MdePkg: Introduce basic Tdx functions in BaseLib

[mirror_edk2.git] / MdePkg / Library / BaseLib / X64 / TdVmcall.nasm

;------------------------------------------------------------------------------\r
;*\r
;* Copyright (c) 2020 - 2021, Intel Corporation. All rights reserved.<BR>\r
;* SPDX-License-Identifier: BSD-2-Clause-Patent\r
;*\r
;*\r
;------------------------------------------------------------------------------\r
\r
DEFAULT REL\r
SECTION .text\r
\r
%define TDVMCALL_EXPOSE_REGS_MASK       0xffec\r
%define TDVMCALL                        0x0\r
\r
%macro tdcall 0\r
    db 0x66,0x0f,0x01,0xcc\r
%endmacro\r
\r
%macro tdcall_push_regs 0\r
    push rbp\r
    mov  rbp, rsp\r
    push r15\r
    push r14\r
    push r13\r
    push r12\r
    push rbx\r
    push rsi\r
    push rdi\r
%endmacro\r
\r
%macro tdcall_pop_regs 0\r
    pop rdi\r
    pop rsi\r
    pop rbx\r
    pop r12\r
    pop r13\r
    pop r14\r
    pop r15\r
    pop rbp\r
%endmacro\r
\r
%define number_of_regs_pushed 8\r
%define number_of_parameters  4\r
\r
;\r
; Keep these in sync for push_regs/pop_regs, code below\r
; uses them to find 5th or greater parameters\r
;\r
%define first_variable_on_stack_offset \\r
  ((number_of_regs_pushed * 8) + (number_of_parameters * 8) + 8)\r
%define second_variable_on_stack_offset \\r
  ((first_variable_on_stack_offset) + 8)\r
\r
%macro tdcall_regs_preamble 2\r
    mov rax, %1\r
\r
    xor rcx, rcx\r
    mov ecx, %2\r
\r
    ; R10 = 0 (standard TDVMCALL)\r
\r
    xor r10d, r10d\r
\r
    ; Zero out unused (for standard TDVMCALL) registers to avoid leaking\r
    ; secrets to the VMM.\r
\r
    xor ebx, ebx\r
    xor esi, esi\r
    xor edi, edi\r
\r
    xor edx, edx\r
    xor ebp, ebp\r
    xor r8d, r8d\r
    xor r9d, r9d\r
%endmacro\r
\r
%macro tdcall_regs_postamble 0\r
    xor ebx, ebx\r
    xor esi, esi\r
    xor edi, edi\r
\r
    xor ecx, ecx\r
    xor edx, edx\r
    xor r8d,  r8d\r
    xor r9d,  r9d\r
    xor r10d, r10d\r
    xor r11d, r11d\r
%endmacro\r
\r
;------------------------------------------------------------------------------\r
; 0   => RAX = TDCALL leaf\r
; M   => RCX = TDVMCALL register behavior\r
; 1   => R10 = standard vs. vendor\r
; RDI => R11 = TDVMCALL function / nr\r
; RSI =  R12 = p1\r
; RDX => R13 = p2\r
; RCX => R14 = p3\r
; R8  => R15 = p4\r
\r
;  UINT64\r
;  EFIAPI\r
;  TdVmCall (\r
;    UINT64  Leaf,  // Rcx\r
;    UINT64  P1,  // Rdx\r
;    UINT64  P2,  // R8\r
;    UINT64  P3,  // R9\r
;    UINT64  P4,  // rsp + 0x28\r
;    UINT64  *Val // rsp + 0x30\r
;    )\r
global ASM_PFX(TdVmCall)\r
ASM_PFX(TdVmCall):\r
       tdcall_push_regs\r
\r
       mov r11, rcx\r
       mov r12, rdx\r
       mov r13, r8\r
       mov r14, r9\r
       mov r15, [rsp + first_variable_on_stack_offset ]\r
\r
       tdcall_regs_preamble TDVMCALL, TDVMCALL_EXPOSE_REGS_MASK\r
\r
       tdcall\r
\r
       ; ignore return dataif TDCALL reports failure.\r
       test rax, rax\r
       jnz .no_return_data\r
\r
       ; Propagate TDVMCALL success/failure to return value.\r
       mov rax, r10\r
\r
       ; Retrieve the Val pointer.\r
       mov r9, [rsp + second_variable_on_stack_offset ]\r
       test r9, r9\r
       jz .no_return_data\r
\r
       ; On success, propagate TDVMCALL output value to output param\r
       test rax, rax\r
       jnz .no_return_data\r
       mov [r9], r11\r
.no_return_data:\r
       tdcall_regs_postamble\r
\r
       tdcall_pop_regs\r
\r
       ret\r