OvmfPkg/PlatformPei/FeatureControl.c

   1 /**@file
   2   Install a callback when necessary for setting the Feature Control MSR on all
   3   processors.
   4
   5   Copyright (C) 2016, Red Hat, Inc.
   6
   7   SPDX-License-Identifier: BSD-2-Clause-Patent
   8 **/
   9
  10 #include <Library/DebugLib.h>
  11 #include <Library/PeiServicesLib.h>
  12 #include <Library/QemuFwCfgLib.h>
  13 #include <Ppi/MpServices.h>
  14 #include <Register/ArchitecturalMsr.h>
  15 #include <IndustryStandard/Tdx.h>
  16
  17 #include "Platform.h"
  18
  19 //
  20 // The value to be written to the Feature Control MSR, retrieved from fw_cfg.
  21 //
  22 STATIC UINT64  mFeatureControlValue;
  23
  24 /**
  25   Write the Feature Control MSR on an Application Processor or the Boot
  26   Processor.
  27
  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 WriteFeatureControl (
  38   IN OUT VOID  *WorkSpace
  39   )
  40 {
  41   if (TdIsEnabled ()) {
  42     TdVmCall (TDVMCALL_WRMSR, (UINT64)MSR_IA32_FEATURE_CONTROL, mFeatureControlValue, 0, 0, 0);
  43   } else {
  44     AsmWriteMsr64 (MSR_IA32_FEATURE_CONTROL, mFeatureControlValue);
  45   }
  46 }
  47
  48 /**
  49   Notification function called when EFI_PEI_MP_SERVICES_PPI becomes available.
  50
  51   @param[in] PeiServices      Indirect reference to the PEI Services Table.
  52   @param[in] NotifyDescriptor Address of the notification descriptor data
  53                               structure.
  54   @param[in] Ppi              Address of the PPI that was installed.
  55
  56   @return  Status of the notification. The status code returned from this
  57            function is ignored.
  58 **/
  59 STATIC
  60 EFI_STATUS
  61 EFIAPI
  62 OnMpServicesAvailable (
  63   IN EFI_PEI_SERVICES           **PeiServices,
  64   IN EFI_PEI_NOTIFY_DESCRIPTOR  *NotifyDescriptor,
  65   IN VOID                       *Ppi
  66   )
  67 {
  68   EFI_PEI_MP_SERVICES_PPI  *MpServices;
  69   EFI_STATUS               Status;
  70
  71   DEBUG ((DEBUG_VERBOSE, "%a: %a\n", gEfiCallerBaseName, __FUNCTION__));
  72
  73   //
  74   // Write the MSR on all the APs in parallel.
  75   //
  76   MpServices = Ppi;
  77   Status     = MpServices->StartupAllAPs (
  78                              (CONST EFI_PEI_SERVICES **)PeiServices,
  79                              MpServices,
  80                              WriteFeatureControl, // Procedure
  81                              FALSE,               // SingleThread
  82                              0,                   // TimeoutInMicroSeconds: inf.
  83                              NULL                 // ProcedureArgument
  84                              );
  85   if (EFI_ERROR (Status) && (Status != EFI_NOT_STARTED)) {
  86     DEBUG ((DEBUG_ERROR, "%a: StartupAllAps(): %r\n", __FUNCTION__, Status));
  87     return Status;
  88   }
  89
  90   //
  91   // Now write the MSR on the BSP too.
  92   //
  93   WriteFeatureControl (NULL);
  94   return EFI_SUCCESS;
  95 }
  96
  97 //
  98 // Notification object for registering the callback, for when
  99 // EFI_PEI_MP_SERVICES_PPI becomes available.
 100 //
 101 STATIC CONST EFI_PEI_NOTIFY_DESCRIPTOR  mMpServicesNotify = {
 102   EFI_PEI_PPI_DESCRIPTOR_NOTIFY_CALLBACK | // Flags
 103   EFI_PEI_PPI_DESCRIPTOR_TERMINATE_LIST,
 104   &gEfiPeiMpServicesPpiGuid,               // Guid
 105   OnMpServicesAvailable                    // Notify
 106 };
 107
 108 VOID
 109 InstallFeatureControlCallback (
 110   VOID
 111   )
 112 {
 113   EFI_STATUS            Status;
 114   FIRMWARE_CONFIG_ITEM  FwCfgItem;
 115   UINTN                 FwCfgSize;
 116
 117   Status = QemuFwCfgFindFile (
 118              "etc/msr_feature_control",
 119              &FwCfgItem,
 120              &FwCfgSize
 121              );
 122   if (EFI_ERROR (Status) || (FwCfgSize != sizeof mFeatureControlValue)) {
 123     //
 124     // Nothing to do.
 125     //
 126     return;
 127   }
 128
 129   QemuFwCfgSelectItem (FwCfgItem);
 130   QemuFwCfgReadBytes (sizeof mFeatureControlValue, &mFeatureControlValue);
 131
 132   Status = PeiServicesNotifyPpi (&mMpServicesNotify);
 133   if (EFI_ERROR (Status)) {
 134     DEBUG ((
 135       DEBUG_ERROR,
 136       "%a: failed to set up MP Services callback: %r\n",
 137       __FUNCTION__,
 138       Status
 139       ));
 140   }
 141 }