UefiCpuPkg/Library/SmmCpuFeaturesLib/X64/SmmStmSupport.c

   1 /** @file
   2   SMM STM support functions
   3
   4   Copyright (c) 2015 - 2016, Intel Corporation. All rights reserved.<BR>
   5   SPDX-License-Identifier: BSD-2-Clause-Patent
   6
   7 **/
   8
   9 #include <PiSmm.h>
  10 #include <Library/DebugLib.h>
  11
  12 #include "SmmStm.h"
  13
  14 ///
  15 /// Page Table Entry
  16 ///
  17 #define IA32_PG_P                   BIT0
  18 #define IA32_PG_RW                  BIT1
  19 #define IA32_PG_PS                  BIT7
  20
  21 /**
  22
  23   Create 4G page table for STM.
  24   2M PAE page table in X64 version.
  25
  26   @param PageTableBase        The page table base in MSEG
  27
  28 **/
  29 VOID
  30 StmGen4GPageTable (
  31   IN UINTN              PageTableBase
  32   )
  33 {
  34   UINTN                             Index;
  35   UINTN                             SubIndex;
  36   UINT64                            *Pde;
  37   UINT64                            *Pte;
  38   UINT64                            *Pml4;
  39
  40   Pml4 = (UINT64*)(UINTN)PageTableBase;
  41   PageTableBase += SIZE_4KB;
  42   *Pml4 = PageTableBase | IA32_PG_RW | IA32_PG_P;
  43
  44   Pde = (UINT64*)(UINTN)PageTableBase;
  45   PageTableBase += SIZE_4KB;
  46   Pte = (UINT64 *)(UINTN)PageTableBase;
  47
  48   for (Index = 0; Index < 4; Index++) {
  49     *Pde = PageTableBase | IA32_PG_RW | IA32_PG_P;
  50     Pde++;
  51     PageTableBase += SIZE_4KB;
  52
  53     for (SubIndex = 0; SubIndex < SIZE_4KB / sizeof (*Pte); SubIndex++) {
  54       *Pte = (((Index << 9) + SubIndex) << 21) | IA32_PG_PS | IA32_PG_RW | IA32_PG_P;
  55       Pte++;
  56     }
  57   }
  58 }
  59
  60 /**
  61   This is SMM exception handle.
  62   Consumed by STM when exception happen.
  63
  64   @param Context  STM protection exception stack frame
  65
  66   @return the EBX value for STM reference.
  67           EBX = 0: resume SMM guest using register state found on exception stack.
  68           EBX = 1 to 0x0F: EBX contains a BIOS error code which the STM must record in the
  69                            TXT.ERRORCODE register and subsequently reset the system via
  70                            TXT.CMD.SYS_RESET. The value of the TXT.ERRORCODE register is calculated as
  71                            follows: TXT.ERRORCODE = (EBX & 0x0F) | STM_CRASH_BIOS_PANIC
  72           EBX = 0x10 to 0xFFFFFFFF - reserved, do not use.
  73
  74 **/
  75 UINT32
  76 EFIAPI
  77 SmmStmExceptionHandler (
  78   IN OUT STM_PROTECTION_EXCEPTION_STACK_FRAME Context
  79   )
  80 {
  81   // TBD - SmmStmExceptionHandler, record information
  82   DEBUG ((DEBUG_ERROR, "SmmStmExceptionHandler ...\n"));
  83   //
  84   // Skip this instruction and continue;
  85   //
  86   Context.X64StackFrame->Rip += Context.X64StackFrame->VmcsExitInstructionLength;
  87
  88   return 0;
  89 }