From 548f7fb22234c6fe13c64459059fbd42058953c4 Mon Sep 17 00:00:00 2001
From: Wanpeng Li <wanpengli@tencent.com>
Date: Fri, 5 Jul 2019 23:23:42 +0800
Subject: [PATCH] KVM: LAPIC: Retry tune per-vCPU timer_advance_ns if adaptive
tuning goes insane
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Retry tune per-vCPU timer_advance_ns if adaptive tuning goes insane which
can happen sporadically in product environment.
Cc: Paolo Bonzini <pbonzini@redhat.com>
Cc: Radim Krčmář <rkrcmar@redhat.com>
Signed-off-by: Wanpeng Li <wanpengli@tencent.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
---
arch/x86/kvm/lapic.c | 7 ++++---
1 file changed, 4 insertions(+), 3 deletions(-)
diff --git a/arch/x86/kvm/lapic.c b/arch/x86/kvm/lapic.c
index e4227ceab0c6..e1a2e2d467ca 100644
--- a/arch/x86/kvm/lapic.c
+++ b/arch/x86/kvm/lapic.c
@@ -71,6 +71,7 @@
#define X2APIC_BROADCAST 0xFFFFFFFFul
#define LAPIC_TIMER_ADVANCE_ADJUST_DONE 100
+#define LAPIC_TIMER_ADVANCE_ADJUST_INIT 1000
/* step-by-step approximation to mitigate fluctuation */
#define LAPIC_TIMER_ADVANCE_ADJUST_STEP 8
@@ -1546,8 +1547,8 @@ 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;
- apic->lapic_timer.timer_advance_adjust_done = true;
+ timer_advance_ns = LAPIC_TIMER_ADVANCE_ADJUST_INIT;
+ apic->lapic_timer.timer_advance_adjust_done = false;
}
apic->lapic_timer.timer_advance_ns = timer_advance_ns;
}
@@ -2344,7 +2345,7 @@ int kvm_create_lapic(struct kvm_vcpu *vcpu, int timer_advance_ns)
HRTIMER_MODE_ABS_PINNED);
apic->lapic_timer.timer.function = apic_timer_fn;
if (timer_advance_ns == -1) {
- apic->lapic_timer.timer_advance_ns = 1000;
+ apic->lapic_timer.timer_advance_ns = LAPIC_TIMER_ADVANCE_ADJUST_INIT;
apic->lapic_timer.timer_advance_adjust_done = false;
} else {
apic->lapic_timer.timer_advance_ns = timer_advance_ns;