KVM: add support for any length io eventfd

Signed-off-by: Jason Wang <jasowang@redhat.com>
Reviewed-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
Acked-by: Paolo Bonzini <pbonzini@redhat.com>
diff --git a/kvm-stub.c b/kvm-stub.c
index a5051f7..dc97a5e 100644
--- a/kvm-stub.c
+++ b/kvm-stub.c
@@ -30,6 +30,7 @@
 bool kvm_gsi_direct_mapping;
 bool kvm_allowed;
 bool kvm_readonly_mem_allowed;
+bool kvm_ioeventfd_any_length_allowed;
 
 int kvm_init_vcpu(CPUState *cpu)
 {