From c69518c86be5000bf4d8eb0e0d279d40779d2a18 Mon Sep 17 00:00:00 2001
From: Wanpeng Li <wanpeng.li@hotmail.com>
Date: Thu, 5 Oct 2017 03:53:51 -0700
Subject: [PATCH] KVM: LAPIC: Fix lapic timer mode transition
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SDM 10.5.4.1 TSC-Deadline Mode mentioned that "Transitioning between TSC-Deadline
mode and other timer modes also disarms the timer". So the APIC Timer Initial Count
Register for one-shot/periodic mode should be reset. This patch do it.

Cc: Paolo Bonzini <pbonzini@redhat.com>
Cc: Radim Krčmář <rkrcmar@redhat.com>
Signed-off-by: Wanpeng Li <wanpeng.li@hotmail.com>
[Removed unnecessary definition of APIC_LVT_TIMER_MASK.]
Signed-off-by: Radim Krčmář <rkrcmar@redhat.com>
---
 arch/x86/kvm/lapic.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/arch/x86/kvm/lapic.c b/arch/x86/kvm/lapic.c
index 69c5612be786f..6723e2ca3d9d2 100644
--- a/arch/x86/kvm/lapic.c
+++ b/arch/x86/kvm/lapic.c
@@ -1307,6 +1307,9 @@ static void apic_update_lvtt(struct kvm_lapic *apic)
 			apic->lapic_timer.timer_mode_mask;
 
 	if (apic->lapic_timer.timer_mode != timer_mode) {
+		if (apic_lvtt_tscdeadline(apic) != (timer_mode ==
+				APIC_LVT_TIMER_TSCDEADLINE))
+			kvm_lapic_set_reg(apic, APIC_TMICT, 0);
 		apic->lapic_timer.timer_mode = timer_mode;
 		hrtimer_cancel(&apic->lapic_timer.timer);
 	}
-- 
2.30.2