diff --git a/OvmfPkg/Library/VmgExitLib/VmgExitVcHandler.c b/OvmfPkg/Library/VmgExitLib/VmgExitVcHandler.c
index e5f14035b0..9bf9d16017 100644
--- a/OvmfPkg/Library/VmgExitLib/VmgExitVcHandler.c
+++ b/OvmfPkg/Library/VmgExitLib/VmgExitVcHandler.c
@@ -664,6 +664,7 @@ MmioExit (
     CopyMem (Ghcb->SharedBuffer, &InstructionData->Ext.RegData, Bytes);
 
     Ghcb->SaveArea.SwScratch = (UINT64) Ghcb->SharedBuffer;
+    VmgSetOffsetValid (Ghcb, GhcbSwScratch);
     Status = VmgExit (Ghcb, SVM_EXIT_MMIO_WRITE, ExitInfo1, ExitInfo2);
     if (Status != 0) {
       return Status;
@@ -693,6 +694,7 @@ MmioExit (
     CopyMem (Ghcb->SharedBuffer, InstructionData->Immediate, Bytes);
 
     Ghcb->SaveArea.SwScratch = (UINT64) Ghcb->SharedBuffer;
+    VmgSetOffsetValid (Ghcb, GhcbSwScratch);
     Status = VmgExit (Ghcb, SVM_EXIT_MMIO_WRITE, ExitInfo1, ExitInfo2);
     if (Status != 0) {
       return Status;
@@ -725,6 +727,7 @@ MmioExit (
     ExitInfo2 = Bytes;
 
     Ghcb->SaveArea.SwScratch = (UINT64) Ghcb->SharedBuffer;
+    VmgSetOffsetValid (Ghcb, GhcbSwScratch);
     Status = VmgExit (Ghcb, SVM_EXIT_MMIO_READ, ExitInfo1, ExitInfo2);
     if (Status != 0) {
       return Status;
@@ -755,6 +758,7 @@ MmioExit (
     ExitInfo2 = Bytes;
 
     Ghcb->SaveArea.SwScratch = (UINT64) Ghcb->SharedBuffer;
+    VmgSetOffsetValid (Ghcb, GhcbSwScratch);
     Status = VmgExit (Ghcb, SVM_EXIT_MMIO_READ, ExitInfo1, ExitInfo2);
     if (Status != 0) {
       return Status;
@@ -780,6 +784,7 @@ MmioExit (
     ExitInfo2 = Bytes;
 
     Ghcb->SaveArea.SwScratch = (UINT64) Ghcb->SharedBuffer;
+    VmgSetOffsetValid (Ghcb, GhcbSwScratch);
     Status = VmgExit (Ghcb, SVM_EXIT_MMIO_READ, ExitInfo1, ExitInfo2);
     if (Status != 0) {
       return Status;