1 files changed, 389 insertions, 0 deletions
diff --git a/drivers/xen/manage.c b/drivers/xen/manage.c
new file mode 100644
index 000000000..cd046684e
--- /dev/null
+++ b/drivers/xen/manage.c
@@ -0,0 +1,389 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * 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. ERANGE is observed when we get
+		 * an empty value (''), this happens when we acknowledge the
+		 * request by writing '\0' below.
+		 */
+		if (err != -ENOENT && err != -ERANGE)
+			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);