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/sysdev.h> 36 #include <linux/capability.h> 37 38 #include <xen/xen.h> 39 #include <xen/interface/xen.h> 40 #include <xen/balloon.h> 41 #include <xen/xenbus.h> 42 #include <xen/features.h> 43 #include <xen/page.h> 44 45 #define PAGES2KB(_p) ((_p)<<(PAGE_SHIFT-10)) 46 47 #define BALLOON_CLASS_NAME "xen_memory" 48 49 static struct sys_device balloon_sysdev; 50 51 static int register_balloon(struct sys_device *sysdev); 52 53 /* React to a change in the target key */ 54 static void watch_target(struct xenbus_watch *watch, 55 const char **vec, unsigned int len) 56 { 57 unsigned long long new_target; 58 int err; 59 60 err = xenbus_scanf(XBT_NIL, "memory", "target", "%llu", &new_target); 61 if (err != 1) { 62 /* This is ok (for domain0 at least) - so just return */ 63 return; 64 } 65 66 /* The given memory/target value is in KiB, so it needs converting to 67 * pages. PAGE_SHIFT converts bytes to pages, hence PAGE_SHIFT - 10. 68 */ 69 balloon_set_new_target(new_target >> (PAGE_SHIFT - 10)); 70 } 71 static struct xenbus_watch target_watch = { 72 .node = "memory/target", 73 .callback = watch_target, 74 }; 75 76 77 static int balloon_init_watcher(struct notifier_block *notifier, 78 unsigned long event, 79 void *data) 80 { 81 int err; 82 83 err = register_xenbus_watch(&target_watch); 84 if (err) 85 printk(KERN_ERR "Failed to set balloon watcher\n"); 86 87 return NOTIFY_DONE; 88 } 89 90 static struct notifier_block xenstore_notifier = { 91 .notifier_call = balloon_init_watcher, 92 }; 93 94 static int __init balloon_init(void) 95 { 96 if (!xen_domain()) 97 return -ENODEV; 98 99 pr_info("xen-balloon: Initialising balloon driver.\n"); 100 101 register_balloon(&balloon_sysdev); 102 103 register_xen_selfballooning(&balloon_sysdev); 104 105 register_xenstore_notifier(&xenstore_notifier); 106 107 return 0; 108 } 109 subsys_initcall(balloon_init); 110 111 static void balloon_exit(void) 112 { 113 /* XXX - release balloon here */ 114 return; 115 } 116 117 module_exit(balloon_exit); 118 119 #define BALLOON_SHOW(name, format, args...) \ 120 static ssize_t show_##name(struct sys_device *dev, \ 121 struct sysdev_attribute *attr, \ 122 char *buf) \ 123 { \ 124 return sprintf(buf, format, ##args); \ 125 } \ 126 static SYSDEV_ATTR(name, S_IRUGO, show_##name, NULL) 127 128 BALLOON_SHOW(current_kb, "%lu\n", PAGES2KB(balloon_stats.current_pages)); 129 BALLOON_SHOW(low_kb, "%lu\n", PAGES2KB(balloon_stats.balloon_low)); 130 BALLOON_SHOW(high_kb, "%lu\n", PAGES2KB(balloon_stats.balloon_high)); 131 132 static SYSDEV_ULONG_ATTR(schedule_delay, 0444, balloon_stats.schedule_delay); 133 static SYSDEV_ULONG_ATTR(max_schedule_delay, 0644, balloon_stats.max_schedule_delay); 134 static SYSDEV_ULONG_ATTR(retry_count, 0444, balloon_stats.retry_count); 135 static SYSDEV_ULONG_ATTR(max_retry_count, 0644, balloon_stats.max_retry_count); 136 137 static ssize_t show_target_kb(struct sys_device *dev, struct sysdev_attribute *attr, 138 char *buf) 139 { 140 return sprintf(buf, "%lu\n", PAGES2KB(balloon_stats.target_pages)); 141 } 142 143 static ssize_t store_target_kb(struct sys_device *dev, 144 struct sysdev_attribute *attr, 145 const char *buf, 146 size_t count) 147 { 148 char *endchar; 149 unsigned long long target_bytes; 150 151 if (!capable(CAP_SYS_ADMIN)) 152 return -EPERM; 153 154 target_bytes = simple_strtoull(buf, &endchar, 0) * 1024; 155 156 balloon_set_new_target(target_bytes >> PAGE_SHIFT); 157 158 return count; 159 } 160 161 static SYSDEV_ATTR(target_kb, S_IRUGO | S_IWUSR, 162 show_target_kb, store_target_kb); 163 164 165 static ssize_t show_target(struct sys_device *dev, struct sysdev_attribute *attr, 166 char *buf) 167 { 168 return sprintf(buf, "%llu\n", 169 (unsigned long long)balloon_stats.target_pages 170 << PAGE_SHIFT); 171 } 172 173 static ssize_t store_target(struct sys_device *dev, 174 struct sysdev_attribute *attr, 175 const char *buf, 176 size_t count) 177 { 178 char *endchar; 179 unsigned long long target_bytes; 180 181 if (!capable(CAP_SYS_ADMIN)) 182 return -EPERM; 183 184 target_bytes = memparse(buf, &endchar); 185 186 balloon_set_new_target(target_bytes >> PAGE_SHIFT); 187 188 return count; 189 } 190 191 static SYSDEV_ATTR(target, S_IRUGO | S_IWUSR, 192 show_target, store_target); 193 194 195 static struct sysdev_attribute *balloon_attrs[] = { 196 &attr_target_kb, 197 &attr_target, 198 &attr_schedule_delay.attr, 199 &attr_max_schedule_delay.attr, 200 &attr_retry_count.attr, 201 &attr_max_retry_count.attr 202 }; 203 204 static struct attribute *balloon_info_attrs[] = { 205 &attr_current_kb.attr, 206 &attr_low_kb.attr, 207 &attr_high_kb.attr, 208 NULL 209 }; 210 211 static struct attribute_group balloon_info_group = { 212 .name = "info", 213 .attrs = balloon_info_attrs 214 }; 215 216 static struct sysdev_class balloon_sysdev_class = { 217 .name = BALLOON_CLASS_NAME 218 }; 219 220 static int register_balloon(struct sys_device *sysdev) 221 { 222 int i, error; 223 224 error = sysdev_class_register(&balloon_sysdev_class); 225 if (error) 226 return error; 227 228 sysdev->id = 0; 229 sysdev->cls = &balloon_sysdev_class; 230 231 error = sysdev_register(sysdev); 232 if (error) { 233 sysdev_class_unregister(&balloon_sysdev_class); 234 return error; 235 } 236 237 for (i = 0; i < ARRAY_SIZE(balloon_attrs); i++) { 238 error = sysdev_create_file(sysdev, balloon_attrs[i]); 239 if (error) 240 goto fail; 241 } 242 243 error = sysfs_create_group(&sysdev->kobj, &balloon_info_group); 244 if (error) 245 goto fail; 246 247 return 0; 248 249 fail: 250 while (--i >= 0) 251 sysdev_remove_file(sysdev, balloon_attrs[i]); 252 sysdev_unregister(sysdev); 253 sysdev_class_unregister(&balloon_sysdev_class); 254 return error; 255 } 256 257 MODULE_LICENSE("GPL"); 258