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   SPDX-License-Identifier: BSD-2-Clause-Patent
  11 **/
  12
  13 #include <Library/CacheMaintenanceLib.h>
  14 #include <Library/DebugLib.h>
  15 #include <Library/PeiServicesLib.h>
  16 #include <Ppi/MpServices.h>
  17
  18 #include "Platform.h"
  19
  20 /**
  21   Invalidate data & instruction caches.
  22   All APs execute this function in parallel. The BSP executes the function
  23   separately.
  24
  25   @param[in,out] WorkSpace  Pointer to the input/output argument workspace
  26                             shared by all processors.
  27 **/
  28 STATIC
  29 VOID
  30 EFIAPI
  31 ClearCache (
  32   IN OUT VOID *WorkSpace
  33   )
  34 {
  35   WriteBackInvalidateDataCache ();
  36   InvalidateInstructionCache ();
  37 }
  38
  39 /**
  40   Notification function called when EFI_PEI_MP_SERVICES_PPI becomes available.
  41
  42   @param[in] PeiServices      Indirect reference to the PEI Services Table.
  43   @param[in] NotifyDescriptor Address of the notification descriptor data
  44                               structure.
  45   @param[in] Ppi              Address of the PPI that was installed.
  46
  47   @return  Status of the notification. The status code returned from this
  48            function is ignored.
  49 **/
  50 STATIC
  51 EFI_STATUS
  52 EFIAPI
  53 ClearCacheOnMpServicesAvailable (
  54   IN EFI_PEI_SERVICES           **PeiServices,
  55   IN EFI_PEI_NOTIFY_DESCRIPTOR  *NotifyDescriptor,
  56   IN VOID                       *Ppi
  57   )
  58 {
  59   EFI_PEI_MP_SERVICES_PPI *MpServices;
  60   EFI_STATUS              Status;
  61
  62   DEBUG ((DEBUG_INFO, "%a: %a\n", gEfiCallerBaseName, __FUNCTION__));
  63
  64   //
  65   // Clear cache on all the APs in parallel.
  66   //
  67   MpServices = Ppi;
  68   Status = MpServices->StartupAllAPs (
  69                          (CONST EFI_PEI_SERVICES **)PeiServices,
  70                          MpServices,
  71                          ClearCache,          // Procedure
  72                          FALSE,               // SingleThread
  73                          0,                   // TimeoutInMicroSeconds: inf.
  74                          NULL                 // ProcedureArgument
  75                          );
  76   if (EFI_ERROR (Status) && Status != EFI_NOT_STARTED) {
  77     DEBUG ((DEBUG_ERROR, "%a: StartupAllAps(): %r\n", __FUNCTION__, Status));
  78     return Status;
  79   }
  80
  81   //
  82   // Now clear cache on the BSP too.
  83   //
  84   ClearCache (NULL);
  85   return EFI_SUCCESS;
  86 }
  87
  88 //
  89 // Notification object for registering the callback, for when
  90 // EFI_PEI_MP_SERVICES_PPI becomes available.
  91 //
  92 STATIC CONST EFI_PEI_NOTIFY_DESCRIPTOR mMpServicesNotify = {
  93   EFI_PEI_PPI_DESCRIPTOR_NOTIFY_CALLBACK | // Flags
  94   EFI_PEI_PPI_DESCRIPTOR_TERMINATE_LIST,
  95   &gEfiPeiMpServicesPpiGuid,               // Guid
  96   ClearCacheOnMpServicesAvailable          // Notify
  97 };
  98
  99 VOID
 100 InstallClearCacheCallback (
 101   VOID
 102   )
 103 {
 104   EFI_STATUS           Status;
 105
 106   Status = PeiServicesNotifyPpi (&mMpServicesNotify);
 107   if (EFI_ERROR (Status)) {
 108     DEBUG ((DEBUG_ERROR, "%a: failed to set up MP Services callback: %r\n",
 109       __FUNCTION__, Status));
 110   }
 111 }