KVM: LAPIC: Drop pending LAPIC timer injection when canceling the timer

[ Upstream commit 619f51d ]

The timer is disarmed when switching between TSC deadline and other modes;
however, the pending timer is still in-flight, so let's accurately remove
any traces of the previous mode.

Fixes: 4427593 ("KVM: x86: thoroughly disarm LAPIC timer around TSC deadline switch")
Signed-off-by: Wanpeng Li <wanpengli@tencent.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>

arch/x86/kvm/lapic.c

@@ -1508,6 +1508,7 @@ static void cancel_apic_timer(struct kvm_lapic *apic)
 	if (apic->lapic_timer.hv_timer_in_use)
 		cancel_hv_timer(apic);
 	preempt_enable();
+	atomic_set(&apic->lapic_timer.pending, 0);
 }
 
 static void apic_update_lvtt(struct kvm_lapic *apic)