3f7922ec13e3d5ecabf46bf01dd48979e1a960a3
[~shefty/rdma-dev.git] / drivers / xen / xen-balloon.c
1 /******************************************************************************
2  * Xen balloon driver - enables returning/claiming memory to/from Xen.
3  *
4  * Copyright (c) 2003, B Dragovic
5  * Copyright (c) 2003-2004, M Williamson, K Fraser
6  * Copyright (c) 2005 Dan M. Smith, IBM Corporation
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 #include <linux/kernel.h>
34 #include <linux/module.h>
35 #include <linux/capability.h>
36
37 #include <xen/xen.h>
38 #include <xen/interface/xen.h>
39 #include <xen/balloon.h>
40 #include <xen/xenbus.h>
41 #include <xen/features.h>
42 #include <xen/page.h>
43
44 #define PAGES2KB(_p) ((_p)<<(PAGE_SHIFT-10))
45
46 #define BALLOON_CLASS_NAME "xen_memory"
47
48 static struct device balloon_dev;
49
50 static int register_balloon(struct device *dev);
51
52 /* React to a change in the target key */
53 static void watch_target(struct xenbus_watch *watch,
54                          const char **vec, unsigned int len)
55 {
56         unsigned long long new_target;
57         int err;
58
59         err = xenbus_scanf(XBT_NIL, "memory", "target", "%llu", &new_target);
60         if (err != 1) {
61                 /* This is ok (for domain0 at least) - so just return */
62                 return;
63         }
64
65         /* The given memory/target value is in KiB, so it needs converting to
66          * pages. PAGE_SHIFT converts bytes to pages, hence PAGE_SHIFT - 10.
67          */
68         balloon_set_new_target(new_target >> (PAGE_SHIFT - 10));
69 }
70 static struct xenbus_watch target_watch = {
71         .node = "memory/target",
72         .callback = watch_target,
73 };
74
75
76 static int balloon_init_watcher(struct notifier_block *notifier,
77                                 unsigned long event,
78                                 void *data)
79 {
80         int err;
81
82         err = register_xenbus_watch(&target_watch);
83         if (err)
84                 printk(KERN_ERR "Failed to set balloon watcher\n");
85
86         return NOTIFY_DONE;
87 }
88
89 static struct notifier_block xenstore_notifier = {
90         .notifier_call = balloon_init_watcher,
91 };
92
93 static int __init balloon_init(void)
94 {
95         if (!xen_domain())
96                 return -ENODEV;
97
98         pr_info("xen-balloon: Initialising balloon driver.\n");
99
100         register_balloon(&balloon_dev);
101
102         register_xen_selfballooning(&balloon_dev);
103
104         register_xenstore_notifier(&xenstore_notifier);
105
106         return 0;
107 }
108 subsys_initcall(balloon_init);
109
110 static void balloon_exit(void)
111 {
112     /* XXX - release balloon here */
113     return;
114 }
115
116 module_exit(balloon_exit);
117
118 #define BALLOON_SHOW(name, format, args...)                             \
119         static ssize_t show_##name(struct device *dev,                  \
120                                    struct device_attribute *attr,       \
121                                    char *buf)                           \
122         {                                                               \
123                 return sprintf(buf, format, ##args);                    \
124         }                                                               \
125         static DEVICE_ATTR(name, S_IRUGO, show_##name, NULL)
126
127 BALLOON_SHOW(current_kb, "%lu\n", PAGES2KB(balloon_stats.current_pages));
128 BALLOON_SHOW(low_kb, "%lu\n", PAGES2KB(balloon_stats.balloon_low));
129 BALLOON_SHOW(high_kb, "%lu\n", PAGES2KB(balloon_stats.balloon_high));
130
131 static DEVICE_ULONG_ATTR(schedule_delay, 0444, balloon_stats.schedule_delay);
132 static DEVICE_ULONG_ATTR(max_schedule_delay, 0644, balloon_stats.max_schedule_delay);
133 static DEVICE_ULONG_ATTR(retry_count, 0444, balloon_stats.retry_count);
134 static DEVICE_ULONG_ATTR(max_retry_count, 0644, balloon_stats.max_retry_count);
135
136 static ssize_t show_target_kb(struct device *dev, struct device_attribute *attr,
137                               char *buf)
138 {
139         return sprintf(buf, "%lu\n", PAGES2KB(balloon_stats.target_pages));
140 }
141
142 static ssize_t store_target_kb(struct device *dev,
143                                struct device_attribute *attr,
144                                const char *buf,
145                                size_t count)
146 {
147         char *endchar;
148         unsigned long long target_bytes;
149
150         if (!capable(CAP_SYS_ADMIN))
151                 return -EPERM;
152
153         target_bytes = simple_strtoull(buf, &endchar, 0) * 1024;
154
155         balloon_set_new_target(target_bytes >> PAGE_SHIFT);
156
157         return count;
158 }
159
160 static DEVICE_ATTR(target_kb, S_IRUGO | S_IWUSR,
161                    show_target_kb, store_target_kb);
162
163
164 static ssize_t show_target(struct device *dev, struct device_attribute *attr,
165                               char *buf)
166 {
167         return sprintf(buf, "%llu\n",
168                        (unsigned long long)balloon_stats.target_pages
169                        << PAGE_SHIFT);
170 }
171
172 static ssize_t store_target(struct device *dev,
173                             struct device_attribute *attr,
174                             const char *buf,
175                             size_t count)
176 {
177         char *endchar;
178         unsigned long long target_bytes;
179
180         if (!capable(CAP_SYS_ADMIN))
181                 return -EPERM;
182
183         target_bytes = memparse(buf, &endchar);
184
185         balloon_set_new_target(target_bytes >> PAGE_SHIFT);
186
187         return count;
188 }
189
190 static DEVICE_ATTR(target, S_IRUGO | S_IWUSR,
191                    show_target, store_target);
192
193
194 static struct device_attribute *balloon_attrs[] = {
195         &dev_attr_target_kb,
196         &dev_attr_target,
197         &dev_attr_schedule_delay.attr,
198         &dev_attr_max_schedule_delay.attr,
199         &dev_attr_retry_count.attr,
200         &dev_attr_max_retry_count.attr
201 };
202
203 static struct attribute *balloon_info_attrs[] = {
204         &dev_attr_current_kb.attr,
205         &dev_attr_low_kb.attr,
206         &dev_attr_high_kb.attr,
207         NULL
208 };
209
210 static const struct attribute_group balloon_info_group = {
211         .name = "info",
212         .attrs = balloon_info_attrs
213 };
214
215 static struct bus_type balloon_subsys = {
216         .name = BALLOON_CLASS_NAME,
217         .dev_name = BALLOON_CLASS_NAME,
218 };
219
220 static int register_balloon(struct device *dev)
221 {
222         int i, error;
223
224         error = bus_register(&balloon_subsys);
225         if (error)
226                 return error;
227
228         dev->id = 0;
229         dev->bus = &balloon_subsys;
230
231         error = device_register(dev);
232         if (error) {
233                 bus_unregister(&balloon_subsys);
234                 return error;
235         }
236
237         for (i = 0; i < ARRAY_SIZE(balloon_attrs); i++) {
238                 error = device_create_file(dev, balloon_attrs[i]);
239                 if (error)
240                         goto fail;
241         }
242
243         error = sysfs_create_group(&dev->kobj, &balloon_info_group);
244         if (error)
245                 goto fail;
246
247         return 0;
248
249  fail:
250         while (--i >= 0)
251                 device_remove_file(dev, balloon_attrs[i]);
252         device_unregister(dev);
253         bus_unregister(&balloon_subsys);
254         return error;
255 }
256
257 MODULE_LICENSE("GPL");