6 files changed, 40 insertions, 5 deletions
diff --git a/OvmfPkg/SmmAccess/SmmAccess2Dxe.c b/OvmfPkg/SmmAccess/SmmAccess2Dxe.c
index d5130399b0..0a99cc5e83 100644
--- a/OvmfPkg/SmmAccess/SmmAccess2Dxe.c
+++ b/OvmfPkg/SmmAccess/SmmAccess2Dxe.c
@@ -149,6 +149,7 @@ SmmAccess2DxeEntryPoint (
   //
   ASSERT (FeaturePcdGet (PcdSmmSmramRequire));
 
+  InitQ35TsegMbytes ();
   GetStates (&mAccess2.LockState, &mAccess2.OpenState);
   return gBS->InstallMultipleProtocolInterfaces (&ImageHandle,
                 &gEfiSmmAccess2ProtocolGuid, &mAccess2,
diff --git a/OvmfPkg/SmmAccess/SmmAccess2Dxe.inf b/OvmfPkg/SmmAccess/SmmAccess2Dxe.inf
index 31e4dfa029..1bc88fa050 100644
--- a/OvmfPkg/SmmAccess/SmmAccess2Dxe.inf
+++ b/OvmfPkg/SmmAccess/SmmAccess2Dxe.inf
@@ -54,5 +54,8 @@
 [FeaturePcd]
   gUefiOvmfPkgTokenSpaceGuid.PcdSmmSmramRequire
 
+[Pcd]
+  gUefiOvmfPkgTokenSpaceGuid.PcdQ35TsegMbytes
+
 [Depex]
   TRUE
diff --git a/OvmfPkg/SmmAccess/SmmAccessPei.c b/OvmfPkg/SmmAccess/SmmAccessPei.c
index 76790e330f..a3631a1b9d 100644
--- a/OvmfPkg/SmmAccess/SmmAccessPei.c
+++ b/OvmfPkg/SmmAccess/SmmAccessPei.c
@@ -318,8 +318,9 @@ SmmAccessPeiEntryPoint (
   //
   // Set TSEG Memory Base.
   //
+  InitQ35TsegMbytes ();
   PciWrite32 (DRAMC_REGISTER_Q35 (MCH_TSEGMB),
-    (TopOfLowRamMb - FixedPcdGet16 (PcdQ35TsegMbytes)) << MCH_TSEGMB_MB_SHIFT);
+    (TopOfLowRamMb - mQ35TsegMbytes) << MCH_TSEGMB_MB_SHIFT);
 
   //
   // Set TSEG size, and disable TSEG visibility outside of SMM. Note that the
@@ -327,8 +328,8 @@ SmmAccessPeiEntryPoint (
   // *restricted* to SMM.
   //
   EsmramcVal &= ~(UINT32)MCH_ESMRAMC_TSEG_MASK;
-  EsmramcVal |= FixedPcdGet16 (PcdQ35TsegMbytes) == 8 ? MCH_ESMRAMC_TSEG_8MB :
-                FixedPcdGet16 (PcdQ35TsegMbytes) == 2 ? MCH_ESMRAMC_TSEG_2MB :
+  EsmramcVal |= mQ35TsegMbytes == 8 ? MCH_ESMRAMC_TSEG_8MB :
+                mQ35TsegMbytes == 2 ? MCH_ESMRAMC_TSEG_2MB :
                 MCH_ESMRAMC_TSEG_1MB;
   EsmramcVal |= MCH_ESMRAMC_T_EN;
   PciWrite8 (DRAMC_REGISTER_Q35 (MCH_ESMRAMC), EsmramcVal);
diff --git a/OvmfPkg/SmmAccess/SmmAccessPei.inf b/OvmfPkg/SmmAccess/SmmAccessPei.inf
index 3908b085da..09f3b63446 100644
--- a/OvmfPkg/SmmAccess/SmmAccessPei.inf
+++ b/OvmfPkg/SmmAccess/SmmAccessPei.inf
@@ -59,11 +59,11 @@
 [FeaturePcd]
   gUefiOvmfPkgTokenSpaceGuid.PcdSmmSmramRequire
 
-[FixedPcd]
+[Pcd]
   gUefiOvmfPkgTokenSpaceGuid.PcdQ35TsegMbytes
 
 [Ppis]
   gPeiSmmAccessPpiGuid           ## PRODUCES
 
 [Depex]
-  TRUE
+  gEfiPeiMemoryDiscoveredPpiGuid
diff --git a/OvmfPkg/SmmAccess/SmramInternal.c b/OvmfPkg/SmmAccess/SmramInternal.c
index c3267ca940..9918a45148 100644
--- a/OvmfPkg/SmmAccess/SmramInternal.c
+++ b/OvmfPkg/SmmAccess/SmramInternal.c
@@ -17,10 +17,27 @@
 #include <Guid/AcpiS3Context.h>
 #include <IndustryStandard/Q35MchIch9.h>
 #include <Library/DebugLib.h>
+#include <Library/PcdLib.h>
 #include <Library/PciLib.h>
 
 #include "SmramInternal.h"
 
+//
+// The value of PcdQ35TsegMbytes is saved into this variable at module startup.
+//
+UINT16 mQ35TsegMbytes;
+
+/**
+  Save PcdQ35TsegMbytes into mQ35TsegMbytes.
+**/
+VOID
+InitQ35TsegMbytes (
+  VOID
+  )
+{
+  mQ35TsegMbytes = PcdGet16 (PcdQ35TsegMbytes);
+}
+
 /**
   Read the MCH_SMRAM and ESMRAMC registers, and update the LockState and
   OpenState fields in the PEI_SMM_ACCESS_PPI / EFI_SMM_ACCESS2_PROTOCOL object,
diff --git a/OvmfPkg/SmmAccess/SmramInternal.h b/OvmfPkg/SmmAccess/SmramInternal.h
index 4e9ac05fad..82b867cf88 100644
--- a/OvmfPkg/SmmAccess/SmramInternal.h
+++ b/OvmfPkg/SmmAccess/SmramInternal.h
@@ -31,6 +31,19 @@ typedef enum {
   DescIdxCount            = 2
 } DESCRIPTOR_INDEX;
 
+//
+// The value of PcdQ35TsegMbytes is saved into this variable at module startup.
+//
+extern UINT16 mQ35TsegMbytes;
+
+/**
+  Save PcdQ35TsegMbytes into mQ35TsegMbytes.
+**/
+VOID
+InitQ35TsegMbytes (
+  VOID
+  );
+
 /**
   Read the MCH_SMRAM and ESMRAMC registers, and update the LockState and
   OpenState fields in the PEI_SMM_ACCESS_PPI / EFI_SMM_ACCESS2_PROTOCOL object,