From 8e7edbbf5d6d169eab0dc57fdeb3cfa835e5641d Mon Sep 17 00:00:00 2001
From: "Lendacky, Thomas" <thomas.lendacky@amd.com>
Date: Thu, 29 Apr 2021 12:12:13 -0500
Subject: OvmfPkg/TpmMmioSevDecryptPei: Mark TPM MMIO range as unencrypted for
 SEV-ES
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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>
---
 .../TpmMmioSevDecryptPei/TpmMmioSevDecryptPei.inf  | 40 ++++++++++++++++++++++
 1 file changed, 40 insertions(+)
 create mode 100644 OvmfPkg/Tcg/TpmMmioSevDecryptPei/TpmMmioSevDecryptPei.inf

(limited to 'OvmfPkg/Tcg/TpmMmioSevDecryptPei/TpmMmioSevDecryptPei.inf')

diff --git a/OvmfPkg/Tcg/TpmMmioSevDecryptPei/TpmMmioSevDecryptPei.inf b/OvmfPkg/Tcg/TpmMmioSevDecryptPei/TpmMmioSevDecryptPei.inf
new file mode 100644
index 0000000000..51ad6d0d05
--- /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
-- 
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