/****************************************************************************** * Xen balloon driver - enables returning/claiming memory to/from Xen. * * Copyright (c) 2003, B Dragovic * Copyright (c) 2003-2004, M Williamson, K Fraser * Copyright (c) 2005 Dan M. Smith, IBM Corporation * * This program is free software; you can redistribute it and/or * modify it under the terms of the GNU General Public License version 2 * as published by the Free Software Foundation; or, when distributed * separately from the Linux kernel or incorporated into other * software packages, subject to the following license: * * Permission is hereby granted, free of charge, to any person obtaining a copy * of this source file (the "Software"), to deal in the Software without * restriction, including without limitation the rights to use, copy, modify, * merge, publish, distribute, sublicense, and/or sell copies of the Software, * and to permit persons to whom the Software is furnished to do so, subject to * the following conditions: * * The above copyright notice and this permission notice shall be included in * all copies or substantial portions of the Software. * * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS * IN THE SOFTWARE. */ #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt #include <linux/kernel.h> #include <linux/errno.h> #include <linux/mm_types.h> #include <linux/init.h> #include <linux/capability.h> #include <xen/xen.h> #include <xen/interface/xen.h> #include <xen/balloon.h> #include <xen/xenbus.h> #include <xen/features.h> #include <xen/page.h> #define PAGES2KB(_p) ((_p)<<(PAGE_SHIFT-10)) #define BALLOON_CLASS_NAME "xen_memory" static struct device balloon_dev; static int register_balloon(struct device *dev); /* React to a change in the target key */ static void watch_target(struct xenbus_watch *watch, const char **vec, unsigned int len) { unsigned long long new_target; int err; err = xenbus_scanf(XBT_NIL, "memory", "target", "%llu", &new_target); if (err != 1) { /* This is ok (for domain0 at least) - so just return */ return; } /* The given memory/target value is in KiB, so it needs converting to * pages. PAGE_SHIFT converts bytes to pages, hence PAGE_SHIFT - 10. */ balloon_set_new_target(new_target >> (PAGE_SHIFT - 10)); } static struct xenbus_watch target_watch = { .node = "memory/target", .callback = watch_target, }; static int balloon_init_watcher(struct notifier_block *notifier, unsigned long event, void *data) { int err; err = register_xenbus_watch(&target_watch); if (err) pr_err("Failed to set balloon watcher\n"); return NOTIFY_DONE; } static struct notifier_block xenstore_notifier = { .notifier_call = balloon_init_watcher, }; static int __init balloon_init(void) { if (!xen_domain()) return -ENODEV; pr_info("Initialising balloon driver\n"); register_balloon(&balloon_dev); register_xen_selfballooning(&balloon_dev); register_xenstore_notifier(&xenstore_notifier); return 0; } subsys_initcall(balloon_init); #define BALLOON_SHOW(name, format, args...) \ static ssize_t show_##name(struct device *dev, \ struct device_attribute *attr, \ char *buf) \ { \ return sprintf(buf, format, ##args); \ } \ static DEVICE_ATTR(name, S_IRUGO, show_##name, NULL) BALLOON_SHOW(current_kb, "%lu\n", PAGES2KB(balloon_stats.current_pages)); BALLOON_SHOW(low_kb, "%lu\n", PAGES2KB(balloon_stats.balloon_low)); BALLOON_SHOW(high_kb, "%lu\n", PAGES2KB(balloon_stats.balloon_high)); static DEVICE_ULONG_ATTR(schedule_delay, 0444, balloon_stats.schedule_delay); static DEVICE_ULONG_ATTR(max_schedule_delay, 0644, balloon_stats.max_schedule_delay); static DEVICE_ULONG_ATTR(retry_count, 0444, balloon_stats.retry_count); static DEVICE_ULONG_ATTR(max_retry_count, 0644, balloon_stats.max_retry_count); static ssize_t show_target_kb(struct device *dev, struct device_attribute *attr, char *buf) { return sprintf(buf, "%lu\n", PAGES2KB(balloon_stats.target_pages)); } static ssize_t store_target_kb(struct device *dev, struct device_attribute *attr, const char *buf, size_t count) { char *endchar; unsigned long long target_bytes; if (!capable(CAP_SYS_ADMIN)) return -EPERM; target_bytes = simple_strtoull(buf, &endchar, 0) * 1024; balloon_set_new_target(target_bytes >> PAGE_SHIFT); return count; } static DEVICE_ATTR(target_kb, S_IRUGO | S_IWUSR, show_target_kb, store_target_kb); static ssize_t show_target(struct device *dev, struct device_attribute *attr, char *buf) { return sprintf(buf, "%llu\n", (unsigned long long)balloon_stats.target_pages << PAGE_SHIFT); } static ssize_t store_target(struct device *dev, struct device_attribute *attr, const char *buf, size_t count) { char *endchar; unsigned long long target_bytes; if (!capable(CAP_SYS_ADMIN)) return -EPERM; target_bytes = memparse(buf, &endchar); balloon_set_new_target(target_bytes >> PAGE_SHIFT); return count; } static DEVICE_ATTR(target, S_IRUGO | S_IWUSR, show_target, store_target); static struct attribute *balloon_attrs[] = { &dev_attr_target_kb.attr, &dev_attr_target.attr, &dev_attr_schedule_delay.attr.attr, &dev_attr_max_schedule_delay.attr.attr, &dev_attr_retry_count.attr.attr, &dev_attr_max_retry_count.attr.attr, NULL }; static const struct attribute_group balloon_group = { .attrs = balloon_attrs }; static struct attribute *balloon_info_attrs[] = { &dev_attr_current_kb.attr, &dev_attr_low_kb.attr, &dev_attr_high_kb.attr, NULL }; static const struct attribute_group balloon_info_group = { .name = "info", .attrs = balloon_info_attrs }; static const struct attribute_group *balloon_groups[] = { &balloon_group, &balloon_info_group, NULL }; static struct bus_type balloon_subsys = { .name = BALLOON_CLASS_NAME, .dev_name = BALLOON_CLASS_NAME, }; static int register_balloon(struct device *dev) { int error; error = subsys_system_register(&balloon_subsys, NULL); if (error) return error; dev->id = 0; dev->bus = &balloon_subsys; dev->groups = balloon_groups; error = device_register(dev); if (error) { bus_unregister(&balloon_subsys); return error; } return 0; }