MdePkg/BaseLib: Add a new VMGEXIT instruction invocation for SVSM

BZ: https://bugzilla.tianocore.org/show_bug.cgi?id=4654

The SVSM specification relies on a specific register calling convention to
hold the parameters that are associated with the SVSM request. The SVSM is
invoked by requesting the hypervisor to run the VMPL0 VMSA of the guest
using the GHCB MSR Protocol or a GHCB NAE event.

Create a new version of the VMGEXIT instruction that will adhere to this
calling convention and load the SVSM function arguments into the proper
register before invoking the VMGEXIT instruction. On return, perform the
atomic exchange on the SVSM call pending value as specified in the SVSM
specification.

Cc: Liming Gao <gaoliming@byosoft.com.cn>
Cc: Michael D Kinney <michael.d.kinney@intel.com>
Cc: Zhiguang Liu <zhiguang.liu@intel.com>
Acked-by: Gerd Hoffmann <kraxel@redhat.com>
Signed-off-by: Tom Lendacky <thomas.lendacky@amd.com>
This commit is contained in:
Tom Lendacky 2024-03-08 07:31:25 -08:00 committed by mergify[bot]
parent 8ccbf075f0
commit c0bf953fe8
4 changed files with 174 additions and 0 deletions

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@ -7876,6 +7876,45 @@ AsmVmgExit (
VOID
);
///
/// The structure used to supply and return data to and from the SVSM.
///
typedef struct {
VOID *Caa;
UINT64 RaxIn;
UINT64 RcxIn;
UINT64 RdxIn;
UINT64 R8In;
UINT64 R9In;
UINT64 RaxOut;
UINT64 RcxOut;
UINT64 RdxOut;
UINT64 R8Out;
UINT64 R9Out;
UINT8 *CallPending;
} SVSM_CALL_DATA;
/**
Executes a VMGEXIT instruction (VMMCALL with a REP prefix) with arguments
and return code
Executes a VMGEXIT instruction placing the specified arguments in the
corresponding registers before invocation. Upon return an XCHG is done to
atomically clear and retrieve the SVSM call pending value. The returned RAX
register value becomes the function return code. This function is intended
for use with an SVSM. This function is only available on IA-32 and x64.
@param[in,out] SvsmCallPending Pointer to the location of the SVSM call data
@return Value of the RAX register on return
**/
UINT32
EFIAPI
AsmVmgExitSvsm (
IN OUT SVSM_CALL_DATA *SvsmCallData
);
/**
Patch the immediate operand of an IA32 or X64 instruction such that the byte,
word, dword or qword operand is encoded at the end of the instruction's

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@ -187,6 +187,7 @@
Ia32/XGetBv.nasm
Ia32/XSetBv.nasm
Ia32/VmgExit.nasm
Ia32/VmgExitSvsm.nasm
Ia32/DivS64x64Remainder.c
Ia32/InternalSwitchStack.c | MSFT
@ -328,6 +329,7 @@
X64/XGetBv.nasm
X64/XSetBv.nasm
X64/VmgExit.nasm
X64/VmgExitSvsm.nasm
ChkStkGcc.c | GCC
[Sources.EBC]

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@ -0,0 +1,39 @@
;------------------------------------------------------------------------------
;
; Copyright (C) 2024, Advanced Micro Devices, Inc. All rights reserved.<BR>
; SPDX-License-Identifier: BSD-2-Clause-Patent
;
; Module Name:
;
; VmgExitSvsm.Asm
;
; Abstract:
;
; AsmVmgExitSvsm function
;
; Notes:
;
;------------------------------------------------------------------------------
DEFAULT REL
SECTION .text
;------------------------------------------------------------------------------
; UINT32
; EFIAPI
; AsmVmgExitSvsm (
; SVSM_CALL_DATA *SvsmCallData
; );
;------------------------------------------------------------------------------
global ASM_PFX(AsmVmgExitSvsm)
ASM_PFX(AsmVmgExitSvsm):
;
; NASM doesn't support the vmmcall instruction in 32-bit mode and NASM versions
; before 2.12 cannot translate the 64-bit "rep vmmcall" instruction into elf32
; format. Given that VMGEXIT does not make sense on IA32, provide a stub
; implementation that is identical to CpuBreakpoint(). In practice,
; AsmVmgExitSvsm() should never be called on IA32.
;
int 3
ret

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@ -0,0 +1,94 @@
;------------------------------------------------------------------------------
;
; Copyright (C) 2024, Advanced Micro Devices, Inc. All rights reserved.<BR>
; SPDX-License-Identifier: BSD-2-Clause-Patent
;
; Module Name:
;
; VmgExitSvsm.Asm
;
; Abstract:
;
; AsmVmgExitSvsm function
;
; Notes:
;
;------------------------------------------------------------------------------
DEFAULT REL
SECTION .text
;------------------------------------------------------------------------------
; typedef struct {
; VOID *Caa;
; UINT64 RaxIn;
; UINT64 RcxIn;
; UINT64 RdxIn;
; UINT64 R8In;
; UINT64 R9In;
; UINT64 RaxOut;
; UINT64 RcxOut;
; UINT64 RdxOut;
; UINT64 R8Out;
; UINT64 R9Out;
; UINT8 *CallPending;
; } SVSM_CALL_DATA;
;
; UINT32
; EFIAPI
; AsmVmgExitSvsm (
; SVSM_CALL_DATA *SvsmCallData
; );
;------------------------------------------------------------------------------
global ASM_PFX(AsmVmgExitSvsm)
ASM_PFX(AsmVmgExitSvsm):
push r10
push r11
push r12
;
; Calling convention has SvsmCallData in RCX. Move RCX to R12 in order to
; properly populate the SVSM register state.
;
mov r12, rcx
mov rax, [r12 + 8]
mov rcx, [r12 + 16]
mov rdx, [r12 + 24]
mov r8, [r12 + 32]
mov r9, [r12 + 40]
;
; Set CA call pending
;
mov r10, [r12]
mov byte [r10], 1
rep vmmcall
mov [r12 + 48], rax
mov [r12 + 56], rcx
mov [r12 + 64], rdx
mov [r12 + 72], r8
mov [r12 + 80], r9
;
; Perform the atomic exchange and return the CA call pending value.
; The call pending value is a one-byte field at offset 0 into the CA,
; which is currently the value in R10.
;
mov r11, [r12 + 88] ; Get CallPending address
mov cl, byte [r11]
xchg byte [r10], cl
mov byte [r11], cl ; Return the exchanged value
pop r12
pop r11
pop r10
;
; RAX has the value to be returned from the SVSM
;
ret