[PATCH V4 21/31] UefiCpuPkg: Update AddressEncMask in CpuPageTable

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

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

MMIO region in Tdx guest is set with PcdTdxSharedBitMask in TdxDxe's
entry point. In SEV guest the page table entries is set with
PcdPteMemoryEncryptionAddressOrMask when creating 1:1 identity table.

So the AddressEncMask in GetPageTableEntry (@CpuPageTable.c) is either
PcdPteMemoryEncryptionAddressOrMask (in SEV guest), or
PcdTdxSharedBitMask (in TDX guest), or all-0 (in Legacy guest).

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: Eric Dong <eric.dong@intel.com>
Cc: Ray Ni <ray.ni@intel.com>
Cc: Rahul Kumar <rahul1.kumar@intel.com>
Cc: Gerd Hoffmann <kraxel@redhat.com>
Signed-off-by: Min Xu <min.m.xu@intel.com>
---
 UefiCpuPkg/CpuDxe/CpuDxe.inf     | 1 +
 UefiCpuPkg/CpuDxe/CpuPageTable.c | 4 ++++
 2 files changed, 5 insertions(+)

diff --git a/UefiCpuPkg/CpuDxe/CpuDxe.inf b/UefiCpuPkg/CpuDxe/CpuDxe.inf
index d87fe503d152..235241899222 100644
--- a/UefiCpuPkg/CpuDxe/CpuDxe.inf
+++ b/UefiCpuPkg/CpuDxe/CpuDxe.inf
@@ -80,6 +80,7 @@
   gEfiMdeModulePkgTokenSpaceGuid.PcdNullPointerDetectionPropertyMask    ## CONSUMES
   gUefiCpuPkgTokenSpaceGuid.PcdCpuStackSwitchExceptionList              ## CONSUMES
   gUefiCpuPkgTokenSpaceGuid.PcdCpuKnownGoodStackSize                    ## CONSUMES
+  gEfiMdeModulePkgTokenSpaceGuid.PcdTdxSharedBitMask                    ## CONSUMES
 
 [Depex]
   TRUE
diff --git a/UefiCpuPkg/CpuDxe/CpuPageTable.c b/UefiCpuPkg/CpuDxe/CpuPageTable.c
index d9e65ab4b22a..28982936fade 100644
--- a/UefiCpuPkg/CpuDxe/CpuPageTable.c
+++ b/UefiCpuPkg/CpuDxe/CpuPageTable.c
@@ -307,6 +307,9 @@ GetPageTableEntry (
   // Make sure AddressEncMask is contained to smallest supported address field.
   //
   AddressEncMask = PcdGet64 (PcdPteMemoryEncryptionAddressOrMask) & PAGING_1G_ADDRESS_MASK_64;
+  if (AddressEncMask == 0) {
+    AddressEncMask = PcdGet64 (PcdTdxSharedBitMask) & PAGING_1G_ADDRESS_MASK_64;
+  }
 
   if (PagingContext->MachineType == IMAGE_FILE_MACHINE_X64) {
     if ((PagingContext->ContextData.X64.Attributes & PAGE_TABLE_LIB_PAGING_CONTEXT_IA32_X64_ATTRIBUTES_5_LEVEL) != 0) {
@@ -357,6 +360,7 @@ GetPageTableEntry (
 
   // 4k
   L1PageTable = (UINT64 *)(UINTN)(L2PageTable[Index2] & ~AddressEncMask & PAGING_4K_ADDRESS_MASK_64);
+
   if ((L1PageTable[Index1] == 0) && (Address != 0)) {
     *PageAttribute = PageNone;
     return NULL;
-- 
2.29.2.windows.2