[patch 6/8] KVM: timer: optimize next_timer_event and vcpu_arm_exit

[Marcelo Tosatti <mtosatti@redhat.com>]

[-- Attachment #1: kvm-armexit-optimize --]
[-- Type: text/plain, Size: 1445 bytes --]

Which reduces the added entry/exit overhead down to ~= 30 cycles.

Signed-off-by: Marcelo Tosatti <mtosatti@redhat.com>

Index: kvm-new/arch/x86/kvm/timer.c
===================================================================
--- kvm-new.orig/arch/x86/kvm/timer.c
+++ kvm-new/arch/x86/kvm/timer.c
@@ -135,14 +135,15 @@ ktime_t kvm_vcpu_next_timer_event(struct
 void kvm_inject_pending_timer_irqs(struct kvm_vcpu *vcpu)
 {
 	struct kvm_timer *ktimer, *n;
-	ktime_t now = ktime_get();
 
 	list_for_each_entry_safe(ktimer, n, &vcpu->arch.timers, vcpu_timer) {
-		ktime_t expire;
+		ktime_t expire, now;
 
 		if (!ktimer->can_inject)
 			continue;
 
+		now = ktime_get();
+
 		expire = kvm_timer_next_event(ktimer);
 		if (ktime_to_ns(now) < ktime_to_ns(expire))
 			continue;
@@ -173,8 +174,12 @@ void kvm_vcpu_arm_exit(struct kvm_vcpu *
 {
 	ktime_t expire;
 	ktime_t now;
-	struct kvm_timer *ktimer = kvm_vcpu_injectable_timer_event(vcpu);
+	struct kvm_timer *ktimer;
+
+	if (hrtimer_active(&vcpu->arch.exit_timer))
+		return;
 
+	ktimer = kvm_vcpu_injectable_timer_event(vcpu);
 	if (!ktimer)
 		return;
 
Index: kvm-new/arch/x86/kvm/x86.c
===================================================================
--- kvm-new.orig/arch/x86/kvm/x86.c
+++ kvm-new/arch/x86/kvm/x86.c
@@ -3567,8 +3567,6 @@ static int vcpu_enter_guest(struct kvm_v
 
 	preempt_enable();
 
-	kvm_vcpu_cleanup_timer(vcpu);
-
 	down_read(&vcpu->kvm->slots_lock);
 
 	/*

--