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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>
This commit is contained in:
Min M Xu 2022-07-07 10:51:20 +08:00 committed by mergify[bot]
parent c4bc1a9498
commit 1b1c58ab32
5 changed files with 78 additions and 36 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

3
OvmfPkg/IntelTdx/IntelTdxX64.dsc
View File

@ -140,7 +140,7 @@
PciCapLib|OvmfPkg/Library/BasePciCapLib/BasePciCapLib.inf
PciCapPciSegmentLib|OvmfPkg/Library/BasePciCapPciSegmentLib/BasePciCapPciSegmentLib.inf
PciCapPciIoLib|OvmfPkg/Library/UefiPciCapPciIoLib/UefiPciCapPciIoLib.inf
CcProbeLib|OvmfPkg/Library/CcProbeLib/CcProbeLib.inf
CcProbeLib|OvmfPkg/Library/CcProbeLib/DxeCcProbeLib.inf
IoLib|MdePkg/Library/BaseIoLibIntrinsic/BaseIoLibIntrinsicSev.inf
OemHookStatusCodeLib|MdeModulePkg/Library/OemHookStatusCodeLibNull/OemHookStatusCodeLibNull.inf
SerialPortLib|PcAtChipsetPkg/Library/SerialIoLib/SerialIoLib.inf
@ -234,6 +234,7 @@
HobLib|EmbeddedPkg/Library/PrePiHobLib/PrePiHobLib.inf
PrePiLib|EmbeddedPkg/Library/PrePiLib/PrePiLib.inf
PeilessStartupLib|OvmfPkg/Library/PeilessStartupLib/PeilessStartupLib.inf
CcProbeLib|OvmfPkg/Library/CcProbeLib/SecPeiCcProbeLib.inf
[LibraryClasses.common.DXE_CORE]
HobLib|MdePkg/Library/DxeCoreHobLib/DxeCoreHobLib.inf

31
OvmfPkg/Library/CcProbeLib/CcProbeLib.c
View File

@ -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;
}

68
OvmfPkg/Library/CcProbeLib/DxeCcProbeLib.c Normal file
View File

@ -0,0 +1,68 @@
/** @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 <Uefi/UefiBaseType.h>
#include <Library/CcProbeLib.h>
#include <WorkArea.h>
STATIC UINT8 mCcProbeGuestType = 0;
STATIC BOOLEAN mCcProbed = FALSE;
/**
* Read the the ConfidentialComputing Guest type from Ovmf work-area.
*
* @return The ConfidentialComputing Guest type
*/
STATIC
UINT8
ReadCcGuestType (
VOID
)
{
OVMF_WORK_AREA *WorkArea;
if (!mCcProbed) {
WorkArea = (OVMF_WORK_AREA *)FixedPcdGet32 (PcdOvmfWorkAreaBase);
mCcProbeGuestType = WorkArea != NULL ? WorkArea->Header.GuestType : CcGuestTypeNonEncrypted;
mCcProbed = TRUE;
}
return mCcProbeGuestType;
}
/**
Probe the ConfidentialComputing Guest type. See defition of
CC_GUEST_TYPE in <ConfidentialComputingGuestAttr.h>.
@return The guest type
**/
UINT8
EFIAPI
CcProbe (
VOID
)
{
return ReadCcGuestType ();
}
/**
* Constructor of DxeCcProbeLib
*
* @return EFI_SUCCESS Successfully called of constructor
*/
EFI_STATUS
EFIAPI
DxeCcProbeLibConstructor (
VOID
)
{
ReadCcGuestType ();
return EFI_SUCCESS;
}

7
OvmfPkg/Library/CcProbeLib/CcProbeLib.inf → OvmfPkg/Library/CcProbeLib/DxeCcProbeLib.inf
View File

@ -8,14 +8,15 @@
[Defines]
INF_VERSION = 0x00010005
BASE_NAME = CcProbeLib
BASE_NAME = DxeCcProbeLib
FILE_GUID = 05184ec9-abb0-4491-8584-e388639a7c48
MODULE_TYPE = BASE
VERSION_STRING = 1.0
LIBRARY_CLASS = CcProbeLib
LIBRARY_CLASS = CcProbeLib|DXE_CORE DXE_DRIVER DXE_RUNTIME_DRIVER DXE_SMM_DRIVER UEFI_DRIVER UEFI_APPLICATION
CONSTRUCTOR = DxeCcProbeLibConstructor
[Sources]
CcProbeLib.c
DxeCcProbeLib.c
[Packages]
MdePkg/MdePkg.dec

5
OvmfPkg/OvmfPkgX64.dsc
View File

@ -204,7 +204,7 @@
!if $(SMM_REQUIRE) == FALSE
LockBoxLib|OvmfPkg/Library/LockBoxLib/LockBoxBaseLib.inf
CcProbeLib|OvmfPkg/Library/CcProbeLib/CcProbeLib.inf
CcProbeLib|OvmfPkg/Library/CcProbeLib/DxeCcProbeLib.inf
!else
CcProbeLib|MdePkg/Library/CcProbeLibNull/CcProbeLibNull.inf
!endif
@ -295,6 +295,7 @@
!endif
VmgExitLib|OvmfPkg/Library/VmgExitLib/SecVmgExitLib.inf
MemEncryptSevLib|OvmfPkg/Library/BaseMemEncryptSevLib/SecMemEncryptSevLib.inf
CcProbeLib|OvmfPkg/Library/CcProbeLib/SecPeiCcProbeLib.inf
[LibraryClasses.common.PEI_CORE]
HobLib|MdePkg/Library/PeiHobLib/PeiHobLib.inf
@ -311,6 +312,7 @@
DebugLib|OvmfPkg/Library/PlatformDebugLibIoPort/PlatformDebugLibIoPort.inf
!endif
PeCoffLib|MdePkg/Library/BasePeCoffLib/BasePeCoffLib.inf
CcProbeLib|OvmfPkg/Library/CcProbeLib/SecPeiCcProbeLib.inf
[LibraryClasses.common.PEIM]
HobLib|MdePkg/Library/PeiHobLib/PeiHobLib.inf
@ -340,6 +342,7 @@
PlatformInitLib|OvmfPkg/Library/PlatformInitLib/PlatformInitLib.inf
MemEncryptSevLib|OvmfPkg/Library/BaseMemEncryptSevLib/PeiMemEncryptSevLib.inf
CcProbeLib|OvmfPkg/Library/CcProbeLib/SecPeiCcProbeLib.inf
[LibraryClasses.common.DXE_CORE]
HobLib|MdePkg/Library/DxeCoreHobLib/DxeCoreHobLib.inf