x86: KVM guest: disable clock before rebooting.

#include <asm/msr.h>

#include <asm/apic.h>

#include <linux/percpu.h>

#include <asm/reboot.h>

#define KVM_SCALE 22

	setup_secondary_APIC_clock();

}

/*

 * After the clock is registered, the host will keep writing to the

 * registered memory location. If the guest happens to shutdown, this memory

 * won't be valid. In cases like kexec, in which you install a new kernel, this

 * means a random memory location will be kept being written. So before any

 * kind of shutdown from our side, we unregister the clock by writting anything

 * that does not have the 'enable' bit set in the msr

 */

#ifdef CONFIG_KEXEC

static void kvm_crash_shutdown(struct pt_regs *regs)

{

	native_write_msr_safe(MSR_KVM_SYSTEM_TIME, 0, 0);

	native_machine_crash_shutdown(regs);

}

#endif

static void kvm_shutdown(void)

{

	native_write_msr_safe(MSR_KVM_SYSTEM_TIME, 0, 0);

	native_machine_shutdown();

}

void __init kvmclock_init(void)

{

	if (!kvm_para_available())

		pv_time_ops.set_wallclock = kvm_set_wallclock;

		pv_time_ops.sched_clock = kvm_clock_read;

		pv_apic_ops.setup_secondary_clock = kvm_setup_secondary_clock;

		machine_ops.shutdown  = kvm_shutdown;

#ifdef CONFIG_KEXEC

		machine_ops.crash_shutdown  = kvm_crash_shutdown;

#endif

		clocksource_register(&kvm_clock);

	}

}