1/******************************************************************************
2 * Talks to Xen Store to figure out what devices we have (backend half).
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 * Copyright (C) 2007 Solarflare Communications, Inc.
8 *
9 * This program is free software; you can redistribute it and/or
10 * modify it under the terms of the GNU General Public License version 2
11 * as published by the Free Software Foundation; or, when distributed
12 * separately from the Linux kernel or incorporated into other
13 * software packages, subject to the following license:
14 *
15 * Permission is hereby granted, free of charge, to any person obtaining a copy
16 * of this source file (the "Software"), to deal in the Software without
17 * restriction, including without limitation the rights to use, copy, modify,
18 * merge, publish, distribute, sublicense, and/or sell copies of the Software,
19 * and to permit persons to whom the Software is furnished to do so, subject to
20 * the following conditions:
21 *
22 * The above copyright notice and this permission notice shall be included in
23 * all copies or substantial portions of the Software.
24 *
25 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
26 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
27 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
28 * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
29 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
30 * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS
31 * IN THE SOFTWARE.
32 */
33
34#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
35
36#define DPRINTK(fmt, ...)				\
37	pr_debug("(%s:%d) " fmt "\n",			\
38		 __func__, __LINE__, ##__VA_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/notifier.h>
47#include <linux/export.h>
48
49#include <asm/page.h>
50#include <asm/pgtable.h>
51#include <asm/xen/hypervisor.h>
52#include <asm/hypervisor.h>
53#include <xen/xenbus.h>
54#include <xen/features.h>
55
56#include "xenbus_comms.h"
57#include "xenbus_probe.h"
58
59/* backend/<type>/<fe-uuid>/<id> => <type>-<fe-domid>-<id> */
60static int backend_bus_id(char bus_id[XEN_BUS_ID_SIZE], const char *nodename)
61{
62	int domid, err;
63	const char *devid, *type, *frontend;
64	unsigned int typelen;
65
66	type = strchr(nodename, '/');
67	if (!type)
68		return -EINVAL;
69	type++;
70	typelen = strcspn(type, "/");
71	if (!typelen || type[typelen] != '/')
72		return -EINVAL;
73
74	devid = strrchr(nodename, '/') + 1;
75
76	err = xenbus_gather(XBT_NIL, nodename, "frontend-id", "%i", &domid,
77			    "frontend", NULL, &frontend,
78			    NULL);
79	if (err)
80		return err;
81	if (strlen(frontend) == 0)
82		err = -ERANGE;
83	if (!err && !xenbus_exists(XBT_NIL, frontend, ""))
84		err = -ENOENT;
85	kfree(frontend);
86
87	if (err)
88		return err;
89
90	if (snprintf(bus_id, XEN_BUS_ID_SIZE, "%.*s-%i-%s",
91		     typelen, type, domid, devid) >= XEN_BUS_ID_SIZE)
92		return -ENOSPC;
93	return 0;
94}
95
96static int xenbus_uevent_backend(struct device *dev,
97				 struct kobj_uevent_env *env)
98{
99	struct xenbus_device *xdev;
100	struct xenbus_driver *drv;
101	struct xen_bus_type *bus;
102
103	DPRINTK("");
104
105	if (dev == NULL)
106		return -ENODEV;
107
108	xdev = to_xenbus_device(dev);
109	bus = container_of(xdev->dev.bus, struct xen_bus_type, bus);
110
111	if (add_uevent_var(env, "MODALIAS=xen-backend:%s", xdev->devicetype))
112		return -ENOMEM;
113
114	/* stuff we want to pass to /sbin/hotplug */
115	if (add_uevent_var(env, "XENBUS_TYPE=%s", xdev->devicetype))
116		return -ENOMEM;
117
118	if (add_uevent_var(env, "XENBUS_PATH=%s", xdev->nodename))
119		return -ENOMEM;
120
121	if (add_uevent_var(env, "XENBUS_BASE_PATH=%s", bus->root))
122		return -ENOMEM;
123
124	if (dev->driver) {
125		drv = to_xenbus_driver(dev->driver);
126		if (drv && drv->uevent)
127			return drv->uevent(xdev, env);
128	}
129
130	return 0;
131}
132
133/* backend/<typename>/<frontend-uuid>/<name> */
134static int xenbus_probe_backend_unit(struct xen_bus_type *bus,
135				     const char *dir,
136				     const char *type,
137				     const char *name)
138{
139	char *nodename;
140	int err;
141
142	nodename = kasprintf(GFP_KERNEL, "%s/%s", dir, name);
143	if (!nodename)
144		return -ENOMEM;
145
146	DPRINTK("%s\n", nodename);
147
148	err = xenbus_probe_node(bus, type, nodename);
149	kfree(nodename);
150	return err;
151}
152
153/* backend/<typename>/<frontend-domid> */
154static int xenbus_probe_backend(struct xen_bus_type *bus, const char *type,
155				const char *domid)
156{
157	char *nodename;
158	int err = 0;
159	char **dir;
160	unsigned int i, dir_n = 0;
161
162	DPRINTK("");
163
164	nodename = kasprintf(GFP_KERNEL, "%s/%s/%s", bus->root, type, domid);
165	if (!nodename)
166		return -ENOMEM;
167
168	dir = xenbus_directory(XBT_NIL, nodename, "", &dir_n);
169	if (IS_ERR(dir)) {
170		kfree(nodename);
171		return PTR_ERR(dir);
172	}
173
174	for (i = 0; i < dir_n; i++) {
175		err = xenbus_probe_backend_unit(bus, nodename, type, dir[i]);
176		if (err)
177			break;
178	}
179	kfree(dir);
180	kfree(nodename);
181	return err;
182}
183
184static void frontend_changed(struct xenbus_watch *watch,
185			    const char **vec, unsigned int len)
186{
187	xenbus_otherend_changed(watch, vec, len, 0);
188}
189
190static struct xen_bus_type xenbus_backend = {
191	.root = "backend",
192	.levels = 3,		/* backend/type/<frontend>/<id> */
193	.get_bus_id = backend_bus_id,
194	.probe = xenbus_probe_backend,
195	.otherend_changed = frontend_changed,
196	.bus = {
197		.name		= "xen-backend",
198		.match		= xenbus_match,
199		.uevent		= xenbus_uevent_backend,
200		.probe		= xenbus_dev_probe,
201		.remove		= xenbus_dev_remove,
202		.shutdown	= xenbus_dev_shutdown,
203		.dev_groups	= xenbus_dev_groups,
204	},
205};
206
207static void backend_changed(struct xenbus_watch *watch,
208			    const char **vec, unsigned int len)
209{
210	DPRINTK("");
211
212	xenbus_dev_changed(vec[XS_WATCH_PATH], &xenbus_backend);
213}
214
215static struct xenbus_watch be_watch = {
216	.node = "backend",
217	.callback = backend_changed,
218};
219
220static int read_frontend_details(struct xenbus_device *xendev)
221{
222	return xenbus_read_otherend_details(xendev, "frontend-id", "frontend");
223}
224
225int xenbus_dev_is_online(struct xenbus_device *dev)
226{
227	int rc, val;
228
229	rc = xenbus_scanf(XBT_NIL, dev->nodename, "online", "%d", &val);
230	if (rc != 1)
231		val = 0; /* no online node present */
232
233	return val;
234}
235EXPORT_SYMBOL_GPL(xenbus_dev_is_online);
236
237int __xenbus_register_backend(struct xenbus_driver *drv, struct module *owner,
238			      const char *mod_name)
239{
240	drv->read_otherend_details = read_frontend_details;
241
242	return xenbus_register_driver_common(drv, &xenbus_backend,
243					     owner, mod_name);
244}
245EXPORT_SYMBOL_GPL(__xenbus_register_backend);
246
247static int backend_probe_and_watch(struct notifier_block *notifier,
248				   unsigned long event,
249				   void *data)
250{
251	/* Enumerate devices in xenstore and watch for changes. */
252	xenbus_probe_devices(&xenbus_backend);
253	register_xenbus_watch(&be_watch);
254
255	return NOTIFY_DONE;
256}
257
258static int __init xenbus_probe_backend_init(void)
259{
260	static struct notifier_block xenstore_notifier = {
261		.notifier_call = backend_probe_and_watch
262	};
263	int err;
264
265	DPRINTK("");
266
267	/* Register ourselves with the kernel bus subsystem */
268	err = bus_register(&xenbus_backend.bus);
269	if (err)
270		return err;
271
272	register_xenstore_notifier(&xenstore_notifier);
273
274	return 0;
275}
276subsys_initcall(xenbus_probe_backend_init);
277