OvmfPkg/PlatformPei/ClearCache.c

   1 /**@file
   2   Install a callback to clear cache on all processors.
   3   This is for conformance with the TCG "Platform Reset Attack Mitigation
   4   Specification". Because clearing the CPU caches at boot doesn't impact
   5   performance significantly, do it unconditionally, for simplicity's
   6   sake.
   7
   8   Copyright (C) 2018, Red Hat, Inc.
   9
  10   This program and the accompanying materials are licensed and made available
  11   under the terms and conditions of the BSD License which accompanies this
  12   distribution.  The full text of the license may be found at
  13   http://opensource.org/licenses/bsd-license.php
  14
  15   THE PROGRAM IS DISTRIBUTED UNDER THE BSD LICENSE ON AN "AS IS" BASIS, WITHOUT
  16   WARRANTIES OR REPRESENTATIONS OF ANY KIND, EITHER EXPRESS OR IMPLIED.
  17 **/
  18
  19 #include <Library/CacheMaintenanceLib.h>
  20 #include <Library/DebugLib.h>
  21 #include <Library/PeiServicesLib.h>
  22 #include <Ppi/MpServices.h>
  23
  24 #include "Platform.h"
  25
  26 /**
  27   Invalidate data & instruction caches.
  28   All APs execute this function in parallel. The BSP executes the function
  29   separately.
  30
  31   @param[in,out] WorkSpace  Pointer to the input/output argument workspace
  32                             shared by all processors.
  33 **/
  34 STATIC
  35 VOID
  36 EFIAPI
  37 ClearCache (
  38   IN OUT VOID *WorkSpace
  39   )
  40 {
  41   WriteBackInvalidateDataCache ();
  42   InvalidateInstructionCache ();
  43 }
  44
  45 /**
  46   Notification function called when EFI_PEI_MP_SERVICES_PPI becomes available.
  47
  48   @param[in] PeiServices      Indirect reference to the PEI Services Table.
  49   @param[in] NotifyDescriptor Address of the notification descriptor data
  50                               structure.
  51   @param[in] Ppi              Address of the PPI that was installed.
  52
  53   @return  Status of the notification. The status code returned from this
  54            function is ignored.
  55 **/
  56 STATIC
  57 EFI_STATUS
  58 EFIAPI
  59 ClearCacheOnMpServicesAvailable (
  60   IN EFI_PEI_SERVICES           **PeiServices,
  61   IN EFI_PEI_NOTIFY_DESCRIPTOR  *NotifyDescriptor,
  62   IN VOID                       *Ppi
  63   )
  64 {
  65   EFI_PEI_MP_SERVICES_PPI *MpServices;
  66   EFI_STATUS              Status;
  67
  68   DEBUG ((DEBUG_INFO, "%a: %a\n", gEfiCallerBaseName, __FUNCTION__));
  69
  70   //
  71   // Clear cache on all the APs in parallel.
  72   //
  73   MpServices = Ppi;
  74   Status = MpServices->StartupAllAPs (
  75                          (CONST EFI_PEI_SERVICES **)PeiServices,
  76                          MpServices,
  77                          ClearCache,          // Procedure
  78                          FALSE,               // SingleThread
  79                          0,                   // TimeoutInMicroSeconds: inf.
  80                          NULL                 // ProcedureArgument
  81                          );
  82   if (EFI_ERROR (Status) && Status != EFI_NOT_STARTED) {
  83     DEBUG ((DEBUG_ERROR, "%a: StartupAllAps(): %r\n", __FUNCTION__, Status));
  84     return Status;
  85   }
  86
  87   //
  88   // Now clear cache on the BSP too.
  89   //
  90   ClearCache (NULL);
  91   return EFI_SUCCESS;
  92 }
  93
  94 //
  95 // Notification object for registering the callback, for when
  96 // EFI_PEI_MP_SERVICES_PPI becomes available.
  97 //
  98 STATIC CONST EFI_PEI_NOTIFY_DESCRIPTOR mMpServicesNotify = {
  99   EFI_PEI_PPI_DESCRIPTOR_NOTIFY_CALLBACK | // Flags
 100   EFI_PEI_PPI_DESCRIPTOR_TERMINATE_LIST,
 101   &gEfiPeiMpServicesPpiGuid,               // Guid
 102   ClearCacheOnMpServicesAvailable          // Notify
 103 };
 104
 105 VOID
 106 InstallClearCacheCallback (
 107   VOID
 108   )
 109 {
 110   EFI_STATUS           Status;
 111
 112   Status = PeiServicesNotifyPpi (&mMpServicesNotify);
 113   if (EFI_ERROR (Status)) {
 114     DEBUG ((DEBUG_ERROR, "%a: failed to set up MP Services callback: %r\n",
 115       __FUNCTION__, Status));
 116   }
 117 }