UefiCpuPkg/Library/SmmCpuFeaturesLib/Ia32/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 <PiMm.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   4M Non-PAE page table in IA32 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   UINT32  *Pte;
  36   UINT32  Address;
  37
  38   Pte = (UINT32 *)(UINTN)PageTableBase;
  39
  40   Address = 0;
  41   for (Index = 0; Index < SIZE_4KB / sizeof (*Pte); Index++) {
  42     *Pte = Address | IA32_PG_PS | IA32_PG_RW | IA32_PG_P;
  43     Pte++;
  44     Address += SIZE_4MB;
  45   }
  46 }
  47
  48 /**
  49   This is SMM exception handle.
  50   Consumed by STM when exception happen.
  51
  52   @param Context  STM protection exception stack frame
  53
  54   @return the EBX value for STM reference.
  55           EBX = 0: resume SMM guest using register state found on exception stack.
  56           EBX = 1 to 0x0F: EBX contains a BIOS error code which the STM must record in the
  57                            TXT.ERRORCODE register and subsequently reset the system via
  58                            TXT.CMD.SYS_RESET. The value of the TXT.ERRORCODE register is calculated as
  59                            follows: TXT.ERRORCODE = (EBX & 0x0F) | STM_CRASH_BIOS_PANIC
  60           EBX = 0x10 to 0xFFFFFFFF - reserved, do not use.
  61
  62 **/
  63 UINT32
  64 EFIAPI
  65 SmmStmExceptionHandler (
  66   IN OUT STM_PROTECTION_EXCEPTION_STACK_FRAME  Context
  67   )
  68 {
  69   // TBD - SmmStmExceptionHandler, record information
  70   DEBUG ((DEBUG_ERROR, "SmmStmExceptionHandler ...\n"));
  71   //
  72   // Skip this instruction and continue;
  73   //
  74   Context.Ia32StackFrame->Rip += Context.Ia32StackFrame->VmcsExitInstructionLength;
  75
  76   return 0;
  77 }