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
66int xen_store_evtchn;
67EXPORT_SYMBOL_GPL(xen_store_evtchn);
68
69struct xenstore_domain_interface *xen_store_interface;
70EXPORT_SYMBOL_GPL(xen_store_interface);
71
72static unsigned long xen_store_mfn;
73
74static BLOCKING_NOTIFIER_HEAD(xenstore_chain);
75
76/* If something in array of ids matches this device, return it. */
77static const struct xenbus_device_id *
78match_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
87int 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}
96EXPORT_SYMBOL_GPL(xenbus_match);
97
98
99static void free_otherend_details(struct xenbus_device *dev)
100{
101	kfree(dev->otherend);
102	dev->otherend = NULL;
103}
104
105
106static 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
116static 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
128static 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
139int 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}
164EXPORT_SYMBOL_GPL(xenbus_read_otherend_details);
165
166void 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}
204EXPORT_SYMBOL_GPL(xenbus_otherend_changed);
205
206int 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;
245fail:
246	xenbus_dev_error(dev, err, "xenbus_dev_probe on %s", dev->nodename);
247	xenbus_switch_state(dev, XenbusStateClosed);
248	return err;
249}
250EXPORT_SYMBOL_GPL(xenbus_dev_probe);
251
252int 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}
269EXPORT_SYMBOL_GPL(xenbus_dev_remove);
270
271void 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}
292EXPORT_SYMBOL_GPL(xenbus_dev_shutdown);
293
294int 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}
301EXPORT_SYMBOL_GPL(xenbus_register_driver_common);
302
303void xenbus_unregister_driver(struct xenbus_driver *drv)
304{
305	driver_unregister(&drv->driver);
306}
307EXPORT_SYMBOL_GPL(xenbus_unregister_driver);
308
309struct xb_find_info {
310	struct xenbus_device *dev;
311	const char *nodename;
312};
313
314static 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
327struct 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
336static 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
357static 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
371static void xenbus_dev_release(struct device *dev)
372{
373	if (dev)
374		kfree(to_xenbus_device(dev));
375}
376
377static 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
383static 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
389static 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
396struct device_attribute xenbus_dev_attrs[] = {
397	__ATTR_RO(nodename),
398	__ATTR_RO(devtype),
399	__ATTR_RO(modalias),
400	__ATTR_NULL
401};
402EXPORT_SYMBOL_GPL(xenbus_dev_attrs);
403
404int 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;
455fail:
456	kfree(xendev);
457	return err;
458}
459EXPORT_SYMBOL_GPL(xenbus_probe_node);
460
461static 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
482int 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}
501EXPORT_SYMBOL_GPL(xenbus_probe_devices);
502
503static 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
513static 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
526void 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}
562EXPORT_SYMBOL_GPL(xenbus_dev_changed);
563
564int 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}
583EXPORT_SYMBOL_GPL(xenbus_dev_suspend);
584
585int 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}
627EXPORT_SYMBOL_GPL(xenbus_dev_resume);
628
629int xenbus_dev_cancel(struct device *dev)
630{
631	/* Do nothing */
632	DPRINTK("cancel");
633	return 0;
634}
635EXPORT_SYMBOL_GPL(xenbus_dev_cancel);
636
637/* A flag to determine if xenstored is 'ready' (i.e. has started) */
638int xenstored_ready;
639
640
641int 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}
652EXPORT_SYMBOL_GPL(register_xenstore_notifier);
653
654void unregister_xenstore_notifier(struct notifier_block *nb)
655{
656	blocking_notifier_chain_unregister(&xenstore_chain, nb);
657}
658EXPORT_SYMBOL_GPL(unregister_xenstore_notifier);
659
660void 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}
667EXPORT_SYMBOL_GPL(xenbus_probe);
668
669static 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
681device_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 */
686static 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
722static int __init xenbus_init(void)
723{
724	int err = 0;
725
726	if (!xen_domain())
727		return -ENODEV;
728
729	xenbus_ring_ops_init();
730
731	if (xen_hvm_domain()) {
732		uint64_t v = 0;
733		err = hvm_get_parameter(HVM_PARAM_STORE_EVTCHN, &v);
734		if (err)
735			goto out_error;
736		xen_store_evtchn = (int)v;
737		err = hvm_get_parameter(HVM_PARAM_STORE_PFN, &v);
738		if (err)
739			goto out_error;
740		xen_store_mfn = (unsigned long)v;
741		xen_store_interface = ioremap(xen_store_mfn << PAGE_SHIFT, PAGE_SIZE);
742	} else {
743		xen_store_evtchn = xen_start_info->store_evtchn;
744		xen_store_mfn = xen_start_info->store_mfn;
745		if (xen_store_evtchn)
746			xenstored_ready = 1;
747		else {
748			err = xenstored_local_init();
749			if (err)
750				goto out_error;
751		}
752		xen_store_interface = mfn_to_virt(xen_store_mfn);
753	}
754
755	/* Initialize the interface to xenstore. */
756	err = xs_init();
757	if (err) {
758		printk(KERN_WARNING
759		       "XENBUS: Error initializing xenstore comms: %i\n", err);
760		goto out_error;
761	}
762
763#ifdef CONFIG_XEN_COMPAT_XENFS
764	/*
765	 * Create xenfs mountpoint in /proc for compatibility with
766	 * utilities that expect to find "xenbus" under "/proc/xen".
767	 */
768	proc_mkdir("xen", NULL);
769#endif
770
771out_error:
772	return err;
773}
774
775postcore_initcall(xenbus_init);
776
777MODULE_LICENSE("GPL");
778