Re: [edk2-devel] [PATCH v10 06/46] MdePkg/BaseLib: Add support for the XGETBV instruction

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

On 7/15/20 10:55 AM, Laszlo Ersek wrote:
> Hi Tom,
> 
> On 07/14/20 16:27, Lendacky, Thomas wrote:
>> 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%7C00c7f97271bf4efd050608d828d79a13%7C3dd8961fe4884e608e11a82d994e183d%7C0%7C0%7C637304253757199823&amp;sdata=hQ%2BP%2F5DintrtGi66sfqRI%2B9h4V1rTB1YlYdY1VX6sLM%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
> 
> This patch no longer applies, it conflicts with commit d3c9e40abcc8
> ("MdePkg/BaseLib: Break out IA32/X64 GCC inline privileged functions",
> 2020-07-15).

Ok, that looks like it landed just after I sent my patches.

> 
> The conflict persists if I successfully apply the series on c7195b9ec3c5
> -- just preceding Mike's series "[Patch v3 00/16] UnitTestFrameworkPkg:
> Enhancements and bug fixes" --, and then try to rebase to current master
> (e77966b341b9) from there.
> 
> Can you please investigate?

Yup, I'll take a look.

Thanks,
Tom

> 
> Thanks,
> Laszlo
> 
>>
>> 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
>> +
>>
>