diff --git a/xen/arch/x86/hvm/emulate.c b/xen/arch/x86/hvm/emulate.c
index f8fca57254..c9aa18884d 100644
--- a/xen/arch/x86/hvm/emulate.c
+++ b/xen/arch/x86/hvm/emulate.c
@@ -2266,22 +2266,20 @@ static int _hvm_emulate_one(struct hvm_emulate_ctxt *hvmemul_ctxt,
 
     vio->mmio_retry = 0;
 
-    switch ( rc = x86_emulate(&hvmemul_ctxt->ctxt, ops) )
+    rc = x86_emulate(&hvmemul_ctxt->ctxt, ops);
+    if ( rc == X86EMUL_OKAY && vio->mmio_retry )
+        rc = X86EMUL_RETRY;
+
+    if ( !hvm_vcpu_io_need_completion(vio) )
     {
-    case X86EMUL_OKAY:
-        if ( vio->mmio_retry )
-            rc = X86EMUL_RETRY;
-        /* fall through */
-    default:
         vio->mmio_cache_count = 0;
         vio->mmio_insn_bytes = 0;
-        break;
-
-    case X86EMUL_RETRY:
+    }
+    else
+    {
         BUILD_BUG_ON(sizeof(vio->mmio_insn) < sizeof(hvmemul_ctxt->insn_buf));
         vio->mmio_insn_bytes = hvmemul_ctxt->insn_buf_bytes;
         memcpy(vio->mmio_insn, hvmemul_ctxt->insn_buf, vio->mmio_insn_bytes);
-        break;
     }
 
     if ( hvmemul_ctxt->ctxt.retire.singlestep )