linux-kernel - [PATCH 1/3] KVM: LAPIC: Extract adaptive tune timer advancement logic

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Message-Id: <1557401361-3828-2-git-send-email-wanpengli@tencent.com>
Date:   Thu,  9 May 2019 19:29:19 +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>,
        Sean Christopherson <sean.j.christopherson@...el.com>,
        Liran Alon <liran.alon@...cle.com>
Subject: [PATCH 1/3] KVM: LAPIC: Extract adaptive tune timer advancement logic

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

Extract adaptive tune timer advancement logic to a single function.

Cc: Paolo Bonzini <pbonzini@...hat.com>
Cc: Radim Krčmář <rkrcmar@...hat.com>
Cc: Sean Christopherson <sean.j.christopherson@...el.com>
Cc: Liran Alon <liran.alon@...cle.com>
Signed-off-by: Wanpeng Li <wanpengli@...cent.com>
---
 arch/x86/kvm/lapic.c | 57 ++++++++++++++++++++++++++++++----------------------
 1 file changed, 33 insertions(+), 24 deletions(-)

diff --git a/arch/x86/kvm/lapic.c b/arch/x86/kvm/lapic.c
index bd13fdd..e7a0660 100644
--- a/arch/x86/kvm/lapic.c
+++ b/arch/x86/kvm/lapic.c
@@ -1501,11 +1501,41 @@ static inline void __wait_lapic_expire(struct kvm_vcpu *vcpu, u64 guest_cycles)
 	}
 }
 
-void wait_lapic_expire(struct kvm_vcpu *vcpu)
+static inline void adaptive_tune_timer_advancement(struct kvm_vcpu *vcpu,
+				u64 guest_tsc, u64 tsc_deadline)
 {
 	struct kvm_lapic *apic = vcpu->arch.apic;
 	u32 timer_advance_ns = apic->lapic_timer.timer_advance_ns;
-	u64 guest_tsc, tsc_deadline, ns;
+	u64 ns;
+
+	if (!apic->lapic_timer.timer_advance_adjust_done) {
+			/* too early */
+			if (guest_tsc < tsc_deadline) {
+				ns = (tsc_deadline - guest_tsc) * 1000000ULL;
+				do_div(ns, vcpu->arch.virtual_tsc_khz);
+				timer_advance_ns -= min((u32)ns,
+					timer_advance_ns / LAPIC_TIMER_ADVANCE_ADJUST_STEP);
+			} else {
+			/* too late */
+				ns = (guest_tsc - tsc_deadline) * 1000000ULL;
+				do_div(ns, vcpu->arch.virtual_tsc_khz);
+				timer_advance_ns += min((u32)ns,
+					timer_advance_ns / LAPIC_TIMER_ADVANCE_ADJUST_STEP);
+			}
+			if (abs(guest_tsc - tsc_deadline) < 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;
+			}
+			apic->lapic_timer.timer_advance_ns = timer_advance_ns;
+		}
+}
+
+void wait_lapic_expire(struct kvm_vcpu *vcpu)
+{
+	struct kvm_lapic *apic = vcpu->arch.apic;
+	u64 guest_tsc, tsc_deadline;
 
 	if (apic->lapic_timer.expired_tscdeadline == 0)
 		return;
@@ -1521,28 +1551,7 @@ void wait_lapic_expire(struct kvm_vcpu *vcpu)
 	if (guest_tsc < tsc_deadline)
 		__wait_lapic_expire(vcpu, tsc_deadline - guest_tsc);
 
-	if (!apic->lapic_timer.timer_advance_adjust_done) {
-		/* too early */
-		if (guest_tsc < tsc_deadline) {
-			ns = (tsc_deadline - guest_tsc) * 1000000ULL;
-			do_div(ns, vcpu->arch.virtual_tsc_khz);
-			timer_advance_ns -= min((u32)ns,
-				timer_advance_ns / LAPIC_TIMER_ADVANCE_ADJUST_STEP);
-		} else {
-		/* too late */
-			ns = (guest_tsc - tsc_deadline) * 1000000ULL;
-			do_div(ns, vcpu->arch.virtual_tsc_khz);
-			timer_advance_ns += min((u32)ns,
-				timer_advance_ns / LAPIC_TIMER_ADVANCE_ADJUST_STEP);
-		}
-		if (abs(guest_tsc - tsc_deadline) < 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;
-		}
-		apic->lapic_timer.timer_advance_ns = timer_advance_ns;
-	}
+	adaptive_tune_timer_advancement(vcpu, guest_tsc, tsc_deadline);
 }
 
 static void start_sw_tscdeadline(struct kvm_lapic *apic)
-- 
2.7.4