From 45388d046c3506bd49dca29aed8ec74756e6165c Mon Sep 17 00:00:00 2001
From: Tom Lendacky <thomas.lendacky@amd.com>
Date: Thu, 7 Jan 2021 12:48:17 -0600
Subject: OvmfPkg: Obtain SEV encryption mask with the new MemEncryptSevLib API

BZ: https://bugzilla.tianocore.org/show_bug.cgi?id=3108

The early assembler code performs validation for some of the SEV-related
information, specifically the encryption bit position. The new
MemEncryptSevGetEncryptionMask() interface provides access to this
validated value.

To ensure that we always use a validated encryption mask for an SEV-ES
guest, update all locations that use CPUID to calculate the encryption
mask to use the new interface.

Also, clean up some call areas where extra masking was being performed
and where a function call was being used instead of the local variable
that was just set using the function.

Cc: Jordan Justen <jordan.l.justen@intel.com>
Cc: Laszlo Ersek <lersek@redhat.com>
Cc: Ard Biesheuvel <ard.biesheuvel@arm.com>
Cc: Rebecca Cran <rebecca@bsdio.com>
Cc: Peter Grehan <grehan@freebsd.org>
Cc: Brijesh Singh <brijesh.singh@amd.com>
Cc: Anthony Perard <anthony.perard@citrix.com>
Cc: Julien Grall <julien@xen.org>
Reviewed-by: Laszlo Ersek <lersek@redhat.com>
Signed-off-by: Tom Lendacky <thomas.lendacky@amd.com>
Message-Id: <9de678c0d66443c6cc33e004a4cac0a0223c2ebc.1610045305.git.thomas.lendacky@amd.com>
---
 OvmfPkg/Library/BaseMemEncryptSevLib/X64/VirtualMemory.c | 15 +++++----------
 1 file changed, 5 insertions(+), 10 deletions(-)

(limited to 'OvmfPkg/Library')

diff --git a/OvmfPkg/Library/BaseMemEncryptSevLib/X64/VirtualMemory.c b/OvmfPkg/Library/BaseMemEncryptSevLib/X64/VirtualMemory.c
index 5e110c84ff..6422bc53bd 100644
--- a/OvmfPkg/Library/BaseMemEncryptSevLib/X64/VirtualMemory.c
+++ b/OvmfPkg/Library/BaseMemEncryptSevLib/X64/VirtualMemory.c
@@ -3,7 +3,7 @@
   Virtual Memory Management Services to set or clear the memory encryption bit
 
   Copyright (c) 2006 - 2018, Intel Corporation. All rights reserved.<BR>
-  Copyright (c) 2017, AMD Incorporated. All rights reserved.<BR>
+  Copyright (c) 2017 - 2020, AMD Incorporated. All rights reserved.<BR>
 
   SPDX-License-Identifier: BSD-2-Clause-Patent
 
@@ -12,6 +12,7 @@
 **/
 
 #include <Library/CpuLib.h>
+#include <Library/MemEncryptSevLib.h>
 #include <Register/Amd/Cpuid.h>
 #include <Register/Cpuid.h>
 
@@ -39,17 +40,12 @@ GetMemEncryptionAddressMask (
   )
 {
   UINT64                            EncryptionMask;
-  CPUID_MEMORY_ENCRYPTION_INFO_EBX  Ebx;
 
   if (mAddressEncMaskChecked) {
     return mAddressEncMask;
   }
 
-  //
-  // CPUID Fn8000_001F[EBX] Bit 0:5 (memory encryption bit position)
-  //
-  AsmCpuid (CPUID_MEMORY_ENCRYPTION_INFO, NULL, &Ebx.Uint32, NULL, NULL);
-  EncryptionMask = LShiftU64 (1, Ebx.Bits.PtePosBits);
+  EncryptionMask = MemEncryptSevGetEncryptionMask ();
 
   mAddressEncMask = EncryptionMask & PAGING_1G_ADDRESS_MASK_64;
   mAddressEncMaskChecked = TRUE;
@@ -289,8 +285,7 @@ SetPageTablePoolReadOnly (
   LevelSize[3] = SIZE_1GB;
   LevelSize[4] = SIZE_512GB;
 
-  AddressEncMask  = GetMemEncryptionAddressMask() &
-                    PAGING_1G_ADDRESS_MASK_64;
+  AddressEncMask  = GetMemEncryptionAddressMask();
   PageTable       = (UINT64 *)(UINTN)PageTableBase;
   PoolUnitSize    = PAGE_TABLE_POOL_UNIT_SIZE;
 
@@ -437,7 +432,7 @@ Split1GPageTo2M (
 
   AddressEncMask = GetMemEncryptionAddressMask ();
   ASSERT (PageDirectoryEntry != NULL);
-  ASSERT (*PageEntry1G & GetMemEncryptionAddressMask ());
+  ASSERT (*PageEntry1G & AddressEncMask);
   //
   // Fill in 1G page entry.
   //
-- 
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