KVM: vmx: speed up TPR below threshold vmexits

Since we're already in VCPU context, all we have to do here is recompute
the PPR value.  That will in turn generate a KVM_REQ_EVENT if necessary.
Reviewed-by: NRoman Kagan <rkagan@virtuozzo.com>
Signed-off-by: NPaolo Bonzini <pbonzini@redhat.com>

arch/x86/kvm/lapic.c

@@ -595,6 +595,12 @@ static void apic_update_ppr(struct kvm_lapic *apic)
 	}
 }
 
+void kvm_apic_update_ppr(struct kvm_vcpu *vcpu)
+{
+	apic_update_ppr(vcpu->arch.apic);
+}
+EXPORT_SYMBOL_GPL(kvm_apic_update_ppr);
+
 static void apic_set_tpr(struct kvm_lapic *apic, u32 tpr)
 {
 	kvm_lapic_set_reg(apic, APIC_TASKPRI, tpr);

arch/x86/kvm/lapic.h

@@ -73,6 +73,7 @@ bool kvm_apic_match_dest(struct kvm_vcpu *vcpu, struct kvm_lapic *source,
 
 void __kvm_apic_update_irr(u32 *pir, void *regs);
 void kvm_apic_update_irr(struct kvm_vcpu *vcpu, u32 *pir);
+void kvm_apic_update_ppr(struct kvm_vcpu *vcpu);
 int kvm_apic_set_irq(struct kvm_vcpu *vcpu, struct kvm_lapic_irq *irq,
 		     struct dest_map *dest_map);
 int kvm_apic_local_deliver(struct kvm_lapic *apic, int lvt_type);

arch/x86/kvm/vmx.c

@@ -6152,7 +6152,7 @@ static int handle_wrmsr(struct kvm_vcpu *vcpu)
 
 static int handle_tpr_below_threshold(struct kvm_vcpu *vcpu)
 {
-	kvm_make_request(KVM_REQ_EVENT, vcpu);
+	kvm_apic_update_ppr(vcpu);
 	return 1;
 }