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> */
backend_bus_id(char bus_id[XEN_BUS_ID_SIZE],const char * nodename)60 static 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
xenbus_uevent_backend(struct device * dev,struct kobj_uevent_env * env)96 static 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> */
xenbus_probe_backend_unit(struct xen_bus_type * bus,const char * dir,const char * type,const char * name)134 static 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> */
xenbus_probe_backend(struct xen_bus_type * bus,const char * type,const char * domid)154 static 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
frontend_will_handle(struct xenbus_watch * watch,const char ** vec,unsigned int len)184 static bool frontend_will_handle(struct xenbus_watch *watch,
185 const char **vec, unsigned int len)
186 {
187 return watch->nr_pending == 0;
188 }
189
frontend_changed(struct xenbus_watch * watch,const char ** vec,unsigned int len)190 static void frontend_changed(struct xenbus_watch *watch,
191 const char **vec, unsigned int len)
192 {
193 xenbus_otherend_changed(watch, vec, len, 0);
194 }
195
196 static struct xen_bus_type xenbus_backend = {
197 .root = "backend",
198 .levels = 3, /* backend/type/<frontend>/<id> */
199 .get_bus_id = backend_bus_id,
200 .probe = xenbus_probe_backend,
201 .otherend_will_handle = frontend_will_handle,
202 .otherend_changed = frontend_changed,
203 .bus = {
204 .name = "xen-backend",
205 .match = xenbus_match,
206 .uevent = xenbus_uevent_backend,
207 .probe = xenbus_dev_probe,
208 .remove = xenbus_dev_remove,
209 .shutdown = xenbus_dev_shutdown,
210 .dev_groups = xenbus_dev_groups,
211 },
212 };
213
backend_changed(struct xenbus_watch * watch,const char ** vec,unsigned int len)214 static void backend_changed(struct xenbus_watch *watch,
215 const char **vec, unsigned int len)
216 {
217 DPRINTK("");
218
219 xenbus_dev_changed(vec[XS_WATCH_PATH], &xenbus_backend);
220 }
221
222 static struct xenbus_watch be_watch = {
223 .node = "backend",
224 .callback = backend_changed,
225 };
226
read_frontend_details(struct xenbus_device * xendev)227 static int read_frontend_details(struct xenbus_device *xendev)
228 {
229 return xenbus_read_otherend_details(xendev, "frontend-id", "frontend");
230 }
231
xenbus_dev_is_online(struct xenbus_device * dev)232 int xenbus_dev_is_online(struct xenbus_device *dev)
233 {
234 int rc, val;
235
236 rc = xenbus_scanf(XBT_NIL, dev->nodename, "online", "%d", &val);
237 if (rc != 1)
238 val = 0; /* no online node present */
239
240 return val;
241 }
242 EXPORT_SYMBOL_GPL(xenbus_dev_is_online);
243
__xenbus_register_backend(struct xenbus_driver * drv,struct module * owner,const char * mod_name)244 int __xenbus_register_backend(struct xenbus_driver *drv, struct module *owner,
245 const char *mod_name)
246 {
247 drv->read_otherend_details = read_frontend_details;
248
249 return xenbus_register_driver_common(drv, &xenbus_backend,
250 owner, mod_name);
251 }
252 EXPORT_SYMBOL_GPL(__xenbus_register_backend);
253
backend_probe_and_watch(struct notifier_block * notifier,unsigned long event,void * data)254 static int backend_probe_and_watch(struct notifier_block *notifier,
255 unsigned long event,
256 void *data)
257 {
258 /* Enumerate devices in xenstore and watch for changes. */
259 xenbus_probe_devices(&xenbus_backend);
260 register_xenbus_watch(&be_watch);
261
262 return NOTIFY_DONE;
263 }
264
xenbus_probe_backend_init(void)265 static int __init xenbus_probe_backend_init(void)
266 {
267 static struct notifier_block xenstore_notifier = {
268 .notifier_call = backend_probe_and_watch
269 };
270 int err;
271
272 DPRINTK("");
273
274 /* Register ourselves with the kernel bus subsystem */
275 err = bus_register(&xenbus_backend.bus);
276 if (err)
277 return err;
278
279 register_xenstore_notifier(&xenstore_notifier);
280
281 return 0;
282 }
283 subsys_initcall(xenbus_probe_backend_init);
284