MdePkg: Define ConfidentialComputingGuestAttr

BZ: https://bugzilla.tianocore.org/show_bug.cgi?id=3275

While initializing APs, the MpInitLib may need to know whether the
guest is running with active AMD SEV or Intel TDX memory encryption.

Add a new ConfidentialComputingGuestAttr PCD that can be used to query
the memory encryption attribute.

Cc: Michael D Kinney <michael.d.kinney@intel.com>
Cc: Liming Gao <gaoliming@byosoft.com.cn>
Cc: Zhiguang Liu <zhiguang.liu@intel.com>
Cc: Michael Roth <michael.roth@amd.com>
Cc: Ray Ni <ray.ni@intel.com>
Cc: Rahul Kumar <rahul1.kumar@intel.com>
Cc: Eric Dong <eric.dong@intel.com>
Cc: James Bottomley <jejb@linux.ibm.com>
Cc: Min Xu <min.m.xu@intel.com>
Cc: Jiewen Yao <jiewen.yao@intel.com>
Cc: Tom Lendacky <thomas.lendacky@amd.com>
Cc: Jordan Justen <jordan.l.justen@intel.com>
Cc: Ard Biesheuvel <ardb+tianocore@kernel.org>
Cc: Erdem Aktas <erdemaktas@google.com>
Cc: Gerd Hoffmann <kraxel@redhat.com>
Acked-by: Ray Ni <ray.ni@intel.com>
Suggested-by: Jiewen Yao <jiewen.yao@intel.com>
Acked-by: Gerd Hoffmann <kraxel@redhat.com>
Signed-off-by: Brijesh Singh <brijesh.singh@amd.com>

MdePkg/Include/ConfidentialComputingGuestAttr.h

@@ -0,0 +1,25 @@
+/** @file
+Definitions for Confidential Computing Attribute
+
+Copyright (c) 2021 AMD Inc. All rights reserved.<BR>
+SPDX-License-Identifier: BSD-2-Clause-Patent
+
+**/
+
+#ifndef CONFIDENTIAL_COMPUTING_GUEST_ATTR_H_
+#define CONFIDENTIAL_COMPUTING_GUEST_ATTR_H_
+
+typedef enum {
+  /* The guest is running with memory encryption disabled. */
+  CCAttrNotEncrypted = 0,
+
+  /* The guest is running with AMD SEV memory encryption enabled. */
+  CCAttrAmdSev    = 0x100,
+  CCAttrAmdSevEs  = 0x101,
+  CCAttrAmdSevSnp = 0x102,
+
+  /* The guest is running with Intel TDX memory encryption enabled. */
+  CCAttrIntelTdx = 0x200,
+} CONFIDENTIAL_COMPUTING_GUEST_ATTR;
+
+#endif

MdePkg/MdePkg.dec

@@ -2396,5 +2396,9 @@
   # @Prompt FSB Clock.
   gEfiMdePkgTokenSpaceGuid.PcdFSBClock|200000000|UINT32|0x0000000c
 
+  ## This dynamic PCD indicates the memory encryption attribute of the guest.
+  # @Prompt Memory encryption attribute
+  gEfiMdePkgTokenSpaceGuid.PcdConfidentialComputingGuestAttr|0|UINT64|0x0000002e
+
 [UserExtensions.TianoCore."ExtraFiles"]
   MdePkgExtra.uni