diff --git a/xen/arch/x86/hvm/emulate.c b/xen/arch/x86/hvm/emulate.c
index e36eefc144..ec2da3b7c4 100644
--- a/xen/arch/x86/hvm/emulate.c
+++ b/xen/arch/x86/hvm/emulate.c
@@ -1620,6 +1620,8 @@ static int hvmemul_vmfunc(
 {
     int rc;
 
+    if ( !hvm_funcs.altp2m_vcpu_emulate_vmfunc )
+        return X86EMUL_UNHANDLEABLE;
     rc = hvm_funcs.altp2m_vcpu_emulate_vmfunc(ctxt->regs);
     if ( rc != X86EMUL_OKAY )
         hvmemul_inject_hw_exception(TRAP_invalid_op, 0, ctxt);