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OvmfPkg/TpmMmioSevDecryptPei: Mark TPM MMIO range as unencrypted for SEV-ES 

BZ: https://bugzilla.tianocore.org/show_bug.cgi?id=3345

During PEI, the MMIO range for the TPM is marked as encrypted when running
as an SEV guest. While this isn't an issue for an SEV guest because of
the way the nested page fault is handled, it does result in an SEV-ES
guest terminating because of a mitigation check in the #VC handler to
prevent MMIO to an encrypted address. For an SEV-ES guest, this range
must be marked as unencrypted.

Create a new x86 PEIM for TPM support that will map the TPM MMIO range as
unencrypted when SEV-ES is active. The gOvmfTpmMmioAccessiblePpiGuid PPI
will be unconditionally installed before exiting. The PEIM will exit with
the EFI_ABORTED status so that the PEIM does not stay resident. This new
PEIM will depend on the installation of the permanent PEI RAM, by
PlatformPei, so that in case page table splitting is required during the
clearing of the encryption bit, the new page table(s) will be allocated
from permanent PEI RAM.

Update all OVMF Ia32 and X64 build packages to include this new PEIM.

Cc: Laszlo Ersek <lersek@redhat.com>
Cc: Ard Biesheuvel <ardb+tianocore@kernel.org>
Cc: Jordan Justen <jordan.l.justen@intel.com>
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: Min Xu <min.m.xu@intel.com>
Cc: Marc-André Lureau <marcandre.lureau@redhat.com>
Cc: Stefan Berger <stefanb@linux.ibm.com>
Signed-off-by: Tom Lendacky <thomas.lendacky@amd.com>
Message-Id: <42794cec1f9d5bc24cbfb9dcdbe5e281ef259ef5.1619716333.git.thomas.lendacky@amd.com>
[lersek@redhat.com: refresh subject line]
Reviewed-by: Laszlo Ersek <lersek@redhat.com>
This commit is contained in:
Lendacky, Thomas 2021-04-29 12:12:13 -05:00 committed by mergify[bot]
parent a3f12cd471
commit 8e7edbbf5d
10 changed files with 135 additions and 0 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

1
OvmfPkg/AmdSev/AmdSevX64.dsc
View File

@ -626,6 +626,7 @@
OvmfPkg/AmdSev/SecretPei/SecretPei.inf
!if $(TPM_ENABLE) == TRUE
OvmfPkg/Tcg/TpmMmioSevDecryptPei/TpmMmioSevDecryptPei.inf
OvmfPkg/Tcg/Tcg2Config/Tcg2ConfigPei.inf
SecurityPkg/Tcg/TcgPei/TcgPei.inf
SecurityPkg/Tcg/Tcg2Pei/Tcg2Pei.inf {

1
OvmfPkg/AmdSev/AmdSevX64.fdf
View File

@ -147,6 +147,7 @@ INF UefiCpuPkg/CpuMpPei/CpuMpPei.inf
INF OvmfPkg/AmdSev/SecretPei/SecretPei.inf
!if $(TPM_ENABLE) == TRUE
INF OvmfPkg/Tcg/TpmMmioSevDecryptPei/TpmMmioSevDecryptPei.inf
INF OvmfPkg/Tcg/Tcg2Config/Tcg2ConfigPei.inf
INF SecurityPkg/Tcg/TcgPei/TcgPei.inf
INF SecurityPkg/Tcg/Tcg2Pei/Tcg2Pei.inf

1
OvmfPkg/OvmfPkgIa32.dsc
View File

@ -706,6 +706,7 @@
UefiCpuPkg/CpuMpPei/CpuMpPei.inf
!if $(TPM_ENABLE) == TRUE
OvmfPkg/Tcg/TpmMmioSevDecryptPei/TpmMmioSevDecryptPei.inf
OvmfPkg/Tcg/Tcg2Config/Tcg2ConfigPei.inf
SecurityPkg/Tcg/TcgPei/TcgPei.inf
SecurityPkg/Tcg/Tcg2Pei/Tcg2Pei.inf {

1
OvmfPkg/OvmfPkgIa32.fdf
View File

@ -162,6 +162,7 @@ INF OvmfPkg/SmmAccess/SmmAccessPei.inf
INF UefiCpuPkg/CpuMpPei/CpuMpPei.inf
!if $(TPM_ENABLE) == TRUE
INF OvmfPkg/Tcg/TpmMmioSevDecryptPei/TpmMmioSevDecryptPei.inf
INF OvmfPkg/Tcg/Tcg2Config/Tcg2ConfigPei.inf
INF SecurityPkg/Tcg/TcgPei/TcgPei.inf
INF SecurityPkg/Tcg/Tcg2Pei/Tcg2Pei.inf

1
OvmfPkg/OvmfPkgIa32X64.dsc
View File

@ -719,6 +719,7 @@
UefiCpuPkg/CpuMpPei/CpuMpPei.inf
!if $(TPM_ENABLE) == TRUE
OvmfPkg/Tcg/TpmMmioSevDecryptPei/TpmMmioSevDecryptPei.inf
OvmfPkg/Tcg/Tcg2Config/Tcg2ConfigPei.inf
SecurityPkg/Tcg/TcgPei/TcgPei.inf
SecurityPkg/Tcg/Tcg2Pei/Tcg2Pei.inf {

1
OvmfPkg/OvmfPkgIa32X64.fdf
View File

@ -162,6 +162,7 @@ INF OvmfPkg/SmmAccess/SmmAccessPei.inf
INF UefiCpuPkg/CpuMpPei/CpuMpPei.inf
!if $(TPM_ENABLE) == TRUE
INF OvmfPkg/Tcg/TpmMmioSevDecryptPei/TpmMmioSevDecryptPei.inf
INF OvmfPkg/Tcg/Tcg2Config/Tcg2ConfigPei.inf
INF SecurityPkg/Tcg/TcgPei/TcgPei.inf
INF SecurityPkg/Tcg/Tcg2Pei/Tcg2Pei.inf

1
OvmfPkg/OvmfPkgX64.dsc
View File

@ -718,6 +718,7 @@
UefiCpuPkg/CpuMpPei/CpuMpPei.inf
!if $(TPM_ENABLE) == TRUE
OvmfPkg/Tcg/TpmMmioSevDecryptPei/TpmMmioSevDecryptPei.inf
OvmfPkg/Tcg/Tcg2Config/Tcg2ConfigPei.inf
SecurityPkg/Tcg/TcgPei/TcgPei.inf
SecurityPkg/Tcg/Tcg2Pei/Tcg2Pei.inf {

1
OvmfPkg/OvmfPkgX64.fdf
View File

@ -174,6 +174,7 @@ INF OvmfPkg/SmmAccess/SmmAccessPei.inf
INF UefiCpuPkg/CpuMpPei/CpuMpPei.inf
!if $(TPM_ENABLE) == TRUE
INF OvmfPkg/Tcg/TpmMmioSevDecryptPei/TpmMmioSevDecryptPei.inf
INF OvmfPkg/Tcg/Tcg2Config/Tcg2ConfigPei.inf
INF SecurityPkg/Tcg/TcgPei/TcgPei.inf
INF SecurityPkg/Tcg/Tcg2Pei/Tcg2Pei.inf

40
OvmfPkg/Tcg/TpmMmioSevDecryptPei/TpmMmioSevDecryptPei.inf Normal file
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@ -0,0 +1,40 @@
## @file
# Map TPM MMIO range unencrypted when SEV-ES is active.
# Install gOvmfTpmMmioAccessiblePpiGuid unconditionally.
#
# Copyright (C) 2021, Advanced Micro Devices, Inc.
#
# SPDX-License-Identifier: BSD-2-Clause-Patent
##
[Defines]
INF_VERSION = 1.29
BASE_NAME = TpmMmioSevDecryptPei
FILE_GUID = F12F698A-E506-4A1B-B32E-6920E55DA1C4
MODULE_TYPE = PEIM
VERSION_STRING = 1.0
ENTRY_POINT = TpmMmioSevDecryptPeimEntryPoint
[Sources]
TpmMmioSevDecryptPeim.c
[Packages]
MdePkg/MdePkg.dec
OvmfPkg/OvmfPkg.dec
SecurityPkg/SecurityPkg.dec
[LibraryClasses]
DebugLib
MemEncryptSevLib
PcdLib
PeimEntryPoint
PeiServicesLib
[Ppis]
gOvmfTpmMmioAccessiblePpiGuid ## PRODUCES
[FixedPcd]
gEfiSecurityPkgTokenSpaceGuid.PcdTpmBaseAddress ## CONSUMES
[Depex]
gEfiPeiMemoryDiscoveredPpiGuid

87
OvmfPkg/Tcg/TpmMmioSevDecryptPei/TpmMmioSevDecryptPeim.c Normal file
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@ -0,0 +1,87 @@
/** @file
Map TPM MMIO range unencrypted when SEV-ES is active.
Install gOvmfTpmMmioAccessiblePpiGuid unconditionally.
Copyright (C) 2021, Advanced Micro Devices, Inc.
SPDX-License-Identifier: BSD-2-Clause-Patent
**/
#include <PiPei.h>
#include <Library/DebugLib.h>
#include <Library/MemEncryptSevLib.h>
#include <Library/PcdLib.h>
#include <Library/PeiServicesLib.h>
STATIC CONST EFI_PEI_PPI_DESCRIPTOR mTpmMmioRangeAccessible = {
EFI_PEI_PPI_DESCRIPTOR_PPI | EFI_PEI_PPI_DESCRIPTOR_TERMINATE_LIST,
&gOvmfTpmMmioAccessiblePpiGuid,
NULL
};
/**
The entry point for TPM MMIO range mapping driver.
@param[in] FileHandle Handle of the file being invoked.
@param[in] PeiServices Describes the list of possible PEI Services.
@retval EFI_ABORTED No need to keep this PEIM resident
**/
EFI_STATUS
EFIAPI
TpmMmioSevDecryptPeimEntryPoint (
IN EFI_PEI_FILE_HANDLE FileHandle,
IN CONST EFI_PEI_SERVICES **PeiServices
)
{
RETURN_STATUS DecryptStatus;
EFI_STATUS Status;
DEBUG ((DEBUG_INFO, "%a\n", __FUNCTION__));
//
// If SEV is active, MMIO succeeds against an encrypted physical address
// because the nested page fault (NPF) that occurs on access does not
// include the encryption bit in the guest physical address provided to the
// hypervisor.
//
// If SEV-ES is active, MMIO would succeed against an encrypted physical
// address because the #VC handler uses the virtual address (which is an
// identity mapped physical address without the encryption bit) as the guest
// physical address of the MMIO target in the VMGEXIT.
//
// However, if SEV-ES is active, before performing the actual MMIO, an
// additional MMIO mitigation check is performed in the #VC handler to ensure
// that MMIO is being done to/from an unencrypted address. To prevent guest
// termination in this scenario, mark the range unencrypted ahead of access.
//
if (MemEncryptSevEsIsEnabled ()) {
DEBUG ((DEBUG_INFO,
"%a: mapping TPM MMIO address range unencrypted\n",
__FUNCTION__));
DecryptStatus = MemEncryptSevClearPageEncMask (
0,
FixedPcdGet64 (PcdTpmBaseAddress),
EFI_SIZE_TO_PAGES ((UINTN) 0x5000),
FALSE
);
if (RETURN_ERROR (DecryptStatus)) {
DEBUG ((DEBUG_ERROR,
"%a: failed to map TPM MMIO address range unencrypted\n",
__FUNCTION__));
ASSERT_RETURN_ERROR (DecryptStatus);
}
}
//
// MMIO range available
//
Status = PeiServicesInstallPpi (&mTpmMmioRangeAccessible);
ASSERT_EFI_ERROR (Status);
return EFI_ABORTED;
}