KVM: Move apic timer migration away from critical section

Migrating the apic timer in the critical section is not very nice, and is
absolutely horrible with the real-time port.  Move migration to the regular
vcpu execution path, triggered by a new bitflag.

Cc: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Avi Kivity <avi@qumranet.com>
diff --git a/arch/x86/kvm/lapic.c b/arch/x86/kvm/lapic.c
index e7513bb..2cbee94 100644
--- a/arch/x86/kvm/lapic.c
+++ b/arch/x86/kvm/lapic.c
@@ -1092,7 +1092,7 @@
 	start_apic_timer(apic);
 }
 
-void kvm_migrate_apic_timer(struct kvm_vcpu *vcpu)
+void __kvm_migrate_apic_timer(struct kvm_vcpu *vcpu)
 {
 	struct kvm_lapic *apic = vcpu->arch.apic;
 	struct hrtimer *timer;
@@ -1104,7 +1104,6 @@
 	if (hrtimer_cancel(timer))
 		hrtimer_start(timer, timer->expires, HRTIMER_MODE_ABS);
 }
-EXPORT_SYMBOL_GPL(kvm_migrate_apic_timer);
 
 void kvm_lapic_sync_from_vapic(struct kvm_vcpu *vcpu)
 {