diff --git a/IntelSiliconPkg/Feature/VTd/IntelVTdDxe/DmaProtection.c b/IntelSiliconPkg/Feature/VTd/IntelVTdDxe/DmaProtection.c
index f221e45938..956ebb2d3d 100644
--- a/IntelSiliconPkg/Feature/VTd/IntelVTdDxe/DmaProtection.c
+++ b/IntelSiliconPkg/Feature/VTd/IntelVTdDxe/DmaProtection.c
@@ -1,6 +1,6 @@
 /** @file
 
-  Copyright (c) 2017 - 2018, Intel Corporation. All rights reserved.<BR>
+  Copyright (c) 2017 - 2019, Intel Corporation. All rights reserved.<BR>
   SPDX-License-Identifier: BSD-2-Clause-Patent
 
 **/
@@ -581,9 +581,20 @@ OnExitBootServices (
   IN VOID                                    *Context
   )
 {
+  UINTN   VtdIndex;
+
   DEBUG ((DEBUG_INFO, "Vtd OnExitBootServices\n"));
   DumpVtdRegsAll ();
 
+  DEBUG ((DEBUG_INFO, "Invalidate all\n"));
+  for (VtdIndex = 0; VtdIndex < mVtdUnitNumber; VtdIndex++) {
+    FlushWriteBuffer (VtdIndex);
+
+    InvalidateContextCache (VtdIndex);
+
+    InvalidateIOTLB (VtdIndex);
+  }
+
   if ((PcdGet8(PcdVTdPolicyPropertyMask) & BIT1) == 0) {
     DisableDmar ();
     DumpVtdRegsAll ();
diff --git a/IntelSiliconPkg/Feature/VTd/IntelVTdDxe/DmaProtection.h b/IntelSiliconPkg/Feature/VTd/IntelVTdDxe/DmaProtection.h
index 72426d23c3..a3331db8f7 100644
--- a/IntelSiliconPkg/Feature/VTd/IntelVTdDxe/DmaProtection.h
+++ b/IntelSiliconPkg/Feature/VTd/IntelVTdDxe/DmaProtection.h
@@ -1,6 +1,6 @@
 /** @file
 
-  Copyright (c) 2017 - 2018, Intel Corporation. All rights reserved.<BR>
+  Copyright (c) 2017 - 2019, Intel Corporation. All rights reserved.<BR>
   SPDX-License-Identifier: BSD-2-Clause-Patent
 
 **/
@@ -168,6 +168,36 @@ DisableDmar (
   VOID
   );
 
+/**
+  Flush VTd engine write buffer.
+
+  @param[in]  VtdIndex          The index used to identify a VTd engine.
+**/
+VOID
+FlushWriteBuffer (
+  IN UINTN  VtdIndex
+  );
+
+/**
+  Invalidate VTd context cache.
+
+  @param[in]  VtdIndex          The index used to identify a VTd engine.
+**/
+EFI_STATUS
+InvalidateContextCache (
+  IN UINTN  VtdIndex
+  );
+
+/**
+  Invalidate VTd IOTLB.
+
+  @param[in]  VtdIndex          The index used to identify a VTd engine.
+**/
+EFI_STATUS
+InvalidateIOTLB (
+  IN UINTN  VtdIndex
+  );
+
 /**
   Invalid VTd global IOTLB.