manage.c

Go to the documentation of this file.

/*
 * Handle extern requests for shutdown, reboot and sysrq
 */
#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/xen-ops.h>

#include <asm/xen/hypercall.h>
#include <asm/xen/page.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;
    unsigned long arg; /* extra hypercall argument */
    void (*pre)(void);
    void (*post)(int cancelled);
};

static void xen_hvm_post_suspend(int cancelled)
{
    xen_arch_hvm_post_suspend(cancelled);
    gnttab_resume();
}

static void xen_pre_suspend(void)
{
    xen_mm_pin_all();
    gnttab_suspend();
    xen_arch_pre_suspend();
}

static void xen_post_suspend(int cancelled)
{
    xen_arch_post_suspend(cancelled);
    gnttab_resume();
    xen_mm_unpin_all();
}

#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) {
        printk(KERN_ERR "xen_suspend: system core suspend failed: %d\n",
            err);
        return err;
    }

    if (si->pre)
        si->pre();

    /*
     * This hypercall returns 1 if suspend was cancelled
     * or the domain was merely checkpointed, and 0 if it
     * is resuming in a new domain.
     */
    si->cancelled = HYPERVISOR_suspend(si->arg);

    if (si->post)
        si->post(si->cancelled);

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

    syscore_resume();

    return 0;
}

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

    shutting_down = SHUTDOWN_SUSPEND;

#ifdef CONFIG_PREEMPT
    /* If the kernel is preemptible, we need to freeze all the processes
       to prevent them from being in the middle of a pagetable update
       during suspend. */
    err = freeze_processes();
    if (err) {
        printk(KERN_ERR "xen suspend: freeze failed %d\n", err);
        goto out;
    }
#endif

    err = dpm_suspend_start(PMSG_FREEZE);
    if (err) {
        printk(KERN_ERR "xen suspend: dpm_suspend_start %d\n", err);
        goto out_thaw;
    }

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

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

    si.cancelled = 1;

    if (xen_hvm_domain()) {
        si.arg = 0UL;
        si.pre = NULL;
        si.post = &xen_hvm_post_suspend;
    } else {
        si.arg = virt_to_mfn(xen_start_info);
        si.pre = &xen_pre_suspend;
        si.post = &xen_post_suspend;
    }

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

    dpm_resume_start(si.cancelled ? PMSG_THAW : PMSG_RESTORE);

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

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

    dpm_resume_end(si.cancelled ? PMSG_THAW : PMSG_RESTORE);

    /* Make sure timer events get retriggered on all CPUs */
    clock_was_set();

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

struct shutdown_handler {
    const char *command;
    void (*cb)(void);
};

static void do_poweroff(void)
{
    shutting_down = SHUTDOWN_POWEROFF;
    orderly_poweroff(false);
}

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

static void shutdown_handler(struct xenbus_watch *watch,
                 const char **vec, unsigned int len)
{
    char *str;
    struct xenbus_transaction xbt;
    int err;
    static struct shutdown_handler handlers[] = {
        { "poweroff",   do_poweroff },
        { "halt",   do_poweroff },
        { "reboot", do_reboot   },
#ifdef CONFIG_HIBERNATE_CALLBACKS
        { "suspend",    do_suspend  },
#endif
        {NULL, NULL},
    };
    static struct shutdown_handler *handler;

    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 (handler = &handlers[0]; handler->command; handler++) {
        if (strcmp(str, handler->command) == 0)
            break;
    }

    /* Only acknowledge commands which we are prepared to handle. */
    if (handler->cb)
        xenbus_write(xbt, "control", "shutdown", "");

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

    if (handler->cb) {
        handler->cb();
    } else {
        printk(KERN_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 **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);
}

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 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;
    }

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

    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);

    return 0;
}
EXPORT_SYMBOL_GPL(xen_setup_shutdown_event);

subsys_initcall(xen_setup_shutdown_event);