linux-kernel - [PATCH] KVM: LAPIC: Reset timer_advance_ns to 1000 after adaptive tuning goes insane

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Date:   Fri,  5 Jul 2019 17:40:51 +0800
From:   Wanpeng Li <kernellwp@...il.com>
To:     linux-kernel@...r.kernel.org, kvm@...r.kernel.org
Cc:     Paolo Bonzini <pbonzini@...hat.com>,
        Radim Krčmář <rkrcmar@...hat.com>
Subject: [PATCH] KVM: LAPIC: Reset timer_advance_ns to 1000 after adaptive tuning goes insane

From: Wanpeng Li <wanpengli@...cent.com>

Reset timer_advance_ns to the default value 1000ns after adaptive tuning 
goes insane which can happen sporadically in product environment.

Cc: Paolo Bonzini <pbonzini@...hat.com>
Cc: Radim Krčmář <rkrcmar@...hat.com>
Signed-off-by: Wanpeng Li <wanpengli@...cent.com>
---
 arch/x86/kvm/lapic.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/arch/x86/kvm/lapic.c b/arch/x86/kvm/lapic.c
index 05d8934..454d3dd 100644
--- a/arch/x86/kvm/lapic.c
+++ b/arch/x86/kvm/lapic.c
@@ -1549,7 +1549,7 @@ static inline void adjust_lapic_timer_advance(struct kvm_vcpu *vcpu,
 	if (abs(advance_expire_delta) < LAPIC_TIMER_ADVANCE_ADJUST_DONE)
 		apic->lapic_timer.timer_advance_adjust_done = true;
 	if (unlikely(timer_advance_ns > 5000)) {
-		timer_advance_ns = 0;
+		timer_advance_ns = 1000;
 		apic->lapic_timer.timer_advance_adjust_done = true;
 	}
 	apic->lapic_timer.timer_advance_ns = timer_advance_ns;
-- 
2.7.4