Re: [Patch v3 1/5] UefiCpuPkg/PiSmmCpuDxeSmm: Use GDT/IDT saved in Smram.

[Laszlo Ersek <lersek@redhat.com>]

On 08/13/18 03:54, Dong, Eric wrote:
> Hi Laszlo,
> 
>> -----Original Message-----
>> From: edk2-devel [mailto:edk2-devel-bounces@lists.01.org] On Behalf Of
>> Laszlo Ersek
>> Sent: Friday, August 10, 2018 11:40 PM
>> To: Dong, Eric <eric.dong@intel.com>; edk2-devel@lists.01.org
>> Cc: Ni, Ruiyu <ruiyu.ni@intel.com>
>> Subject: Re: [edk2] [Patch v3 1/5] UefiCpuPkg/PiSmmCpuDxeSmm: Use
>> GDT/IDT saved in Smram.
>>
>> On 08/10/18 06:19, Eric Dong wrote:
>>> Current implementation copies GDT/IDT at SmmReadyToLock point from
>>> ACPI NVS memory to Smram. Later at S3 resume phase, it restores memory
>>> saved in Smram to ACPI NVS. Driver can directly use GDT/IDT saved in
>>> Smram instead of restore the original ACPI NVS memory.
>>>
>>> This patch do this change.
>>>
>>> Test Done:
>>>   Do the OS boot and S3 resume test.
>>>
>>> Cc: Laszlo Ersek <lersek@redhat.com>
>>> Cc: Ruiyu Ni <ruiyu.ni@intel.com>
>>> Contributed-under: TianoCore Contribution Agreement 1.1
>>> Signed-off-by: Eric Dong <eric.dong@intel.com>
>>> ---
>>>  UefiCpuPkg/PiSmmCpuDxeSmm/CpuS3.c | 11 ++++-------
>>>  1 file changed, 4 insertions(+), 7 deletions(-)
>>>
>>> diff --git a/UefiCpuPkg/PiSmmCpuDxeSmm/CpuS3.c
>>> b/UefiCpuPkg/PiSmmCpuDxeSmm/CpuS3.c
>>> index 0b8ef70359..764d8276d3 100644
>>> --- a/UefiCpuPkg/PiSmmCpuDxeSmm/CpuS3.c
>>> +++ b/UefiCpuPkg/PiSmmCpuDxeSmm/CpuS3.c
>>> @@ -448,13 +448,6 @@ PrepareApStartupVector (
>>>    CopyMem ((VOID *) (UINTN) &mExchangeInfo->GdtrProfile, (VOID *)
>> (UINTN) mAcpiCpuData.GdtrProfile, sizeof (IA32_DESCRIPTOR));
>>>    CopyMem ((VOID *) (UINTN) &mExchangeInfo->IdtrProfile, (VOID *)
>>> (UINTN) mAcpiCpuData.IdtrProfile, sizeof (IA32_DESCRIPTOR));
>>>
>>> -  //
>>> -  // Copy AP's GDT, IDT and Machine Check handler from SMRAM to ACPI
>>> NVS memory
>>> -  //
>>> -  CopyMem ((VOID *) mExchangeInfo->GdtrProfile.Base, mGdtForAp,
>>> mExchangeInfo->GdtrProfile.Limit + 1);
>>> -  CopyMem ((VOID *) mExchangeInfo->IdtrProfile.Base, mIdtForAp,
>>> mExchangeInfo->IdtrProfile.Limit + 1);
>>> -  CopyMem ((VOID *)(UINTN)
>> mAcpiCpuData.ApMachineCheckHandlerBase,
>>> mMachineCheckHandlerForAp,
>> mAcpiCpuData.ApMachineCheckHandlerSize);
>>> -
>>>    mExchangeInfo->StackStart  = (VOID *) (UINTN)
>> mAcpiCpuData.StackAddress;
>>>    mExchangeInfo->StackSize   = mAcpiCpuData.StackSize;
>>>    mExchangeInfo->BufferStart = (UINT32) StartupVector; @@ -901,6
>>> +894,10 @@ GetAcpiCpuData (
>>>    CopyMem (mGdtForAp, (VOID *)Gdtr->Base, Gdtr->Limit + 1);
>>>    CopyMem (mIdtForAp, (VOID *)Idtr->Base, Idtr->Limit + 1);
>>>    CopyMem (mMachineCheckHandlerForAp, (VOID
>>> *)(UINTN)mAcpiCpuData.ApMachineCheckHandlerBase,
>>> mAcpiCpuData.ApMachineCheckHandlerSize);
>>> +
>>> +  Gdtr->Base = (UINTN)mGdtForAp;
>>> +  Idtr->Base = (UINTN)mIdtForAp;
>>> +  mAcpiCpuData.ApMachineCheckHandlerBase =
>>> + (EFI_PHYSICAL_ADDRESS)(UINTN)mMachineCheckHandlerForAp;
>>>  }
>>>
>>>  /**
>>>
>>
>> This patch looks good to me (I'm ready to give R-b), but I think we can simplify
>> the code further. Can we replace the mGdtForAp, mIdtForAp and
>> mMachineCheckHandlerForAp global variables, with GdtForAp, IdtForAp and
>> MachineCheckHandlerForAp local variables, used only in the
>> GetAcpiCpuData() function?
>>
> 
> Agree to do this change in my next version change. Will send new patches after finishing AllocateZeroPages related discussion.

OK, cool, thanks! I will test that version then.

Laszlo

> 
>> If you prefer to do that as an incremental patch, that's fine too.
>>
>> Thanks,
>> Laszlo
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