[PATCH V4 20/31] MdeModulePkg: Add PcdTdxSharedBitMask

["Min Xu" <min.m.xu@intel.com>]

RFC: https://bugzilla.tianocore.org/show_bug.cgi?id=3429

Guest Physical Address (GPA) space in Td guest is divided into private
and shared sub-spaces, determined by the SHARED bit of GPA. This PCD
holds the shared bit mask. Its default value is 0 and it will be set
in PlatformPei driver if it is of Td guest.

Cc: Jian J Wang <jian.j.wang@intel.com>
Cc: Hao A Wu <hao.a.wu@intel.com>
Cc: Brijesh Singh <brijesh.singh@amd.com>
Cc: Erdem Aktas <erdemaktas@google.com>
Cc: James Bottomley <jejb@linux.ibm.com>
Cc: Jiewen Yao <jiewen.yao@intel.com>
Cc: Tom Lendacky <thomas.lendacky@amd.com>
Cc: Gerd Hoffmann <kraxel@redhat.com>
Signed-off-by: Min Xu <min.m.xu@intel.com>
---
 MdeModulePkg/MdeModulePkg.dec | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/MdeModulePkg/MdeModulePkg.dec b/MdeModulePkg/MdeModulePkg.dec
index 453f2a74b11d..e90a7f38708c 100644
--- a/MdeModulePkg/MdeModulePkg.dec
+++ b/MdeModulePkg/MdeModulePkg.dec
@@ -2143,6 +2143,10 @@
   # @Prompt The flag which indicates if IA32_EFER is allowed to be changed.
   gEfiMdeModulePkgTokenSpaceGuid.PcdIa32EferChangeAllowed|TRUE|BOOLEAN|0x00030009
 
+  ## This PCD holds the shared bit mask for page table entries when Tdx is enabled.
+  # @Prompt The shared bit mask when Intel Tdx is enabled.
+  gEfiMdeModulePkgTokenSpaceGuid.PcdTdxSharedBitMask|0x0|UINT64|0x0003000a
+
 [PcdsDynamicEx]
   ## This dynamic PCD enables the default variable setting.
   #  Its value is the default store ID value. The default value is zero as Standard default.
-- 
2.29.2.windows.2