KVM: fix LAPIC timer period overflow

Don't overflow when computing the 64-bit period from 32-bit registers.

Fixes sourceforge bug #2826486.
Signed-off-by: NAurelien Jarno <aurelien@aurel32.net>
Cc: stable@kernel.org
Signed-off-by: NMarcelo Tosatti <mtosatti@redhat.com>

arch/x86/kvm/lapic.c

@@ -664,7 +664,7 @@ static void start_apic_timer(struct kvm_lapic *apic)
 {
 	ktime_t now = apic->lapic_timer.timer.base->get_time();
 
-	apic->lapic_timer.period = apic_get_reg(apic, APIC_TMICT) *
+	apic->lapic_timer.period = (u64)apic_get_reg(apic, APIC_TMICT) *
 		    APIC_BUS_CYCLE_NS * apic->divide_count;
 	atomic_set(&apic->lapic_timer.pending, 0);