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

["Ni, Ruiyu" <ruiyu.ni@intel.com>]

Thanks/Ray

> -----Original Message-----
> From: Laszlo Ersek <lersek@redhat.com>
> 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: [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?
Great code cleanup to remove 3 global variables.
> 
> If you prefer to do that as an incremental patch, that's fine too.
> 
> Thanks,
> Laszlo