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 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt 34 35 #include <linux/kernel.h> 36 #include <linux/errno.h> 37 #include <linux/mm_types.h> 38 #include <linux/init.h> 39 #include <linux/capability.h> 40 41 #include <xen/xen.h> 42 #include <xen/interface/xen.h> 43 #include <xen/balloon.h> 44 #include <xen/xenbus.h> 45 #include <xen/features.h> 46 #include <xen/page.h> 47 #include <xen/mem-reservation.h> 48 49 #define PAGES2KB(_p) ((_p)<<(PAGE_SHIFT-10)) 50 51 #define BALLOON_CLASS_NAME "xen_memory" 52 53 static struct device balloon_dev; 54 55 static int register_balloon(struct device *dev); 56 57 /* React to a change in the target key */ 58 static void watch_target(struct xenbus_watch *watch, 59 const char *path, const char *token) 60 { 61 unsigned long long new_target, static_max; 62 int err; 63 static bool watch_fired; 64 static long target_diff; 65 66 err = xenbus_scanf(XBT_NIL, "memory", "target", "%llu", &new_target); 67 if (err != 1) { 68 /* This is ok (for domain0 at least) - so just return */ 69 return; 70 } 71 72 /* The given memory/target value is in KiB, so it needs converting to 73 * pages. PAGE_SHIFT converts bytes to pages, hence PAGE_SHIFT - 10. 74 */ 75 new_target >>= PAGE_SHIFT - 10; 76 77 if (!watch_fired) { 78 watch_fired = true; 79 80 if ((xenbus_scanf(XBT_NIL, "memory", "static-max", 81 "%llu", &static_max) == 1) || 82 (xenbus_scanf(XBT_NIL, "memory", "memory_static_max", 83 "%llu", &static_max) == 1)) 84 static_max >>= PAGE_SHIFT - 10; 85 else 86 static_max = new_target; 87 88 target_diff = (xen_pv_domain() || xen_initial_domain()) ? 0 89 : static_max - balloon_stats.target_pages; 90 } 91 92 balloon_set_new_target(new_target - target_diff); 93 } 94 static struct xenbus_watch target_watch = { 95 .node = "memory/target", 96 .callback = watch_target, 97 }; 98 99 100 static int balloon_init_watcher(struct notifier_block *notifier, 101 unsigned long event, 102 void *data) 103 { 104 int err; 105 106 err = register_xenbus_watch(&target_watch); 107 if (err) 108 pr_err("Failed to set balloon watcher\n"); 109 110 return NOTIFY_DONE; 111 } 112 113 static struct notifier_block xenstore_notifier = { 114 .notifier_call = balloon_init_watcher, 115 }; 116 117 void xen_balloon_init(void) 118 { 119 register_balloon(&balloon_dev); 120 121 register_xen_selfballooning(&balloon_dev); 122 123 register_xenstore_notifier(&xenstore_notifier); 124 } 125 EXPORT_SYMBOL_GPL(xen_balloon_init); 126 127 #define BALLOON_SHOW(name, format, args...) \ 128 static ssize_t show_##name(struct device *dev, \ 129 struct device_attribute *attr, \ 130 char *buf) \ 131 { \ 132 return sprintf(buf, format, ##args); \ 133 } \ 134 static DEVICE_ATTR(name, S_IRUGO, show_##name, NULL) 135 136 BALLOON_SHOW(current_kb, "%lu\n", PAGES2KB(balloon_stats.current_pages)); 137 BALLOON_SHOW(low_kb, "%lu\n", PAGES2KB(balloon_stats.balloon_low)); 138 BALLOON_SHOW(high_kb, "%lu\n", PAGES2KB(balloon_stats.balloon_high)); 139 140 static DEVICE_ULONG_ATTR(schedule_delay, 0444, balloon_stats.schedule_delay); 141 static DEVICE_ULONG_ATTR(max_schedule_delay, 0644, balloon_stats.max_schedule_delay); 142 static DEVICE_ULONG_ATTR(retry_count, 0444, balloon_stats.retry_count); 143 static DEVICE_ULONG_ATTR(max_retry_count, 0644, balloon_stats.max_retry_count); 144 static DEVICE_BOOL_ATTR(scrub_pages, 0644, xen_scrub_pages); 145 146 static ssize_t show_target_kb(struct device *dev, struct device_attribute *attr, 147 char *buf) 148 { 149 return sprintf(buf, "%lu\n", PAGES2KB(balloon_stats.target_pages)); 150 } 151 152 static ssize_t store_target_kb(struct device *dev, 153 struct device_attribute *attr, 154 const char *buf, 155 size_t count) 156 { 157 char *endchar; 158 unsigned long long target_bytes; 159 160 if (!capable(CAP_SYS_ADMIN)) 161 return -EPERM; 162 163 target_bytes = simple_strtoull(buf, &endchar, 0) * 1024; 164 165 balloon_set_new_target(target_bytes >> PAGE_SHIFT); 166 167 return count; 168 } 169 170 static DEVICE_ATTR(target_kb, S_IRUGO | S_IWUSR, 171 show_target_kb, store_target_kb); 172 173 174 static ssize_t show_target(struct device *dev, struct device_attribute *attr, 175 char *buf) 176 { 177 return sprintf(buf, "%llu\n", 178 (unsigned long long)balloon_stats.target_pages 179 << PAGE_SHIFT); 180 } 181 182 static ssize_t store_target(struct device *dev, 183 struct device_attribute *attr, 184 const char *buf, 185 size_t count) 186 { 187 char *endchar; 188 unsigned long long target_bytes; 189 190 if (!capable(CAP_SYS_ADMIN)) 191 return -EPERM; 192 193 target_bytes = memparse(buf, &endchar); 194 195 balloon_set_new_target(target_bytes >> PAGE_SHIFT); 196 197 return count; 198 } 199 200 static DEVICE_ATTR(target, S_IRUGO | S_IWUSR, 201 show_target, store_target); 202 203 204 static struct attribute *balloon_attrs[] = { 205 &dev_attr_target_kb.attr, 206 &dev_attr_target.attr, 207 &dev_attr_schedule_delay.attr.attr, 208 &dev_attr_max_schedule_delay.attr.attr, 209 &dev_attr_retry_count.attr.attr, 210 &dev_attr_max_retry_count.attr.attr, 211 &dev_attr_scrub_pages.attr.attr, 212 NULL 213 }; 214 215 static const struct attribute_group balloon_group = { 216 .attrs = balloon_attrs 217 }; 218 219 static struct attribute *balloon_info_attrs[] = { 220 &dev_attr_current_kb.attr, 221 &dev_attr_low_kb.attr, 222 &dev_attr_high_kb.attr, 223 NULL 224 }; 225 226 static const struct attribute_group balloon_info_group = { 227 .name = "info", 228 .attrs = balloon_info_attrs 229 }; 230 231 static const struct attribute_group *balloon_groups[] = { 232 &balloon_group, 233 &balloon_info_group, 234 NULL 235 }; 236 237 static struct bus_type balloon_subsys = { 238 .name = BALLOON_CLASS_NAME, 239 .dev_name = BALLOON_CLASS_NAME, 240 }; 241 242 static int register_balloon(struct device *dev) 243 { 244 int error; 245 246 error = subsys_system_register(&balloon_subsys, NULL); 247 if (error) 248 return error; 249 250 dev->id = 0; 251 dev->bus = &balloon_subsys; 252 dev->groups = balloon_groups; 253 254 error = device_register(dev); 255 if (error) { 256 bus_unregister(&balloon_subsys); 257 return error; 258 } 259 260 return 0; 261 } 262