diff --git a/meson.build b/meson.build
index c669d0f9a07446590b8ed26a9ba5deecda9c53bf..e9c45426bde10eb10d1d9e948da0da035b9d3cdf 100644
--- a/meson.build
+++ b/meson.build
@@ -584,7 +584,6 @@ config_host_data.set('CONFIG_HUGEPAGE_POD', have_hugepage_pod)
 # ub
 have_ub = get_option('ub') \
   .require(targetos == 'linux', error_message: 'UB is supported only on Linux') \
-  .require(cpu == 'aarch64', error_message: 'UB is supported only on aarch64') \
   .allowed()
 
 if cpu in ['aarch64']
diff --git a/target/i386/kvm/kvm.c b/target/i386/kvm/kvm.c
index 37e30d01947b3fd13c48a21616310aa2faea6d26..b959e9caf414a0b4145cee2558d2dc06a453e370 100644
--- a/target/i386/kvm/kvm.c
+++ b/target/i386/kvm/kvm.c
@@ -6022,3 +6022,11 @@ void kvm_set_max_apic_id(uint32_t max_apic_id)
 {
     kvm_vm_enable_cap(kvm_state, KVM_CAP_MAX_VCPU_ID, 0, max_apic_id);
 }
+
+#ifdef CONFIG_UB
+int kvm_arch_fixup_usi_route(struct kvm_irq_routing_entry *route,
+                             uint64_t address, uint32_t data, UBDevice *dev)
+{
+    return -ENOSYS;
+}
+#endif // CONFIG_UB