OvmfPkg: Update CcProbeLib to DxeCcProbeLib

BZ: https://bugzilla.tianocore.org/show_bug.cgi?id=3974

CcProbeLib once was designed to probe the Confidential Computing guest
type by checking the PcdOvmfWorkArea. But this memory is allocated with
either EfiACPIMemoryNVS or EfiBootServicesData. It cannot be accessed
after ExitBootService. Please see the detailed analysis in BZ#3974.

To fix this issue, CcProbeLib is redesigned as 2 implementation:
 - SecPeiCcProbeLib
 - DxeCcProbeLib

In SecPeiCcProbeLib we check the CC guest type by reading the
PcdOvmfWorkArea. Because it is used in SEC / PEI and we don't worry about
the issues in BZ#3974.

In DxeCcProbeLib we cache the GuestType in Ovmf work area in a variable.
After that the Guest type is returned with the cached value. So that we
don't need to worry about the access to Ovmf work area after
ExitBootService.

The reason why we probe CC guest type in 2 different ways is the global
varialbe. Global variable cannot be used in SEC/PEI and CcProbe is called
very frequently.

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

1 files changed, 0 insertions, 31 deletions

diff --git a/OvmfPkg/Library/CcProbeLib/CcProbeLib.c b/OvmfPkg/Library/CcProbeLib/CcProbeLib.c
deleted file mode 100644
index d698e5c8d7..0000000000
--- a/OvmfPkg/Library/CcProbeLib/CcProbeLib.c
+++ /dev/null
@@ -1,31 +0,0 @@
-/** @file

-

-  CcProbeLib is used to probe the Confidential computing guest type.

-

-  Copyright (c) 2022, Intel Corporation. All rights reserved.<BR>

-  SPDX-License-Identifier: BSD-2-Clause-Patent

-

-**/

-

-#include <Library/CcProbeLib.h>

-#include <WorkArea.h>

-

-/**

-  Probe the ConfidentialComputing Guest type. See defition of

-  CC_GUEST_TYPE in <ConfidentialComputingGuestAttr.h>.

-

-  @return The guest type

-

-**/

-UINT8

-EFIAPI

-CcProbe (

-  VOID

-  )

-{

-  OVMF_WORK_AREA  *WorkArea;

-

-  WorkArea = (OVMF_WORK_AREA *)FixedPcdGet32 (PcdOvmfWorkAreaBase);

-

-  return WorkArea != NULL ? WorkArea->Header.GuestType : CcGuestTypeNonEncrypted;

-}