diff --git a/OvmfPkg/Library/SmmCpuFeaturesLib/SmmCpuFeaturesLib.c b/OvmfPkg/Library/SmmCpuFeaturesLib/SmmCpuFeaturesLib.c
index 0bfdeda78d..7ef7ed9834 100644
--- a/OvmfPkg/Library/SmmCpuFeaturesLib/SmmCpuFeaturesLib.c
+++ b/OvmfPkg/Library/SmmCpuFeaturesLib/SmmCpuFeaturesLib.c
@@ -6,14 +6,17 @@
   SPDX-License-Identifier: BSD-2-Clause-Patent
 **/
 
+#include <IndustryStandard/Q35MchIch9.h>
 #include <Library/BaseLib.h>
 #include <Library/BaseMemoryLib.h>
 #include <Library/DebugLib.h>
 #include <Library/MemEncryptSevLib.h>
+#include <Library/PcdLib.h>
 #include <Library/SmmCpuFeaturesLib.h>
 #include <Library/SmmServicesTableLib.h>
 #include <Library/UefiBootServicesTableLib.h>
 #include <PiSmm.h>
+#include <Register/Intel/SmramSaveStateMap.h>
 #include <Register/QemuSmramSaveStateMap.h>
 
 //
@@ -215,8 +218,22 @@ SmmCpuFeaturesSmmRelocationComplete (
 
   ZeroMem ((VOID *)MapPagesBase, EFI_PAGES_TO_SIZE (MapPagesCount));
 
-  Status = gBS->FreePages (MapPagesBase, MapPagesCount);
-  ASSERT_EFI_ERROR (Status);
+  if (PcdGetBool (PcdQ35SmramAtDefaultSmbase)) {
+    //
+    // The initial SMRAM Save State Map has been covered as part of a larger
+    // reserved memory allocation in PlatformPei's InitializeRamRegions(). That
+    // allocation is supposed to survive into OS runtime; we must not release
+    // any part of it. Only re-assert the containment here.
+    //
+    ASSERT (SMM_DEFAULT_SMBASE <= MapPagesBase);
+    ASSERT (
+      (MapPagesBase + EFI_PAGES_TO_SIZE (MapPagesCount) <=
+       SMM_DEFAULT_SMBASE + MCH_DEFAULT_SMBASE_SIZE)
+      );
+  } else {
+    Status = gBS->FreePages (MapPagesBase, MapPagesCount);
+    ASSERT_EFI_ERROR (Status);
+  }
 }
 
 /**
diff --git a/OvmfPkg/Library/SmmCpuFeaturesLib/SmmCpuFeaturesLib.inf b/OvmfPkg/Library/SmmCpuFeaturesLib/SmmCpuFeaturesLib.inf
index dd316f2b1b..97a10afb6e 100644
--- a/OvmfPkg/Library/SmmCpuFeaturesLib/SmmCpuFeaturesLib.inf
+++ b/OvmfPkg/Library/SmmCpuFeaturesLib/SmmCpuFeaturesLib.inf
@@ -30,5 +30,9 @@
   BaseMemoryLib
   DebugLib
   MemEncryptSevLib
+  PcdLib
   SmmServicesTableLib
   UefiBootServicesTableLib
+
+[Pcd]
+  gUefiOvmfPkgTokenSpaceGuid.PcdQ35SmramAtDefaultSmbase
diff --git a/OvmfPkg/PlatformPei/AmdSev.c b/OvmfPkg/PlatformPei/AmdSev.c
index 2ae8126ccf..e484f4b311 100644
--- a/OvmfPkg/PlatformPei/AmdSev.c
+++ b/OvmfPkg/PlatformPei/AmdSev.c
@@ -9,6 +9,7 @@
 //
 // The package level header files this module uses
 //
+#include <IndustryStandard/Q35MchIch9.h>
 #include <Library/DebugLib.h>
 #include <Library/HobLib.h>
 #include <Library/MemEncryptSevLib.h>
@@ -16,6 +17,7 @@
 #include <PiPei.h>
 #include <Register/Amd/Cpuid.h>
 #include <Register/Cpuid.h>
+#include <Register/Intel/SmramSaveStateMap.h>
 
 #include "Platform.h"
 
@@ -83,10 +85,22 @@ AmdSevInitialize (
                         );
     ASSERT_RETURN_ERROR (LocateMapStatus);
 
-    BuildMemoryAllocationHob (
-      MapPagesBase,                      // BaseAddress
-      EFI_PAGES_TO_SIZE (MapPagesCount), // Length
-      EfiBootServicesData                // MemoryType
-      );
+    if (mQ35SmramAtDefaultSmbase) {
+      //
+      // The initial SMRAM Save State Map has been covered as part of a larger
+      // reserved memory allocation in InitializeRamRegions().
+      //
+      ASSERT (SMM_DEFAULT_SMBASE <= MapPagesBase);
+      ASSERT (
+        (MapPagesBase + EFI_PAGES_TO_SIZE (MapPagesCount) <=
+         SMM_DEFAULT_SMBASE + MCH_DEFAULT_SMBASE_SIZE)
+        );
+    } else {
+      BuildMemoryAllocationHob (
+        MapPagesBase,                      // BaseAddress
+        EFI_PAGES_TO_SIZE (MapPagesCount), // Length
+        EfiBootServicesData                // MemoryType
+        );
+    }
   }
 }