UefiCpuPkg: Extend VmgExitLibNull to handle #VE exception

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

VmgExitLib performs the necessary processing to handle a #VC exception.
VmgExitLibNull is a NULL instance of VmgExitLib which provides a
default limited interface. In this commit VmgExitLibNull is extended to
handle a #VE exception with a default limited interface. A full feature
version of #VE handler will be created later.

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>
Acked-by: Gerd Hoffmann <kraxel@redhat.com>
Reviewed-by: Ray Ni <ray.ni@intel.com>
Reviewed-by: Jiewen Yao <jiewen.yao@intel.com>
Signed-off-by: Min Xu <min.m.xu@intel.com>

UefiCpuPkg/Include/Library/VmgExitLib.h

@@ -15,6 +15,8 @@
 #include <Protocol/DebugSupport.h>
 #include <Register/Amd/Ghcb.h>
 
+#define VE_EXCEPTION  20
+
 /**
   Perform VMGEXIT.
 
@@ -142,4 +144,30 @@ VmgExitHandleVc (
   IN OUT EFI_SYSTEM_CONTEXT  SystemContext
   );
 
+/**
+  Handle a #VE exception.
+
+  Performs the necessary processing to handle a #VE exception.
+
+  The base library function returns an error equal to VE_EXCEPTION,
+  to be propagated to the standard exception handling stack.
+
+  @param[in, out]  ExceptionType  Pointer to an EFI_EXCEPTION_TYPE to be set
+                                  as value to use on error.
+  @param[in, out]  SystemContext  Pointer to EFI_SYSTEM_CONTEXT
+
+  @retval  EFI_SUCCESS            Exception handled
+  @retval  EFI_UNSUPPORTED        #VE not supported, (new) exception value to
+                                  propagate provided
+  @retval  EFI_PROTOCOL_ERROR     #VE handling failed, (new) exception value to
+                                  propagate provided
+
+**/
+EFI_STATUS
+EFIAPI
+VmTdExitHandleVe (
+  IN OUT EFI_EXCEPTION_TYPE  *ExceptionType,
+  IN OUT EFI_SYSTEM_CONTEXT  SystemContext
+  );
+
 #endif

UefiCpuPkg/Library/VmgExitLibNull/VmTdExitNull.c

@@ -0,0 +1,38 @@
+/** @file
+
+  Copyright (c) 2021, Intel Corporation. All rights reserved.<BR>
+
+  SPDX-License-Identifier: BSD-2-Clause-Patent
+
+**/
+#include <Base.h>
+#include <Uefi.h>
+#include <Library/VmgExitLib.h>
+
+/**
+  Handle a #VE exception.
+
+  Performs the necessary processing to handle a #VE exception.
+
+  @param[in, out]  ExceptionType  Pointer to an EFI_EXCEPTION_TYPE to be set
+                                  as value to use on error.
+  @param[in, out]  SystemContext  Pointer to EFI_SYSTEM_CONTEXT
+
+  @retval  EFI_SUCCESS            Exception handled
+  @retval  EFI_UNSUPPORTED        #VE not supported, (new) exception value to
+                                  propagate provided
+  @retval  EFI_PROTOCOL_ERROR     #VE handling failed, (new) exception value to
+                                  propagate provided
+
+**/
+EFI_STATUS
+EFIAPI
+VmTdExitHandleVe (
+  IN OUT EFI_EXCEPTION_TYPE  *ExceptionType,
+  IN OUT EFI_SYSTEM_CONTEXT  SystemContext
+  )
+{
+  *ExceptionType = VE_EXCEPTION;
+
+  return EFI_UNSUPPORTED;
+}

UefiCpuPkg/Library/VmgExitLibNull/VmgExitLibNull.inf

@@ -17,6 +17,7 @@
 
 [Sources.common]
   VmgExitLibNull.c
+  VmTdExitNull.c
 
 [Packages]
   MdePkg/MdePkg.dec