conf: default to virtio bus for input passthrough

Other buses are not supported.
Signed-off-by: NJán Tomko <jtomko@redhat.com>
Reviewed-by: NDaniel Henrique Barboza <danielhb413@gmail.com>

src/conf/domain_conf.c

@@ -13677,7 +13677,8 @@ virDomainInputDefParseXML(virDomainXMLOptionPtr xmlopt,
                 def->type == VIR_DOMAIN_INPUT_TYPE_KBD) &&
                 (ARCH_IS_X86(dom->os.arch) || dom->os.arch == VIR_ARCH_NONE)) {
                 def->bus = VIR_DOMAIN_INPUT_BUS_PS2;
-            } else if (ARCH_IS_S390(dom->os.arch)) {
+            } else if (ARCH_IS_S390(dom->os.arch) ||
+                       def->type == VIR_DOMAIN_INPUT_TYPE_PASSTHROUGH) {
                 def->bus = VIR_DOMAIN_INPUT_BUS_VIRTIO;
             } else {
                 def->bus = VIR_DOMAIN_INPUT_BUS_USB;