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 <[email protected]>
Dasharo · Sep 4, 2024 · 1f42592 · 1f42592
1 parent ad2124e
commit 1f42592
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diff --git 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
@@ -62,6 +62,7 @@
   UefiLib
   UefiRuntimeServicesTableLib
   Tcg2PhysicalPresencePlatformLib
+  CacheMaintenanceLib
 
 [Protocols]
   gEfiTcg2ProtocolGuid                 ## SOMETIMES_CONSUMES