1 files changed, 256 insertions, 0 deletions

diff --git a/drivers/xen/xen-balloon.c b/drivers/xen/xen-balloon.c
new file mode 100644
index 000000000000..a4ff225ee868
--- /dev/null
+++ b/drivers/xen/xen-balloon.c
@@ -0,0 +1,256 @@
+/******************************************************************************
+ * 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.
+ */
+
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/sysdev.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 sys_device balloon_sysdev;
+
+static int register_balloon(struct sys_device *sysdev);
+
+static struct xenbus_watch target_watch =
+{
+        .node = "memory/target"
+};
+
+/* 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 int balloon_init_watcher(struct notifier_block *notifier,
+                                unsigned long event,
+                                void *data)
+{
+        int err;
+
+        err = register_xenbus_watch(&target_watch);
+        if (err)
+                printk(KERN_ERR "Failed to set balloon watcher\n");
+
+        return NOTIFY_DONE;
+}
+
+static struct notifier_block xenstore_notifier;
+
+static int __init balloon_init(void)
+{
+        if (!xen_domain())
+                return -ENODEV;
+
+        pr_info("xen-balloon: Initialising balloon driver.\n");
+
+        register_balloon(&balloon_sysdev);
+
+        target_watch.callback = watch_target;
+        xenstore_notifier.notifier_call = balloon_init_watcher;
+
+        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 sys_device *dev,              \
+                                   struct sysdev_attribute *attr,       \
+                                   char *buf)                           \
+        {                                                               \
+                return sprintf(buf, format, ##args);                    \
+        }                                                               \
+        static SYSDEV_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 SYSDEV_ULONG_ATTR(schedule_delay, 0444, balloon_stats.schedule_delay);
+static SYSDEV_ULONG_ATTR(max_schedule_delay, 0644, balloon_stats.max_schedule_delay);
+static SYSDEV_ULONG_ATTR(retry_count, 0444, balloon_stats.retry_count);
+static SYSDEV_ULONG_ATTR(max_retry_count, 0644, balloon_stats.max_retry_count);
+
+static ssize_t show_target_kb(struct sys_device *dev, struct sysdev_attribute *attr,
+                              char *buf)
+{
+        return sprintf(buf, "%lu\n", PAGES2KB(balloon_stats.target_pages));
+}
+
+static ssize_t store_target_kb(struct sys_device *dev,
+                               struct sysdev_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 SYSDEV_ATTR(target_kb, S_IRUGO | S_IWUSR,
+                   show_target_kb, store_target_kb);
+
+
+static ssize_t show_target(struct sys_device *dev, struct sysdev_attribute *attr,
+                              char *buf)
+{
+        return sprintf(buf, "%llu\n",
+                       (unsigned long long)balloon_stats.target_pages
+                       << PAGE_SHIFT);
+}
+
+static ssize_t store_target(struct sys_device *dev,
+                            struct sysdev_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 SYSDEV_ATTR(target, S_IRUGO | S_IWUSR,
+                   show_target, store_target);
+
+
+static struct sysdev_attribute *balloon_attrs[] = {
+        &attr_target_kb,
+        &attr_target,
+        &attr_schedule_delay.attr,
+        &attr_max_schedule_delay.attr,
+        &attr_retry_count.attr,
+        &attr_max_retry_count.attr
+};
+
+static struct attribute *balloon_info_attrs[] = {
+        &attr_current_kb.attr,
+        &attr_low_kb.attr,
+        &attr_high_kb.attr,
+        NULL
+};
+
+static struct attribute_group balloon_info_group = {
+        .name = "info",
+        .attrs = balloon_info_attrs
+};
+
+static struct sysdev_class balloon_sysdev_class = {
+        .name = BALLOON_CLASS_NAME
+};
+
+static int register_balloon(struct sys_device *sysdev)
+{
+        int i, error;
+
+        error = sysdev_class_register(&balloon_sysdev_class);
+        if (error)
+                return error;
+
+        sysdev->id = 0;
+        sysdev->cls = &balloon_sysdev_class;
+
+        error = sysdev_register(sysdev);
+        if (error) {
+                sysdev_class_unregister(&balloon_sysdev_class);
+                return error;
+        }
+
+        for (i = 0; i < ARRAY_SIZE(balloon_attrs); i++) {
+                error = sysdev_create_file(sysdev, balloon_attrs[i]);
+                if (error)
+                        goto fail;
+        }
+
+        error = sysfs_create_group(&sysdev->kobj, &balloon_info_group);
+        if (error)
+                goto fail;
+
+        return 0;
+
+ fail:
+        while (--i >= 0)
+                sysdev_remove_file(sysdev, balloon_attrs[i]);
+        sysdev_unregister(sysdev);
+        sysdev_class_unregister(&balloon_sysdev_class);
+        return error;
+}
+
+MODULE_LICENSE("GPL");