Re: 回复: [edk2-devel] [RFC PATCH 09/19] MdePkg: Add AsmPvalidate() support

["Brijesh Singh" <brijesh.singh@amd.com>]

On 3/24/21 9:49 PM, gaoliming wrote:
> Is this API X64 only? Or IA32 and X64 both?


Theoretically the instruction is available on both IA32 and X64 but its
used only in X64. AMD SEV, SEV-ES and SEV-SNP support is available for
X64 arch only. I was not sure if the EDK2 community is okay with the
dead-code. Do you think it still makes sense to add the IA32 API for it ?


>
> Thanks
> Liming
>> -----邮件原件-----
>> 发件人: devel@edk2.groups.io <devel@edk2.groups.io> 代表 Brijesh Singh
>> 发送时间: 2021年3月24日 23:32
>> 收件人: devel@edk2.groups.io
>> 抄送: Brijesh Singh <brijesh.singh@amd.com>; James Bottomley
>> <jejb@linux.ibm.com>; Min Xu <min.m.xu@intel.com>; Jiewen Yao
>> <jiewen.yao@intel.com>; Tom Lendacky <thomas.lendacky@amd.com>;
>> Jordan Justen <jordan.l.justen@intel.com>; Ard Biesheuvel
>> <ardb+tianocore@kernel.org>; Laszlo Ersek <lersek@redhat.com>
>> 主题: [edk2-devel] [RFC PATCH 09/19] MdePkg: Add AsmPvalidate() support
>>
>> BZ: https://nam11.safelinks.protection.outlook.com/?url=https%3A%2F%2Fbugzilla.tianocore.org%2Fshow_bug.cgi%3Fid%3D3275&amp;data=04%7C01%7Cbrijesh.singh%40amd.com%7C125d11ea64cf4f4ecd2108d8ef38a8e7%7C3dd8961fe4884e608e11a82d994e183d%7C0%7C0%7C637522373939810930%7CUnknown%7CTWFpbGZsb3d8eyJWIjoiMC4wLjAwMDAiLCJQIjoiV2luMzIiLCJBTiI6Ik1haWwiLCJXVCI6Mn0%3D%7C1000&amp;sdata=f3fM%2Fnw3X1lHhf7SPKTxDOLo0GcnU465yvyf0IIyD80%3D&amp;reserved=0
>>
>> The PVALIDATE instruction validates or rescinds validation of a guest
>> page RMP entry. Upon completion, a return code is stored in EAX, rFLAGS
>> bits OF, ZF, AF, PF and SF are set based on this return code. If the
>> instruction completed succesfully, the rFLAGS bit CF indicates if the
>> contents of the RMP entry were changed or not.
>>
>> For more information about the instruction see AMD APM volume 3.
>>
>> Cc: James Bottomley <jejb@linux.ibm.com>
>> Cc: Min Xu <min.m.xu@intel.com>
>> Cc: Jiewen Yao <jiewen.yao@intel.com>
>> Cc: Tom Lendacky <thomas.lendacky@amd.com>
>> Cc: Jordan Justen <jordan.l.justen@intel.com>
>> Cc: Ard Biesheuvel <ardb+tianocore@kernel.org>
>> Cc: Laszlo Ersek <lersek@redhat.com>
>> Signed-off-by: Brijesh Singh <brijesh.singh@amd.com>
>> ---
>>  MdePkg/Include/Library/BaseLib.h          | 37 +++++++++++++++++
>>  MdePkg/Library/BaseLib/BaseLib.inf        |  1 +
>>  MdePkg/Library/BaseLib/X64/Pvalidate.nasm | 43 ++++++++++++++++++++
>>  3 files changed, 81 insertions(+)
>>
>> diff --git a/MdePkg/Include/Library/BaseLib.h
>> b/MdePkg/Include/Library/BaseLib.h
>> index 1171a0ffb5..fee27e9a1b 100644
>> --- a/MdePkg/Include/Library/BaseLib.h
>> +++ b/MdePkg/Include/Library/BaseLib.h
>> @@ -7495,5 +7495,42 @@ PatchInstructionX86 (
>>    IN  UINTN                    ValueSize
>>    );
>>
>> +/**
>> + Execute a PVALIDATE instruction to validate or rescnids validation of a
> guest
>> + page's RMP entry.
>> +
>> + Upon completion, in addition to the return value the instruction also
>> updates
>> + the eFlags. A caller must check both the return code as well as eFlags
> to
>> + determine if the RMP entry has been updated.
>> +
>> + The function is available on x64.
>> +
>> + @param[in]    Address        The guest virtual address to validate.
>> + @param[in]    PageSize       The page size to use.
>> + @param[i]     Validate       Validate or rescinds.
>> + @param[out]   Eflags         The value of Eflags after PVALIDATE
>> completion.
>> +
>> + @retval       PvalidateRetValue  The return value from the PVALIDATE
>> instruction.
>> +**/
>> +typedef enum {
>> +  PVALIDATE_PAGE_SIZE_4K = 0,
>> +  PVALIDATE_PAGE_SIZE_2M,
>> +} PvalidatePageSize;
>> +
>> +typedef enum {
>> +  PVALIDATE_RET_SUCCESS = 0,
>> +  PVALIDATE_RET_FAIL_INPUT = 1,
>> +  PVALIDATE_RET_FAIL_SIZEMISMATCH = 6,
>> +} PvalidateRetValue;
>> +
>> +PvalidateRetValue
>> +EFIAPI
>> +AsmPvalidate (
>> +  IN   PvalidatePageSize       PageSize,
>> +  IN   BOOLEAN                 Validate,
>> +  IN   UINTN                   Address,
>> +  OUT  IA32_EFLAGS32           *Eflags
>> +  );
>> +
>>  #endif // defined (MDE_CPU_IA32) || defined (MDE_CPU_X64)
>>  #endif // !defined (__BASE_LIB__)
>> diff --git a/MdePkg/Library/BaseLib/BaseLib.inf
>> b/MdePkg/Library/BaseLib/BaseLib.inf
>> index 3b85c56c3c..01aa5cc7a4 100644
>> --- a/MdePkg/Library/BaseLib/BaseLib.inf
>> +++ b/MdePkg/Library/BaseLib/BaseLib.inf
>> @@ -319,6 +319,7 @@
>>    X64/RdRand.nasm
>>    X64/XGetBv.nasm
>>    X64/VmgExit.nasm
>> +  X64/Pvalidate.nasm
>>    ChkStkGcc.c  | GCC
>>
>>  [Sources.EBC]
>> diff --git a/MdePkg/Library/BaseLib/X64/Pvalidate.nasm
>> b/MdePkg/Library/BaseLib/X64/Pvalidate.nasm
>> new file mode 100644
>> index 0000000000..f2aba114ac
>> --- /dev/null
>> +++ b/MdePkg/Library/BaseLib/X64/Pvalidate.nasm
>> @@ -0,0 +1,43 @@
>>
> +;--------------------------------------------------------------------------
> ---
>> +;
>> +; Copyright (c) 2020-2021, AMD. All rights reserved.<BR>
>> +; SPDX-License-Identifier: BSD-2-Clause-Patent
>> +;
>> +; Module Name:
>> +;
>> +;   Pvalidate.Asm
>> +;
>> +; Abstract:
>> +;
>> +;   AsmPvalidate function
>> +;
>> +; Notes:
>> +;
>>
> +;--------------------------------------------------------------------------
> ---
>> +
>> +    SECTION .text
>> +
>>
> +;--------------------------------------------------------------------------
> ---
>> +;  PvalidateRetValue
>> +;  EFIAPI
>> +;  AsmPvalidate (
>> +;    IN   UINT32  RmpPageSize
>> +;    IN   UINT32  Validate,
>> +;    IN   UINTN   Address,
>> +;    OUT  UINTN  *Eflags,
>> +;    )
>>
> +;--------------------------------------------------------------------------
> ---
>> +global ASM_PFX(AsmPvalidate)
>> +ASM_PFX(AsmPvalidate):
>> +  mov     rax, r8
>> +
>> +  ; PVALIDATE instruction opcode
>> +  DB      0xF2, 0x0F, 0x01, 0xFF
>> +
>> +  ; Read the Eflags
>> +  pushfq
>> +  pop     r8
>> +  mov     [r9], r8
>> +
>> +  ; The PVALIDATE instruction returns the status in rax register.
>> +  ret
>> --
>> 2.17.1
>>
>>
>>
>> 
>>
>
>