drivers/xen/manage.c - third_party/linux - Git at Google

 /*
  * Handle extern requests for shutdown, reboot and sysrq
  */

 #define pr_fmt(fmt) "xen:" KBUILD_MODNAME ": " fmt

 #include <linux/kernel.h>
 #include <linux/err.h>
 #include <linux/slab.h>
 #include <linux/reboot.h>
 #include <linux/sysrq.h>
 #include <linux/stop_machine.h>
 #include <linux/freezer.h>
 #include <linux/syscore_ops.h>
 #include <linux/export.h>

 #include <xen/xen.h>
 #include <xen/xenbus.h>
 #include <xen/grant_table.h>
 #include <xen/events.h>
 #include <xen/hvc-console.h>
 #include <xen/page.h>
 #include <xen/xen-ops.h>

 #include <asm/xen/hypercall.h>
 #include <asm/xen/hypervisor.h>

 enum shutdown_state {
 	SHUTDOWN_INVALID = -1,
 	SHUTDOWN_POWEROFF = 0,
 	SHUTDOWN_SUSPEND = 2,
 	/* Code 3 is SHUTDOWN_CRASH, which we don't use because the domain can only
 	   report a crash, not be instructed to crash!
 	   HALT is the same as POWEROFF, as far as we're concerned.  The tools use
 	   the distinction when we return the reason code to them.  */
 	 SHUTDOWN_HALT = 4,
 };

 /* Ignore multiple shutdown requests. */
 static enum shutdown_state shutting_down = SHUTDOWN_INVALID;

 struct suspend_info {
 	int cancelled;
 };

 static RAW_NOTIFIER_HEAD(xen_resume_notifier);

 void xen_resume_notifier_register(struct notifier_block *nb)
 {
 	raw_notifier_chain_register(&xen_resume_notifier, nb);
 }
 EXPORT_SYMBOL_GPL(xen_resume_notifier_register);

 void xen_resume_notifier_unregister(struct notifier_block *nb)
 {
 	raw_notifier_chain_unregister(&xen_resume_notifier, nb);
 }
 EXPORT_SYMBOL_GPL(xen_resume_notifier_unregister);

 #ifdef CONFIG_HIBERNATE_CALLBACKS
 static int xen_suspend(void *data)
 {
 	struct suspend_info *si = data;
 	int err;

 	BUG_ON(!irqs_disabled());

 	err = syscore_suspend();
 	if (err) {
 		pr_err("%s: system core suspend failed: %d\n", __func__, err);
 		return err;
 	}

 	gnttab_suspend();
 	xen_manage_runstate_time(-1);
 	xen_arch_pre_suspend();

 	si->cancelled = HYPERVISOR_suspend(xen_pv_domain()
                                            ? virt_to_gfn(xen_start_info)
                                            : 0);

 	xen_arch_post_suspend(si->cancelled);
 	xen_manage_runstate_time(si->cancelled ? 1 : 0);
 	gnttab_resume();

 	if (!si->cancelled) {
 		xen_irq_resume();
 		xen_timer_resume();
 	}

 	syscore_resume();

 	return 0;
 }

 static void do_suspend(void)
 {
 	int err;
 	struct suspend_info si;

 	shutting_down = SHUTDOWN_SUSPEND;

 	err = freeze_processes();
 	if (err) {
 		pr_err("%s: freeze processes failed %d\n", __func__, err);
 		goto out;
 	}

 	err = freeze_kernel_threads();
 	if (err) {
 		pr_err("%s: freeze kernel threads failed %d\n", __func__, err);
 		goto out_thaw;
 	}

 	err = dpm_suspend_start(PMSG_FREEZE);
 	if (err) {
 		pr_err("%s: dpm_suspend_start %d\n", __func__, err);
 		goto out_thaw;
 	}

 	printk(KERN_DEBUG "suspending xenstore...\n");
 	xs_suspend();

 	err = dpm_suspend_end(PMSG_FREEZE);
 	if (err) {
 		pr_err("dpm_suspend_end failed: %d\n", err);
 		si.cancelled = 0;
 		goto out_resume;
 	}

 	xen_arch_suspend();

 	si.cancelled = 1;

 	err = stop_machine(xen_suspend, &si, cpumask_of(0));

 	/* Resume console as early as possible. */
 	if (!si.cancelled)
 		xen_console_resume();

 	raw_notifier_call_chain(&xen_resume_notifier, 0, NULL);

 	dpm_resume_start(si.cancelled ? PMSG_THAW : PMSG_RESTORE);

 	if (err) {
 		pr_err("failed to start xen_suspend: %d\n", err);
 		si.cancelled = 1;
 	}

 	xen_arch_resume();

 out_resume:
 	if (!si.cancelled)
 		xs_resume();
 	else
 		xs_suspend_cancel();

 	dpm_resume_end(si.cancelled ? PMSG_THAW : PMSG_RESTORE);

 out_thaw:
 	thaw_processes();
 out:
 	shutting_down = SHUTDOWN_INVALID;
 }
 #endif	/* CONFIG_HIBERNATE_CALLBACKS */

 struct shutdown_handler {
 #define SHUTDOWN_CMD_SIZE 11
 	const char command[SHUTDOWN_CMD_SIZE];
 	bool flag;
 	void (*cb)(void);
 };

 static int poweroff_nb(struct notifier_block *cb, unsigned long code, void *unused)
 {
 	switch (code) {
 	case SYS_DOWN:
 	case SYS_HALT:
 	case SYS_POWER_OFF:
 		shutting_down = SHUTDOWN_POWEROFF;
 	default:
 		break;
 	}
 	return NOTIFY_DONE;
 }
 static void do_poweroff(void)
 {
 	switch (system_state) {
 	case SYSTEM_BOOTING:
 	case SYSTEM_SCHEDULING:
 		orderly_poweroff(true);
 		break;
 	case SYSTEM_RUNNING:
 		orderly_poweroff(false);
 		break;
 	default:
 		/* Don't do it when we are halting/rebooting. */
 		pr_info("Ignoring Xen toolstack shutdown.\n");
 		break;
 	}
 }

 static void do_reboot(void)
 {
 	shutting_down = SHUTDOWN_POWEROFF; /* ? */
 	ctrl_alt_del();
 }

 static struct shutdown_handler shutdown_handlers[] = {
 	{ "poweroff",	true,	do_poweroff },
 	{ "halt",	false,	do_poweroff },
 	{ "reboot",	true,	do_reboot   },
 #ifdef CONFIG_HIBERNATE_CALLBACKS
 	{ "suspend",	true,	do_suspend  },
 #endif
 };

 static void shutdown_handler(struct xenbus_watch *watch,
 			     const char *path, const char *token)
 {
 	char *str;
 	struct xenbus_transaction xbt;
 	int err;
 	int idx;

 	if (shutting_down != SHUTDOWN_INVALID)
 		return;

  again:
 	err = xenbus_transaction_start(&xbt);
 	if (err)
 		return;

 	str = (char *)xenbus_read(xbt, "control", "shutdown", NULL);
 	/* Ignore read errors and empty reads. */
 	if (XENBUS_IS_ERR_READ(str)) {
 		xenbus_transaction_end(xbt, 1);
 		return;
 	}

 	for (idx = 0; idx < ARRAY_SIZE(shutdown_handlers); idx++) {
 		if (strcmp(str, shutdown_handlers[idx].command) == 0)
 			break;
 	}

 	/* Only acknowledge commands which we are prepared to handle. */
 	if (idx < ARRAY_SIZE(shutdown_handlers))
 		xenbus_write(xbt, "control", "shutdown", "");

 	err = xenbus_transaction_end(xbt, 0);
 	if (err == -EAGAIN) {
 		kfree(str);
 		goto again;
 	}

 	if (idx < ARRAY_SIZE(shutdown_handlers)) {
 		shutdown_handlers[idx].cb();
 	} else {
 		pr_info("Ignoring shutdown request: %s\n", str);
 		shutting_down = SHUTDOWN_INVALID;
 	}

 	kfree(str);
 }

 #ifdef CONFIG_MAGIC_SYSRQ
 static void sysrq_handler(struct xenbus_watch *watch, const char *path,
 			  const char *token)
 {
 	char sysrq_key = '\0';
 	struct xenbus_transaction xbt;
 	int err;

  again:
 	err = xenbus_transaction_start(&xbt);
 	if (err)
 		return;
 	err = xenbus_scanf(xbt, "control", "sysrq", "%c", &sysrq_key);
 	if (err < 0) {
 		/*
 		 * The Xenstore watch fires directly after registering it and
 		 * after a suspend/resume cycle. So ENOENT is no error but
 		 * might happen in those cases.
 		 */
 		if (err != -ENOENT)
 			pr_err("Error %d reading sysrq code in control/sysrq\n",
 			       err);
 		xenbus_transaction_end(xbt, 1);
 		return;
 	}

 	if (sysrq_key != '\0') {
 		err = xenbus_printf(xbt, "control", "sysrq", "%c", '\0');
 		if (err) {
 			pr_err("%s: Error %d writing sysrq in control/sysrq\n",
 			       __func__, err);
 			xenbus_transaction_end(xbt, 1);
 			return;
 		}
 	}

 	err = xenbus_transaction_end(xbt, 0);
 	if (err == -EAGAIN)
 		goto again;

 	if (sysrq_key != '\0')
 		handle_sysrq(sysrq_key);
 }

 static struct xenbus_watch sysrq_watch = {
 	.node = "control/sysrq",
 	.callback = sysrq_handler
 };
 #endif

 static struct xenbus_watch shutdown_watch = {
 	.node = "control/shutdown",
 	.callback = shutdown_handler
 };

 static struct notifier_block xen_reboot_nb = {
 	.notifier_call = poweroff_nb,
 };

 static int setup_shutdown_watcher(void)
 {
 	int err;
 	int idx;
 #define FEATURE_PATH_SIZE (SHUTDOWN_CMD_SIZE + sizeof("feature-"))
 	char node[FEATURE_PATH_SIZE];

 	err = register_xenbus_watch(&shutdown_watch);
 	if (err) {
 		pr_err("Failed to set shutdown watcher\n");
 		return err;
 	}


 #ifdef CONFIG_MAGIC_SYSRQ
 	err = register_xenbus_watch(&sysrq_watch);
 	if (err) {
 		pr_err("Failed to set sysrq watcher\n");
 		return err;
 	}
 #endif

 	for (idx = 0; idx < ARRAY_SIZE(shutdown_handlers); idx++) {
 		if (!shutdown_handlers[idx].flag)
 			continue;
 		snprintf(node, FEATURE_PATH_SIZE, "feature-%s",
 			 shutdown_handlers[idx].command);
 		err = xenbus_printf(XBT_NIL, "control", node, "%u", 1);
 		if (err) {
 			pr_err("%s: Error %d writing %s\n", __func__,
 				err, node);
 			return err;
 		}
 	}

 	return 0;
 }

 static int shutdown_event(struct notifier_block *notifier,
 			  unsigned long event,
 			  void *data)
 {
 	setup_shutdown_watcher();
 	return NOTIFY_DONE;
 }

 int xen_setup_shutdown_event(void)
 {
 	static struct notifier_block xenstore_notifier = {
 		.notifier_call = shutdown_event
 	};

 	if (!xen_domain())
 		return -ENODEV;
 	register_xenstore_notifier(&xenstore_notifier);
 	register_reboot_notifier(&xen_reboot_nb);

 	return 0;
 }
 EXPORT_SYMBOL_GPL(xen_setup_shutdown_event);

 subsys_initcall(xen_setup_shutdown_event);
	/*
	* Handle extern requests for shutdown, reboot and sysrq
	*/

	#define pr_fmt(fmt) "xen:" KBUILD_MODNAME ": " fmt

	#include <linux/kernel.h>
	#include <linux/err.h>
	#include <linux/slab.h>
	#include <linux/reboot.h>
	#include <linux/sysrq.h>
	#include <linux/stop_machine.h>
	#include <linux/freezer.h>
	#include <linux/syscore_ops.h>
	#include <linux/export.h>

	#include <xen/xen.h>
	#include <xen/xenbus.h>
	#include <xen/grant_table.h>
	#include <xen/events.h>
	#include <xen/hvc-console.h>
	#include <xen/page.h>
	#include <xen/xen-ops.h>

	#include <asm/xen/hypercall.h>
	#include <asm/xen/hypervisor.h>

	enum shutdown_state {
	SHUTDOWN_INVALID = -1,
	SHUTDOWN_POWEROFF = 0,
	SHUTDOWN_SUSPEND = 2,
	/* Code 3 is SHUTDOWN_CRASH, which we don't use because the domain can only
	report a crash, not be instructed to crash!
	HALT is the same as POWEROFF, as far as we're concerned. The tools use
	the distinction when we return the reason code to them. */
	SHUTDOWN_HALT = 4,
	};

	/* Ignore multiple shutdown requests. */
	static enum shutdown_state shutting_down = SHUTDOWN_INVALID;

	struct suspend_info {
	int cancelled;
	};

	static RAW_NOTIFIER_HEAD(xen_resume_notifier);

	void xen_resume_notifier_register(struct notifier_block *nb)
	{
	raw_notifier_chain_register(&xen_resume_notifier, nb);
	}
	EXPORT_SYMBOL_GPL(xen_resume_notifier_register);

	void xen_resume_notifier_unregister(struct notifier_block *nb)
	{
	raw_notifier_chain_unregister(&xen_resume_notifier, nb);
	}
	EXPORT_SYMBOL_GPL(xen_resume_notifier_unregister);

	#ifdef CONFIG_HIBERNATE_CALLBACKS
	static int xen_suspend(void *data)
	{
	struct suspend_info *si = data;
	int err;

	BUG_ON(!irqs_disabled());

	err = syscore_suspend();
	if (err) {
	pr_err("%s: system core suspend failed: %d\n", __func__, err);
	return err;
	}

	gnttab_suspend();
	xen_manage_runstate_time(-1);
	xen_arch_pre_suspend();

	si->cancelled = HYPERVISOR_suspend(xen_pv_domain()
	? virt_to_gfn(xen_start_info)
	: 0);

	xen_arch_post_suspend(si->cancelled);
	xen_manage_runstate_time(si->cancelled ? 1 : 0);
	gnttab_resume();

	if (!si->cancelled) {
	xen_irq_resume();
	xen_timer_resume();
	}

	syscore_resume();

	return 0;
	}

	static void do_suspend(void)
	{
	int err;
	struct suspend_info si;

	shutting_down = SHUTDOWN_SUSPEND;

	err = freeze_processes();
	if (err) {
	pr_err("%s: freeze processes failed %d\n", __func__, err);
	goto out;
	}

	err = freeze_kernel_threads();
	if (err) {
	pr_err("%s: freeze kernel threads failed %d\n", __func__, err);
	goto out_thaw;
	}

	err = dpm_suspend_start(PMSG_FREEZE);
	if (err) {
	pr_err("%s: dpm_suspend_start %d\n", __func__, err);
	goto out_thaw;
	}

	printk(KERN_DEBUG "suspending xenstore...\n");
	xs_suspend();

	err = dpm_suspend_end(PMSG_FREEZE);
	if (err) {
	pr_err("dpm_suspend_end failed: %d\n", err);
	si.cancelled = 0;
	goto out_resume;
	}

	xen_arch_suspend();

	si.cancelled = 1;

	err = stop_machine(xen_suspend, &si, cpumask_of(0));

	/* Resume console as early as possible. */
	if (!si.cancelled)
	xen_console_resume();

	raw_notifier_call_chain(&xen_resume_notifier, 0, NULL);

	dpm_resume_start(si.cancelled ? PMSG_THAW : PMSG_RESTORE);

	if (err) {
	pr_err("failed to start xen_suspend: %d\n", err);
	si.cancelled = 1;
	}

	xen_arch_resume();

	out_resume:
	if (!si.cancelled)
	xs_resume();
	else
	xs_suspend_cancel();

	dpm_resume_end(si.cancelled ? PMSG_THAW : PMSG_RESTORE);

	out_thaw:
	thaw_processes();
	out:
	shutting_down = SHUTDOWN_INVALID;
	}
	#endif /* CONFIG_HIBERNATE_CALLBACKS */

	struct shutdown_handler {
	#define SHUTDOWN_CMD_SIZE 11
	const char command[SHUTDOWN_CMD_SIZE];
	bool flag;
	void (*cb)(void);
	};

	static int poweroff_nb(struct notifier_block cb, unsigned long code, void unused)
	{
	switch (code) {
	case SYS_DOWN:
	case SYS_HALT:
	case SYS_POWER_OFF:
	shutting_down = SHUTDOWN_POWEROFF;
	default:
	break;
	}
	return NOTIFY_DONE;
	}
	static void do_poweroff(void)
	{
	switch (system_state) {
	case SYSTEM_BOOTING:
	case SYSTEM_SCHEDULING:
	orderly_poweroff(true);
	break;
	case SYSTEM_RUNNING:
	orderly_poweroff(false);
	break;
	default:
	/* Don't do it when we are halting/rebooting. */
	pr_info("Ignoring Xen toolstack shutdown.\n");
	break;
	}
	}

	static void do_reboot(void)
	{
	shutting_down = SHUTDOWN_POWEROFF; /* ? */
	ctrl_alt_del();
	}

	static struct shutdown_handler shutdown_handlers[] = {
	{ "poweroff", true, do_poweroff },
	{ "halt", false, do_poweroff },
	{ "reboot", true, do_reboot },
	#ifdef CONFIG_HIBERNATE_CALLBACKS
	{ "suspend", true, do_suspend },
	#endif
	};

	static void shutdown_handler(struct xenbus_watch *watch,
	const char path, const char token)
	{
	char *str;
	struct xenbus_transaction xbt;
	int err;
	int idx;

	if (shutting_down != SHUTDOWN_INVALID)
	return;

	again:
	err = xenbus_transaction_start(&xbt);
	if (err)
	return;

	str = (char *)xenbus_read(xbt, "control", "shutdown", NULL);
	/* Ignore read errors and empty reads. */
	if (XENBUS_IS_ERR_READ(str)) {
	xenbus_transaction_end(xbt, 1);
	return;
	}

	for (idx = 0; idx < ARRAY_SIZE(shutdown_handlers); idx++) {
	if (strcmp(str, shutdown_handlers[idx].command) == 0)
	break;
	}

	/* Only acknowledge commands which we are prepared to handle. */
	if (idx < ARRAY_SIZE(shutdown_handlers))
	xenbus_write(xbt, "control", "shutdown", "");

	err = xenbus_transaction_end(xbt, 0);
	if (err == -EAGAIN) {
	kfree(str);
	goto again;
	}

	if (idx < ARRAY_SIZE(shutdown_handlers)) {
	shutdown_handlers[idx].cb();
	} else {
	pr_info("Ignoring shutdown request: %s\n", str);
	shutting_down = SHUTDOWN_INVALID;
	}

	kfree(str);
	}

	#ifdef CONFIG_MAGIC_SYSRQ
	static void sysrq_handler(struct xenbus_watch watch, const char path,
	const char *token)
	{
	char sysrq_key = '\0';
	struct xenbus_transaction xbt;
	int err;

	again:
	err = xenbus_transaction_start(&xbt);
	if (err)
	return;
	err = xenbus_scanf(xbt, "control", "sysrq", "%c", &sysrq_key);
	if (err < 0) {
	/*
	* The Xenstore watch fires directly after registering it and
	* after a suspend/resume cycle. So ENOENT is no error but
	* might happen in those cases.
	*/
	if (err != -ENOENT)
	pr_err("Error %d reading sysrq code in control/sysrq\n",
	err);
	xenbus_transaction_end(xbt, 1);
	return;
	}

	if (sysrq_key != '\0') {
	err = xenbus_printf(xbt, "control", "sysrq", "%c", '\0');
	if (err) {
	pr_err("%s: Error %d writing sysrq in control/sysrq\n",
	__func__, err);
	xenbus_transaction_end(xbt, 1);
	return;
	}
	}

	err = xenbus_transaction_end(xbt, 0);
	if (err == -EAGAIN)
	goto again;

	if (sysrq_key != '\0')
	handle_sysrq(sysrq_key);
	}

	static struct xenbus_watch sysrq_watch = {
	.node = "control/sysrq",
	.callback = sysrq_handler
	};
	#endif

	static struct xenbus_watch shutdown_watch = {
	.node = "control/shutdown",
	.callback = shutdown_handler
	};

	static struct notifier_block xen_reboot_nb = {
	.notifier_call = poweroff_nb,
	};

	static int setup_shutdown_watcher(void)
	{
	int err;
	int idx;
	#define FEATURE_PATH_SIZE (SHUTDOWN_CMD_SIZE + sizeof("feature-"))
	char node[FEATURE_PATH_SIZE];

	err = register_xenbus_watch(&shutdown_watch);
	if (err) {
	pr_err("Failed to set shutdown watcher\n");
	return err;
	}


	#ifdef CONFIG_MAGIC_SYSRQ
	err = register_xenbus_watch(&sysrq_watch);
	if (err) {
	pr_err("Failed to set sysrq watcher\n");
	return err;
	}
	#endif

	for (idx = 0; idx < ARRAY_SIZE(shutdown_handlers); idx++) {
	if (!shutdown_handlers[idx].flag)
	continue;
	snprintf(node, FEATURE_PATH_SIZE, "feature-%s",
	shutdown_handlers[idx].command);
	err = xenbus_printf(XBT_NIL, "control", node, "%u", 1);
	if (err) {
	pr_err("%s: Error %d writing %s\n", __func__,
	err, node);
	return err;
	}
	}

	return 0;
	}

	static int shutdown_event(struct notifier_block *notifier,
	unsigned long event,
	void *data)
	{
	setup_shutdown_watcher();
	return NOTIFY_DONE;
	}

	int xen_setup_shutdown_event(void)
	{
	static struct notifier_block xenstore_notifier = {
	.notifier_call = shutdown_event
	};

	if (!xen_domain())
	return -ENODEV;
	register_xenstore_notifier(&xenstore_notifier);
	register_reboot_notifier(&xen_reboot_nb);

	return 0;
	}
	EXPORT_SYMBOL_GPL(xen_setup_shutdown_event);

	subsys_initcall(xen_setup_shutdown_event);