OvmfPkg/ResetVector/Main.asm

   1 ;------------------------------------------------------------------------------
   2 ; @file
   3 ; Main routine of the pre-SEC code up through the jump into SEC
   4 ;
   5 ; Copyright (c) 2008 - 2009, Intel Corporation. All rights reserved.<BR>
   6 ; SPDX-License-Identifier: BSD-2-Clause-Patent
   7 ;
   8 ;------------------------------------------------------------------------------
   9
  10
  11 BITS    16
  12
  13 ;
  14 ; Modified:  EBX, ECX, EDX, EBP
  15 ;
  16 ; @param[in,out]  RAX/EAX  Initial value of the EAX register
  17 ;                          (BIST: Built-in Self Test)
  18 ; @param[in,out]  DI       'BP': boot-strap processor, or
  19 ;                          'AP': application processor
  20 ; @param[out]     RBP/EBP  Address of Boot Firmware Volume (BFV)
  21 ; @param[out]     DS       Selector allowing flat access to all addresses
  22 ; @param[out]     ES       Selector allowing flat access to all addresses
  23 ; @param[out]     FS       Selector allowing flat access to all addresses
  24 ; @param[out]     GS       Selector allowing flat access to all addresses
  25 ; @param[out]     SS       Selector allowing flat access to all addresses
  26 ;
  27 ; @return         None  This routine jumps to SEC and does not return
  28 ;
  29 Main16:
  30     OneTimeCall EarlyInit16
  31
  32     ;
  33     ; Transition the processor from 16-bit real mode to 32-bit flat mode
  34     ;
  35     OneTimeCall TransitionFromReal16To32BitFlat
  36
  37 BITS    32
  38
  39     ; Clear the WorkArea header. The SEV probe routines will populate the
  40     ; work area when detected.
  41     mov     byte[WORK_AREA_GUEST_TYPE], 0
  42
  43 %ifdef ARCH_X64
  44
  45     jmp SearchBfv
  46
  47 ;
  48 ; Entry point of Main32
  49 ;
  50 Main32:
  51     OneTimeCall InitTdx
  52
  53 SearchBfv:
  54
  55 %endif
  56
  57     ;
  58     ; Search for the Boot Firmware Volume (BFV)
  59     ;
  60     OneTimeCall Flat32SearchForBfvBase
  61
  62     ;
  63     ; EBP - Start of BFV
  64     ;
  65
  66     ;
  67     ; Search for the SEC entry point
  68     ;
  69     OneTimeCall Flat32SearchForSecEntryPoint
  70
  71     ;
  72     ; ESI - SEC Core entry point
  73     ; EBP - Start of BFV
  74     ;
  75
  76 %ifdef ARCH_IA32
  77
  78     ;
  79     ; SEV support can be built and run using the Ia32/X64 split environment.
  80     ; Set the OVMF/SEV work area as appropriate.
  81     ;
  82     OneTimeCall CheckSevFeatures
  83
  84     ;
  85     ; Restore initial EAX value into the EAX register
  86     ;
  87     mov     eax, esp
  88
  89     ;
  90     ; Jump to the 32-bit SEC entry point
  91     ;
  92     jmp     esi
  93
  94 %else
  95
  96     ;
  97     ; Transition the processor from 32-bit flat mode to 64-bit flat mode
  98     ;
  99     OneTimeCall Transition32FlatTo64Flat
 100
 101 BITS    64
 102
 103     ;
 104     ; Some values were calculated in 32-bit mode.  Make sure the upper
 105     ; 32-bits of 64-bit registers are zero for these values.
 106     ;
 107     mov     rax, 0x00000000ffffffff
 108     and     rsi, rax
 109     and     rbp, rax
 110     and     rsp, rax
 111
 112     ;
 113     ; RSI - SEC Core entry point
 114     ; RBP - Start of BFV
 115     ;
 116
 117     ;
 118     ; Restore initial EAX value into the RAX register
 119     ;
 120     mov     rax, rsp
 121
 122     ;
 123     ; Jump to the 64-bit SEC entry point
 124     ;
 125     jmp     rsi
 126
 127 %endif