diff --git a/UefiCpuPkg/UefiCpuPkg.dec b/UefiCpuPkg/UefiCpuPkg.dec
index 86ad61f64b..83acd33612 100644
--- a/UefiCpuPkg/UefiCpuPkg.dec
+++ b/UefiCpuPkg/UefiCpuPkg.dec
@@ -278,6 +278,18 @@
   # @Prompt Current boot is a power-on reset.
   gUefiCpuPkgTokenSpaceGuid.PcdIsPowerOnReset|FALSE|BOOLEAN|0x0000001B
 
+[PcdsFixedAtBuild.X64, PcdsPatchableInModule.X64, PcdsDynamic.X64, PcdsDynamicEx.X64]
+  ## Indicate access to non-SMRAM memory is restricted to reserved, runtime and ACPI NVS type after SmmReadyToLock.
+  #  MMIO access is always allowed regardless of the value of this PCD.
+  #  Loose of such restriction is only required by RAS components in X64 platforms.
+  #  The PCD value is considered as constantly TRUE in IA32 platforms.
+  #  When the PCD value is TRUE, page table is initialized to cover all memory spaces
+  #  and the memory occupied by page table is protected by page table itself as read-only.
+  #   TRUE  - Access to non-SMRAM memory is restricted to reserved, runtime and ACPI NVS type after SmmReadyToLock.<BR>
+  #   FALSE - Access to any type of non-SMRAM memory after SmmReadyToLock is allowed.<BR>
+  # @Prompt Access to non-SMRAM memory is restricted to reserved, runtime and ACPI NVS type after SmmReadyToLock.
+  gUefiCpuPkgTokenSpaceGuid.PcdCpuSmmRestrictedMemoryAccess|TRUE|BOOLEAN|0x3213210F
+
 [PcdsDynamic, PcdsDynamicEx]
   ## Contains the pointer to a CPU S3 data buffer of structure ACPI_CPU_DATA.
   # @Prompt The pointer to a CPU S3 data buffer.