Re: [PATCH v8] UefiCpuPkg\CpuSmm: Save & restore CR2 on-demand paging in SMM

["Ni, Ray" <ray.ni@intel.com>]

Reviewed-by: Ray Ni <Ray.ni@intel.com>

Sent from small device

> 在 2019年3月29日，下午11:45，Vanguput, Narendra K <narendra.k.vanguput@intel.com> 写道：
> 
> BZ: https://bugzilla.tianocore.org/show_bug.cgi?id=1593
> 
> For every SMI occurrence, save and restore CR2 register only when SMM
> on-demand paging support is enabled in 64 bit operation mode.
> This is not a bug but to have better improvement of code.
> 
> Patch5 is updated with separate functions for Save and Restore of CR2
> based on review feedback.
> 
> Patch6 - Removed Global Cr2 instead used function parameter
> 
> Patch7 - Removed checking Cr2 with 0 as per feedback
> 
> Contributed-under: TianoCore Contribution Agreement 1.1
> Signed-off-by: Vanguput Narendra K <narendra.k.vanguput@intel.com>
> Cc: Eric Dong <eric.dong@intel.com>
> Cc: Ray Ni <ray.ni@intel.com>
> Cc: Laszlo Ersek <lersek@redhat.com>
> Cc: Yao Jiewen <jiewen.yao@intel.com>
> ---
> UefiCpuPkg/PiSmmCpuDxeSmm/Ia32/PageTbl.c   | 26 ++++++++++++++++++++++++++
> UefiCpuPkg/PiSmmCpuDxeSmm/MpService.c      |  9 ++++++---
> UefiCpuPkg/PiSmmCpuDxeSmm/PiSmmCpuDxeSmm.h | 22 ++++++++++++++++++++++
> UefiCpuPkg/PiSmmCpuDxeSmm/X64/PageTbl.c    | 30 ++++++++++++++++++++++++++++++
> 4 files changed, 84 insertions(+), 3 deletions(-)
> 
> diff --git a/UefiCpuPkg/PiSmmCpuDxeSmm/Ia32/PageTbl.c b/UefiCpuPkg/PiSmmCpuDxeSmm/Ia32/PageTbl.c
> index b734a1ea8c..d3f62ed806 100644
> --- a/UefiCpuPkg/PiSmmCpuDxeSmm/Ia32/PageTbl.c
> +++ b/UefiCpuPkg/PiSmmCpuDxeSmm/Ia32/PageTbl.c
> @@ -316,3 +316,29 @@ SetPageTableAttributes (
> 
>   return ;
> }
> +
> +/**
> +  This function returns with no action for 32 bit.
> +
> +  @param[out]  *Cr2  Pointer to variable to hold CR2 register value
> +**/
> +VOID
> +SaveCr2 (
> +  UINTN  *Cr2
> +  )
> +{
> +  return ;
> +}
> +
> +/**
> +  This function returns with no action for 32 bit.
> +
> +  @param[in]  Cr2  Value to write into CR2 register
> +**/
> +VOID
> +RestoreCr2 (
> +  UINTN  Cr2
> +  )
> +{
> +  return ;
> +}
> diff --git a/UefiCpuPkg/PiSmmCpuDxeSmm/MpService.c b/UefiCpuPkg/PiSmmCpuDxeSmm/MpService.c
> index 3b0b3b52ac..ce70f77709 100644
> --- a/UefiCpuPkg/PiSmmCpuDxeSmm/MpService.c
> +++ b/UefiCpuPkg/PiSmmCpuDxeSmm/MpService.c
> @@ -1112,9 +1112,11 @@ SmiRendezvous (
>   ASSERT(CpuIndex < mMaxNumberOfCpus);
> 
>   //
> -  // Save Cr2 because Page Fault exception in SMM may override its value
> +  // Save Cr2 because Page Fault exception in SMM may override its value,
> +  // when using on-demand paging for above 4G memory.
>   //
> -  Cr2 = AsmReadCr2 ();
> +  Cr2 = 0;
> +  SaveCr2 (&Cr2);
> 
>   //
>   // Perform CPU specific entry hooks
> @@ -1253,10 +1255,11 @@ SmiRendezvous (
> 
> Exit:
>   SmmCpuFeaturesRendezvousExit (CpuIndex);
> +
>   //
>   // Restore Cr2
>   //
> -  AsmWriteCr2 (Cr2);
> +  RestoreCr2 (Cr2);
> }
> 
> /**
> diff --git a/UefiCpuPkg/PiSmmCpuDxeSmm/PiSmmCpuDxeSmm.h b/UefiCpuPkg/PiSmmCpuDxeSmm/PiSmmCpuDxeSmm.h
> index 84efb22981..05e1b54ed2 100644
> --- a/UefiCpuPkg/PiSmmCpuDxeSmm/PiSmmCpuDxeSmm.h
> +++ b/UefiCpuPkg/PiSmmCpuDxeSmm/PiSmmCpuDxeSmm.h
> @@ -1243,4 +1243,26 @@ EFIAPI
> PiSmmCpuSmiEntryFixupAddress (
>  );
> 
> +/**
> +  This function reads CR2 register when on-demand paging is enabled
> +  for 64 bit and no action for 32 bit.
> +
> +  @param[out]  *Cr2  Pointer to variable to hold CR2 register value
> +**/
> +VOID
> +SaveCr2 (
> +  UINTN  *Cr2
> +  );
> +
> +/**
> +  This function writes into CR2 register when on-demand paging is enabled
> +  for 64 bit and no action for 32 bit.
> +
> +  @param[in]  Cr2  Value to write into CR2 register
> +**/
> +VOID
> +RestoreCr2 (
> +  UINTN  Cr2
> +  );
> +
> #endif
> diff --git a/UefiCpuPkg/PiSmmCpuDxeSmm/X64/PageTbl.c b/UefiCpuPkg/PiSmmCpuDxeSmm/X64/PageTbl.c
> index 2c77cb47a4..e60628c080 100644
> --- a/UefiCpuPkg/PiSmmCpuDxeSmm/X64/PageTbl.c
> +++ b/UefiCpuPkg/PiSmmCpuDxeSmm/X64/PageTbl.c
> @@ -1053,3 +1053,33 @@ SetPageTableAttributes (
> 
>   return ;
> }
> +
> +/**
> +  This function reads CR2 register when on-demand paging is enabled
> +
> +  @param[out]  *Cr2  Pointer to variable to hold CR2 register value
> +**/
> +VOID
> +SaveCr2 (
> +  UINTN  *Cr2
> +  )
> +{
> +  if (!mCpuSmmStaticPageTable) {
> +    *Cr2 = AsmReadCr2 ();
> +  }
> +}
> +
> +/**
> +  This function restores CR2 register when on-demand paging is enabled
> +
> +  @param[in]  Cr2  Value to write into CR2 register
> +**/
> +VOID
> +RestoreCr2 (
> +  UINTN  Cr2
> +  )
> +{
> +  if (!mCpuSmmStaticPageTable) {
> +    AsmWriteCr2 (Cr2);
> +  }
> +}
> -- 
> 2.16.2.windows.1
>