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Subject[PATCH v2 1/4] KVM: LAPIC: Extract adaptive tune timer advancement logic
Date
From: Wanpeng Li <wanpengli@tencent.com>

Extract adaptive tune timer advancement logic to a single function.

Cc: Paolo Bonzini <pbonzini@redhat.com>
Cc: Radim Krčmář <rkrcmar@redhat.com>
Cc: Sean Christopherson <sean.j.christopherson@intel.com>
Cc: Liran Alon <liran.alon@oracle.com>
Signed-off-by: Wanpeng Li <wanpengli@tencent.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..2f364fe 100644
--- a/arch/x86/kvm/lapic.c
+++ b/arch/x86/kvm/lapic.c
@@ -1501,11 +1501,40 @@ 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;
+
+ /* 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 +1550,8 @@ 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;
- }
+ if (unlikely(!apic->lapic_timer.timer_advance_adjust_done))
+ adaptive_tune_timer_advancement(vcpu, guest_tsc, tsc_deadline);
}

static void start_sw_tscdeadline(struct kvm_lapic *apic)
--
2.7.4
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