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>

10 files changed, 135 insertions, 0 deletions

diff --git a/OvmfPkg/AmdSev/AmdSevX64.dsc b/OvmfPkg/AmdSev/AmdSevX64.dsc
index cdb29d5..66bbbc8 100644
--- a/OvmfPkg/AmdSev/AmdSevX64.dsc
+++ b/OvmfPkg/AmdSev/AmdSevX64.dsc
@@ -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 {

diff --git a/OvmfPkg/AmdSev/AmdSevX64.fdf b/OvmfPkg/AmdSev/AmdSevX64.fdf
index c009850..dd0030d 100644
--- a/OvmfPkg/AmdSev/AmdSevX64.fdf
+++ b/OvmfPkg/AmdSev/AmdSevX64.fdf
@@ -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

diff --git a/OvmfPkg/OvmfPkgIa32.dsc b/OvmfPkg/OvmfPkgIa32.dsc
index 1730b65..33fbd76 100644
--- a/OvmfPkg/OvmfPkgIa32.dsc
+++ b/OvmfPkg/OvmfPkgIa32.dsc
@@ -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 {

diff --git a/OvmfPkg/OvmfPkgIa32.fdf b/OvmfPkg/OvmfPkgIa32.fdf
index f400c84..b3c8b56 100644
--- a/OvmfPkg/OvmfPkgIa32.fdf
+++ b/OvmfPkg/OvmfPkgIa32.fdf
@@ -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

diff --git a/OvmfPkg/OvmfPkgIa32X64.dsc b/OvmfPkg/OvmfPkgIa32X64.dsc
index 78a559d..b13e5cf 100644
--- a/OvmfPkg/OvmfPkgIa32X64.dsc
+++ b/OvmfPkg/OvmfPkgIa32X64.dsc
@@ -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 {

diff --git a/OvmfPkg/OvmfPkgIa32X64.fdf b/OvmfPkg/OvmfPkgIa32X64.fdf
index d055552..86592c2 100644
--- a/OvmfPkg/OvmfPkgIa32X64.fdf
+++ b/OvmfPkg/OvmfPkgIa32X64.fdf
@@ -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

diff --git a/OvmfPkg/OvmfPkgX64.dsc b/OvmfPkg/OvmfPkgX64.dsc
index a7d747f..999738d 100644
--- a/OvmfPkg/OvmfPkgX64.dsc
+++ b/OvmfPkg/OvmfPkgX64.dsc
@@ -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 {

diff --git a/OvmfPkg/OvmfPkgX64.fdf b/OvmfPkg/OvmfPkgX64.fdf
index d519f85..d6be798 100644
--- a/OvmfPkg/OvmfPkgX64.fdf
+++ b/OvmfPkg/OvmfPkgX64.fdf
@@ -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

diff --git a/OvmfPkg/Tcg/TpmMmioSevDecryptPei/TpmMmioSevDecryptPei.inf b/OvmfPkg/Tcg/TpmMmioSevDecryptPei/TpmMmioSevDecryptPei.inf
new file mode 100644
index 0000000..51ad6d0
--- /dev/null
+++ b/OvmfPkg/Tcg/TpmMmioSevDecryptPei/TpmMmioSevDecryptPei.inf
@@ -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

diff --git a/OvmfPkg/Tcg/TpmMmioSevDecryptPei/TpmMmioSevDecryptPeim.c b/OvmfPkg/Tcg/TpmMmioSevDecryptPei/TpmMmioSevDecryptPeim.c
new file mode 100644
index 0000000..df2ad62
--- /dev/null
+++ b/OvmfPkg/Tcg/TpmMmioSevDecryptPei/TpmMmioSevDecryptPeim.c
@@ -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;

+}