UefiCpuPkg/Library/CpuCommonFeaturesLib/ExecuteDisable.c

   1 /** @file
   2   Execute Disable feature.
   3
   4   Copyright (c) 2017, Intel Corporation. All rights reserved.<BR>
   5   SPDX-License-Identifier: BSD-2-Clause-Patent
   6
   7 **/
   8
   9 #include "CpuCommonFeatures.h"
  10
  11 /**
  12   Detects if Execute Disable feature supported on current processor.
  13
  14   @param[in]  ProcessorNumber  The index of the CPU executing this function.
  15   @param[in]  CpuInfo          A pointer to the REGISTER_CPU_FEATURE_INFORMATION
  16                                structure for the CPU executing this function.
  17   @param[in]  ConfigData       A pointer to the configuration buffer returned
  18                                by CPU_FEATURE_GET_CONFIG_DATA.  NULL if
  19                                CPU_FEATURE_GET_CONFIG_DATA was not provided in
  20                                RegisterCpuFeature().
  21
  22   @retval TRUE     Execute Disable feature is supported.
  23   @retval FALSE    Execute Disable feature is not supported.
  24
  25   @note This service could be called by BSP/APs.
  26 **/
  27 BOOLEAN
  28 EFIAPI
  29 ExecuteDisableSupport (
  30   IN UINTN                             ProcessorNumber,
  31   IN REGISTER_CPU_FEATURE_INFORMATION  *CpuInfo,
  32   IN VOID                              *ConfigData  OPTIONAL
  33   )
  34 {
  35   UINT32                         Eax;
  36   CPUID_EXTENDED_CPU_SIG_EDX     Edx;
  37
  38   AsmCpuid (CPUID_EXTENDED_FUNCTION, &Eax, NULL, NULL, NULL);
  39   if (Eax <= CPUID_EXTENDED_FUNCTION) {
  40     //
  41     // Extended CPUID functions are not supported on this processor.
  42     //
  43     return FALSE;
  44   }
  45
  46   AsmCpuid (CPUID_EXTENDED_CPU_SIG, NULL, NULL, NULL, &Edx.Uint32);
  47   return (Edx.Bits.NX != 0);
  48 }
  49
  50 /**
  51   Initializes Execute Disable feature to specific state.
  52
  53   @param[in]  ProcessorNumber  The index of the CPU executing this function.
  54   @param[in]  CpuInfo          A pointer to the REGISTER_CPU_FEATURE_INFORMATION
  55                                structure for the CPU executing this function.
  56   @param[in]  ConfigData       A pointer to the configuration buffer returned
  57                                by CPU_FEATURE_GET_CONFIG_DATA.  NULL if
  58                                CPU_FEATURE_GET_CONFIG_DATA was not provided in
  59                                RegisterCpuFeature().
  60   @param[in]  State            If TRUE, then the Execute Disable feature must be enabled.
  61                                If FALSE, then the Execute Disable feature must be disabled.
  62
  63   @retval RETURN_SUCCESS       Execute Disable feature is initialized.
  64
  65   @note This service could be called by BSP only.
  66 **/
  67 RETURN_STATUS
  68 EFIAPI
  69 ExecuteDisableInitialize (
  70   IN UINTN                             ProcessorNumber,
  71   IN REGISTER_CPU_FEATURE_INFORMATION  *CpuInfo,
  72   IN VOID                              *ConfigData,  OPTIONAL
  73   IN BOOLEAN                           State
  74   )
  75 {
  76   //
  77   // The scope of the MSR_IA32_EFER is core for below processor type, only program
  78   // MSR_IA32_EFER for thread 0 in each core.
  79   //
  80   if (IS_SILVERMONT_PROCESSOR (CpuInfo->DisplayFamily, CpuInfo->DisplayModel)) {
  81     if (CpuInfo->ProcessorInfo.Location.Thread != 0) {
  82       return RETURN_SUCCESS;
  83     }
  84   }
  85
  86   CPU_REGISTER_TABLE_WRITE_FIELD (
  87     ProcessorNumber,
  88     Msr,
  89     MSR_IA32_EFER,
  90     MSR_IA32_EFER_REGISTER,
  91     Bits.NXE,
  92     (State) ? 1 : 0
  93     );
  94   return RETURN_SUCCESS;
  95 }