Re: [edk2-devel] [PATCH V3] UefiCpuPkg PiSmmCpuDxeSmm: Reduce SMRAM consumption in CpuS3.c

["Laszlo Ersek" <lersek@redhat.com>]

Hi Star,

On 01/08/21 15:13, Zeng, Star wrote:
> Thanks Laszlo.
> 
> Ray, Laszlo or Eric, need your help to commit it if no further comment to the patch.

the merge request

  https://github.com/tianocore/edk2/pull/1326

failed, due to the following ECC error report:

  ERROR - EFI coding style error
  ERROR - *Error code: 9002
  ERROR - *The function headers should follow Doxygen special documentation blocks in section 2.3.5
  ERROR - *file: //home/vsts/work/1/s/UefiCpuPkg/PiSmmCpuDxeSmm/CpuS3.c
  ERROR - *Line number: 985
  ERROR - *in Comment, <@retval TRUE> does NOT consistent with parameter name NumberOfCpus

As far as I understand, the issue is that the "NumberOfCpus" parameter of IsRegisterTableEmpty() does not have its own @param[in] stanza, in the preceding comment block.

Please submit a v4.

Thanks,
Laszlo

>> -----Original Message-----
>> From: devel@edk2.groups.io <devel@edk2.groups.io> On Behalf Of Laszlo
>> Ersek
>> Sent: Thursday, January 7, 2021 7:01 PM
>> To: Zeng, Star <star.zeng@intel.com>; devel@edk2.groups.io
>> Cc: Ni, Ray <ray.ni@intel.com>; Dong, Eric <eric.dong@intel.com>
>> Subject: Re: [edk2-devel] [PATCH V3] UefiCpuPkg PiSmmCpuDxeSmm: Reduce
>> SMRAM consumption in CpuS3.c
>>
>> On 01/07/21 11:46, Star Zeng wrote:
>>> This patch makes two refinements to reduce SMRAM consumption in
>> CpuS3.c.
>>> 1. Only do CopyRegisterTable() when register table is not empty,
>>>   IsRegisterTableEmpty() is created to check whether the register table
>>>   is empty or not.
>>>
>>>   Take empty PreSmmInitRegisterTable as example, about 24K SMRAM
>> consumption
>>>   could be reduced when mAcpiCpuData.NumberOfCpus=1024.
>>>   sizeof (CPU_REGISTER_TABLE) = 24
>>>   mAcpiCpuData.NumberOfCpus = 1024 = 1K
>>>   mAcpiCpuData.NumberOfCpus * sizeof (CPU_REGISTER_TABLE) = 24K
>>>
>>> 2. Only copy table entries buffer instead of whole buffer.
>>>   AllocatedSize in SourceRegisterTableList is the whole buffer size.
>>>   Actually, only the table entries buffer needs to be copied, and the size
>>>   is TableLength * sizeof (CPU_REGISTER_TABLE_ENTRY).
>>>
>>>   Take AllocatedSize=0x1000=4096, TableLength=100 and
>> NumberOfCpus=1024 as example,
>>>   about 1696K SMRAM consumption could be reduced.
>>>   sizeof (CPU_REGISTER_TABLE_ENTRY) = 24
>>>   TableLength = 100
>>>   TableLength * sizeof (CPU_REGISTER_TABLE_ENTRY) = 2400
>>>   AllocatedSize = 0x1000 = 4096
>>>   AllocatedSize - TableLength * sizeof (CPU_REGISTER_TABLE_ENTRY) = 4096
>> - 2400 = 1696
>>>   NumberOfCpus = 1024 = 1K
>>>   NumberOfCpus * (AllocatedSize - TableLength * sizeof
>>> (CPU_REGISTER_TABLE_ENTRY)) = 1696K
>>>
>>> This patch also corrects the CopyRegisterTable() function description.
>>>
>>> Signed-off-by: Star Zeng <star.zeng@intel.com>
>>> Reviewed-by: Ray Ni <ray.ni@intel.com>
>>> Reviewed-by: Laszlo Ersek <lersek@redhat.com>
>>> Cc: Ray Ni <ray.ni@intel.com>
>>> Cc: Eric Dong <eric.dong@intel.com>
>>> Cc: Laszlo Ersek <lersek@redhat.com>
>>> ---
>>>  UefiCpuPkg/PiSmmCpuDxeSmm/CpuS3.c | 73
>>> ++++++++++++++++++++++++-------
>>>  1 file changed, 56 insertions(+), 17 deletions(-)
>>
>> Thanks for the update, my R-b stands.
>>
>> Laszlo
>>
>>>
>>> diff --git a/UefiCpuPkg/PiSmmCpuDxeSmm/CpuS3.c
>>> b/UefiCpuPkg/PiSmmCpuDxeSmm/CpuS3.c
>>> index 9592430636ec..724e5460ba6f 100644
>>> --- a/UefiCpuPkg/PiSmmCpuDxeSmm/CpuS3.c
>>> +++ b/UefiCpuPkg/PiSmmCpuDxeSmm/CpuS3.c
>>> @@ -1,7 +1,7 @@
>>>  /** @file
>>>  Code for Processor S3 restoration
>>>
>>> -Copyright (c) 2006 - 2020, Intel Corporation. All rights
>>> reserved.<BR>
>>> +Copyright (c) 2006 - 2021, Intel Corporation. All rights
>>> +reserved.<BR>
>>>  SPDX-License-Identifier: BSD-2-Clause-Patent
>>>
>>>  **/
>>> @@ -487,6 +487,9 @@ SetRegister (
>>>    } else {
>>>      RegisterTables = (CPU_REGISTER_TABLE
>> *)(UINTN)mAcpiCpuData.RegisterTable;
>>>    }
>>> +  if (RegisterTables == NULL) {
>>> +    return;
>>> +  }
>>>
>>>    InitApicId = GetInitialApicId ();
>>>    RegisterTable = NULL;
>>> @@ -948,7 +951,7 @@ InitSmmS3ResumeState (  }
>>>
>>>  /**
>>> -  Copy register table from ACPI NVS memory into SMRAM.
>>> +  Copy register table from non-SMRAM into SMRAM.
>>>
>>>    @param[in] DestinationRegisterTableList  Points to destination register
>> table.
>>>    @param[in] SourceRegisterTableList       Points to source register table.
>>> @@ -967,7 +970,8 @@ CopyRegisterTable (
>>>
>>>    CopyMem (DestinationRegisterTableList, SourceRegisterTableList,
>> NumberOfCpus * sizeof (CPU_REGISTER_TABLE));
>>>    for (Index = 0; Index < NumberOfCpus; Index++) {
>>> -    if (DestinationRegisterTableList[Index].AllocatedSize != 0) {
>>> +    if (DestinationRegisterTableList[Index].TableLength != 0) {
>>> +      DestinationRegisterTableList[Index].AllocatedSize =
>>> + DestinationRegisterTableList[Index].TableLength * sizeof
>>> + (CPU_REGISTER_TABLE_ENTRY);
>>>        RegisterTableEntry = AllocateCopyPool (
>>>          DestinationRegisterTableList[Index].AllocatedSize,
>>>          (VOID
>>> *)(UINTN)SourceRegisterTableList[Index].RegisterTableEntry
>>> @@ -978,6 +982,33 @@ CopyRegisterTable (
>>>    }
>>>  }
>>>
>>> +/**
>>> +  Check whether the register table is empty or not.
>>> +
>>> +  @param[in] RegisterTable  Point to the register table.
>>> +
>>> +  @retval TRUE              The register table is empty.
>>> +  @retval FALSE             The register table is not empty.
>>> +**/
>>> +BOOLEAN
>>> +IsRegisterTableEmpty (
>>> +  IN CPU_REGISTER_TABLE     *RegisterTable,
>>> +  IN UINT32                 NumberOfCpus
>>> +  )
>>> +{
>>> +  UINTN                     Index;
>>> +
>>> +  if (RegisterTable != NULL) {
>>> +    for (Index = 0; Index < NumberOfCpus; Index++) {
>>> +      if (RegisterTable[Index].TableLength != 0) {
>>> +        return FALSE;
>>> +      }
>>> +    }
>>> +  }
>>> +
>>> +  return TRUE;
>>> +}
>>> +
>>>  /**
>>>    Get ACPI CPU data.
>>>
>>> @@ -1032,23 +1063,31 @@ GetAcpiCpuData (
>>>
>>>    CopyMem ((VOID *)(UINTN)mAcpiCpuData.IdtrProfile, (VOID
>>> *)(UINTN)AcpiCpuData->IdtrProfile, sizeof (IA32_DESCRIPTOR));
>>>
>>> -  mAcpiCpuData.PreSmmInitRegisterTable =
>>> (EFI_PHYSICAL_ADDRESS)(UINTN)AllocatePool
>> (mAcpiCpuData.NumberOfCpus *
>>> sizeof (CPU_REGISTER_TABLE));
>>> -  ASSERT (mAcpiCpuData.PreSmmInitRegisterTable != 0);
>>> +  if (!IsRegisterTableEmpty ((CPU_REGISTER_TABLE
>> *)(UINTN)AcpiCpuData->PreSmmInitRegisterTable,
>> mAcpiCpuData.NumberOfCpus)) {
>>> +    mAcpiCpuData.PreSmmInitRegisterTable =
>> (EFI_PHYSICAL_ADDRESS)(UINTN)AllocatePool
>> (mAcpiCpuData.NumberOfCpus * sizeof (CPU_REGISTER_TABLE));
>>> +    ASSERT (mAcpiCpuData.PreSmmInitRegisterTable != 0);
>>>
>>> -  CopyRegisterTable (
>>> -    (CPU_REGISTER_TABLE
>> *)(UINTN)mAcpiCpuData.PreSmmInitRegisterTable,
>>> -    (CPU_REGISTER_TABLE *)(UINTN)AcpiCpuData-
>>> PreSmmInitRegisterTable,
>>> -    mAcpiCpuData.NumberOfCpus
>>> -    );
>>> +    CopyRegisterTable (
>>> +      (CPU_REGISTER_TABLE
>> *)(UINTN)mAcpiCpuData.PreSmmInitRegisterTable,
>>> +      (CPU_REGISTER_TABLE *)(UINTN)AcpiCpuData-
>>> PreSmmInitRegisterTable,
>>> +      mAcpiCpuData.NumberOfCpus
>>> +      );
>>> +  } else {
>>> +    mAcpiCpuData.PreSmmInitRegisterTable = 0;  }
>>>
>>> -  mAcpiCpuData.RegisterTable =
>>> (EFI_PHYSICAL_ADDRESS)(UINTN)AllocatePool
>> (mAcpiCpuData.NumberOfCpus *
>>> sizeof (CPU_REGISTER_TABLE));
>>> -  ASSERT (mAcpiCpuData.RegisterTable != 0);
>>> +  if (!IsRegisterTableEmpty ((CPU_REGISTER_TABLE
>> *)(UINTN)AcpiCpuData->RegisterTable, mAcpiCpuData.NumberOfCpus)) {
>>> +    mAcpiCpuData.RegisterTable =
>> (EFI_PHYSICAL_ADDRESS)(UINTN)AllocatePool
>> (mAcpiCpuData.NumberOfCpus * sizeof (CPU_REGISTER_TABLE));
>>> +    ASSERT (mAcpiCpuData.RegisterTable != 0);
>>>
>>> -  CopyRegisterTable (
>>> -    (CPU_REGISTER_TABLE *)(UINTN)mAcpiCpuData.RegisterTable,
>>> -    (CPU_REGISTER_TABLE *)(UINTN)AcpiCpuData->RegisterTable,
>>> -    mAcpiCpuData.NumberOfCpus
>>> -    );
>>> +    CopyRegisterTable (
>>> +      (CPU_REGISTER_TABLE *)(UINTN)mAcpiCpuData.RegisterTable,
>>> +      (CPU_REGISTER_TABLE *)(UINTN)AcpiCpuData->RegisterTable,
>>> +      mAcpiCpuData.NumberOfCpus
>>> +      );
>>> +  } else {
>>> +    mAcpiCpuData.RegisterTable = 0;
>>> +  }
>>>
>>>    //
>>>    // Copy AP's GDT, IDT and Machine Check handler into SMRAM.
>>>
>>
>>
>>
>>
>>
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