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33#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
34
35#include <linux/kernel.h>
36#include <linux/module.h>
37#include <linux/capability.h>
38
39#include <xen/xen.h>
40#include <xen/interface/xen.h>
41#include <xen/balloon.h>
42#include <xen/xenbus.h>
43#include <xen/features.h>
44#include <xen/page.h>
45
46#define PAGES2KB(_p) ((_p)<<(PAGE_SHIFT-10))
47
48#define BALLOON_CLASS_NAME "xen_memory"
49
50static struct device balloon_dev;
51
52static int register_balloon(struct device *dev);
53
54
55static void watch_target(struct xenbus_watch *watch,
56 const char **vec, unsigned int len)
57{
58 unsigned long long new_target;
59 int err;
60
61 err = xenbus_scanf(XBT_NIL, "memory", "target", "%llu", &new_target);
62 if (err != 1) {
63
64 return;
65 }
66
67
68
69
70 balloon_set_new_target(new_target >> (PAGE_SHIFT - 10));
71}
72static struct xenbus_watch target_watch = {
73 .node = "memory/target",
74 .callback = watch_target,
75};
76
77
78static int balloon_init_watcher(struct notifier_block *notifier,
79 unsigned long event,
80 void *data)
81{
82 int err;
83
84 err = register_xenbus_watch(&target_watch);
85 if (err)
86 pr_err("Failed to set balloon watcher\n");
87
88 return NOTIFY_DONE;
89}
90
91static struct notifier_block xenstore_notifier = {
92 .notifier_call = balloon_init_watcher,
93};
94
95static int __init balloon_init(void)
96{
97 if (!xen_domain())
98 return -ENODEV;
99
100 pr_info("Initialising balloon driver\n");
101
102 register_balloon(&balloon_dev);
103
104 register_xen_selfballooning(&balloon_dev);
105
106 register_xenstore_notifier(&xenstore_notifier);
107
108 return 0;
109}
110subsys_initcall(balloon_init);
111
112static void balloon_exit(void)
113{
114
115 return;
116}
117
118module_exit(balloon_exit);
119
120#define BALLOON_SHOW(name, format, args...) \
121 static ssize_t show_##name(struct device *dev, \
122 struct device_attribute *attr, \
123 char *buf) \
124 { \
125 return sprintf(buf, format, ##args); \
126 } \
127 static DEVICE_ATTR(name, S_IRUGO, show_##name, NULL)
128
129BALLOON_SHOW(current_kb, "%lu\n", PAGES2KB(balloon_stats.current_pages));
130BALLOON_SHOW(low_kb, "%lu\n", PAGES2KB(balloon_stats.balloon_low));
131BALLOON_SHOW(high_kb, "%lu\n", PAGES2KB(balloon_stats.balloon_high));
132
133static DEVICE_ULONG_ATTR(schedule_delay, 0444, balloon_stats.schedule_delay);
134static DEVICE_ULONG_ATTR(max_schedule_delay, 0644, balloon_stats.max_schedule_delay);
135static DEVICE_ULONG_ATTR(retry_count, 0444, balloon_stats.retry_count);
136static DEVICE_ULONG_ATTR(max_retry_count, 0644, balloon_stats.max_retry_count);
137
138static ssize_t show_target_kb(struct device *dev, struct device_attribute *attr,
139 char *buf)
140{
141 return sprintf(buf, "%lu\n", PAGES2KB(balloon_stats.target_pages));
142}
143
144static ssize_t store_target_kb(struct device *dev,
145 struct device_attribute *attr,
146 const char *buf,
147 size_t count)
148{
149 char *endchar;
150 unsigned long long target_bytes;
151
152 if (!capable(CAP_SYS_ADMIN))
153 return -EPERM;
154
155 target_bytes = simple_strtoull(buf, &endchar, 0) * 1024;
156
157 balloon_set_new_target(target_bytes >> PAGE_SHIFT);
158
159 return count;
160}
161
162static DEVICE_ATTR(target_kb, S_IRUGO | S_IWUSR,
163 show_target_kb, store_target_kb);
164
165
166static ssize_t show_target(struct device *dev, struct device_attribute *attr,
167 char *buf)
168{
169 return sprintf(buf, "%llu\n",
170 (unsigned long long)balloon_stats.target_pages
171 << PAGE_SHIFT);
172}
173
174static ssize_t store_target(struct device *dev,
175 struct device_attribute *attr,
176 const char *buf,
177 size_t count)
178{
179 char *endchar;
180 unsigned long long target_bytes;
181
182 if (!capable(CAP_SYS_ADMIN))
183 return -EPERM;
184
185 target_bytes = memparse(buf, &endchar);
186
187 balloon_set_new_target(target_bytes >> PAGE_SHIFT);
188
189 return count;
190}
191
192static DEVICE_ATTR(target, S_IRUGO | S_IWUSR,
193 show_target, store_target);
194
195
196static struct device_attribute *balloon_attrs[] = {
197 &dev_attr_target_kb,
198 &dev_attr_target,
199 &dev_attr_schedule_delay.attr,
200 &dev_attr_max_schedule_delay.attr,
201 &dev_attr_retry_count.attr,
202 &dev_attr_max_retry_count.attr
203};
204
205static struct attribute *balloon_info_attrs[] = {
206 &dev_attr_current_kb.attr,
207 &dev_attr_low_kb.attr,
208 &dev_attr_high_kb.attr,
209 NULL
210};
211
212static const struct attribute_group balloon_info_group = {
213 .name = "info",
214 .attrs = balloon_info_attrs
215};
216
217static struct bus_type balloon_subsys = {
218 .name = BALLOON_CLASS_NAME,
219 .dev_name = BALLOON_CLASS_NAME,
220};
221
222static int register_balloon(struct device *dev)
223{
224 int i, error;
225
226 error = subsys_system_register(&balloon_subsys, NULL);
227 if (error)
228 return error;
229
230 dev->id = 0;
231 dev->bus = &balloon_subsys;
232
233 error = device_register(dev);
234 if (error) {
235 bus_unregister(&balloon_subsys);
236 return error;
237 }
238
239 for (i = 0; i < ARRAY_SIZE(balloon_attrs); i++) {
240 error = device_create_file(dev, balloon_attrs[i]);
241 if (error)
242 goto fail;
243 }
244
245 error = sysfs_create_group(&dev->kobj, &balloon_info_group);
246 if (error)
247 goto fail;
248
249 return 0;
250
251 fail:
252 while (--i >= 0)
253 device_remove_file(dev, balloon_attrs[i]);
254 device_unregister(dev);
255 bus_unregister(&balloon_subsys);
256 return error;
257}
258
259MODULE_LICENSE("GPL");
260