Hi Ray, While programming, I thought this cannot be 0 as in SDM, it says page-fault linear address. >> CR2 - Contains the page-fault linear address (the linear address that caused >> a page fault).
So added a check for 0. Now as the function is changed like program into CR2 register based on input parameter and checking for 0 is up to caller of this function. And also we don't need to require for checking 0 means, will remove it. Please confirm. Thanks, Naren -----Original Message----- From: Ni, Ray Sent: Friday, March 29, 2019 10:40 AM To: Vanguput, Narendra K <narendra.k.vangu...@intel.com>; edk2-devel@lists.01.org Cc: Yao, Jiewen <jiewen....@intel.com>; Dong, Eric <eric.d...@intel.com>; Laszlo Ersek <ler...@redhat.com> Subject: RE: [edk2] [PATCH v6] UefiCpuPkg\CpuSmm: Save & restore CR2 on-demand paging in SMM > + 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 > > _______________________________________________ > edk2-devel mailing list > edk2-devel@lists.01.org > https://lists.01.org/mailman/listinfo/edk2-devel _______________________________________________ edk2-devel mailing list edk2-devel@lists.01.org https://lists.01.org/mailman/listinfo/edk2-devel