OvmfPkg/ResetVector/Ia16/ResetVectorVtf0.asm

   1 ;------------------------------------------------------------------------------
   2 ; @file
   3 ; First code executed by processor after resetting.
   4 ; Derived from UefiCpuPkg/ResetVector/Vtf0/Ia16/ResetVectorVtf0.asm
   5 ;
   6 ; Copyright (c) 2008 - 2014, Intel Corporation. All rights reserved.<BR>
   7 ; SPDX-License-Identifier: BSD-2-Clause-Patent
   8 ;
   9 ;------------------------------------------------------------------------------
  10
  11 BITS    16
  12
  13 ALIGN   16
  14
  15 ;
  16 ; Pad the image size to 4k when page tables are in VTF0
  17 ;
  18 ; If the VTF0 image has page tables built in, then we need to make
  19 ; sure the end of VTF0 is 4k above where the page tables end.
  20 ;
  21 ; This is required so the page tables will be 4k aligned when VTF0 is
  22 ; located just below 0x100000000 (4GB) in the firmware device.
  23 ;
  24 %ifdef ALIGN_TOP_TO_4K_FOR_PAGING
  25     TIMES (0x1000 - ($ - EndOfPageTables) - 0x20) DB 0
  26 %endif
  27
  28 ;
  29 ; Padding to ensure first guid starts at 0xffffffd0
  30 ;
  31 TIMES (15 - ((guidedStructureEnd - guidedStructureStart + 15) % 16)) DB 0
  32
  33 ; GUIDed structure.  To traverse this you should first verify the
  34 ; presence of the table footer guid
  35 ; (96b582de-1fb2-45f7-baea-a366c55a082d) at 0xffffffd0.  If that
  36 ; is found, the two bytes at 0xffffffce are the entire table length.
  37 ;
  38 ; The table is composed of structures with the form:
  39 ;
  40 ; Data (arbitrary bytes identified by guid)
  41 ; length from start of data to end of guid (2 bytes)
  42 ; guid (16 bytes)
  43 ;
  44 ; so work back from the footer using the length to traverse until you
  45 ; either find the guid you're looking for or run off the beginning of
  46 ; the table.
  47 ;
  48 guidedStructureStart:
  49
  50 ;
  51 ; SEV-ES Processor Reset support
  52 ;
  53 ; sevEsResetBlock:
  54 ;   For the initial boot of an AP under SEV-ES, the "reset" RIP must be
  55 ;   programmed to the RAM area defined by SEV_ES_AP_RESET_IP. The data
  56 ;   format is:
  57 ;
  58 ;   IP value [0:15]
  59 ;   CS segment base [31:16]
  60 ;
  61 ;   GUID (SEV-ES reset block): 00f771de-1a7e-4fcb-890e-68c77e2fb44e
  62 ;
  63 ;   A hypervisor reads the CS segement base and IP value. The CS segment base
  64 ;   value represents the high order 16-bits of the CS segment base, so the
  65 ;   hypervisor must left shift the value of the CS segement base by 16 bits to
  66 ;   form the full CS segment base for the CS segment register. It would then
  67 ;   program the EIP register with the IP value as read.
  68 ;
  69
  70 sevEsResetBlockStart:
  71     DD      SEV_ES_AP_RESET_IP
  72     DW      sevEsResetBlockEnd - sevEsResetBlockStart
  73     DB      0xDE, 0x71, 0xF7, 0x00, 0x7E, 0x1A, 0xCB, 0x4F
  74     DB      0x89, 0x0E, 0x68, 0xC7, 0x7E, 0x2F, 0xB4, 0x4E
  75 sevEsResetBlockEnd:
  76
  77 ;
  78 ; Table footer:
  79 ;
  80 ; length of whole table (16 bit word)
  81 ; GUID (table footer): 96b582de-1fb2-45f7-baea-a366c55a082d
  82 ;
  83     DW      guidedStructureEnd - guidedStructureStart
  84     DB      0xDE, 0x82, 0xB5, 0x96, 0xB2, 0x1F, 0xF7, 0x45
  85     DB      0xBA, 0xEA, 0xA3, 0x66, 0xC5, 0x5A, 0x08, 0x2D
  86
  87 guidedStructureEnd:
  88
  89 ALIGN   16
  90
  91 applicationProcessorEntryPoint:
  92 ;
  93 ; Application Processors entry point
  94 ;
  95 ; GenFv generates code aligned on a 4k boundary which will jump to this
  96 ; location.  (0xffffffe0)  This allows the Local APIC Startup IPI to be
  97 ; used to wake up the application processors.
  98 ;
  99     jmp     EarlyApInitReal16
 100
 101 ALIGN   8
 102
 103     DD      0
 104
 105 ;
 106 ; The VTF signature
 107 ;
 108 ; VTF-0 means that the VTF (Volume Top File) code does not require
 109 ; any fixups.
 110 ;
 111 vtfSignature:
 112     DB      'V', 'T', 'F', 0
 113
 114 ALIGN   16
 115
 116 resetVector:
 117 ;
 118 ; Reset Vector
 119 ;
 120 ; This is where the processor will begin execution
 121 ;
 122     nop
 123     nop
 124     jmp     EarlyBspInitReal16
 125
 126 ALIGN   16
 127
 128 fourGigabytes:
 129