From c0bf953fe889f5a47fb830cec53a57bfa2380b4d Mon Sep 17 00:00:00 2001 From: Tom Lendacky Date: Fri, 8 Mar 2024 07:31:25 -0800 Subject: 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 Cc: Michael D Kinney Cc: Zhiguang Liu Acked-by: Gerd Hoffmann Signed-off-by: Tom Lendacky --- MdePkg/Include/Library/BaseLib.h | 39 ++++++++++++ MdePkg/Library/BaseLib/BaseLib.inf | 2 + MdePkg/Library/BaseLib/Ia32/VmgExitSvsm.nasm | 39 ++++++++++++ MdePkg/Library/BaseLib/X64/VmgExitSvsm.nasm | 94 ++++++++++++++++++++++++++++ 4 files changed, 174 insertions(+) create mode 100644 MdePkg/Library/BaseLib/Ia32/VmgExitSvsm.nasm create mode 100644 MdePkg/Library/BaseLib/X64/VmgExitSvsm.nasm diff --git a/MdePkg/Include/Library/BaseLib.h b/MdePkg/Include/Library/BaseLib.h index 1fff0fb224..95f805599d 100644 --- a/MdePkg/Include/Library/BaseLib.h +++ b/MdePkg/Include/Library/BaseLib.h @@ -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 diff --git a/MdePkg/Library/BaseLib/BaseLib.inf b/MdePkg/Library/BaseLib/BaseLib.inf index 4dbe94be71..26e66a8d67 100644 --- a/MdePkg/Library/BaseLib/BaseLib.inf +++ b/MdePkg/Library/BaseLib/BaseLib.inf @@ -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] diff --git a/MdePkg/Library/BaseLib/Ia32/VmgExitSvsm.nasm b/MdePkg/Library/BaseLib/Ia32/VmgExitSvsm.nasm new file mode 100644 index 0000000000..14717bd1af --- /dev/null +++ b/MdePkg/Library/BaseLib/Ia32/VmgExitSvsm.nasm @@ -0,0 +1,39 @@ +;------------------------------------------------------------------------------ +; +; Copyright (C) 2024, Advanced Micro Devices, Inc. All rights reserved.
+; 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 + diff --git a/MdePkg/Library/BaseLib/X64/VmgExitSvsm.nasm b/MdePkg/Library/BaseLib/X64/VmgExitSvsm.nasm new file mode 100644 index 0000000000..b8af788906 --- /dev/null +++ b/MdePkg/Library/BaseLib/X64/VmgExitSvsm.nasm @@ -0,0 +1,94 @@ +;------------------------------------------------------------------------------ +; +; Copyright (C) 2024, Advanced Micro Devices, Inc. All rights reserved.
+; 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 + -- cgit v1.2.3