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Diffstat (limited to 'drivers/xen/xen-balloon.c')
| -rw-r--r-- | drivers/xen/xen-balloon.c | 254 |
1 files changed, 254 insertions, 0 deletions
diff --git a/drivers/xen/xen-balloon.c b/drivers/xen/xen-balloon.c new file mode 100644 index 000000000..39e7ef8d3 --- /dev/null +++ b/drivers/xen/xen-balloon.c @@ -0,0 +1,254 @@ +/****************************************************************************** + * 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/module.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); + +static void balloon_exit(void) +{ + /* XXX - release balloon here */ + return; +} + +module_exit(balloon_exit); + +#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; +} + +MODULE_LICENSE("GPL"); |