UefiCpuPkg/MpInitLib: Use SEV-SNP AP Creation NAE event to launch APs

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

Use the SEV-SNP AP Creation NAE event to create and launch APs under
SEV-SNP. This capability will be advertised in the SEV Hypervisor
Feature Support PCD (PcdSevEsHypervisorFeatures).

Cc: Michael Roth <michael.roth@amd.com>
Cc: Eric Dong <eric.dong@intel.com>
Cc: Ray Ni <ray.ni@intel.com>
Cc: Rahul Kumar <rahul1.kumar@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>
Acked-by: Gerd Hoffmann <kraxel@redhat.com>
Signed-off-by: Tom Lendacky <thomas.lendacky@amd.com>
Signed-off-by: Brijesh Singh <brijesh.singh@amd.com>

UefiCpuPkg/Library/MpInitLib/Ia32/AmdSev.c

@@ -0,0 +1,70 @@
+/** @file
+
+  AMD SEV helper function.
+
+  Copyright (c) 2021, AMD Incorporated. All rights reserved.<BR>
+
+  SPDX-License-Identifier: BSD-2-Clause-Patent
+
+**/
+
+#include "MpLib.h"
+
+/**
+  Create an SEV-SNP AP save area (VMSA) for use in running the vCPU.
+
+  @param[in]  CpuMpData        Pointer to CPU MP Data
+  @param[in]  CpuData          Pointer to CPU AP Data
+  @param[in]  ApicId           APIC ID of the vCPU
+**/
+VOID
+SevSnpCreateSaveArea (
+  IN CPU_MP_DATA  *CpuMpData,
+  IN CPU_AP_DATA  *CpuData,
+  UINT32          ApicId
+  )
+{
+  //
+  // SEV-SNP is not support on 32-bit build.
+  //
+  ASSERT (FALSE);
+}
+
+/**
+  Create SEV-SNP APs.
+
+  @param[in]  CpuMpData        Pointer to CPU MP Data
+  @param[in]  ProcessorNumber  The handle number of specified processor
+                               (-1 for all APs)
+**/
+VOID
+SevSnpCreateAP (
+  IN CPU_MP_DATA  *CpuMpData,
+  IN INTN         ProcessorNumber
+  )
+{
+  //
+  // SEV-SNP is not support on 32-bit build.
+  //
+  ASSERT (FALSE);
+}
+
+/**
+  Issue RMPADJUST to adjust the VMSA attribute of an SEV-SNP page.
+
+  @param[in]  PageAddress
+  @param[in]  VmsaPage
+
+  @return  RMPADJUST return value
+**/
+UINT32
+SevSnpRmpAdjust (
+  IN  EFI_PHYSICAL_ADDRESS  PageAddress,
+  IN  BOOLEAN               VmsaPage
+  )
+{
+  //
+  // RMPADJUST is not supported in 32-bit mode
+  //
+  return RETURN_UNSUPPORTED;
+}