Re: [edk2-devel] [PATCH v9 06/46] MdePkg/BaseLib: Add support for the XGETBV instruction

["Zhiguang Liu" <zhiguang.liu@intel.com>]

Hi Tom,
I notice that you create a nasm file, which is good for cross-OS.
Why do you need to create a c file for the same function for GCC compiler when we can use nasm file in Linux?
Thanks
Zhiguang


> -----Original Message-----
> From: devel@edk2.groups.io <devel@edk2.groups.io> On Behalf Of
> Lendacky, Thomas
> Sent: Friday, June 5, 2020 9:27 PM
> To: devel@edk2.groups.io
> Cc: Brijesh Singh <brijesh.singh@amd.com>; Ard Biesheuvel
> <ard.biesheuvel@arm.com>; Dong, Eric <eric.dong@intel.com>; Justen,
> Jordan L <jordan.l.justen@intel.com>; Laszlo Ersek <lersek@redhat.com>;
> Gao, Liming <liming.gao@intel.com>; Kinney, Michael D
> <michael.d.kinney@intel.com>; Ni, Ray <ray.ni@intel.com>
> Subject: [edk2-devel] [PATCH v9 06/46] 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 <michael.d.kinney@intel.com>
> Cc: Liming Gao <liming.gao@intel.com>
> Signed-off-by: Tom Lendacky <thomas.lendacky@amd.com>
> ---
>  MdePkg/Library/BaseLib/BaseLib.inf      |  2 ++
>  MdePkg/Include/Library/BaseLib.h        | 17 ++++++++++
>  MdePkg/Library/BaseLib/Ia32/GccInline.c | 28 ++++++++++++++++
>  MdePkg/Library/BaseLib/X64/GccInline.c  | 30 +++++++++++++++++
>  MdePkg/Library/BaseLib/Ia32/XGetBv.nasm | 31 ++++++++++++++++++
>  MdePkg/Library/BaseLib/X64/XGetBv.nasm  | 34 ++++++++++++++++++++
>  6 files changed, 142 insertions(+)
> 
> diff --git a/MdePkg/Library/BaseLib/BaseLib.inf
> b/MdePkg/Library/BaseLib/BaseLib.inf
> index a57ae2da31f3..da6bc22a3e2b 100644
> --- a/MdePkg/Library/BaseLib/BaseLib.inf
> +++ b/MdePkg/Library/BaseLib/BaseLib.inf
> @@ -153,6 +153,7 @@ [Sources.Ia32]
>    Ia32/ARShiftU64.c | MSFT
> 
> 
>    Ia32/EnableCache.c | MSFT
> 
> 
>    Ia32/DisableCache.c | MSFT
> 
> 
> +  Ia32/XGetBv.nasm | MSFT
> 
> 
> 
> 
> 
> 
> 
> 
>    Ia32/GccInline.c | GCC
> 
> 
> @@ -287,6 +288,7 @@ [Sources.X64]
>    X64/ReadCr2.nasm| MSFT
> 
> 
>    X64/ReadCr0.nasm| MSFT
> 
> 
>    X64/ReadEflags.nasm| MSFT
> 
> 
> +  X64/XGetBv.nasm | MSFT
> 
> 
> 
> 
> 
> 
> 
> 
>    X64/Non-existing.c
> 
> 
> diff --git a/MdePkg/Include/Library/BaseLib.h
> b/MdePkg/Include/Library/BaseLib.h
> index 8e7b87cbda4e..7edf0051a0a0 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/Ia32/GccInline.c
> b/MdePkg/Library/BaseLib/Ia32/GccInline.c
> index 5287200f8754..c962bcfa4617 100644
> --- a/MdePkg/Library/BaseLib/Ia32/GccInline.c
> +++ b/MdePkg/Library/BaseLib/Ia32/GccInline.c
> @@ -1763,3 +1763,31 @@ AsmFlushCacheLine (
>  }
> 
> 
> 
> 
> 
> 
> 
> 
> +/**
> 
> 
> +  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
> 
> 
> +  )
> 
> 
> +{
> 
> 
> +  UINT64 Data;
> 
> 
> +
> 
> 
> +  __asm__ __volatile__ (
> 
> 
> +    "xgetbv"
> 
> 
> +    : "=A" (Data)
> 
> 
> +    : "c"  (Index)
> 
> 
> +    );
> 
> 
> +
> 
> 
> +  return Data;
> 
> 
> +}
> 
> 
> +
> 
> 
> +
> 
> 
> diff --git a/MdePkg/Library/BaseLib/X64/GccInline.c
> b/MdePkg/Library/BaseLib/X64/GccInline.c
> index 154ce1f57e92..915555198f9f 100644
> --- a/MdePkg/Library/BaseLib/X64/GccInline.c
> +++ b/MdePkg/Library/BaseLib/X64/GccInline.c
> @@ -1798,3 +1798,33 @@ AsmFlushCacheLine (
>  }
> 
> 
> 
> 
> 
> 
> 
> 
> +/**
> 
> 
> +  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
> 
> 
> +  )
> 
> 
> +{
> 
> 
> +  UINT32 LowData;
> 
> 
> +  UINT32 HighData;
> 
> 
> +
> 
> 
> +  __asm__ __volatile__ (
> 
> 
> +    "xgetbv"
> 
> 
> +    : "=a" (LowData),
> 
> 
> +      "=d" (HighData)
> 
> 
> +    : "c"  (Index)
> 
> 
> +    );
> 
> 
> +
> 
> 
> +  return (((UINT64)HighData) << 32) | LowData;
> 
> 
> +}
> 
> 
> +
> 
> 
> +
> 
> 
> diff --git a/MdePkg/Library/BaseLib/Ia32/XGetBv.nasm
> b/MdePkg/Library/BaseLib/Ia32/XGetBv.nasm
> new file mode 100644
> index 000000000000..9f7b03bbff35
> --- /dev/null
> +++ b/MdePkg/Library/BaseLib/Ia32/XGetBv.nasm
> @@ -0,0 +1,31 @@
> +;------------------------------------------------------------------------------
> 
> 
> +;
> 
> 
> +; Copyright (C) 2020, Advanced Micro Devices, Inc. All rights reserved.<BR>
> 
> 
> +; 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 000000000000..09f3be8ae0a8
> --- /dev/null
> +++ b/MdePkg/Library/BaseLib/X64/XGetBv.nasm
> @@ -0,0 +1,34 @@
> +;------------------------------------------------------------------------------
> 
> 
> +;
> 
> 
> +; Copyright (C) 2020, Advanced Micro Devices, Inc. All rights reserved.<BR>
> 
> 
> +; 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
> 
> 
> +
> 
> 
> --
> 2.27.0
> 
> 
>