[PATCH] Xen watchdog driver

[PATCH] Xen watchdog driver

[Jan Beulich]

[-- Attachment #1: Type: text/plain, Size: 12102 bytes --]

While the hypervisor change adding SCHEDOP_watchdog support included a
daemon to make use of the new functionality, having a kernel driver
for /dev/watchdog so that user space code doesn't need to distinguish
non-Xen and Xen seems to be preferable.

Signed-off-by: Jan Beulich <jbeulich@novell.com>

---
 drivers/watchdog/Kconfig      |   10 +
 drivers/watchdog/Makefile     |    3 
 drivers/watchdog/xen_wdt.c    |  359 ++++++++++++++++++++++++++++++++++++++++++
 include/xen/interface/sched.h |   34 +++
 4 files changed, 406 insertions(+)

--- linux-2.6.36-rc6/drivers/watchdog/Kconfig
+++ 2.6.36-rc6-xen-watchdog/drivers/watchdog/Kconfig
@@ -1043,6 +1043,16 @@ config WATCHDOG_RIO
 
 # XTENSA Architecture
 
+# Xen Architecture
+
+config XEN_WDT
+	tristate "Xen Watchdog support"
+	depends on XEN
+	help
+	  Say Y here to support the hypervisor watchdog capability provided
+	  by Xen 4.0 and newer.  The watchdog timeout period is normally one
+	  minute but can be changed with a boot-time parameter.
+
 #
 # ISA-based Watchdog Cards
 #
--- linux-2.6.36-rc6/drivers/watchdog/Makefile
+++ 2.6.36-rc6-xen-watchdog/drivers/watchdog/Makefile
@@ -145,6 +145,9 @@ obj-$(CONFIG_WATCHDOG_CP1XXX)		+= cpwd.o
 
 # XTENSA Architecture
 
+# Xen
+obj-$(CONFIG_XEN_WDT) += xen_wdt.o
+
 # Architecture Independant
 obj-$(CONFIG_WM831X_WATCHDOG) += wm831x_wdt.o
 obj-$(CONFIG_WM8350_WATCHDOG) += wm8350_wdt.o
--- linux-2.6.36-rc6/drivers/watchdog/xen_wdt.c
+++ 2.6.36-rc6-xen-watchdog/drivers/watchdog/xen_wdt.c
@@ -0,0 +1,359 @@
+/*
+ *	Xen Watchdog Driver
+ *
+ *	(c) Copyright 2010 Novell, Inc.
+ *
+ *	This program is free software; you can redistribute it and/or
+ *	modify it under the terms of the GNU General Public License
+ *	as published by the Free Software Foundation; either version
+ *	2 of the License, or (at your option) any later version.
+ */
+
+#define DRV_NAME	"wdt"
+#define DRV_VERSION	"0.01"
+#define PFX		DRV_NAME ": "
+
+#include <linux/bug.h>
+#include <linux/errno.h>
+#include <linux/fs.h>
+#include <linux/hrtimer.h>
+#include <linux/kernel.h>
+#include <linux/ktime.h>
+#include <linux/init.h>
+#include <linux/miscdevice.h>
+#include <linux/module.h>
+#include <linux/moduleparam.h>
+#include <linux/platform_device.h>
+#include <linux/spinlock.h>
+#include <linux/uaccess.h>
+#include <linux/watchdog.h>
+#include <xen/xen.h>
+#include <asm/xen/hypercall.h>
+#include <xen/interface/sched.h>
+
+static struct platform_device *platform_device;
+static DEFINE_SPINLOCK(wdt_lock);
+static struct sched_watchdog wdt;
+static __kernel_time_t wdt_expires;
+static bool is_active, expect_release;
+
+#define WATCHDOG_TIMEOUT 60 /* in seconds */
+static unsigned int timeout = WATCHDOG_TIMEOUT;
+module_param(timeout, uint, S_IRUGO);
+MODULE_PARM_DESC(timeout, "Watchdog timeout in seconds "
+	"(default=" __MODULE_STRING(WATCHDOG_TIMEOUT) ")");
+
+static bool nowayout = WATCHDOG_NOWAYOUT;
+module_param(nowayout, bool, S_IRUGO);
+MODULE_PARM_DESC(nowayout, "Watchdog cannot be stopped once started "
+	"(default=" __MODULE_STRING(WATCHDOG_NOWAYOUT) ")");
+
+static inline __kernel_time_t set_timeout(void)
+{
+	wdt.timeout = timeout;
+	return ktime_to_timespec(ktime_get()).tv_sec + timeout;
+}
+
+static int xen_wdt_start(void)
+{
+	__kernel_time_t expires;
+	int err;
+
+	spin_lock(&wdt_lock);
+
+	expires = set_timeout();
+	if (!wdt.id)
+		err = HYPERVISOR_sched_op(SCHEDOP_watchdog, &wdt);
+	else
+		err = -EBUSY;
+	if (err > 0) {
+		wdt.id = err;
+		wdt_expires = expires;
+		err = 0;
+	} else
+		BUG_ON(!err);
+
+	spin_unlock(&wdt_lock);
+
+	return err;
+}
+
+static int xen_wdt_stop(void)
+{
+	int err = 0;
+
+	spin_lock(&wdt_lock);
+
+	wdt.timeout = 0;
+	if (wdt.id)
+		err = HYPERVISOR_sched_op(SCHEDOP_watchdog, &wdt);
+	if (!err)
+		wdt.id = 0;
+
+	spin_unlock(&wdt_lock);
+
+	return err;
+}
+
+static int xen_wdt_kick(void)
+{
+	__kernel_time_t expires;
+	int err;
+
+	spin_lock(&wdt_lock);
+
+	expires = set_timeout();
+	if (wdt.id)
+		err = HYPERVISOR_sched_op(SCHEDOP_watchdog, &wdt);
+	else
+		err = -ENXIO;
+	if (!err)
+		wdt_expires = expires;
+
+	spin_unlock(&wdt_lock);
+
+	return err;
+}
+
+static int xen_wdt_open(struct inode *inode, struct file *file)
+{
+	int err;
+
+	/* /dev/watchdog can only be opened once */
+	if (xchg(&is_active, true))
+		return -EBUSY;
+
+	err = xen_wdt_start();
+	if (err == -EBUSY)
+		err = xen_wdt_kick();
+	return err ?: nonseekable_open(inode, file);
+}
+
+static int xen_wdt_release(struct inode *inode, struct file *file)
+{
+	if (expect_release)
+		xen_wdt_stop();
+	else {
+		printk(KERN_CRIT PFX
+		       "unexpected close, not stopping watchdog!\n");
+		xen_wdt_kick();
+	}
+	is_active = false;
+	expect_release = false;
+	return 0;
+}
+
+static ssize_t xen_wdt_write(struct file *file, const char __user *data,
+			     size_t len, loff_t *ppos)
+{
+	/* See if we got the magic character 'V' and reload the timer */
+	if (len) {
+		if (!nowayout) {
+			size_t i;
+
+			/* in case it was set long ago */
+			expect_release = false;
+
+			/* scan to see whether or not we got the magic
+			   character */
+			for (i = 0; i != len; i++) {
+				char c;
+				if (get_user(c, data + i))
+					return -EFAULT;
+				if (c == 'V')
+					expect_release = true;
+			}
+		}
+
+		/* someone wrote to us, we should reload the timer */
+		xen_wdt_kick();
+	}
+	return len;
+}
+
+static long xen_wdt_ioctl(struct file *file, unsigned int cmd,
+			  unsigned long arg)
+{
+	int new_options, retval = -EINVAL;
+	int new_timeout;
+	int __user *argp = (void __user *)arg;
+	static const struct watchdog_info ident = {
+		.options =		WDIOF_SETTIMEOUT | WDIOF_MAGICCLOSE,
+		.firmware_version =	0,
+		.identity =		DRV_NAME,
+	};
+
+	switch (cmd) {
+	case WDIOC_GETSUPPORT:
+		return copy_to_user(argp, &ident, sizeof(ident)) ? -EFAULT : 0;
+
+	case WDIOC_GETSTATUS:
+	case WDIOC_GETBOOTSTATUS:
+		return put_user(0, argp);
+
+	case WDIOC_SETOPTIONS:
+		if (get_user(new_options, argp))
+			return -EFAULT;
+
+		if (new_options & WDIOS_DISABLECARD)
+			retval = xen_wdt_stop();
+		if (new_options & WDIOS_ENABLECARD) {
+			retval = xen_wdt_start();
+			if (retval == -EBUSY)
+				retval = xen_wdt_kick();
+		}
+		return retval;
+
+	case WDIOC_KEEPALIVE:
+		xen_wdt_kick();
+		return 0;
+
+	case WDIOC_SETTIMEOUT:
+		if (get_user(new_timeout, argp))
+			return -EFAULT;
+		if (!new_timeout)
+			return -EINVAL;
+		timeout = new_timeout;
+		xen_wdt_kick();
+		/* fall through */
+	case WDIOC_GETTIMEOUT:
+		return put_user(timeout, argp);
+
+	case WDIOC_GETTIMELEFT:
+		retval = wdt_expires - ktime_to_timespec(ktime_get()).tv_sec;
+		return put_user(retval, argp);
+	}
+
+	return -ENOTTY;
+}
+
+static const struct file_operations xen_wdt_fops = {
+	.owner =		THIS_MODULE,
+	.llseek =		no_llseek,
+	.write =		xen_wdt_write,
+	.unlocked_ioctl =	xen_wdt_ioctl,
+	.open =			xen_wdt_open,
+	.release =		xen_wdt_release,
+};
+
+static struct miscdevice xen_wdt_miscdev = {
+	.minor =	WATCHDOG_MINOR,
+	.name =		"watchdog",
+	.fops =		&xen_wdt_fops,
+};
+
+static int __devinit xen_wdt_probe(struct platform_device *dev)
+{
+	struct sched_watchdog wd = { .id = ~0 };
+	int ret = HYPERVISOR_sched_op(SCHEDOP_watchdog, &wd);
+
+	switch (ret) {
+	case -EINVAL:
+		if (!timeout) {
+			timeout = WATCHDOG_TIMEOUT;
+			printk(KERN_INFO PFX
+			       "timeout value invalid, using %d\n", timeout);
+		}
+
+		ret = misc_register(&xen_wdt_miscdev);
+		if (ret) {
+			printk(KERN_ERR PFX
+			       "cannot register miscdev on minor=%d (%d)\n",
+			       WATCHDOG_MINOR, ret);
+			break;
+		}
+
+		printk(KERN_INFO PFX
+		       "initialized (timeout=%ds, nowayout=%d)\n",
+		       timeout, nowayout);
+		break;
+
+	case -ENOSYS:
+		printk(KERN_INFO PFX "not supported\n");
+		ret = -ENODEV;
+		break;
+
+	default:
+		printk(KERN_INFO PFX "bogus return value %d\n", ret);
+		break;
+	}
+
+	return ret;
+}
+
+static int __devexit xen_wdt_remove(struct platform_device *dev)
+{
+	/* Stop the timer before we leave */
+	if (!nowayout)
+		xen_wdt_stop();
+
+	misc_deregister(&xen_wdt_miscdev);
+
+	return 0;
+}
+
+static void xen_wdt_shutdown(struct platform_device *dev)
+{
+	xen_wdt_stop();
+}
+
+static int xen_wdt_suspend(struct platform_device *dev, pm_message_t state)
+{
+	return xen_wdt_stop();
+}
+
+static int xen_wdt_resume(struct platform_device *dev)
+{
+	return xen_wdt_start();
+}
+
+static struct platform_driver xen_wdt_driver = {
+	.probe          = xen_wdt_probe,
+	.remove         = __devexit_p(xen_wdt_remove),
+	.shutdown       = xen_wdt_shutdown,
+	.suspend        = xen_wdt_suspend,
+	.resume         = xen_wdt_resume,
+	.driver         = {
+		.owner  = THIS_MODULE,
+		.name   = DRV_NAME,
+	},
+};
+
+static int __init xen_wdt_init_module(void)
+{
+	int err;
+
+	if (!xen_domain())
+		return -ENODEV;
+
+	printk(KERN_INFO PFX "Xen WatchDog Timer Driver v%s\n", DRV_VERSION);
+
+	err = platform_driver_register(&xen_wdt_driver);
+	if (err)
+		return err;
+
+	platform_device = platform_device_register_simple(DRV_NAME,
+								  -1, NULL, 0);
+	if (IS_ERR(platform_device)) {
+		err = PTR_ERR(platform_device);
+		platform_driver_unregister(&xen_wdt_driver);
+	}
+
+	return err;
+}
+
+static void __exit xen_wdt_cleanup_module(void)
+{
+	platform_device_unregister(platform_device);
+	platform_driver_unregister(&xen_wdt_driver);
+	printk(KERN_INFO PFX "module unloaded\n");
+}
+
+module_init(xen_wdt_init_module);
+module_exit(xen_wdt_cleanup_module);
+
+MODULE_AUTHOR("Jen Beulich <jbeulich@novell.com>");
+MODULE_DESCRIPTION("Xen WatchDog Timer Driver");
+MODULE_VERSION(DRV_VERSION);
+MODULE_LICENSE("GPL");
+MODULE_ALIAS_MISCDEV(WATCHDOG_MINOR);
--- linux-2.6.36-rc6/include/xen/interface/sched.h
+++ 2.6.36-rc6-xen-watchdog/include/xen/interface/sched.h
@@ -65,6 +65,39 @@ struct sched_poll {
 DEFINE_GUEST_HANDLE_STRUCT(sched_poll);
 
 /*
+ * Declare a shutdown for another domain. The main use of this function is
+ * in interpreting shutdown requests and reasons for fully-virtualized
+ * domains.  A para-virtualized domain may use SCHEDOP_shutdown directly.
+ * @arg == pointer to sched_remote_shutdown structure.
+ */
+#define SCHEDOP_remote_shutdown        4
+struct sched_remote_shutdown {
+    domid_t domain_id;         /* Remote domain ID */
+    unsigned int reason;       /* SHUTDOWN_xxx reason */
+};
+
+/*
+ * Latch a shutdown code, so that when the domain later shuts down it
+ * reports this code to the control tools.
+ * @arg == as for SCHEDOP_shutdown.
+ */
+#define SCHEDOP_shutdown_code 5
+
+/*
+ * Setup, poke and destroy a domain watchdog timer.
+ * @arg == pointer to sched_watchdog structure.
+ * With id == 0, setup a domain watchdog timer to cause domain shutdown
+ *               after timeout, returns watchdog id.
+ * With id != 0 and timeout == 0, destroy domain watchdog timer.
+ * With id != 0 and timeout != 0, poke watchdog timer and set new timeout.
+ */
+#define SCHEDOP_watchdog    6
+struct sched_watchdog {
+    uint32_t id;                /* watchdog ID */
+    uint32_t timeout;           /* timeout */
+};
+
+/*
  * Reason codes for SCHEDOP_shutdown. These may be interpreted by control
  * software to determine the appropriate action. For the most part, Xen does
  * not care about the shutdown code.
@@ -73,5 +106,6 @@ DEFINE_GUEST_HANDLE_STRUCT(sched_poll);
 #define SHUTDOWN_reboot     1  /* Clean up, kill, and then restart.          */
 #define SHUTDOWN_suspend    2  /* Clean up, save suspend info, kill.         */
 #define SHUTDOWN_crash      3  /* Tell controller we've crashed.             */
+#define SHUTDOWN_watchdog   4  /* Restart because watchdog time expired.     */
 
 #endif /* __XEN_PUBLIC_SCHED_H__ */



[-- Attachment #2: linux-2.6.36-rc6-xen-watchdog.patch --]
[-- Type: text/plain, Size: 12098 bytes --]

While the hypervisor change adding SCHEDOP_watchdog support included a
daemon to make use of the new functionality, having a kernel driver
for /dev/watchdog so that user space code doesn't need to distinguish
non-Xen and Xen seems to be preferable.

Signed-off-by: Jan Beulich <jbeulich@novell.com>

---
 drivers/watchdog/Kconfig      |   10 +
 drivers/watchdog/Makefile     |    3 
 drivers/watchdog/xen_wdt.c    |  359 ++++++++++++++++++++++++++++++++++++++++++
 include/xen/interface/sched.h |   34 +++
 4 files changed, 406 insertions(+)

--- linux-2.6.36-rc6/drivers/watchdog/Kconfig
+++ 2.6.36-rc6-xen-watchdog/drivers/watchdog/Kconfig
@@ -1043,6 +1043,16 @@ config WATCHDOG_RIO
 
 # XTENSA Architecture
 
+# Xen Architecture
+
+config XEN_WDT
+	tristate "Xen Watchdog support"
+	depends on XEN
+	help
+	  Say Y here to support the hypervisor watchdog capability provided
+	  by Xen 4.0 and newer.  The watchdog timeout period is normally one
+	  minute but can be changed with a boot-time parameter.
+
 #
 # ISA-based Watchdog Cards
 #
--- linux-2.6.36-rc6/drivers/watchdog/Makefile
+++ 2.6.36-rc6-xen-watchdog/drivers/watchdog/Makefile
@@ -145,6 +145,9 @@ obj-$(CONFIG_WATCHDOG_CP1XXX)		+= cpwd.o
 
 # XTENSA Architecture
 
+# Xen
+obj-$(CONFIG_XEN_WDT) += xen_wdt.o
+
 # Architecture Independant
 obj-$(CONFIG_WM831X_WATCHDOG) += wm831x_wdt.o
 obj-$(CONFIG_WM8350_WATCHDOG) += wm8350_wdt.o
--- linux-2.6.36-rc6/drivers/watchdog/xen_wdt.c
+++ 2.6.36-rc6-xen-watchdog/drivers/watchdog/xen_wdt.c
@@ -0,0 +1,359 @@
+/*
+ *	Xen Watchdog Driver
+ *
+ *	(c) Copyright 2010 Novell, Inc.
+ *
+ *	This program is free software; you can redistribute it and/or
+ *	modify it under the terms of the GNU General Public License
+ *	as published by the Free Software Foundation; either version
+ *	2 of the License, or (at your option) any later version.
+ */
+
+#define DRV_NAME	"wdt"
+#define DRV_VERSION	"0.01"
+#define PFX		DRV_NAME ": "
+
+#include <linux/bug.h>
+#include <linux/errno.h>
+#include <linux/fs.h>
+#include <linux/hrtimer.h>
+#include <linux/kernel.h>
+#include <linux/ktime.h>
+#include <linux/init.h>
+#include <linux/miscdevice.h>
+#include <linux/module.h>
+#include <linux/moduleparam.h>
+#include <linux/platform_device.h>
+#include <linux/spinlock.h>
+#include <linux/uaccess.h>
+#include <linux/watchdog.h>
+#include <xen/xen.h>
+#include <asm/xen/hypercall.h>
+#include <xen/interface/sched.h>
+
+static struct platform_device *platform_device;
+static DEFINE_SPINLOCK(wdt_lock);
+static struct sched_watchdog wdt;
+static __kernel_time_t wdt_expires;
+static bool is_active, expect_release;
+
+#define WATCHDOG_TIMEOUT 60 /* in seconds */
+static unsigned int timeout = WATCHDOG_TIMEOUT;
+module_param(timeout, uint, S_IRUGO);
+MODULE_PARM_DESC(timeout, "Watchdog timeout in seconds "
+	"(default=" __MODULE_STRING(WATCHDOG_TIMEOUT) ")");
+
+static bool nowayout = WATCHDOG_NOWAYOUT;
+module_param(nowayout, bool, S_IRUGO);
+MODULE_PARM_DESC(nowayout, "Watchdog cannot be stopped once started "
+	"(default=" __MODULE_STRING(WATCHDOG_NOWAYOUT) ")");
+
+static inline __kernel_time_t set_timeout(void)
+{
+	wdt.timeout = timeout;
+	return ktime_to_timespec(ktime_get()).tv_sec + timeout;
+}
+
+static int xen_wdt_start(void)
+{
+	__kernel_time_t expires;
+	int err;
+
+	spin_lock(&wdt_lock);
+
+	expires = set_timeout();
+	if (!wdt.id)
+		err = HYPERVISOR_sched_op(SCHEDOP_watchdog, &wdt);
+	else
+		err = -EBUSY;
+	if (err > 0) {
+		wdt.id = err;
+		wdt_expires = expires;
+		err = 0;
+	} else
+		BUG_ON(!err);
+
+	spin_unlock(&wdt_lock);
+
+	return err;
+}
+
+static int xen_wdt_stop(void)
+{
+	int err = 0;
+
+	spin_lock(&wdt_lock);
+
+	wdt.timeout = 0;
+	if (wdt.id)
+		err = HYPERVISOR_sched_op(SCHEDOP_watchdog, &wdt);
+	if (!err)
+		wdt.id = 0;
+
+	spin_unlock(&wdt_lock);
+
+	return err;
+}
+
+static int xen_wdt_kick(void)
+{
+	__kernel_time_t expires;
+	int err;
+
+	spin_lock(&wdt_lock);
+
+	expires = set_timeout();
+	if (wdt.id)
+		err = HYPERVISOR_sched_op(SCHEDOP_watchdog, &wdt);
+	else
+		err = -ENXIO;
+	if (!err)
+		wdt_expires = expires;
+
+	spin_unlock(&wdt_lock);
+
+	return err;
+}
+
+static int xen_wdt_open(struct inode *inode, struct file *file)
+{
+	int err;
+
+	/* /dev/watchdog can only be opened once */
+	if (xchg(&is_active, true))
+		return -EBUSY;
+
+	err = xen_wdt_start();
+	if (err == -EBUSY)
+		err = xen_wdt_kick();
+	return err ?: nonseekable_open(inode, file);
+}
+
+static int xen_wdt_release(struct inode *inode, struct file *file)
+{
+	if (expect_release)
+		xen_wdt_stop();
+	else {
+		printk(KERN_CRIT PFX
+		       "unexpected close, not stopping watchdog!\n");
+		xen_wdt_kick();
+	}
+	is_active = false;
+	expect_release = false;
+	return 0;
+}
+
+static ssize_t xen_wdt_write(struct file *file, const char __user *data,
+			     size_t len, loff_t *ppos)
+{
+	/* See if we got the magic character 'V' and reload the timer */
+	if (len) {
+		if (!nowayout) {
+			size_t i;
+
+			/* in case it was set long ago */
+			expect_release = false;
+
+			/* scan to see whether or not we got the magic
+			   character */
+			for (i = 0; i != len; i++) {
+				char c;
+				if (get_user(c, data + i))
+					return -EFAULT;
+				if (c == 'V')
+					expect_release = true;
+			}
+		}
+
+		/* someone wrote to us, we should reload the timer */
+		xen_wdt_kick();
+	}
+	return len;
+}
+
+static long xen_wdt_ioctl(struct file *file, unsigned int cmd,
+			  unsigned long arg)
+{
+	int new_options, retval = -EINVAL;
+	int new_timeout;
+	int __user *argp = (void __user *)arg;
+	static const struct watchdog_info ident = {
+		.options =		WDIOF_SETTIMEOUT | WDIOF_MAGICCLOSE,
+		.firmware_version =	0,
+		.identity =		DRV_NAME,
+	};
+
+	switch (cmd) {
+	case WDIOC_GETSUPPORT:
+		return copy_to_user(argp, &ident, sizeof(ident)) ? -EFAULT : 0;
+
+	case WDIOC_GETSTATUS:
+	case WDIOC_GETBOOTSTATUS:
+		return put_user(0, argp);
+
+	case WDIOC_SETOPTIONS:
+		if (get_user(new_options, argp))
+			return -EFAULT;
+
+		if (new_options & WDIOS_DISABLECARD)
+			retval = xen_wdt_stop();
+		if (new_options & WDIOS_ENABLECARD) {
+			retval = xen_wdt_start();
+			if (retval == -EBUSY)
+				retval = xen_wdt_kick();
+		}
+		return retval;
+
+	case WDIOC_KEEPALIVE:
+		xen_wdt_kick();
+		return 0;
+
+	case WDIOC_SETTIMEOUT:
+		if (get_user(new_timeout, argp))
+			return -EFAULT;
+		if (!new_timeout)
+			return -EINVAL;
+		timeout = new_timeout;
+		xen_wdt_kick();
+		/* fall through */
+	case WDIOC_GETTIMEOUT:
+		return put_user(timeout, argp);
+
+	case WDIOC_GETTIMELEFT:
+		retval = wdt_expires - ktime_to_timespec(ktime_get()).tv_sec;
+		return put_user(retval, argp);
+	}
+
+	return -ENOTTY;
+}
+
+static const struct file_operations xen_wdt_fops = {
+	.owner =		THIS_MODULE,
+	.llseek =		no_llseek,
+	.write =		xen_wdt_write,
+	.unlocked_ioctl =	xen_wdt_ioctl,
+	.open =			xen_wdt_open,
+	.release =		xen_wdt_release,
+};
+
+static struct miscdevice xen_wdt_miscdev = {
+	.minor =	WATCHDOG_MINOR,
+	.name =		"watchdog",
+	.fops =		&xen_wdt_fops,
+};
+
+static int __devinit xen_wdt_probe(struct platform_device *dev)
+{
+	struct sched_watchdog wd = { .id = ~0 };
+	int ret = HYPERVISOR_sched_op(SCHEDOP_watchdog, &wd);
+
+	switch (ret) {
+	case -EINVAL:
+		if (!timeout) {
+			timeout = WATCHDOG_TIMEOUT;
+			printk(KERN_INFO PFX
+			       "timeout value invalid, using %d\n", timeout);
+		}
+
+		ret = misc_register(&xen_wdt_miscdev);
+		if (ret) {
+			printk(KERN_ERR PFX
+			       "cannot register miscdev on minor=%d (%d)\n",
+			       WATCHDOG_MINOR, ret);
+			break;
+		}
+
+		printk(KERN_INFO PFX
+		       "initialized (timeout=%ds, nowayout=%d)\n",
+		       timeout, nowayout);
+		break;
+
+	case -ENOSYS:
+		printk(KERN_INFO PFX "not supported\n");
+		ret = -ENODEV;
+		break;
+
+	default:
+		printk(KERN_INFO PFX "bogus return value %d\n", ret);
+		break;
+	}
+
+	return ret;
+}
+
+static int __devexit xen_wdt_remove(struct platform_device *dev)
+{
+	/* Stop the timer before we leave */
+	if (!nowayout)
+		xen_wdt_stop();
+
+	misc_deregister(&xen_wdt_miscdev);
+
+	return 0;
+}
+
+static void xen_wdt_shutdown(struct platform_device *dev)
+{
+	xen_wdt_stop();
+}
+
+static int xen_wdt_suspend(struct platform_device *dev, pm_message_t state)
+{
+	return xen_wdt_stop();
+}
+
+static int xen_wdt_resume(struct platform_device *dev)
+{
+	return xen_wdt_start();
+}
+
+static struct platform_driver xen_wdt_driver = {
+	.probe          = xen_wdt_probe,
+	.remove         = __devexit_p(xen_wdt_remove),
+	.shutdown       = xen_wdt_shutdown,
+	.suspend        = xen_wdt_suspend,
+	.resume         = xen_wdt_resume,
+	.driver         = {
+		.owner  = THIS_MODULE,
+		.name   = DRV_NAME,
+	},
+};
+
+static int __init xen_wdt_init_module(void)
+{
+	int err;
+
+	if (!xen_domain())
+		return -ENODEV;
+
+	printk(KERN_INFO PFX "Xen WatchDog Timer Driver v%s\n", DRV_VERSION);
+
+	err = platform_driver_register(&xen_wdt_driver);
+	if (err)
+		return err;
+
+	platform_device = platform_device_register_simple(DRV_NAME,
+								  -1, NULL, 0);
+	if (IS_ERR(platform_device)) {
+		err = PTR_ERR(platform_device);
+		platform_driver_unregister(&xen_wdt_driver);
+	}
+
+	return err;
+}
+
+static void __exit xen_wdt_cleanup_module(void)
+{
+	platform_device_unregister(platform_device);
+	platform_driver_unregister(&xen_wdt_driver);
+	printk(KERN_INFO PFX "module unloaded\n");
+}
+
+module_init(xen_wdt_init_module);
+module_exit(xen_wdt_cleanup_module);
+
+MODULE_AUTHOR("Jen Beulich <jbeulich@novell.com>");
+MODULE_DESCRIPTION("Xen WatchDog Timer Driver");
+MODULE_VERSION(DRV_VERSION);
+MODULE_LICENSE("GPL");
+MODULE_ALIAS_MISCDEV(WATCHDOG_MINOR);
--- linux-2.6.36-rc6/include/xen/interface/sched.h
+++ 2.6.36-rc6-xen-watchdog/include/xen/interface/sched.h
@@ -65,6 +65,39 @@ struct sched_poll {
 DEFINE_GUEST_HANDLE_STRUCT(sched_poll);
 
 /*
+ * Declare a shutdown for another domain. The main use of this function is
+ * in interpreting shutdown requests and reasons for fully-virtualized
+ * domains.  A para-virtualized domain may use SCHEDOP_shutdown directly.
+ * @arg == pointer to sched_remote_shutdown structure.
+ */
+#define SCHEDOP_remote_shutdown        4
+struct sched_remote_shutdown {
+    domid_t domain_id;         /* Remote domain ID */
+    unsigned int reason;       /* SHUTDOWN_xxx reason */
+};
+
+/*
+ * Latch a shutdown code, so that when the domain later shuts down it
+ * reports this code to the control tools.
+ * @arg == as for SCHEDOP_shutdown.
+ */
+#define SCHEDOP_shutdown_code 5
+
+/*
+ * Setup, poke and destroy a domain watchdog timer.
+ * @arg == pointer to sched_watchdog structure.
+ * With id == 0, setup a domain watchdog timer to cause domain shutdown
+ *               after timeout, returns watchdog id.
+ * With id != 0 and timeout == 0, destroy domain watchdog timer.
+ * With id != 0 and timeout != 0, poke watchdog timer and set new timeout.
+ */
+#define SCHEDOP_watchdog    6
+struct sched_watchdog {
+    uint32_t id;                /* watchdog ID */
+    uint32_t timeout;           /* timeout */
+};
+
+/*
  * Reason codes for SCHEDOP_shutdown. These may be interpreted by control
  * software to determine the appropriate action. For the most part, Xen does
  * not care about the shutdown code.
@@ -73,5 +106,6 @@ DEFINE_GUEST_HANDLE_STRUCT(sched_poll);
 #define SHUTDOWN_reboot     1  /* Clean up, kill, and then restart.          */
 #define SHUTDOWN_suspend    2  /* Clean up, save suspend info, kill.         */
 #define SHUTDOWN_crash      3  /* Tell controller we've crashed.             */
+#define SHUTDOWN_watchdog   4  /* Restart because watchdog time expired.     */
 
 #endif /* __XEN_PUBLIC_SCHED_H__ */

[-- Attachment #3: Type: text/plain, Size: 138 bytes --]

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Re: [PATCH] Xen watchdog driver

[Jeremy Fitzhardinge]

 On 09/30/2010 07:01 AM, Jan Beulich wrote:
> While the hypervisor change adding SCHEDOP_watchdog support included a
> daemon to make use of the new functionality, having a kernel driver
> for /dev/watchdog so that user space code doesn't need to distinguish
> non-Xen and Xen seems to be preferable.

Looks good.  Are you going to submit this upstream?

    J

> Signed-off-by: Jan Beulich <jbeulich@novell.com>
>
> ---
>  drivers/watchdog/Kconfig      |   10 +
>  drivers/watchdog/Makefile     |    3 
>  drivers/watchdog/xen_wdt.c    |  359 ++++++++++++++++++++++++++++++++++++++++++
>  include/xen/interface/sched.h |   34 +++
>  4 files changed, 406 insertions(+)
>
> --- linux-2.6.36-rc6/drivers/watchdog/Kconfig
> +++ 2.6.36-rc6-xen-watchdog/drivers/watchdog/Kconfig
> @@ -1043,6 +1043,16 @@ config WATCHDOG_RIO
>  
>  # XTENSA Architecture
>  
> +# Xen Architecture
> +
> +config XEN_WDT
> +	tristate "Xen Watchdog support"
> +	depends on XEN
> +	help
> +	  Say Y here to support the hypervisor watchdog capability provided
> +	  by Xen 4.0 and newer.  The watchdog timeout period is normally one
> +	  minute but can be changed with a boot-time parameter.
> +
>  #
>  # ISA-based Watchdog Cards
>  #
> --- linux-2.6.36-rc6/drivers/watchdog/Makefile
> +++ 2.6.36-rc6-xen-watchdog/drivers/watchdog/Makefile
> @@ -145,6 +145,9 @@ obj-$(CONFIG_WATCHDOG_CP1XXX)		+= cpwd.o
>  
>  # XTENSA Architecture
>  
> +# Xen
> +obj-$(CONFIG_XEN_WDT) += xen_wdt.o
> +
>  # Architecture Independant
>  obj-$(CONFIG_WM831X_WATCHDOG) += wm831x_wdt.o
>  obj-$(CONFIG_WM8350_WATCHDOG) += wm8350_wdt.o
> --- linux-2.6.36-rc6/drivers/watchdog/xen_wdt.c
> +++ 2.6.36-rc6-xen-watchdog/drivers/watchdog/xen_wdt.c
> @@ -0,0 +1,359 @@
> +/*
> + *	Xen Watchdog Driver
> + *
> + *	(c) Copyright 2010 Novell, Inc.
> + *
> + *	This program is free software; you can redistribute it and/or
> + *	modify it under the terms of the GNU General Public License
> + *	as published by the Free Software Foundation; either version
> + *	2 of the License, or (at your option) any later version.
> + */
> +
> +#define DRV_NAME	"wdt"
> +#define DRV_VERSION	"0.01"
> +#define PFX		DRV_NAME ": "
> +
> +#include <linux/bug.h>
> +#include <linux/errno.h>
> +#include <linux/fs.h>
> +#include <linux/hrtimer.h>
> +#include <linux/kernel.h>
> +#include <linux/ktime.h>
> +#include <linux/init.h>
> +#include <linux/miscdevice.h>
> +#include <linux/module.h>
> +#include <linux/moduleparam.h>
> +#include <linux/platform_device.h>
> +#include <linux/spinlock.h>
> +#include <linux/uaccess.h>
> +#include <linux/watchdog.h>
> +#include <xen/xen.h>
> +#include <asm/xen/hypercall.h>
> +#include <xen/interface/sched.h>
> +
> +static struct platform_device *platform_device;
> +static DEFINE_SPINLOCK(wdt_lock);
> +static struct sched_watchdog wdt;
> +static __kernel_time_t wdt_expires;
> +static bool is_active, expect_release;
> +
> +#define WATCHDOG_TIMEOUT 60 /* in seconds */
> +static unsigned int timeout = WATCHDOG_TIMEOUT;
> +module_param(timeout, uint, S_IRUGO);
> +MODULE_PARM_DESC(timeout, "Watchdog timeout in seconds "
> +	"(default=" __MODULE_STRING(WATCHDOG_TIMEOUT) ")");
> +
> +static bool nowayout = WATCHDOG_NOWAYOUT;
> +module_param(nowayout, bool, S_IRUGO);
> +MODULE_PARM_DESC(nowayout, "Watchdog cannot be stopped once started "
> +	"(default=" __MODULE_STRING(WATCHDOG_NOWAYOUT) ")");
> +
> +static inline __kernel_time_t set_timeout(void)
> +{
> +	wdt.timeout = timeout;
> +	return ktime_to_timespec(ktime_get()).tv_sec + timeout;
> +}
> +
> +static int xen_wdt_start(void)
> +{
> +	__kernel_time_t expires;
> +	int err;
> +
> +	spin_lock(&wdt_lock);
> +
> +	expires = set_timeout();
> +	if (!wdt.id)
> +		err = HYPERVISOR_sched_op(SCHEDOP_watchdog, &wdt);
> +	else
> +		err = -EBUSY;
> +	if (err > 0) {
> +		wdt.id = err;
> +		wdt_expires = expires;
> +		err = 0;
> +	} else
> +		BUG_ON(!err);
> +
> +	spin_unlock(&wdt_lock);
> +
> +	return err;
> +}
> +
> +static int xen_wdt_stop(void)
> +{
> +	int err = 0;
> +
> +	spin_lock(&wdt_lock);
> +
> +	wdt.timeout = 0;
> +	if (wdt.id)
> +		err = HYPERVISOR_sched_op(SCHEDOP_watchdog, &wdt);
> +	if (!err)
> +		wdt.id = 0;
> +
> +	spin_unlock(&wdt_lock);
> +
> +	return err;
> +}
> +
> +static int xen_wdt_kick(void)
> +{
> +	__kernel_time_t expires;
> +	int err;
> +
> +	spin_lock(&wdt_lock);
> +
> +	expires = set_timeout();
> +	if (wdt.id)
> +		err = HYPERVISOR_sched_op(SCHEDOP_watchdog, &wdt);
> +	else
> +		err = -ENXIO;
> +	if (!err)
> +		wdt_expires = expires;
> +
> +	spin_unlock(&wdt_lock);
> +
> +	return err;
> +}
> +
> +static int xen_wdt_open(struct inode *inode, struct file *file)
> +{
> +	int err;
> +
> +	/* /dev/watchdog can only be opened once */
> +	if (xchg(&is_active, true))
> +		return -EBUSY;
> +
> +	err = xen_wdt_start();
> +	if (err == -EBUSY)
> +		err = xen_wdt_kick();
> +	return err ?: nonseekable_open(inode, file);
> +}
> +
> +static int xen_wdt_release(struct inode *inode, struct file *file)
> +{
> +	if (expect_release)
> +		xen_wdt_stop();
> +	else {
> +		printk(KERN_CRIT PFX
> +		       "unexpected close, not stopping watchdog!\n");
> +		xen_wdt_kick();
> +	}
> +	is_active = false;
> +	expect_release = false;
> +	return 0;
> +}
> +
> +static ssize_t xen_wdt_write(struct file *file, const char __user *data,
> +			     size_t len, loff_t *ppos)
> +{
> +	/* See if we got the magic character 'V' and reload the timer */
> +	if (len) {
> +		if (!nowayout) {
> +			size_t i;
> +
> +			/* in case it was set long ago */
> +			expect_release = false;
> +
> +			/* scan to see whether or not we got the magic
> +			   character */
> +			for (i = 0; i != len; i++) {
> +				char c;
> +				if (get_user(c, data + i))
> +					return -EFAULT;
> +				if (c == 'V')
> +					expect_release = true;
> +			}
> +		}
> +
> +		/* someone wrote to us, we should reload the timer */
> +		xen_wdt_kick();
> +	}
> +	return len;
> +}
> +
> +static long xen_wdt_ioctl(struct file *file, unsigned int cmd,
> +			  unsigned long arg)
> +{
> +	int new_options, retval = -EINVAL;
> +	int new_timeout;
> +	int __user *argp = (void __user *)arg;
> +	static const struct watchdog_info ident = {
> +		.options =		WDIOF_SETTIMEOUT | WDIOF_MAGICCLOSE,
> +		.firmware_version =	0,
> +		.identity =		DRV_NAME,
> +	};
> +
> +	switch (cmd) {
> +	case WDIOC_GETSUPPORT:
> +		return copy_to_user(argp, &ident, sizeof(ident)) ? -EFAULT : 0;
> +
> +	case WDIOC_GETSTATUS:
> +	case WDIOC_GETBOOTSTATUS:
> +		return put_user(0, argp);
> +
> +	case WDIOC_SETOPTIONS:
> +		if (get_user(new_options, argp))
> +			return -EFAULT;
> +
> +		if (new_options & WDIOS_DISABLECARD)
> +			retval = xen_wdt_stop();
> +		if (new_options & WDIOS_ENABLECARD) {
> +			retval = xen_wdt_start();
> +			if (retval == -EBUSY)
> +				retval = xen_wdt_kick();
> +		}
> +		return retval;
> +
> +	case WDIOC_KEEPALIVE:
> +		xen_wdt_kick();
> +		return 0;
> +
> +	case WDIOC_SETTIMEOUT:
> +		if (get_user(new_timeout, argp))
> +			return -EFAULT;
> +		if (!new_timeout)
> +			return -EINVAL;
> +		timeout = new_timeout;
> +		xen_wdt_kick();
> +		/* fall through */
> +	case WDIOC_GETTIMEOUT:
> +		return put_user(timeout, argp);
> +
> +	case WDIOC_GETTIMELEFT:
> +		retval = wdt_expires - ktime_to_timespec(ktime_get()).tv_sec;
> +		return put_user(retval, argp);
> +	}
> +
> +	return -ENOTTY;
> +}
> +
> +static const struct file_operations xen_wdt_fops = {
> +	.owner =		THIS_MODULE,
> +	.llseek =		no_llseek,
> +	.write =		xen_wdt_write,
> +	.unlocked_ioctl =	xen_wdt_ioctl,
> +	.open =			xen_wdt_open,
> +	.release =		xen_wdt_release,
> +};
> +
> +static struct miscdevice xen_wdt_miscdev = {
> +	.minor =	WATCHDOG_MINOR,
> +	.name =		"watchdog",
> +	.fops =		&xen_wdt_fops,
> +};
> +
> +static int __devinit xen_wdt_probe(struct platform_device *dev)
> +{
> +	struct sched_watchdog wd = { .id = ~0 };
> +	int ret = HYPERVISOR_sched_op(SCHEDOP_watchdog, &wd);
> +
> +	switch (ret) {
> +	case -EINVAL:
> +		if (!timeout) {
> +			timeout = WATCHDOG_TIMEOUT;
> +			printk(KERN_INFO PFX
> +			       "timeout value invalid, using %d\n", timeout);
> +		}
> +
> +		ret = misc_register(&xen_wdt_miscdev);
> +		if (ret) {
> +			printk(KERN_ERR PFX
> +			       "cannot register miscdev on minor=%d (%d)\n",
> +			       WATCHDOG_MINOR, ret);
> +			break;
> +		}
> +
> +		printk(KERN_INFO PFX
> +		       "initialized (timeout=%ds, nowayout=%d)\n",
> +		       timeout, nowayout);
> +		break;
> +
> +	case -ENOSYS:
> +		printk(KERN_INFO PFX "not supported\n");
> +		ret = -ENODEV;
> +		break;
> +
> +	default:
> +		printk(KERN_INFO PFX "bogus return value %d\n", ret);
> +		break;
> +	}
> +
> +	return ret;
> +}
> +
> +static int __devexit xen_wdt_remove(struct platform_device *dev)
> +{
> +	/* Stop the timer before we leave */
> +	if (!nowayout)
> +		xen_wdt_stop();
> +
> +	misc_deregister(&xen_wdt_miscdev);
> +
> +	return 0;
> +}
> +
> +static void xen_wdt_shutdown(struct platform_device *dev)
> +{
> +	xen_wdt_stop();
> +}
> +
> +static int xen_wdt_suspend(struct platform_device *dev, pm_message_t state)
> +{
> +	return xen_wdt_stop();
> +}
> +
> +static int xen_wdt_resume(struct platform_device *dev)
> +{
> +	return xen_wdt_start();
> +}
> +
> +static struct platform_driver xen_wdt_driver = {
> +	.probe          = xen_wdt_probe,
> +	.remove         = __devexit_p(xen_wdt_remove),
> +	.shutdown       = xen_wdt_shutdown,
> +	.suspend        = xen_wdt_suspend,
> +	.resume         = xen_wdt_resume,
> +	.driver         = {
> +		.owner  = THIS_MODULE,
> +		.name   = DRV_NAME,
> +	},
> +};
> +
> +static int __init xen_wdt_init_module(void)
> +{
> +	int err;
> +
> +	if (!xen_domain())
> +		return -ENODEV;
> +
> +	printk(KERN_INFO PFX "Xen WatchDog Timer Driver v%s\n", DRV_VERSION);
> +
> +	err = platform_driver_register(&xen_wdt_driver);
> +	if (err)
> +		return err;
> +
> +	platform_device = platform_device_register_simple(DRV_NAME,
> +								  -1, NULL, 0);
> +	if (IS_ERR(platform_device)) {
> +		err = PTR_ERR(platform_device);
> +		platform_driver_unregister(&xen_wdt_driver);
> +	}
> +
> +	return err;
> +}
> +
> +static void __exit xen_wdt_cleanup_module(void)
> +{
> +	platform_device_unregister(platform_device);
> +	platform_driver_unregister(&xen_wdt_driver);
> +	printk(KERN_INFO PFX "module unloaded\n");
> +}
> +
> +module_init(xen_wdt_init_module);
> +module_exit(xen_wdt_cleanup_module);
> +
> +MODULE_AUTHOR("Jen Beulich <jbeulich@novell.com>");
> +MODULE_DESCRIPTION("Xen WatchDog Timer Driver");
> +MODULE_VERSION(DRV_VERSION);
> +MODULE_LICENSE("GPL");
> +MODULE_ALIAS_MISCDEV(WATCHDOG_MINOR);
> --- linux-2.6.36-rc6/include/xen/interface/sched.h
> +++ 2.6.36-rc6-xen-watchdog/include/xen/interface/sched.h
> @@ -65,6 +65,39 @@ struct sched_poll {
>  DEFINE_GUEST_HANDLE_STRUCT(sched_poll);
>  
>  /*
> + * Declare a shutdown for another domain. The main use of this function is
> + * in interpreting shutdown requests and reasons for fully-virtualized
> + * domains.  A para-virtualized domain may use SCHEDOP_shutdown directly.
> + * @arg == pointer to sched_remote_shutdown structure.
> + */
> +#define SCHEDOP_remote_shutdown        4
> +struct sched_remote_shutdown {
> +    domid_t domain_id;         /* Remote domain ID */
> +    unsigned int reason;       /* SHUTDOWN_xxx reason */
> +};
> +
> +/*
> + * Latch a shutdown code, so that when the domain later shuts down it
> + * reports this code to the control tools.
> + * @arg == as for SCHEDOP_shutdown.
> + */
> +#define SCHEDOP_shutdown_code 5
> +
> +/*
> + * Setup, poke and destroy a domain watchdog timer.
> + * @arg == pointer to sched_watchdog structure.
> + * With id == 0, setup a domain watchdog timer to cause domain shutdown
> + *               after timeout, returns watchdog id.
> + * With id != 0 and timeout == 0, destroy domain watchdog timer.
> + * With id != 0 and timeout != 0, poke watchdog timer and set new timeout.
> + */
> +#define SCHEDOP_watchdog    6
> +struct sched_watchdog {
> +    uint32_t id;                /* watchdog ID */
> +    uint32_t timeout;           /* timeout */
> +};
> +
> +/*
>   * Reason codes for SCHEDOP_shutdown. These may be interpreted by control
>   * software to determine the appropriate action. For the most part, Xen does
>   * not care about the shutdown code.
> @@ -73,5 +106,6 @@ DEFINE_GUEST_HANDLE_STRUCT(sched_poll);
>  #define SHUTDOWN_reboot     1  /* Clean up, kill, and then restart.          */
>  #define SHUTDOWN_suspend    2  /* Clean up, save suspend info, kill.         */
>  #define SHUTDOWN_crash      3  /* Tell controller we've crashed.             */
> +#define SHUTDOWN_watchdog   4  /* Restart because watchdog time expired.     */
>  
>  #endif /* __XEN_PUBLIC_SCHED_H__ */
>
>

Re: [PATCH] Xen watchdog driver

[Olaf Hering]

On Thu, Sep 30, Jan Beulich wrote:

> +MODULE_AUTHOR("Jen Beulich <jbeulich@novell.com>");

s/e/a/

Olaf

Re: [PATCH] Xen watchdog driver

[Jan Beulich]

 >>> On 30.09.10 at 18:16, Jeremy Fitzhardinge <jeremy@goop.org> wrote:
> On 09/30/2010 07:01 AM, Jan Beulich wrote:
>> While the hypervisor change adding SCHEDOP_watchdog support included a
>> daemon to make use of the new functionality, having a kernel driver
>> for /dev/watchdog so that user space code doesn't need to distinguish
>> non-Xen and Xen seems to be preferable.
> 
> Looks good.  Are you going to submit this upstream?

By sending it to you I thought I did.

Confused, Jan

>> Signed-off-by: Jan Beulich <jbeulich@novell.com>
>>
>> ---
>>  drivers/watchdog/Kconfig      |   10 +
>>  drivers/watchdog/Makefile     |    3 
>>  drivers/watchdog/xen_wdt.c    |  359 
> ++++++++++++++++++++++++++++++++++++++++++
>>  include/xen/interface/sched.h |   34 +++
>>  4 files changed, 406 insertions(+)
>>
>> --- linux-2.6.36-rc6/drivers/watchdog/Kconfig
>> +++ 2.6.36-rc6-xen-watchdog/drivers/watchdog/Kconfig
>> @@ -1043,6 +1043,16 @@ config WATCHDOG_RIO
>>  
>>  # XTENSA Architecture
>>  
>> +# Xen Architecture
>> +
>> +config XEN_WDT
>> +	tristate "Xen Watchdog support"
>> +	depends on XEN
>> +	help
>> +	  Say Y here to support the hypervisor watchdog capability provided
>> +	  by Xen 4.0 and newer.  The watchdog timeout period is normally one
>> +	  minute but can be changed with a boot-time parameter.
>> +
>>  #
>>  # ISA-based Watchdog Cards
>>  #
>> --- linux-2.6.36-rc6/drivers/watchdog/Makefile
>> +++ 2.6.36-rc6-xen-watchdog/drivers/watchdog/Makefile
>> @@ -145,6 +145,9 @@ obj-$(CONFIG_WATCHDOG_CP1XXX)		+= cpwd.o
>>  
>>  # XTENSA Architecture
>>  
>> +# Xen
>> +obj-$(CONFIG_XEN_WDT) += xen_wdt.o
>> +
>>  # Architecture Independant
>>  obj-$(CONFIG_WM831X_WATCHDOG) += wm831x_wdt.o
>>  obj-$(CONFIG_WM8350_WATCHDOG) += wm8350_wdt.o
>> --- linux-2.6.36-rc6/drivers/watchdog/xen_wdt.c
>> +++ 2.6.36-rc6-xen-watchdog/drivers/watchdog/xen_wdt.c
>> @@ -0,0 +1,359 @@
>> +/*
>> + *	Xen Watchdog Driver
>> + *
>> + *	(c) Copyright 2010 Novell, Inc.
>> + *
>> + *	This program is free software; you can redistribute it and/or
>> + *	modify it under the terms of the GNU General Public License
>> + *	as published by the Free Software Foundation; either version
>> + *	2 of the License, or (at your option) any later version.
>> + */
>> +
>> +#define DRV_NAME	"wdt"
>> +#define DRV_VERSION	"0.01"
>> +#define PFX		DRV_NAME ": "
>> +
>> +#include <linux/bug.h>
>> +#include <linux/errno.h>
>> +#include <linux/fs.h>
>> +#include <linux/hrtimer.h>
>> +#include <linux/kernel.h>
>> +#include <linux/ktime.h>
>> +#include <linux/init.h>
>> +#include <linux/miscdevice.h>
>> +#include <linux/module.h>
>> +#include <linux/moduleparam.h>
>> +#include <linux/platform_device.h>
>> +#include <linux/spinlock.h>
>> +#include <linux/uaccess.h>
>> +#include <linux/watchdog.h>
>> +#include <xen/xen.h>
>> +#include <asm/xen/hypercall.h>
>> +#include <xen/interface/sched.h>
>> +
>> +static struct platform_device *platform_device;
>> +static DEFINE_SPINLOCK(wdt_lock);
>> +static struct sched_watchdog wdt;
>> +static __kernel_time_t wdt_expires;
>> +static bool is_active, expect_release;
>> +
>> +#define WATCHDOG_TIMEOUT 60 /* in seconds */
>> +static unsigned int timeout = WATCHDOG_TIMEOUT;
>> +module_param(timeout, uint, S_IRUGO);
>> +MODULE_PARM_DESC(timeout, "Watchdog timeout in seconds "
>> +	"(default=" __MODULE_STRING(WATCHDOG_TIMEOUT) ")");
>> +
>> +static bool nowayout = WATCHDOG_NOWAYOUT;
>> +module_param(nowayout, bool, S_IRUGO);
>> +MODULE_PARM_DESC(nowayout, "Watchdog cannot be stopped once started "
>> +	"(default=" __MODULE_STRING(WATCHDOG_NOWAYOUT) ")");
>> +
>> +static inline __kernel_time_t set_timeout(void)
>> +{
>> +	wdt.timeout = timeout;
>> +	return ktime_to_timespec(ktime_get()).tv_sec + timeout;
>> +}
>> +
>> +static int xen_wdt_start(void)
>> +{
>> +	__kernel_time_t expires;
>> +	int err;
>> +
>> +	spin_lock(&wdt_lock);
>> +
>> +	expires = set_timeout();
>> +	if (!wdt.id)
>> +		err = HYPERVISOR_sched_op(SCHEDOP_watchdog, &wdt);
>> +	else
>> +		err = -EBUSY;
>> +	if (err > 0) {
>> +		wdt.id = err;
>> +		wdt_expires = expires;
>> +		err = 0;
>> +	} else
>> +		BUG_ON(!err);
>> +
>> +	spin_unlock(&wdt_lock);
>> +
>> +	return err;
>> +}
>> +
>> +static int xen_wdt_stop(void)
>> +{
>> +	int err = 0;
>> +
>> +	spin_lock(&wdt_lock);
>> +
>> +	wdt.timeout = 0;
>> +	if (wdt.id)
>> +		err = HYPERVISOR_sched_op(SCHEDOP_watchdog, &wdt);
>> +	if (!err)
>> +		wdt.id = 0;
>> +
>> +	spin_unlock(&wdt_lock);
>> +
>> +	return err;
>> +}
>> +
>> +static int xen_wdt_kick(void)
>> +{
>> +	__kernel_time_t expires;
>> +	int err;
>> +
>> +	spin_lock(&wdt_lock);
>> +
>> +	expires = set_timeout();
>> +	if (wdt.id)
>> +		err = HYPERVISOR_sched_op(SCHEDOP_watchdog, &wdt);
>> +	else
>> +		err = -ENXIO;
>> +	if (!err)
>> +		wdt_expires = expires;
>> +
>> +	spin_unlock(&wdt_lock);
>> +
>> +	return err;
>> +}
>> +
>> +static int xen_wdt_open(struct inode *inode, struct file *file)
>> +{
>> +	int err;
>> +
>> +	/* /dev/watchdog can only be opened once */
>> +	if (xchg(&is_active, true))
>> +		return -EBUSY;
>> +
>> +	err = xen_wdt_start();
>> +	if (err == -EBUSY)
>> +		err = xen_wdt_kick();
>> +	return err ?: nonseekable_open(inode, file);
>> +}
>> +
>> +static int xen_wdt_release(struct inode *inode, struct file *file)
>> +{
>> +	if (expect_release)
>> +		xen_wdt_stop();
>> +	else {
>> +		printk(KERN_CRIT PFX
>> +		       "unexpected close, not stopping watchdog!\n");
>> +		xen_wdt_kick();
>> +	}
>> +	is_active = false;
>> +	expect_release = false;
>> +	return 0;
>> +}
>> +
>> +static ssize_t xen_wdt_write(struct file *file, const char __user *data,
>> +			     size_t len, loff_t *ppos)
>> +{
>> +	/* See if we got the magic character 'V' and reload the timer */
>> +	if (len) {
>> +		if (!nowayout) {
>> +			size_t i;
>> +
>> +			/* in case it was set long ago */
>> +			expect_release = false;
>> +
>> +			/* scan to see whether or not we got the magic
>> +			   character */
>> +			for (i = 0; i != len; i++) {
>> +				char c;
>> +				if (get_user(c, data + i))
>> +					return -EFAULT;
>> +				if (c == 'V')
>> +					expect_release = true;
>> +			}
>> +		}
>> +
>> +		/* someone wrote to us, we should reload the timer */
>> +		xen_wdt_kick();
>> +	}
>> +	return len;
>> +}
>> +
>> +static long xen_wdt_ioctl(struct file *file, unsigned int cmd,
>> +			  unsigned long arg)
>> +{
>> +	int new_options, retval = -EINVAL;
>> +	int new_timeout;
>> +	int __user *argp = (void __user *)arg;
>> +	static const struct watchdog_info ident = {
>> +		.options =		WDIOF_SETTIMEOUT | WDIOF_MAGICCLOSE,
>> +		.firmware_version =	0,
>> +		.identity =		DRV_NAME,
>> +	};
>> +
>> +	switch (cmd) {
>> +	case WDIOC_GETSUPPORT:
>> +		return copy_to_user(argp, &ident, sizeof(ident)) ? -EFAULT : 0;
>> +
>> +	case WDIOC_GETSTATUS:
>> +	case WDIOC_GETBOOTSTATUS:
>> +		return put_user(0, argp);
>> +
>> +	case WDIOC_SETOPTIONS:
>> +		if (get_user(new_options, argp))
>> +			return -EFAULT;
>> +
>> +		if (new_options & WDIOS_DISABLECARD)
>> +			retval = xen_wdt_stop();
>> +		if (new_options & WDIOS_ENABLECARD) {
>> +			retval = xen_wdt_start();
>> +			if (retval == -EBUSY)
>> +				retval = xen_wdt_kick();
>> +		}
>> +		return retval;
>> +
>> +	case WDIOC_KEEPALIVE:
>> +		xen_wdt_kick();
>> +		return 0;
>> +
>> +	case WDIOC_SETTIMEOUT:
>> +		if (get_user(new_timeout, argp))
>> +			return -EFAULT;
>> +		if (!new_timeout)
>> +			return -EINVAL;
>> +		timeout = new_timeout;
>> +		xen_wdt_kick();
>> +		/* fall through */
>> +	case WDIOC_GETTIMEOUT:
>> +		return put_user(timeout, argp);
>> +
>> +	case WDIOC_GETTIMELEFT:
>> +		retval = wdt_expires - ktime_to_timespec(ktime_get()).tv_sec;
>> +		return put_user(retval, argp);
>> +	}
>> +
>> +	return -ENOTTY;
>> +}
>> +
>> +static const struct file_operations xen_wdt_fops = {
>> +	.owner =		THIS_MODULE,
>> +	.llseek =		no_llseek,
>> +	.write =		xen_wdt_write,
>> +	.unlocked_ioctl =	xen_wdt_ioctl,
>> +	.open =			xen_wdt_open,
>> +	.release =		xen_wdt_release,
>> +};
>> +
>> +static struct miscdevice xen_wdt_miscdev = {
>> +	.minor =	WATCHDOG_MINOR,
>> +	.name =		"watchdog",
>> +	.fops =		&xen_wdt_fops,
>> +};
>> +
>> +static int __devinit xen_wdt_probe(struct platform_device *dev)
>> +{
>> +	struct sched_watchdog wd = { .id = ~0 };
>> +	int ret = HYPERVISOR_sched_op(SCHEDOP_watchdog, &wd);
>> +
>> +	switch (ret) {
>> +	case -EINVAL:
>> +		if (!timeout) {
>> +			timeout = WATCHDOG_TIMEOUT;
>> +			printk(KERN_INFO PFX
>> +			       "timeout value invalid, using %d\n", timeout);
>> +		}
>> +
>> +		ret = misc_register(&xen_wdt_miscdev);
>> +		if (ret) {
>> +			printk(KERN_ERR PFX
>> +			       "cannot register miscdev on minor=%d (%d)\n",
>> +			       WATCHDOG_MINOR, ret);
>> +			break;
>> +		}
>> +
>> +		printk(KERN_INFO PFX
>> +		       "initialized (timeout=%ds, nowayout=%d)\n",
>> +		       timeout, nowayout);
>> +		break;
>> +
>> +	case -ENOSYS:
>> +		printk(KERN_INFO PFX "not supported\n");
>> +		ret = -ENODEV;
>> +		break;
>> +
>> +	default:
>> +		printk(KERN_INFO PFX "bogus return value %d\n", ret);
>> +		break;
>> +	}
>> +
>> +	return ret;
>> +}
>> +
>> +static int __devexit xen_wdt_remove(struct platform_device *dev)
>> +{
>> +	/* Stop the timer before we leave */
>> +	if (!nowayout)
>> +		xen_wdt_stop();
>> +
>> +	misc_deregister(&xen_wdt_miscdev);
>> +
>> +	return 0;
>> +}
>> +
>> +static void xen_wdt_shutdown(struct platform_device *dev)
>> +{
>> +	xen_wdt_stop();
>> +}
>> +
>> +static int xen_wdt_suspend(struct platform_device *dev, pm_message_t state)
>> +{
>> +	return xen_wdt_stop();
>> +}
>> +
>> +static int xen_wdt_resume(struct platform_device *dev)
>> +{
>> +	return xen_wdt_start();
>> +}
>> +
>> +static struct platform_driver xen_wdt_driver = {
>> +	.probe          = xen_wdt_probe,
>> +	.remove         = __devexit_p(xen_wdt_remove),
>> +	.shutdown       = xen_wdt_shutdown,
>> +	.suspend        = xen_wdt_suspend,
>> +	.resume         = xen_wdt_resume,
>> +	.driver         = {
>> +		.owner  = THIS_MODULE,
>> +		.name   = DRV_NAME,
>> +	},
>> +};
>> +
>> +static int __init xen_wdt_init_module(void)
>> +{
>> +	int err;
>> +
>> +	if (!xen_domain())
>> +		return -ENODEV;
>> +
>> +	printk(KERN_INFO PFX "Xen WatchDog Timer Driver v%s\n", DRV_VERSION);
>> +
>> +	err = platform_driver_register(&xen_wdt_driver);
>> +	if (err)
>> +		return err;
>> +
>> +	platform_device = platform_device_register_simple(DRV_NAME,
>> +								  -1, NULL, 0);
>> +	if (IS_ERR(platform_device)) {
>> +		err = PTR_ERR(platform_device);
>> +		platform_driver_unregister(&xen_wdt_driver);
>> +	}
>> +
>> +	return err;
>> +}
>> +
>> +static void __exit xen_wdt_cleanup_module(void)
>> +{
>> +	platform_device_unregister(platform_device);
>> +	platform_driver_unregister(&xen_wdt_driver);
>> +	printk(KERN_INFO PFX "module unloaded\n");
>> +}
>> +
>> +module_init(xen_wdt_init_module);
>> +module_exit(xen_wdt_cleanup_module);
>> +
>> +MODULE_AUTHOR("Jen Beulich <jbeulich@novell.com>");
>> +MODULE_DESCRIPTION("Xen WatchDog Timer Driver");
>> +MODULE_VERSION(DRV_VERSION);
>> +MODULE_LICENSE("GPL");
>> +MODULE_ALIAS_MISCDEV(WATCHDOG_MINOR);
>> --- linux-2.6.36-rc6/include/xen/interface/sched.h
>> +++ 2.6.36-rc6-xen-watchdog/include/xen/interface/sched.h
>> @@ -65,6 +65,39 @@ struct sched_poll {
>>  DEFINE_GUEST_HANDLE_STRUCT(sched_poll);
>>  
>>  /*
>> + * Declare a shutdown for another domain. The main use of this function is
>> + * in interpreting shutdown requests and reasons for fully-virtualized
>> + * domains.  A para-virtualized domain may use SCHEDOP_shutdown directly.
>> + * @arg == pointer to sched_remote_shutdown structure.
>> + */
>> +#define SCHEDOP_remote_shutdown        4
>> +struct sched_remote_shutdown {
>> +    domid_t domain_id;         /* Remote domain ID */
>> +    unsigned int reason;       /* SHUTDOWN_xxx reason */
>> +};
>> +
>> +/*
>> + * Latch a shutdown code, so that when the domain later shuts down it
>> + * reports this code to the control tools.
>> + * @arg == as for SCHEDOP_shutdown.
>> + */
>> +#define SCHEDOP_shutdown_code 5
>> +
>> +/*
>> + * Setup, poke and destroy a domain watchdog timer.
>> + * @arg == pointer to sched_watchdog structure.
>> + * With id == 0, setup a domain watchdog timer to cause domain shutdown
>> + *               after timeout, returns watchdog id.
>> + * With id != 0 and timeout == 0, destroy domain watchdog timer.
>> + * With id != 0 and timeout != 0, poke watchdog timer and set new timeout.
>> + */
>> +#define SCHEDOP_watchdog    6
>> +struct sched_watchdog {
>> +    uint32_t id;                /* watchdog ID */
>> +    uint32_t timeout;           /* timeout */
>> +};
>> +
>> +/*
>>   * Reason codes for SCHEDOP_shutdown. These may be interpreted by control
>>   * software to determine the appropriate action. For the most part, Xen 
> does
>>   * not care about the shutdown code.
>> @@ -73,5 +106,6 @@ DEFINE_GUEST_HANDLE_STRUCT(sched_poll);
>>  #define SHUTDOWN_reboot     1  /* Clean up, kill, and then restart.         
>  */
>>  #define SHUTDOWN_suspend    2  /* Clean up, save suspend info, kill.        
>  */
>>  #define SHUTDOWN_crash      3  /* Tell controller we've crashed.            
>  */
>> +#define SHUTDOWN_watchdog   4  /* Restart because watchdog time expired.    
>  */
>>  
>>  #endif /* __XEN_PUBLIC_SCHED_H__ */
>>
>>

Re: [PATCH] Xen watchdog driver

[Jeremy Fitzhardinge]

 On 09/30/2010 11:56 PM, Jan Beulich wrote:
>  >>> On 30.09.10 at 18:16, Jeremy Fitzhardinge <jeremy@goop.org> wrote:
>> On 09/30/2010 07:01 AM, Jan Beulich wrote:
>>> While the hypervisor change adding SCHEDOP_watchdog support included a
>>> daemon to make use of the new functionality, having a kernel driver
>>> for /dev/watchdog so that user space code doesn't need to distinguish
>>> non-Xen and Xen seems to be preferable.
>> Looks good.  Are you going to submit this upstream?
> By sending it to you I thought I did.

I'm not the exclusive path for upstream Xen; I'm happy to ack things and
let others submit them.  But I'm also happy to submit this too.

    J

> Confused, Jan
>
>>> Signed-off-by: Jan Beulich <jbeulich@novell.com>
>>>
>>> ---
>>>  drivers/watchdog/Kconfig      |   10 +
>>>  drivers/watchdog/Makefile     |    3 
>>>  drivers/watchdog/xen_wdt.c    |  359 
>> ++++++++++++++++++++++++++++++++++++++++++
>>>  include/xen/interface/sched.h |   34 +++
>>>  4 files changed, 406 insertions(+)
>>>
>>> --- linux-2.6.36-rc6/drivers/watchdog/Kconfig
>>> +++ 2.6.36-rc6-xen-watchdog/drivers/watchdog/Kconfig
>>> @@ -1043,6 +1043,16 @@ config WATCHDOG_RIO
>>>  
>>>  # XTENSA Architecture
>>>  
>>> +# Xen Architecture
>>> +
>>> +config XEN_WDT
>>> +	tristate "Xen Watchdog support"
>>> +	depends on XEN
>>> +	help
>>> +	  Say Y here to support the hypervisor watchdog capability provided
>>> +	  by Xen 4.0 and newer.  The watchdog timeout period is normally one
>>> +	  minute but can be changed with a boot-time parameter.
>>> +
>>>  #
>>>  # ISA-based Watchdog Cards
>>>  #
>>> --- linux-2.6.36-rc6/drivers/watchdog/Makefile
>>> +++ 2.6.36-rc6-xen-watchdog/drivers/watchdog/Makefile
>>> @@ -145,6 +145,9 @@ obj-$(CONFIG_WATCHDOG_CP1XXX)		+= cpwd.o
>>>  
>>>  # XTENSA Architecture
>>>  
>>> +# Xen
>>> +obj-$(CONFIG_XEN_WDT) += xen_wdt.o
>>> +
>>>  # Architecture Independant
>>>  obj-$(CONFIG_WM831X_WATCHDOG) += wm831x_wdt.o
>>>  obj-$(CONFIG_WM8350_WATCHDOG) += wm8350_wdt.o
>>> --- linux-2.6.36-rc6/drivers/watchdog/xen_wdt.c
>>> +++ 2.6.36-rc6-xen-watchdog/drivers/watchdog/xen_wdt.c
>>> @@ -0,0 +1,359 @@
>>> +/*
>>> + *	Xen Watchdog Driver
>>> + *
>>> + *	(c) Copyright 2010 Novell, Inc.
>>> + *
>>> + *	This program is free software; you can redistribute it and/or
>>> + *	modify it under the terms of the GNU General Public License
>>> + *	as published by the Free Software Foundation; either version
>>> + *	2 of the License, or (at your option) any later version.
>>> + */
>>> +
>>> +#define DRV_NAME	"wdt"
>>> +#define DRV_VERSION	"0.01"
>>> +#define PFX		DRV_NAME ": "
>>> +
>>> +#include <linux/bug.h>
>>> +#include <linux/errno.h>
>>> +#include <linux/fs.h>
>>> +#include <linux/hrtimer.h>
>>> +#include <linux/kernel.h>
>>> +#include <linux/ktime.h>
>>> +#include <linux/init.h>
>>> +#include <linux/miscdevice.h>
>>> +#include <linux/module.h>
>>> +#include <linux/moduleparam.h>
>>> +#include <linux/platform_device.h>
>>> +#include <linux/spinlock.h>
>>> +#include <linux/uaccess.h>
>>> +#include <linux/watchdog.h>
>>> +#include <xen/xen.h>
>>> +#include <asm/xen/hypercall.h>
>>> +#include <xen/interface/sched.h>
>>> +
>>> +static struct platform_device *platform_device;
>>> +static DEFINE_SPINLOCK(wdt_lock);
>>> +static struct sched_watchdog wdt;
>>> +static __kernel_time_t wdt_expires;
>>> +static bool is_active, expect_release;
>>> +
>>> +#define WATCHDOG_TIMEOUT 60 /* in seconds */
>>> +static unsigned int timeout = WATCHDOG_TIMEOUT;
>>> +module_param(timeout, uint, S_IRUGO);
>>> +MODULE_PARM_DESC(timeout, "Watchdog timeout in seconds "
>>> +	"(default=" __MODULE_STRING(WATCHDOG_TIMEOUT) ")");
>>> +
>>> +static bool nowayout = WATCHDOG_NOWAYOUT;
>>> +module_param(nowayout, bool, S_IRUGO);
>>> +MODULE_PARM_DESC(nowayout, "Watchdog cannot be stopped once started "
>>> +	"(default=" __MODULE_STRING(WATCHDOG_NOWAYOUT) ")");
>>> +
>>> +static inline __kernel_time_t set_timeout(void)
>>> +{
>>> +	wdt.timeout = timeout;
>>> +	return ktime_to_timespec(ktime_get()).tv_sec + timeout;
>>> +}
>>> +
>>> +static int xen_wdt_start(void)
>>> +{
>>> +	__kernel_time_t expires;
>>> +	int err;
>>> +
>>> +	spin_lock(&wdt_lock);
>>> +
>>> +	expires = set_timeout();
>>> +	if (!wdt.id)
>>> +		err = HYPERVISOR_sched_op(SCHEDOP_watchdog, &wdt);
>>> +	else
>>> +		err = -EBUSY;
>>> +	if (err > 0) {
>>> +		wdt.id = err;
>>> +		wdt_expires = expires;
>>> +		err = 0;
>>> +	} else
>>> +		BUG_ON(!err);
>>> +
>>> +	spin_unlock(&wdt_lock);
>>> +
>>> +	return err;
>>> +}
>>> +
>>> +static int xen_wdt_stop(void)
>>> +{
>>> +	int err = 0;
>>> +
>>> +	spin_lock(&wdt_lock);
>>> +
>>> +	wdt.timeout = 0;
>>> +	if (wdt.id)
>>> +		err = HYPERVISOR_sched_op(SCHEDOP_watchdog, &wdt);
>>> +	if (!err)
>>> +		wdt.id = 0;
>>> +
>>> +	spin_unlock(&wdt_lock);
>>> +
>>> +	return err;
>>> +}
>>> +
>>> +static int xen_wdt_kick(void)
>>> +{
>>> +	__kernel_time_t expires;
>>> +	int err;
>>> +
>>> +	spin_lock(&wdt_lock);
>>> +
>>> +	expires = set_timeout();
>>> +	if (wdt.id)
>>> +		err = HYPERVISOR_sched_op(SCHEDOP_watchdog, &wdt);
>>> +	else
>>> +		err = -ENXIO;
>>> +	if (!err)
>>> +		wdt_expires = expires;
>>> +
>>> +	spin_unlock(&wdt_lock);
>>> +
>>> +	return err;
>>> +}
>>> +
>>> +static int xen_wdt_open(struct inode *inode, struct file *file)
>>> +{
>>> +	int err;
>>> +
>>> +	/* /dev/watchdog can only be opened once */
>>> +	if (xchg(&is_active, true))
>>> +		return -EBUSY;
>>> +
>>> +	err = xen_wdt_start();
>>> +	if (err == -EBUSY)
>>> +		err = xen_wdt_kick();
>>> +	return err ?: nonseekable_open(inode, file);
>>> +}
>>> +
>>> +static int xen_wdt_release(struct inode *inode, struct file *file)
>>> +{
>>> +	if (expect_release)
>>> +		xen_wdt_stop();
>>> +	else {
>>> +		printk(KERN_CRIT PFX
>>> +		       "unexpected close, not stopping watchdog!\n");
>>> +		xen_wdt_kick();
>>> +	}
>>> +	is_active = false;
>>> +	expect_release = false;
>>> +	return 0;
>>> +}
>>> +
>>> +static ssize_t xen_wdt_write(struct file *file, const char __user *data,
>>> +			     size_t len, loff_t *ppos)
>>> +{
>>> +	/* See if we got the magic character 'V' and reload the timer */
>>> +	if (len) {
>>> +		if (!nowayout) {
>>> +			size_t i;
>>> +
>>> +			/* in case it was set long ago */
>>> +			expect_release = false;
>>> +
>>> +			/* scan to see whether or not we got the magic
>>> +			   character */
>>> +			for (i = 0; i != len; i++) {
>>> +				char c;
>>> +				if (get_user(c, data + i))
>>> +					return -EFAULT;
>>> +				if (c == 'V')
>>> +					expect_release = true;
>>> +			}
>>> +		}
>>> +
>>> +		/* someone wrote to us, we should reload the timer */
>>> +		xen_wdt_kick();
>>> +	}
>>> +	return len;
>>> +}
>>> +
>>> +static long xen_wdt_ioctl(struct file *file, unsigned int cmd,
>>> +			  unsigned long arg)
>>> +{
>>> +	int new_options, retval = -EINVAL;
>>> +	int new_timeout;
>>> +	int __user *argp = (void __user *)arg;
>>> +	static const struct watchdog_info ident = {
>>> +		.options =		WDIOF_SETTIMEOUT | WDIOF_MAGICCLOSE,
>>> +		.firmware_version =	0,
>>> +		.identity =		DRV_NAME,
>>> +	};
>>> +
>>> +	switch (cmd) {
>>> +	case WDIOC_GETSUPPORT:
>>> +		return copy_to_user(argp, &ident, sizeof(ident)) ? -EFAULT : 0;
>>> +
>>> +	case WDIOC_GETSTATUS:
>>> +	case WDIOC_GETBOOTSTATUS:
>>> +		return put_user(0, argp);
>>> +
>>> +	case WDIOC_SETOPTIONS:
>>> +		if (get_user(new_options, argp))
>>> +			return -EFAULT;
>>> +
>>> +		if (new_options & WDIOS_DISABLECARD)
>>> +			retval = xen_wdt_stop();
>>> +		if (new_options & WDIOS_ENABLECARD) {
>>> +			retval = xen_wdt_start();
>>> +			if (retval == -EBUSY)
>>> +				retval = xen_wdt_kick();
>>> +		}
>>> +		return retval;
>>> +
>>> +	case WDIOC_KEEPALIVE:
>>> +		xen_wdt_kick();
>>> +		return 0;
>>> +
>>> +	case WDIOC_SETTIMEOUT:
>>> +		if (get_user(new_timeout, argp))
>>> +			return -EFAULT;
>>> +		if (!new_timeout)
>>> +			return -EINVAL;
>>> +		timeout = new_timeout;
>>> +		xen_wdt_kick();
>>> +		/* fall through */
>>> +	case WDIOC_GETTIMEOUT:
>>> +		return put_user(timeout, argp);
>>> +
>>> +	case WDIOC_GETTIMELEFT:
>>> +		retval = wdt_expires - ktime_to_timespec(ktime_get()).tv_sec;
>>> +		return put_user(retval, argp);
>>> +	}
>>> +
>>> +	return -ENOTTY;
>>> +}
>>> +
>>> +static const struct file_operations xen_wdt_fops = {
>>> +	.owner =		THIS_MODULE,
>>> +	.llseek =		no_llseek,
>>> +	.write =		xen_wdt_write,
>>> +	.unlocked_ioctl =	xen_wdt_ioctl,
>>> +	.open =			xen_wdt_open,
>>> +	.release =		xen_wdt_release,
>>> +};
>>> +
>>> +static struct miscdevice xen_wdt_miscdev = {
>>> +	.minor =	WATCHDOG_MINOR,
>>> +	.name =		"watchdog",
>>> +	.fops =		&xen_wdt_fops,
>>> +};
>>> +
>>> +static int __devinit xen_wdt_probe(struct platform_device *dev)
>>> +{
>>> +	struct sched_watchdog wd = { .id = ~0 };
>>> +	int ret = HYPERVISOR_sched_op(SCHEDOP_watchdog, &wd);
>>> +
>>> +	switch (ret) {
>>> +	case -EINVAL:
>>> +		if (!timeout) {
>>> +			timeout = WATCHDOG_TIMEOUT;
>>> +			printk(KERN_INFO PFX
>>> +			       "timeout value invalid, using %d\n", timeout);
>>> +		}
>>> +
>>> +		ret = misc_register(&xen_wdt_miscdev);
>>> +		if (ret) {
>>> +			printk(KERN_ERR PFX
>>> +			       "cannot register miscdev on minor=%d (%d)\n",
>>> +			       WATCHDOG_MINOR, ret);
>>> +			break;
>>> +		}
>>> +
>>> +		printk(KERN_INFO PFX
>>> +		       "initialized (timeout=%ds, nowayout=%d)\n",
>>> +		       timeout, nowayout);
>>> +		break;
>>> +
>>> +	case -ENOSYS:
>>> +		printk(KERN_INFO PFX "not supported\n");
>>> +		ret = -ENODEV;
>>> +		break;
>>> +
>>> +	default:
>>> +		printk(KERN_INFO PFX "bogus return value %d\n", ret);
>>> +		break;
>>> +	}
>>> +
>>> +	return ret;
>>> +}
>>> +
>>> +static int __devexit xen_wdt_remove(struct platform_device *dev)
>>> +{
>>> +	/* Stop the timer before we leave */
>>> +	if (!nowayout)
>>> +		xen_wdt_stop();
>>> +
>>> +	misc_deregister(&xen_wdt_miscdev);
>>> +
>>> +	return 0;
>>> +}
>>> +
>>> +static void xen_wdt_shutdown(struct platform_device *dev)
>>> +{
>>> +	xen_wdt_stop();
>>> +}
>>> +
>>> +static int xen_wdt_suspend(struct platform_device *dev, pm_message_t state)
>>> +{
>>> +	return xen_wdt_stop();
>>> +}
>>> +
>>> +static int xen_wdt_resume(struct platform_device *dev)
>>> +{
>>> +	return xen_wdt_start();
>>> +}
>>> +
>>> +static struct platform_driver xen_wdt_driver = {
>>> +	.probe          = xen_wdt_probe,
>>> +	.remove         = __devexit_p(xen_wdt_remove),
>>> +	.shutdown       = xen_wdt_shutdown,
>>> +	.suspend        = xen_wdt_suspend,
>>> +	.resume         = xen_wdt_resume,
>>> +	.driver         = {
>>> +		.owner  = THIS_MODULE,
>>> +		.name   = DRV_NAME,
>>> +	},
>>> +};
>>> +
>>> +static int __init xen_wdt_init_module(void)
>>> +{
>>> +	int err;
>>> +
>>> +	if (!xen_domain())
>>> +		return -ENODEV;
>>> +
>>> +	printk(KERN_INFO PFX "Xen WatchDog Timer Driver v%s\n", DRV_VERSION);
>>> +
>>> +	err = platform_driver_register(&xen_wdt_driver);
>>> +	if (err)
>>> +		return err;
>>> +
>>> +	platform_device = platform_device_register_simple(DRV_NAME,
>>> +								  -1, NULL, 0);
>>> +	if (IS_ERR(platform_device)) {
>>> +		err = PTR_ERR(platform_device);
>>> +		platform_driver_unregister(&xen_wdt_driver);
>>> +	}
>>> +
>>> +	return err;
>>> +}
>>> +
>>> +static void __exit xen_wdt_cleanup_module(void)
>>> +{
>>> +	platform_device_unregister(platform_device);
>>> +	platform_driver_unregister(&xen_wdt_driver);
>>> +	printk(KERN_INFO PFX "module unloaded\n");
>>> +}
>>> +
>>> +module_init(xen_wdt_init_module);
>>> +module_exit(xen_wdt_cleanup_module);
>>> +
>>> +MODULE_AUTHOR("Jen Beulich <jbeulich@novell.com>");
>>> +MODULE_DESCRIPTION("Xen WatchDog Timer Driver");
>>> +MODULE_VERSION(DRV_VERSION);
>>> +MODULE_LICENSE("GPL");
>>> +MODULE_ALIAS_MISCDEV(WATCHDOG_MINOR);
>>> --- linux-2.6.36-rc6/include/xen/interface/sched.h
>>> +++ 2.6.36-rc6-xen-watchdog/include/xen/interface/sched.h
>>> @@ -65,6 +65,39 @@ struct sched_poll {
>>>  DEFINE_GUEST_HANDLE_STRUCT(sched_poll);
>>>  
>>>  /*
>>> + * Declare a shutdown for another domain. The main use of this function is
>>> + * in interpreting shutdown requests and reasons for fully-virtualized
>>> + * domains.  A para-virtualized domain may use SCHEDOP_shutdown directly.
>>> + * @arg == pointer to sched_remote_shutdown structure.
>>> + */
>>> +#define SCHEDOP_remote_shutdown        4
>>> +struct sched_remote_shutdown {
>>> +    domid_t domain_id;         /* Remote domain ID */
>>> +    unsigned int reason;       /* SHUTDOWN_xxx reason */
>>> +};
>>> +
>>> +/*
>>> + * Latch a shutdown code, so that when the domain later shuts down it
>>> + * reports this code to the control tools.
>>> + * @arg == as for SCHEDOP_shutdown.
>>> + */
>>> +#define SCHEDOP_shutdown_code 5
>>> +
>>> +/*
>>> + * Setup, poke and destroy a domain watchdog timer.
>>> + * @arg == pointer to sched_watchdog structure.
>>> + * With id == 0, setup a domain watchdog timer to cause domain shutdown
>>> + *               after timeout, returns watchdog id.
>>> + * With id != 0 and timeout == 0, destroy domain watchdog timer.
>>> + * With id != 0 and timeout != 0, poke watchdog timer and set new timeout.
>>> + */
>>> +#define SCHEDOP_watchdog    6
>>> +struct sched_watchdog {
>>> +    uint32_t id;                /* watchdog ID */
>>> +    uint32_t timeout;           /* timeout */
>>> +};
>>> +
>>> +/*
>>>   * Reason codes for SCHEDOP_shutdown. These may be interpreted by control
>>>   * software to determine the appropriate action. For the most part, Xen 
>> does
>>>   * not care about the shutdown code.
>>> @@ -73,5 +106,6 @@ DEFINE_GUEST_HANDLE_STRUCT(sched_poll);
>>>  #define SHUTDOWN_reboot     1  /* Clean up, kill, and then restart.         
>>  */
>>>  #define SHUTDOWN_suspend    2  /* Clean up, save suspend info, kill.        
>>  */
>>>  #define SHUTDOWN_crash      3  /* Tell controller we've crashed.            
>>  */
>>> +#define SHUTDOWN_watchdog   4  /* Restart because watchdog time expired.    
>>  */
>>>  
>>>  #endif /* __XEN_PUBLIC_SCHED_H__ */
>>>
>>>
>

[PATCH] Xen watchdog driver

[Jan Beulich]

While the hypervisor change adding SCHEDOP_watchdog support included a
daemon to make use of the new functionality, having a kernel driver
for /dev/watchdog so that user space code doesn't need to distinguish
non-Xen and Xen seems to be preferable.

Signed-off-by: Jan Beulich <jbeulich@novell.com>
Cc: Jeremy Fitzhardinge <jeremy@goop.org>

---
 drivers/watchdog/Kconfig      |   10 +
 drivers/watchdog/Makefile     |    3 
 drivers/watchdog/xen_wdt.c    |  359 ++++++++++++++++++++++++++++++++++++++++++
 include/xen/interface/sched.h |   34 +++
 4 files changed, 406 insertions(+)

--- linux-2.6.36-rc6/drivers/watchdog/Kconfig
+++ 2.6.36-rc6-xen-watchdog/drivers/watchdog/Kconfig
@@ -1043,6 +1043,16 @@ config WATCHDOG_RIO
 
 # XTENSA Architecture
 
+# Xen Architecture
+
+config XEN_WDT
+	tristate "Xen Watchdog support"
+	depends on XEN
+	help
+	  Say Y here to support the hypervisor watchdog capability provided
+	  by Xen 4.0 and newer.  The watchdog timeout period is normally one
+	  minute but can be changed with a boot-time parameter.
+
 #
 # ISA-based Watchdog Cards
 #
--- linux-2.6.36-rc6/drivers/watchdog/Makefile
+++ 2.6.36-rc6-xen-watchdog/drivers/watchdog/Makefile
@@ -145,6 +145,9 @@ obj-$(CONFIG_WATCHDOG_CP1XXX)		+= cpwd.o
 
 # XTENSA Architecture
 
+# Xen
+obj-$(CONFIG_XEN_WDT) += xen_wdt.o
+
 # Architecture Independant
 obj-$(CONFIG_WM831X_WATCHDOG) += wm831x_wdt.o
 obj-$(CONFIG_WM8350_WATCHDOG) += wm8350_wdt.o
--- linux-2.6.36-rc6/drivers/watchdog/xen_wdt.c
+++ 2.6.36-rc6-xen-watchdog/drivers/watchdog/xen_wdt.c
@@ -0,0 +1,359 @@
+/*
+ *	Xen Watchdog Driver
+ *
+ *	(c) Copyright 2010 Novell, Inc.
+ *
+ *	This program is free software; you can redistribute it and/or
+ *	modify it under the terms of the GNU General Public License
+ *	as published by the Free Software Foundation; either version
+ *	2 of the License, or (at your option) any later version.
+ */
+
+#define DRV_NAME	"wdt"
+#define DRV_VERSION	"0.01"
+#define PFX		DRV_NAME ": "
+
+#include <linux/bug.h>
+#include <linux/errno.h>
+#include <linux/fs.h>
+#include <linux/hrtimer.h>
+#include <linux/kernel.h>
+#include <linux/ktime.h>
+#include <linux/init.h>
+#include <linux/miscdevice.h>
+#include <linux/module.h>
+#include <linux/moduleparam.h>
+#include <linux/platform_device.h>
+#include <linux/spinlock.h>
+#include <linux/uaccess.h>
+#include <linux/watchdog.h>
+#include <xen/xen.h>
+#include <asm/xen/hypercall.h>
+#include <xen/interface/sched.h>
+
+static struct platform_device *platform_device;
+static DEFINE_SPINLOCK(wdt_lock);
+static struct sched_watchdog wdt;
+static __kernel_time_t wdt_expires;
+static bool is_active, expect_release;
+
+#define WATCHDOG_TIMEOUT 60 /* in seconds */
+static unsigned int timeout = WATCHDOG_TIMEOUT;
+module_param(timeout, uint, S_IRUGO);
+MODULE_PARM_DESC(timeout, "Watchdog timeout in seconds "
+	"(default=" __MODULE_STRING(WATCHDOG_TIMEOUT) ")");
+
+static bool nowayout = WATCHDOG_NOWAYOUT;
+module_param(nowayout, bool, S_IRUGO);
+MODULE_PARM_DESC(nowayout, "Watchdog cannot be stopped once started "
+	"(default=" __MODULE_STRING(WATCHDOG_NOWAYOUT) ")");
+
+static inline __kernel_time_t set_timeout(void)
+{
+	wdt.timeout = timeout;
+	return ktime_to_timespec(ktime_get()).tv_sec + timeout;
+}
+
+static int xen_wdt_start(void)
+{
+	__kernel_time_t expires;
+	int err;
+
+	spin_lock(&wdt_lock);
+
+	expires = set_timeout();
+	if (!wdt.id)
+		err = HYPERVISOR_sched_op(SCHEDOP_watchdog, &wdt);
+	else
+		err = -EBUSY;
+	if (err > 0) {
+		wdt.id = err;
+		wdt_expires = expires;
+		err = 0;
+	} else
+		BUG_ON(!err);
+
+	spin_unlock(&wdt_lock);
+
+	return err;
+}
+
+static int xen_wdt_stop(void)
+{
+	int err = 0;
+
+	spin_lock(&wdt_lock);
+
+	wdt.timeout = 0;
+	if (wdt.id)
+		err = HYPERVISOR_sched_op(SCHEDOP_watchdog, &wdt);
+	if (!err)
+		wdt.id = 0;
+
+	spin_unlock(&wdt_lock);
+
+	return err;
+}
+
+static int xen_wdt_kick(void)
+{
+	__kernel_time_t expires;
+	int err;
+
+	spin_lock(&wdt_lock);
+
+	expires = set_timeout();
+	if (wdt.id)
+		err = HYPERVISOR_sched_op(SCHEDOP_watchdog, &wdt);
+	else
+		err = -ENXIO;
+	if (!err)
+		wdt_expires = expires;
+
+	spin_unlock(&wdt_lock);
+
+	return err;
+}
+
+static int xen_wdt_open(struct inode *inode, struct file *file)
+{
+	int err;
+
+	/* /dev/watchdog can only be opened once */
+	if (xchg(&is_active, true))
+		return -EBUSY;
+
+	err = xen_wdt_start();
+	if (err == -EBUSY)
+		err = xen_wdt_kick();
+	return err ?: nonseekable_open(inode, file);
+}
+
+static int xen_wdt_release(struct inode *inode, struct file *file)
+{
+	if (expect_release)
+		xen_wdt_stop();
+	else {
+		printk(KERN_CRIT PFX
+		       "unexpected close, not stopping watchdog!\n");
+		xen_wdt_kick();
+	}
+	is_active = false;
+	expect_release = false;
+	return 0;
+}
+
+static ssize_t xen_wdt_write(struct file *file, const char __user *data,
+			     size_t len, loff_t *ppos)
+{
+	/* See if we got the magic character 'V' and reload the timer */
+	if (len) {
+		if (!nowayout) {
+			size_t i;
+
+			/* in case it was set long ago */
+			expect_release = false;
+
+			/* scan to see whether or not we got the magic
+			   character */
+			for (i = 0; i != len; i++) {
+				char c;
+				if (get_user(c, data + i))
+					return -EFAULT;
+				if (c == 'V')
+					expect_release = true;
+			}
+		}
+
+		/* someone wrote to us, we should reload the timer */
+		xen_wdt_kick();
+	}
+	return len;
+}
+
+static long xen_wdt_ioctl(struct file *file, unsigned int cmd,
+			  unsigned long arg)
+{
+	int new_options, retval = -EINVAL;
+	int new_timeout;
+	int __user *argp = (void __user *)arg;
+	static const struct watchdog_info ident = {
+		.options =		WDIOF_SETTIMEOUT | WDIOF_MAGICCLOSE,
+		.firmware_version =	0,
+		.identity =		DRV_NAME,
+	};
+
+	switch (cmd) {
+	case WDIOC_GETSUPPORT:
+		return copy_to_user(argp, &ident, sizeof(ident)) ? -EFAULT : 0;
+
+	case WDIOC_GETSTATUS:
+	case WDIOC_GETBOOTSTATUS:
+		return put_user(0, argp);
+
+	case WDIOC_SETOPTIONS:
+		if (get_user(new_options, argp))
+			return -EFAULT;
+
+		if (new_options & WDIOS_DISABLECARD)
+			retval = xen_wdt_stop();
+		if (new_options & WDIOS_ENABLECARD) {
+			retval = xen_wdt_start();
+			if (retval == -EBUSY)
+				retval = xen_wdt_kick();
+		}
+		return retval;
+
+	case WDIOC_KEEPALIVE:
+		xen_wdt_kick();
+		return 0;
+
+	case WDIOC_SETTIMEOUT:
+		if (get_user(new_timeout, argp))
+			return -EFAULT;
+		if (!new_timeout)
+			return -EINVAL;
+		timeout = new_timeout;
+		xen_wdt_kick();
+		/* fall through */
+	case WDIOC_GETTIMEOUT:
+		return put_user(timeout, argp);
+
+	case WDIOC_GETTIMELEFT:
+		retval = wdt_expires - ktime_to_timespec(ktime_get()).tv_sec;
+		return put_user(retval, argp);
+	}
+
+	return -ENOTTY;
+}
+
+static const struct file_operations xen_wdt_fops = {
+	.owner =		THIS_MODULE,
+	.llseek =		no_llseek,
+	.write =		xen_wdt_write,
+	.unlocked_ioctl =	xen_wdt_ioctl,
+	.open =			xen_wdt_open,
+	.release =		xen_wdt_release,
+};
+
+static struct miscdevice xen_wdt_miscdev = {
+	.minor =	WATCHDOG_MINOR,
+	.name =		"watchdog",
+	.fops =		&xen_wdt_fops,
+};
+
+static int __devinit xen_wdt_probe(struct platform_device *dev)
+{
+	struct sched_watchdog wd = { .id = ~0 };
+	int ret = HYPERVISOR_sched_op(SCHEDOP_watchdog, &wd);
+
+	switch (ret) {
+	case -EINVAL:
+		if (!timeout) {
+			timeout = WATCHDOG_TIMEOUT;
+			printk(KERN_INFO PFX
+			       "timeout value invalid, using %d\n", timeout);
+		}
+
+		ret = misc_register(&xen_wdt_miscdev);
+		if (ret) {
+			printk(KERN_ERR PFX
+			       "cannot register miscdev on minor=%d (%d)\n",
+			       WATCHDOG_MINOR, ret);
+			break;
+		}
+
+		printk(KERN_INFO PFX
+		       "initialized (timeout=%ds, nowayout=%d)\n",
+		       timeout, nowayout);
+		break;
+
+	case -ENOSYS:
+		printk(KERN_INFO PFX "not supported\n");
+		ret = -ENODEV;
+		break;
+
+	default:
+		printk(KERN_INFO PFX "bogus return value %d\n", ret);
+		break;
+	}
+
+	return ret;
+}
+
+static int __devexit xen_wdt_remove(struct platform_device *dev)
+{
+	/* Stop the timer before we leave */
+	if (!nowayout)
+		xen_wdt_stop();
+
+	misc_deregister(&xen_wdt_miscdev);
+
+	return 0;
+}
+
+static void xen_wdt_shutdown(struct platform_device *dev)
+{
+	xen_wdt_stop();
+}
+
+static int xen_wdt_suspend(struct platform_device *dev, pm_message_t state)
+{
+	return xen_wdt_stop();
+}
+
+static int xen_wdt_resume(struct platform_device *dev)
+{
+	return xen_wdt_start();
+}
+
+static struct platform_driver xen_wdt_driver = {
+	.probe          = xen_wdt_probe,
+	.remove         = __devexit_p(xen_wdt_remove),
+	.shutdown       = xen_wdt_shutdown,
+	.suspend        = xen_wdt_suspend,
+	.resume         = xen_wdt_resume,
+	.driver         = {
+		.owner  = THIS_MODULE,
+		.name   = DRV_NAME,
+	},
+};
+
+static int __init xen_wdt_init_module(void)
+{
+	int err;
+
+	if (!xen_domain())
+		return -ENODEV;
+
+	printk(KERN_INFO PFX "Xen WatchDog Timer Driver v%s\n", DRV_VERSION);
+
+	err = platform_driver_register(&xen_wdt_driver);
+	if (err)
+		return err;
+
+	platform_device = platform_device_register_simple(DRV_NAME,
+								  -1, NULL, 0);
+	if (IS_ERR(platform_device)) {
+		err = PTR_ERR(platform_device);
+		platform_driver_unregister(&xen_wdt_driver);
+	}
+
+	return err;
+}
+
+static void __exit xen_wdt_cleanup_module(void)
+{
+	platform_device_unregister(platform_device);
+	platform_driver_unregister(&xen_wdt_driver);
+	printk(KERN_INFO PFX "module unloaded\n");
+}
+
+module_init(xen_wdt_init_module);
+module_exit(xen_wdt_cleanup_module);
+
+MODULE_AUTHOR("Jan Beulich <jbeulich@novell.com>");
+MODULE_DESCRIPTION("Xen WatchDog Timer Driver");
+MODULE_VERSION(DRV_VERSION);
+MODULE_LICENSE("GPL");
+MODULE_ALIAS_MISCDEV(WATCHDOG_MINOR);
--- linux-2.6.36-rc6/include/xen/interface/sched.h
+++ 2.6.36-rc6-xen-watchdog/include/xen/interface/sched.h
@@ -65,6 +65,39 @@ struct sched_poll {
 DEFINE_GUEST_HANDLE_STRUCT(sched_poll);
 
 /*
+ * Declare a shutdown for another domain. The main use of this function is
+ * in interpreting shutdown requests and reasons for fully-virtualized
+ * domains.  A para-virtualized domain may use SCHEDOP_shutdown directly.
+ * @arg == pointer to sched_remote_shutdown structure.
+ */
+#define SCHEDOP_remote_shutdown        4
+struct sched_remote_shutdown {
+    domid_t domain_id;         /* Remote domain ID */
+    unsigned int reason;       /* SHUTDOWN_xxx reason */
+};
+
+/*
+ * Latch a shutdown code, so that when the domain later shuts down it
+ * reports this code to the control tools.
+ * @arg == as for SCHEDOP_shutdown.
+ */
+#define SCHEDOP_shutdown_code 5
+
+/*
+ * Setup, poke and destroy a domain watchdog timer.
+ * @arg == pointer to sched_watchdog structure.
+ * With id == 0, setup a domain watchdog timer to cause domain shutdown
+ *               after timeout, returns watchdog id.
+ * With id != 0 and timeout == 0, destroy domain watchdog timer.
+ * With id != 0 and timeout != 0, poke watchdog timer and set new timeout.
+ */
+#define SCHEDOP_watchdog    6
+struct sched_watchdog {
+    uint32_t id;                /* watchdog ID */
+    uint32_t timeout;           /* timeout */
+};
+
+/*
  * Reason codes for SCHEDOP_shutdown. These may be interpreted by control
  * software to determine the appropriate action. For the most part, Xen does
  * not care about the shutdown code.
@@ -73,5 +106,6 @@ DEFINE_GUEST_HANDLE_STRUCT(sched_poll);
 #define SHUTDOWN_reboot     1  /* Clean up, kill, and then restart.          */
 #define SHUTDOWN_suspend    2  /* Clean up, save suspend info, kill.         */
 #define SHUTDOWN_crash      3  /* Tell controller we've crashed.             */
+#define SHUTDOWN_watchdog   4  /* Restart because watchdog time expired.     */
 
 #endif /* __XEN_PUBLIC_SCHED_H__ */