From 9b3ca509abd4e45439bbdfe2c2fa8780c950320a Mon Sep 17 00:00:00 2001 From: Tom Lendacky Date: Wed, 12 Aug 2020 15:21:35 -0500 Subject: [PATCH] MdePkg/BaseLib: Add support for the XGETBV instruction BZ: https://bugzilla.tianocore.org/show_bug.cgi?id=2198 Under SEV-ES, a CPUID instruction requires the current value of the XCR0 register. In order to retrieve that value, the XGETBV instruction needs to be executed. Provide the necessary support to execute the XGETBV instruction. Cc: Michael D Kinney Cc: Liming Gao Reviewed-by: Liming Gao Signed-off-by: Tom Lendacky Regression-tested-by: Laszlo Ersek --- MdePkg/Include/Library/BaseLib.h | 17 +++++++++++++ MdePkg/Library/BaseLib/BaseLib.inf | 2 ++ MdePkg/Library/BaseLib/Ia32/XGetBv.nasm | 31 ++++++++++++++++++++++ MdePkg/Library/BaseLib/X64/XGetBv.nasm | 34 +++++++++++++++++++++++++ 4 files changed, 84 insertions(+) create mode 100644 MdePkg/Library/BaseLib/Ia32/XGetBv.nasm create mode 100644 MdePkg/Library/BaseLib/X64/XGetBv.nasm diff --git a/MdePkg/Include/Library/BaseLib.h b/MdePkg/Include/Library/BaseLib.h index 8e7b87cbda..7edf0051a0 100644 --- a/MdePkg/Include/Library/BaseLib.h +++ b/MdePkg/Include/Library/BaseLib.h @@ -7831,6 +7831,23 @@ AsmLfence ( VOID ); +/** + Executes a XGETBV instruction + + Executes a XGETBV instruction. This function is only available on IA-32 and + x64. + + @param[in] Index Extended control register index + + @return The current value of the extended control register +**/ +UINT64 +EFIAPI +AsmXGetBv ( + IN UINT32 Index + ); + + /** 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 c740a819ca..3b93b5db8d 100644 --- a/MdePkg/Library/BaseLib/BaseLib.inf +++ b/MdePkg/Library/BaseLib/BaseLib.inf @@ -183,6 +183,7 @@ Ia32/EnableCache.nasm| GCC Ia32/DisableCache.nasm| GCC Ia32/RdRand.nasm + Ia32/XGetBv.nasm Ia32/DivS64x64Remainder.c Ia32/InternalSwitchStack.c | MSFT @@ -315,6 +316,7 @@ X64/EnableDisableInterrupts.nasm X64/DisablePaging64.nasm X64/RdRand.nasm + X64/XGetBv.nasm ChkStkGcc.c | GCC [Sources.EBC] diff --git a/MdePkg/Library/BaseLib/Ia32/XGetBv.nasm b/MdePkg/Library/BaseLib/Ia32/XGetBv.nasm new file mode 100644 index 0000000000..9f7b03bbff --- /dev/null +++ b/MdePkg/Library/BaseLib/Ia32/XGetBv.nasm @@ -0,0 +1,31 @@ +;------------------------------------------------------------------------------ +; +; Copyright (C) 2020, Advanced Micro Devices, Inc. All rights reserved.
+; SPDX-License-Identifier: BSD-2-Clause-Patent +; +; Module Name: +; +; XGetBv.Asm +; +; Abstract: +; +; AsmXgetBv function +; +; Notes: +; +;------------------------------------------------------------------------------ + + SECTION .text + +;------------------------------------------------------------------------------ +; UINT64 +; EFIAPI +; AsmXGetBv ( +; IN UINT32 Index +; ); +;------------------------------------------------------------------------------ +global ASM_PFX(AsmXGetBv) +ASM_PFX(AsmXGetBv): + mov ecx, [esp + 4] + xgetbv + ret diff --git a/MdePkg/Library/BaseLib/X64/XGetBv.nasm b/MdePkg/Library/BaseLib/X64/XGetBv.nasm new file mode 100644 index 0000000000..09f3be8ae0 --- /dev/null +++ b/MdePkg/Library/BaseLib/X64/XGetBv.nasm @@ -0,0 +1,34 @@ +;------------------------------------------------------------------------------ +; +; Copyright (C) 2020, Advanced Micro Devices, Inc. All rights reserved.
+; SPDX-License-Identifier: BSD-2-Clause-Patent +; +; Module Name: +; +; XGetBv.Asm +; +; Abstract: +; +; AsmXgetBv function +; +; Notes: +; +;------------------------------------------------------------------------------ + + DEFAULT REL + SECTION .text + +;------------------------------------------------------------------------------ +; UINT64 +; EFIAPI +; AsmXGetBv ( +; IN UINT32 Index +; ); +;------------------------------------------------------------------------------ +global ASM_PFX(AsmXGetBv) +ASM_PFX(AsmXGetBv): + xgetbv + shl rdx, 32 + or rax, rdx + ret +