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   This program and the accompanying materials
   6   are licensed and made available under the terms and conditions of the BSD License
   7   which accompanies this distribution.  The full text of the license may be found at
   8   http://opensource.org/licenses/bsd-license.php.
   9
  10   THE PROGRAM IS DISTRIBUTED UNDER THE BSD LICENSE ON AN "AS IS" BASIS,
  11   WITHOUT WARRANTIES OR REPRESENTATIONS OF ANY KIND, EITHER EXPRESS OR IMPLIED.
  12
  13 **/
  14
  15 #include <PiSmm.h>
  16 #include <Library/DebugLib.h>
  17
  18 #include "SmmStm.h"
  19
  20 ///
  21 /// Page Table Entry
  22 ///
  23 #define IA32_PG_P                   BIT0
  24 #define IA32_PG_RW                  BIT1
  25 #define IA32_PG_PS                  BIT7
  26
  27 /**
  28
  29   Create 4G page table for STM.
  30   4M Non-PAE page table in IA32 version.
  31
  32   @param PageTableBase        The page table base in MSEG
  33
  34 **/
  35 VOID
  36 StmGen4GPageTable (
  37   IN UINTN              PageTableBase
  38   )
  39 {
  40   UINTN                             Index;
  41   UINT32                            *Pte;
  42   UINT32                            Address;
  43
  44   Pte = (UINT32*)(UINTN)PageTableBase;
  45
  46   Address = 0;
  47   for (Index = 0; Index < SIZE_4KB / sizeof (*Pte); Index++) {
  48     *Pte = Address | IA32_PG_PS | IA32_PG_RW | IA32_PG_P;
  49     Pte++;
  50     Address += SIZE_4MB;
  51   }
  52 }
  53
  54 /**
  55   This is SMM exception handle.
  56   Consumed by STM when exception happen.
  57
  58   @param Context  STM protection exception stack frame
  59
  60   @return the EBX value for STM reference.
  61           EBX = 0: resume SMM guest using register state found on exception stack.
  62           EBX = 1 to 0x0F: EBX contains a BIOS error code which the STM must record in the
  63                            TXT.ERRORCODE register and subsequently reset the system via
  64                            TXT.CMD.SYS_RESET. The value of the TXT.ERRORCODE register is calculated as
  65                            follows: TXT.ERRORCODE = (EBX & 0x0F) | STM_CRASH_BIOS_PANIC
  66           EBX = 0x10 to 0xFFFFFFFF - reserved, do not use.
  67
  68 **/
  69 UINT32
  70 EFIAPI
  71 SmmStmExceptionHandler (
  72   IN OUT STM_PROTECTION_EXCEPTION_STACK_FRAME Context
  73   )
  74 {
  75   // TBD - SmmStmExceptionHandler, record information
  76   DEBUG ((DEBUG_ERROR, "SmmStmExceptionHandler ...\n"));
  77   //
  78   // Skip this instruction and continue;
  79   //
  80   Context.Ia32StackFrame->Rip += Context.Ia32StackFrame->VmcsExitInstructionLength;
  81
  82   return 0;
  83 }