Re: [edk2-devel] [PATCH v11 06/46] MdePkg/BaseLib: Add support for the XGETBV instruction

["Lendacky, Thomas" <thomas.lendacky@amd.com>]

On 7/22/20 8:16 PM, Gao, Liming wrote:
> Laszlo:
> 
> -----Original Message-----
> From: Laszlo Ersek <lersek@redhat.com>
> Sent: 2020年7月23日 4:28
> To: Liu, Zhiguang <zhiguang.liu@intel.com>; devel@edk2.groups.io; thomas.lendacky@amd.com
> 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>; Gao, Liming <liming.gao@intel.com>; Kinney, Michael D <michael.d.kinney@intel.com>; Ni, Ray <ray.ni@intel.com>
> Subject: Re: [edk2-devel] [PATCH v11 06/46] MdePkg/BaseLib: Add support for the XGETBV instruction
> 
> On 07/22/20 02:55, Liu, Zhiguang wrote:
>> Hi Tom,
>> Nasm is a cross-OS assembly code and can be used in Linux.
>> So I think we don't need implement the same function in GccInline.c, we can just use the nasm file in Linux.
> 
> I could agree, but this would create an inconsistency with the existent functions (where both gcc inline assembly and NASM exists).
> [Liming] Yes. This is clean up task to make the existing ones be consistent. The new one X86 assembly function (IA32 and X64) should follow nasm style.

I was following what I thought was convention. If you'd like, I can remove 
the "| MSFT" from the .nasm entries in the .inf file and delete (not add) 
the functions in the GccInline.c file.

Let me know what you would like done.

Thanks,
Tom

> 
> For example, consider AsmReadEflags():
> - inline assembly for MSFT IA32 ("Ia32/ReadEflags.c")
> - NASM for MSFT X64 ("X64/ReadEflags.nasm")
> - inline assembly for GCC IA32 ("Ia32/GccInline.c")
> - inline assembly for GCC X64 ("X64/GccInline.c")
> 
> The source file "X64/ReadEflags.nasm" could be used with GCC X64 too, not just with MSFT X64.
> 
> So why do we have the gcc inline implementation for AsmReadEflags() in "X64/GccInline.c", in the first place?
> [Liming] This is the history. Nasm migration replaces .S and .asm. But, the remaining one in C source is not replaced.
> 
> Thanks
> Liming
> The pattern that a contributor is supposed to follow is not clear to me.
> 
> Thanks,
> Laszlo
> 
>>> -----Original Message-----
>>> From: devel@edk2.groups.io <devel@edk2.groups.io> On Behalf Of
>>> Lendacky, Thomas
>>> Sent: Wednesday, July 22, 2020 5:19 AM
>>> 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 v11 06/46] MdePkg/BaseLib: Add support
>>> for the XGETBV instruction
>>>
>>> From: Tom Lendacky <thomas.lendacky@amd.com>
>>>
>>> BZ: https://nam11.safelinks.protection.outlook.com/?url=https%3A%2F%2Fbugzilla.tianocore.org%2Fshow_bug.cgi%3Fid%3D2198&amp;data=02%7C01%7Cthomas.lendacky%40amd.com%7C7cbbd5ae7ded4963ad1e08d82ea5ff27%7C3dd8961fe4884e608e11a82d994e183d%7C0%7C0%7C637310637778599307&amp;sdata=GPutAlSGucRGFnjU4rxWXfeiy4fJhZHHZe5YJ8hhPSQ%3D&amp;reserved=0
>>>
>>> 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(+)
>>>   create mode 100644 MdePkg/Library/BaseLib/Ia32/XGetBv.nasm
>>>   create mode 100644 MdePkg/Library/BaseLib/X64/XGetBv.nasm
>>>
>>> diff --git a/MdePkg/Library/BaseLib/BaseLib.inf
>>> b/MdePkg/Library/BaseLib/BaseLib.inf
>>> index c740a819cacf..e26c0d8cb0ac 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
>>> @@ -288,6 +289,7 @@ [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 6ed938187a08..c2565ab9a183 100644
>>> --- a/MdePkg/Library/BaseLib/Ia32/GccInline.c
>>> +++ b/MdePkg/Library/BaseLib/Ia32/GccInline.c
>>> @@ -584,3 +584,31 @@ AsmReadTsc (
>>>
>>>     return Data;
>>>   }
>>> +
>>> +
>>> +/**
>>> +  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 40a208f1985f..65f864e35922 100644
>>> --- a/MdePkg/Library/BaseLib/X64/GccInline.c
>>> +++ b/MdePkg/Library/BaseLib/X64/GccInline.c
>>> @@ -560,3 +560,33 @@ AsmReadTsc (
>>>
>>>     return (((UINT64)HiData) << 32) | LowData;  }
>>> +
>>> +
>>> +/**
>>> +  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
>>>
>>>
>>> 
>>
>