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 · Aug 27, 2024 · 8294b19 · 8294b19
1 parent 6be227e
commit 8294b19
Show file tree

Hide file tree

Showing 2 changed files with 3 additions and 0 deletions.
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