xen: handle external requests for shutdown, reboot and sysrq
The guest domain can be asked to shutdown or reboot itself, or have a
sysrq key injected, via xenbus. This patch adds a watcher for those
events, and does the appropriate action.
Signed-off-by: Jeremy Fitzhardinge <jeremy@xensource.com>
Cc: Chris Wright <chrisw@sous-sol.org>
diff --git a/arch/i386/xen/manage.c b/arch/i386/xen/manage.c
new file mode 100644
index 0000000..aa7af9e
--- /dev/null
+++ b/arch/i386/xen/manage.c
@@ -0,0 +1,143 @@
+/*
+ * Handle extern requests for shutdown, reboot and sysrq
+ */
+#include <linux/kernel.h>
+#include <linux/err.h>
+#include <linux/reboot.h>
+#include <linux/sysrq.h>
+
+#include <xen/xenbus.h>
+
+#define SHUTDOWN_INVALID -1
+#define SHUTDOWN_POWEROFF 0
+#define 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.
+ */
+#define SHUTDOWN_HALT 4
+
+/* Ignore multiple shutdown requests. */
+static int shutting_down = SHUTDOWN_INVALID;
+
+static void shutdown_handler(struct xenbus_watch *watch,
+ const char **vec, unsigned int len)
+{
+ char *str;
+ struct xenbus_transaction xbt;
+ int err;
+
+ 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;
+ }
+
+ xenbus_write(xbt, "control", "shutdown", "");
+
+ err = xenbus_transaction_end(xbt, 0);
+ if (err == -EAGAIN) {
+ kfree(str);
+ goto again;
+ }
+
+ if (strcmp(str, "poweroff") == 0 ||
+ strcmp(str, "halt") == 0)
+ orderly_poweroff(false);
+ else if (strcmp(str, "reboot") == 0)
+ ctrl_alt_del();
+ else {
+ printk(KERN_INFO "Ignoring shutdown request: %s\n", str);
+ shutting_down = SHUTDOWN_INVALID;
+ }
+
+ kfree(str);
+}
+
+static void sysrq_handler(struct xenbus_watch *watch, const char **vec,
+ unsigned int len)
+{
+ char sysrq_key = '\0';
+ struct xenbus_transaction xbt;
+ int err;
+
+ again:
+ err = xenbus_transaction_start(&xbt);
+ if (err)
+ return;
+ if (!xenbus_scanf(xbt, "control", "sysrq", "%c", &sysrq_key)) {
+ printk(KERN_ERR "Unable to read sysrq code in "
+ "control/sysrq\n");
+ xenbus_transaction_end(xbt, 1);
+ return;
+ }
+
+ if (sysrq_key != '\0')
+ xenbus_printf(xbt, "control", "sysrq", "%c", '\0');
+
+ err = xenbus_transaction_end(xbt, 0);
+ if (err == -EAGAIN)
+ goto again;
+
+ if (sysrq_key != '\0')
+ handle_sysrq(sysrq_key, NULL);
+}
+
+static struct xenbus_watch shutdown_watch = {
+ .node = "control/shutdown",
+ .callback = shutdown_handler
+};
+
+static struct xenbus_watch sysrq_watch = {
+ .node = "control/sysrq",
+ .callback = sysrq_handler
+};
+
+static int setup_shutdown_watcher(void)
+{
+ int err;
+
+ err = register_xenbus_watch(&shutdown_watch);
+ if (err) {
+ printk(KERN_ERR "Failed to set shutdown watcher\n");
+ return err;
+ }
+
+ err = register_xenbus_watch(&sysrq_watch);
+ if (err) {
+ printk(KERN_ERR "Failed to set sysrq watcher\n");
+ return err;
+ }
+
+ return 0;
+}
+
+static int shutdown_event(struct notifier_block *notifier,
+ unsigned long event,
+ void *data)
+{
+ setup_shutdown_watcher();
+ return NOTIFY_DONE;
+}
+
+static int __init setup_shutdown_event(void)
+{
+ static struct notifier_block xenstore_notifier = {
+ .notifier_call = shutdown_event
+ };
+ register_xenstore_notifier(&xenstore_notifier);
+
+ return 0;
+}
+
+subsys_initcall(setup_shutdown_event);
