kvm/eventfd: avoid loop inside irqfd_update()

The loop(for) inside irqfd_update() is unnecessary
because any other value for irq_entry.type will just trigger
schedule_work(&irqfd->inject) in irqfd_wakeup.

Signed-off-by: Andrey Smetanin <asmetanin@virtuozzo.com>
Reviewed-by: Roman Kagan <rkagan@virtuozzo.com>
Signed-off-by: Denis V. Lunev <den@openvz.org>
CC: Vitaly Kuznetsov <vkuznets@redhat.com>
CC: "K. Y. Srinivasan" <kys@microsoft.com>
CC: Gleb Natapov <gleb@kernel.org>
CC: Paolo Bonzini <pbonzini@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

virt/kvm/eventfd.c

@@ -238,20 +238,17 @@ static void irqfd_update(struct kvm *kvm, struct kvm_kernel_irqfd *irqfd)
 {
 	struct kvm_kernel_irq_routing_entry *e;
 	struct kvm_kernel_irq_routing_entry entries[KVM_NR_IRQCHIPS];
-	int i, n_entries;
+	int n_entries;
 
 	n_entries = kvm_irq_map_gsi(kvm, entries, irqfd->gsi);
 
 	write_seqcount_begin(&irqfd->irq_entry_sc);
 
-	irqfd->irq_entry.type = 0;
-
 	e = entries;
-	for (i = 0; i < n_entries; ++i, ++e) {
-		/* Only fast-path MSI. */
-		if (e->type == KVM_IRQ_ROUTING_MSI)
-			irqfd->irq_entry = *e;
-	}
+	if (n_entries == 1)
+		irqfd->irq_entry = *e;
+	else
+		irqfd->irq_entry.type = 0;
 
 	write_seqcount_end(&irqfd->irq_entry_sc);
 }