KVM: convert io_bus to SRCU

Signed-off-by: Marcelo Tosatti <mtosatti@redhat.com>
diff --git a/arch/x86/kvm/i8259.c b/arch/x86/kvm/i8259.c
index d057c0c..b7d145b 100644
--- a/arch/x86/kvm/i8259.c
+++ b/arch/x86/kvm/i8259.c
@@ -533,7 +533,9 @@
 	 * Initialize PIO device
 	 */
 	kvm_iodevice_init(&s->dev, &picdev_ops);
-	ret = kvm_io_bus_register_dev(kvm, &kvm->pio_bus, &s->dev);
+	down_write(&kvm->slots_lock);
+	ret = kvm_io_bus_register_dev(kvm, KVM_PIO_BUS, &s->dev);
+	up_write(&kvm->slots_lock);
 	if (ret < 0) {
 		kfree(s);
 		return NULL;