> + if ((!mCpuSmmStaticPageTable) && (Cr2 != 0)) {
Can the "Cr2 != 0" be removed?
> -----Original Message-----
> From: edk2-devel <edk2-devel-boun...@lists.01.org> On Behalf Of
> nkvangup
> Sent: Friday, March 29, 2019 12:58 PM
> To: edk2-devel@lists.01.org
> Cc: Yao, Jiewen <jiewen....@intel.com>; Dong, Eric <eric.d...@intel.com>;
> Laszlo Ersek <ler...@redhat.com>
> Subject: [edk2] [PATCH v6] UefiCpuPkg\CpuSmm: Save & restore CR2 on-
> demand paging in SMM
>
> 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.
>
> Contributed-under: TianoCore Contribution Agreement 1.1
> Signed-off-by: Vanguput Narendra K <narendra.k.vangu...@intel.com>
> Cc: Eric Dong <eric.d...@intel.com>
> Cc: Ray Ni <ray...@intel.com>
> Cc: Laszlo Ersek <ler...@redhat.com>
> Cc: Yao Jiewen <jiewen....@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..af96e42982 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[in] *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..c9d147c8a1 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[in] *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..6cb44fbbe5 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[in] *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) && (Cr2 != 0)) {
> + AsmWriteCr2 (Cr2);
> + }
> +}
> --
> 2.16.2.windows.1
>
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