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

["Andrew Fish" <afish@apple.com>]

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> On Mar 25, 2021, at 3:54 AM, Brijesh Singh <brijesh.singh@amd.com> wrote:
> 
> 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 ?
> 

If this is only implemented for MDE_CPU_X64 should it be only defined in BaseLIib.h for MDE_CPU_X64? vs. "#endif // defined (MDE_CPU_IA32) || defined (MDE_CPU_X64)”?

I think today we may only have types in MDE_CPU_X64 only and all the lib functions are in "#if defined (MDE_CPU_IA32) || defined (MDE_CPU_X64)”. So we should think about adding an IA32 function implementation or not defining the function to exist for MDE_CPU_IA32 in BaseLib.h?

What do other people think?

Thanks,

Andrew Fish

> 
>> 
>> 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 <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 <mailto:jejb@linux.ibm.com>>
>>> Cc: Min Xu <min.m.xu@intel.com <mailto:min.m.xu@intel.com>>
>>> Cc: Jiewen Yao <jiewen.yao@intel.com <mailto:jiewen.yao@intel.com>>
>>> Cc: Tom Lendacky <thomas.lendacky@amd.com <mailto:thomas.lendacky@amd.com>>
>>> Cc: Jordan Justen <jordan.l.justen@intel.com <mailto:jordan.l.justen@intel.com>>
>>> Cc: Ard Biesheuvel <ardb+tianocore@kernel.org <mailto:ardb+tianocore@kernel.org>>
>>> Cc: Laszlo Ersek <lersek@redhat.com <mailto:lersek@redhat.com>>
>>> Signed-off-by: Brijesh Singh <brijesh.singh@amd.com <mailto: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
>>> 
>>> 
>>> 
>>> 
>>> 
>> 
>> 
> 
> 
> 


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