KVM: LAPIC: micro-optimize fixed mode ipi delivery

This patch optimizes redundancy logic before fixed mode ipi is delivered
in the fast path, broadcast handling needs to go slow path, so the delivery
mode repair can be delayed to before slow path.
Signed-off-by: Wanpeng Li <wanpengli@tencent.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

arch/x86/kvm/irq_comm.c

@@ -52,15 +52,15 @@ int kvm_irq_delivery_to_apic(struct kvm *kvm, struct kvm_lapic *src,
 	unsigned long dest_vcpu_bitmap[BITS_TO_LONGS(KVM_MAX_VCPUS)];
 	unsigned int dest_vcpus = 0;
 
+	if (kvm_irq_delivery_to_apic_fast(kvm, src, irq, &r, dest_map))
+		return r;
+
 	if (irq->dest_mode == APIC_DEST_PHYSICAL &&
 	    irq->dest_id == 0xff && kvm_lowest_prio_delivery(irq)) {
 		printk(KERN_INFO "kvm: apic: phys broadcast and lowest prio\n");
 		irq->delivery_mode = APIC_DM_FIXED;
 	}
 
-	if (kvm_irq_delivery_to_apic_fast(kvm, src, irq, &r, dest_map))
-		return r;
-
 	memset(dest_vcpu_bitmap, 0, sizeof(dest_vcpu_bitmap));
 
 	kvm_for_each_vcpu(i, vcpu, kvm) {