OvmfPkg/XenPlatformPei/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   Copyright (c) 2019, Citrix Systems, Inc.
  10
  11   SPDX-License-Identifier: BSD-2-Clause-Patent
  12 **/
  13
  14 #include <Library/CacheMaintenanceLib.h>
  15 #include <Library/DebugLib.h>
  16 #include <Library/PeiServicesLib.h>
  17 #include <Ppi/MpServices.h>
  18
  19 #include "Platform.h"
  20
  21 /**
  22   Invalidate data & instruction caches.
  23   All APs execute this function in parallel. The BSP executes the function
  24   separately.
  25
  26   @param[in,out] WorkSpace  Pointer to the input/output argument workspace
  27                             shared by all processors.
  28 **/
  29 STATIC
  30 VOID
  31 EFIAPI
  32 ClearCache (
  33   IN OUT VOID  *WorkSpace
  34   )
  35 {
  36   WriteBackInvalidateDataCache ();
  37   InvalidateInstructionCache ();
  38 }
  39
  40 /**
  41   Notification function called when EFI_PEI_MP_SERVICES_PPI becomes available.
  42
  43   @param[in] PeiServices      Indirect reference to the PEI Services Table.
  44   @param[in] NotifyDescriptor Address of the notification descriptor data
  45                               structure.
  46   @param[in] Ppi              Address of the PPI that was installed.
  47
  48   @return  Status of the notification. The status code returned from this
  49            function is ignored.
  50 **/
  51 STATIC
  52 EFI_STATUS
  53 EFIAPI
  54 ClearCacheOnMpServicesAvailable (
  55   IN EFI_PEI_SERVICES           **PeiServices,
  56   IN EFI_PEI_NOTIFY_DESCRIPTOR  *NotifyDescriptor,
  57   IN VOID                       *Ppi
  58   )
  59 {
  60   EFI_PEI_MP_SERVICES_PPI  *MpServices;
  61   EFI_STATUS               Status;
  62
  63   DEBUG ((DEBUG_INFO, "%a: %a\n", gEfiCallerBaseName, __FUNCTION__));
  64
  65   //
  66   // Clear cache on all the APs in parallel.
  67   //
  68   MpServices = Ppi;
  69   Status     = MpServices->StartupAllAPs (
  70                              (CONST EFI_PEI_SERVICES **)PeiServices,
  71                              MpServices,
  72                              ClearCache,      // Procedure
  73                              FALSE,           // SingleThread
  74                              0,               // TimeoutInMicroSeconds: inf.
  75                              NULL             // ProcedureArgument
  76                              );
  77   if (EFI_ERROR (Status) && (Status != EFI_NOT_STARTED)) {
  78     DEBUG ((DEBUG_ERROR, "%a: StartupAllAps(): %r\n", __FUNCTION__, Status));
  79     return Status;
  80   }
  81
  82   //
  83   // Now clear cache on the BSP too.
  84   //
  85   ClearCache (NULL);
  86   return EFI_SUCCESS;
  87 }
  88
  89 //
  90 // Notification object for registering the callback, for when
  91 // EFI_PEI_MP_SERVICES_PPI becomes available.
  92 //
  93 STATIC CONST EFI_PEI_NOTIFY_DESCRIPTOR  mMpServicesNotify = {
  94   EFI_PEI_PPI_DESCRIPTOR_NOTIFY_CALLBACK | // Flags
  95   EFI_PEI_PPI_DESCRIPTOR_TERMINATE_LIST,
  96   &gEfiPeiMpServicesPpiGuid,               // Guid
  97   ClearCacheOnMpServicesAvailable          // Notify
  98 };
  99
 100 VOID
 101 InstallClearCacheCallback (
 102   VOID
 103   )
 104 {
 105   EFI_STATUS  Status;
 106
 107   Status = PeiServicesNotifyPpi (&mMpServicesNotify);
 108   if (EFI_ERROR (Status)) {
 109     DEBUG ((
 110       DEBUG_ERROR,
 111       "%a: failed to set up MP Services callback: %r\n",
 112       __FUNCTION__,
 113       Status
 114       ));
 115   }
 116 }