true when XenStore init must be deferred in order to
782 * allow the PCI platform device to be initialised, before we
783 * can actually have event channel interrupts working.
784 */
785static bool xs_hvm_defer_init_for_callback(void)
786{
787#ifdef CONFIG_XEN_PVHVM
788	return xen_store_domain_type == XS_HVM &&
789		!xen_have_vector_callback;
790#else
791	return false;
792#endif
793}
794
795static int xenbus_probe_thread(void *unused)
796{
797	DEFINE_WAIT(w);
798
799	/*
800	 * We actually just want to wait for *any* trigger of xb_waitq,
801	 * and run xenbus_probe() the moment it occurs.
802	 */
803	prepare_to_wait(&xb_waitq, &w, TASK_INTERRUPTIBLE);
804	schedule();
805	finish_wait(&xb_waitq, &w);
806
807	DPRINTK("probing");
808	xenbus_probe();
809	return 0;
810}
811
812static int __init xenbus_probe_initcall(void)
813{
814	if (!xen_domain())
815		return -ENODEV;
816
817	/*
818	 * Probe XenBus here in the XS_PV case, and also XS_HVM unless we
819	 * need to wait for the platform PCI device to come up or
820	 * xen_store_interface is not ready.
821	 */
822	if (xen_store_domain_type == XS_PV ||
823	    (xen_store_domain_type == XS_HVM &&
824	     !xs_hvm_defer_init_for_callback() &&
825	     xen_store_interface != NULL))
826		xenbus_probe();
827
828	/*
829	 * For XS_LOCAL or when xen_store_interface is not ready, spawn a
830	 * thread which will wait for xenstored or a xenstore-stubdom to be
831	 * started, then probe.  It will be triggered when communication
832	 * starts happening, by waiting on xb_waitq.
833	 */
834	if (xen_store_domain_type == XS_LOCAL || xen_store_interface == NULL) {
835		struct task_struct *probe_task;
836
837		probe_task = kthread_run(xenbus_probe_thread, NULL,
838					 "xenbus_probe");
839		if (IS_ERR(probe_task))
840			return PTR_ERR(probe_task);
841	}
842	return 0;
843}
844device_initcall(xenbus_probe_initcall);
845
846int xen_set_callback_via(uint64_t via)
847{
848	struct xen_hvm_param a;
849	int ret;
850
851	a.domid = DOMID_SELF;
852	a.index = HVM_PARAM_CALLBACK_IRQ;
853	a.value = via;
854
855	ret = HYPERVISOR_hvm_op(HVMOP_set_param, &a);
856	if (ret)
857		return ret;
858
859	/*
860	 * If xenbus_probe_initcall() deferred the xenbus_probe()
861	 * due to the callback not functioning yet, we can do it now.
862	 */
863	if (!xenstored_ready && xs_hvm_defer_init_for_callback())
864		xenbus_probe();
865
866	return ret;
867}
868EXPORT_SYMBOL_GPL(xen_set_callback_via);
869
870/* Set up event channel for xenstored which is run as a local process
871 * (this is normally used only in dom0)
872 */
873static int __init xenstored_local_init(void)
874{
875	int err = -ENOMEM;
876	unsigned long page = 0;
877	struct evtchn_alloc_unbound alloc_unbound;
878
879	/* Allocate Xenstore page */
880	page = get_zeroed_page(GFP_KERNEL);
881	if (!page)
882		goto out_err;
883
884	xen_store_gfn = virt_to_gfn((void *)page);
885
886	/* Next allocate a local port which xenstored can bind to */
887	alloc_unbound.dom        = DOMID_SELF;
888	alloc_unbound.remote_dom = DOMID_SELF;
889
890	err = HYPERVISOR_event_channel_op(EVTCHNOP_alloc_unbound,
891					  &alloc_unbound);
892	if (err == -ENOSYS)
893		goto out_err;
894
895	BUG_ON(err);
896	xen_store_evtchn = alloc_unbound.port;
897
898	return 0;
899
900 out_err:
901	if (page != 0)
902		free_page(page);
903	return err;
904}
905
906static int xenbus_resume_cb(struct notifier_block *nb,
907			    unsigned long action, void *data)
908{
909	int err = 0;
910
911	if (xen_hvm_domain()) {
912		uint64_t v = 0;
913
914		err = hvm_get_parameter(HVM_PARAM_STORE_EVTCHN, &v);
915		if (!err && v)
916			xen_store_evtchn = v;
917		else
918			pr_warn("Cannot update xenstore event channel: %d\n",
919				err);
920	} else
921		xen_store_evtchn = xen_start_info->store_evtchn;
922
923	return err;
924}
925
926static struct notifier_block xenbus_resume_nb = {
927	.notifier_call = xenbus_resume_cb,
928};
929
930static irqreturn_t xenbus_late_init(int irq, void *unused)
931{
932	int err;
933	uint64_t v = 0;
934
935	err = hvm_get_parameter(HVM_PARAM_STORE_PFN, &v);
936	if (err || !v || !~v)
937		return IRQ_HANDLED;
938	xen_store_gfn = (unsigned long)v;
939
940	wake_up(&xb_waitq);
941	return IRQ_HANDLED;
942}
943
944static int __init xenbus_init(void)
945{
946	int err;
947	uint64_t v = 0;
948	bool wait = false;
949	xen_store_domain_type = XS_UNKNOWN;
950
951	if (!xen_domain())
952		return -ENODEV;
953
954	xenbus_ring_ops_init();
955
956	if (xen_pv_domain())
957		xen_store_domain_type = XS_PV;
958	if (xen_hvm_domain())
959		xen_store_domain_type = XS_HVM;
960	if (xen_hvm_domain() && xen_initial_domain())
961		xen_store_domain_type = XS_LOCAL;
962	if (xen_pv_domain() && !xen_start_info->store_evtchn)
963		xen_store_domain_type = XS_LOCAL;
964	if (xen_pv_domain() && xen_start_info->store_evtchn)
965		xenstored_ready = 1;
966
967	switch (xen_store_domain_type) {
968	case XS_LOCAL:
969		err = xenstored_local_init();
970		if (err)
971			goto out_error;
972		xen_store_interface = gfn_to_virt(xen_store_gfn);
973		break;
974	case XS_PV:
975		xen_store_evtchn = xen_start_info->store_evtchn;
976		xen_store_gfn = xen_start_info->store_mfn;
977		xen_store_interface = gfn_to_virt(xen_store_gfn);
978		break;
979	case XS_HVM:
980		err = hvm_get_parameter(HVM_PARAM_STORE_EVTCHN, &v);
981		if (err)
982			goto out_error;
983		xen_store_evtchn = (int)v;
984		err = hvm_get_parameter(HVM_PARAM_STORE_PFN, &v);
985		if (err)
986			goto out_error;
987		/*
988		 * Uninitialized hvm_params are zero and return no error.
989		 * Although it is theoretically possible to have
990		 * HVM_PARAM_STORE_PFN set to zero on purpose, in reality it is
991		 * not zero when valid. If zero, it means that Xenstore hasn't
992		 * been properly initialized. Instead of attempting to map a
993		 * wrong guest physical address return error.
994		 *
995		 * Also recognize all bits set as an invalid/uninitialized value.
996		 */
997		if (!v) {
998			err = -ENOENT;
999			goto out_error;
1000		}
1001		if (v == ~0ULL) {
1002			wait = true;
1003		} else {
1004			/* Avoid truncation on 32-bit. */
1005#if BITS_PER_LONG == 32
1006			if (v > ULONG_MAX) {
1007				pr_err("%s: cannot handle HVM_PARAM_STORE_PFN=%llx > ULONG_MAX\n",
1008				       __func__, v);
1009				err = -EINVAL;
1010				goto out_error;
1011			}
1012#endif
1013			xen_store_gfn = (unsigned long)v;
1014			xen_store_interface =
1015				memremap(xen_store_gfn << XEN_PAGE_SHIFT,
1016					 XEN_PAGE_SIZE, MEMREMAP_WB);
1017			if (xen_store_interface->connection != XENSTORE_CONNECTED)
1018				wait = true;
1019		}
1020		if (wait) {
1021			err = bind_evtchn_to_irqhandler(xen_store_evtchn,
1022							xenbus_late_init,
1023							0, "xenstore_late_init",
1024							&xb_waitq);
1025			if (err < 0) {
1026				pr_err("xenstore_late_init couldn't bind irq err=%d\n",
1027				       err);
1028				goto out_error;
1029			}
1030
1031			xs_init_irq = err;
1032		}
1033		break;
1034	default:
1035		pr_warn("Xenstore state unknown\n");
1036		break;
1037	}
1038
1039	/*
1040	 * HVM domains may not have a functional callback yet. In that
1041	 * case let xs_init() be called from xenbus_probe(), which will
1042	 * get invoked at an appropriate time.
1043	 */
1044	if (xen_store_domain_type != XS_HVM) {
1045		err = xs_init();
1046		if (err) {
1047			pr_warn("Error initializing xenstore comms: %i\n", err);
1048			goto out_error;
1049		}
1050	}
1051
1052	if ((xen_store_domain_type != XS_LOCAL) &&
1053	    (xen_store_domain_type != XS_UNKNOWN))
1054		xen_resume_notifier_register(&xenbus_resume_nb);
1055
1056#ifdef CONFIG_XEN_COMPAT_XENFS
1057	/*
1058	 * Create xenfs mountpoint in /proc for compatibility with
1059	 * utilities that expect to find "xenbus" under "/proc/xen".
1060	 */
1061	proc_create_mount_point("xen");
1062#endif
1063	return 0;
1064
1065out_error:
1066	xen_store_domain_type = XS_UNKNOWN;
1067	return err;
1068}
1069
1070postcore_initcall(xenbus_init);
1071
1072MODULE_LICENSE("GPL");
1073