From 1f425925b734951f53785aca1a763517db3e4591 Mon Sep 17 00:00:00 2001
From: Artur Kowalski <artur.kowalski@3mdeb.com>
Date: Tue, 27 Aug 2024 14:55:05 +0200
Subject: [PATCH] OvmfPkg: DxeTcg2PhysicalPresenceLib: fix changing of PCR
 banks

Tcg2PhysicalPresenceLibSubmitRequestToPreOSFunction writes to TPM2
physical presence PPI provided by coreboot (a memory region preserved
across reboots). CPU caches must be explicitly flushed prior to platform
reboot or request written to PPI will be lost.

Signed-off-by: Artur Kowalski <artur.kowalski@3mdeb.com>
---
 .../Tcg2PhysicalPresenceLibQemu/DxeTcg2PhysicalPresenceLib.c    | 2 ++
 .../Tcg2PhysicalPresenceLibQemu/DxeTcg2PhysicalPresenceLib.inf  | 1 +
 2 files changed, 3 insertions(+)

diff --git a/OvmfPkg/Library/Tcg2PhysicalPresenceLibQemu/DxeTcg2PhysicalPresenceLib.c b/OvmfPkg/Library/Tcg2PhysicalPresenceLibQemu/DxeTcg2PhysicalPresenceLib.c
index 5e8bf3a0b9..421eb9a77f 100644
--- a/OvmfPkg/Library/Tcg2PhysicalPresenceLibQemu/DxeTcg2PhysicalPresenceLib.c
+++ b/OvmfPkg/Library/Tcg2PhysicalPresenceLibQemu/DxeTcg2PhysicalPresenceLib.c
@@ -32,6 +32,7 @@ SPDX-License-Identifier: BSD-2-Clause-Patent
 #include <Library/UefiBootServicesTableLib.h>
 #include <Library/UefiLib.h>
 #include <Library/UefiRuntimeServicesTableLib.h>
+#include <Library/CacheMaintenanceLib.h>
 
 #include <Library/Tcg2PhysicalPresenceLib.h>
 
@@ -902,6 +903,7 @@ Tcg2PhysicalPresenceLibSubmitRequestToPreOSFunction (
 
   mPpi->Request = OperationRequest;
   mPpi->RequestParameter = RequestParameter;
+  WriteBackDataCache();
 
   return TCG_PP_SUBMIT_REQUEST_TO_PREOS_SUCCESS;
 }
diff --git a/OvmfPkg/Library/Tcg2PhysicalPresenceLibQemu/DxeTcg2PhysicalPresenceLib.inf b/OvmfPkg/Library/Tcg2PhysicalPresenceLibQemu/DxeTcg2PhysicalPresenceLib.inf
index de39ef056a..26b715df37 100644
--- a/OvmfPkg/Library/Tcg2PhysicalPresenceLibQemu/DxeTcg2PhysicalPresenceLib.inf
+++ b/OvmfPkg/Library/Tcg2PhysicalPresenceLibQemu/DxeTcg2PhysicalPresenceLib.inf
@@ -62,6 +62,7 @@
   UefiLib
   UefiRuntimeServicesTableLib
   Tcg2PhysicalPresencePlatformLib
+  CacheMaintenanceLib
 
 [Protocols]
   gEfiTcg2ProtocolGuid                 ## SOMETIMES_CONSUMES