Re: [RFC PATCH v1 5/5] OvmfPkg/BaseIoLibIntrinsic: Unroll String I/O when SEV is active

[Brijesh Singh <brijesh.ksingh@gmail.com>]

On Tue, Mar 7, 2017 at 10:49 AM, Tom Lendacky <thomas.lendacky@amd.com>
wrote:

> On 3/6/2017 5:28 PM, Brijesh Singh wrote:
>
>> Secure Encrypted Virtualization (SEV) does not support string I/O, so
>> unroll the string I/O operation into a loop operating on one element at
>> a time.
>>
>> Contributed-under: TianoCore Contribution Agreement 1.0
>> Signed-off-by: Brijesh Singh <brijesh.singh@amd.com>
>> ---
>>  .../BaseIoLibIntrinsic/BaseIoLibIntrinsic.inf      |    3
>>  .../Library/BaseIoLibIntrinsic/Ia32/IoFifo.nasm    |   19 +++
>>  .../Library/BaseIoLibIntrinsic/Ia32/SevIoFifo.nasm |  141
>> ++++++++++++++++++++
>>  OvmfPkg/Library/BaseIoLibIntrinsic/X64/IoFifo.nasm |   19 +++
>>  .../Library/BaseIoLibIntrinsic/X64/SevIoFifo.nasm  |  143
>> ++++++++++++++++++++
>>  5 files changed, 324 insertions(+), 1 deletion(-)
>>  create mode 100644 OvmfPkg/Library/BaseIoLibIntri
>> nsic/Ia32/SevIoFifo.nasm
>>  create mode 100644 OvmfPkg/Library/BaseIoLibIntrinsic/X64/SevIoFifo.nasm
>>
>> diff --git a/OvmfPkg/Library/BaseIoLibIntrinsic/BaseIoLibIntrinsic.inf
>> b/OvmfPkg/Library/BaseIoLibIntrinsic/BaseIoLibIntrinsic.inf
>> index 8844b1c..e7eeb59 100644
>> --- a/OvmfPkg/Library/BaseIoLibIntrinsic/BaseIoLibIntrinsic.inf
>> +++ b/OvmfPkg/Library/BaseIoLibIntrinsic/BaseIoLibIntrinsic.inf
>> @@ -28,7 +28,6 @@
>>    VERSION_STRING                 = 1.0
>>    LIBRARY_CLASS                  = IoLib
>>
>> -
>>  #
>>  #  VALID_ARCHITECTURES           = IA32 X64 EBC IPF ARM AARCH64
>>  #
>> @@ -45,6 +44,7 @@
>>    IoLib.c
>>    Ia32/IoFifo.nasm
>>    Ia32/IoFifo.asm
>> +  Ia32/SevIoFifo.nasm
>>
>>  [Sources.X64]
>>    IoLibGcc.c    | GCC
>> @@ -53,6 +53,7 @@
>>    IoLib.c
>>    X64/IoFifo.nasm
>>    X64/IoFifo.asm
>> +  X64/SevIoFifo.nasm
>>
>>  [Sources.EBC]
>>    IoLibEbc.c
>> diff --git a/OvmfPkg/Library/BaseIoLibIntrinsic/Ia32/IoFifo.nasm
>> b/OvmfPkg/Library/BaseIoLibIntrinsic/Ia32/IoFifo.nasm
>> index bcaa743..fb585e6 100644
>> --- a/OvmfPkg/Library/BaseIoLibIntrinsic/Ia32/IoFifo.nasm
>> +++ b/OvmfPkg/Library/BaseIoLibIntrinsic/Ia32/IoFifo.nasm
>> @@ -13,6 +13,10 @@
>>  ;
>>  ;----------------------------------------------------------
>> --------------------
>>
>> +    EXTERN ASM_PFX(SevIoReadFifo8)
>> +    EXTERN ASM_PFX(SevIoReadFifo16)
>> +    EXTERN ASM_PFX(SevIoReadFifo32)
>> +
>>      SECTION .text
>>
>>  ;----------------------------------------------------------
>> --------------------
>> @@ -31,7 +35,12 @@ ASM_PFX(IoReadFifo8):
>>      mov     dx, [esp + 8]
>>      mov     ecx, [esp + 12]
>>      mov     edi, [esp + 16]
>> +    call    SevIoReadFifo8
>>
>
> Maybe just add a comment here (and in the other places) that if SEV
> isn't active we drop through and perform the "rep" form of the
> instruction.
>
>
Thanks, I will add comments in next rev.