Re: [Patch V4 03/21] UefiCpuPkg/CpuPageTableLib:Initialize some LocalVariable at beginning

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

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

> -----Original Message-----
> From: Tan, Dun <dun.tan@intel.com>
> Sent: Thursday, March 23, 2023 3:41 PM
> To: devel@edk2.groups.io
> Cc: Dong, Eric <eric.dong@intel.com>; Ni, Ray <ray.ni@intel.com>; Kumar,
> Rahul R <rahul.r.kumar@intel.com>; Gerd Hoffmann <kraxel@redhat.com>
> Subject: [Patch V4 03/21] UefiCpuPkg/CpuPageTableLib:Initialize some
> LocalVariable at beginning
> 
> Move some local variable initialization to the beginning of the
> function. Also delete duplicated calculation for RegionLength.
> 
> Signed-off-by: Dun Tan <dun.tan@intel.com>
> Cc: Eric Dong <eric.dong@intel.com>
> Cc: Ray Ni <ray.ni@intel.com>
> Cc: Rahul Kumar <rahul1.kumar@intel.com>
> Cc: Gerd Hoffmann <kraxel@redhat.com>
> ---
>  UefiCpuPkg/Library/CpuPageTableLib/CpuPageTableMap.c | 21
> ++++++++++++---------
>  1 file changed, 12 insertions(+), 9 deletions(-)
> 
> diff --git a/UefiCpuPkg/Library/CpuPageTableLib/CpuPageTableMap.c
> b/UefiCpuPkg/Library/CpuPageTableLib/CpuPageTableMap.c
> index 218068a3e1..127b65183f 100644
> --- a/UefiCpuPkg/Library/CpuPageTableLib/CpuPageTableMap.c
> +++ b/UefiCpuPkg/Library/CpuPageTableLib/CpuPageTableMap.c
> @@ -258,6 +258,7 @@ PageTableLibMapInLevel (
>    UINTN               BitStart;
>    UINTN               Index;
>    IA32_PAGING_ENTRY   *PagingEntry;
> +  UINTN               PagingEntryIndex;
>    IA32_PAGING_ENTRY   *CurrentPagingEntry;
>    UINT64              RegionLength;
>    UINT64              SubLength;
> @@ -288,6 +289,14 @@ PageTableLibMapInLevel (
>    LocalParentAttribute.Uint64 = ParentAttribute->Uint64;
>    ParentAttribute             = &LocalParentAttribute;
> 
> +  //
> +  // RegionLength: 256T (1 << 48) 512G (1 << 39), 1G (1 << 30), 2M (1 << 21)
> or 4K (1 << 12).
> +  //
> +  BitStart         = 12 + (Level - 1) * 9;
> +  PagingEntryIndex = (UINTN)BitFieldRead64 (LinearAddress + Offset,
> BitStart, BitStart + 9 - 1);
> +  RegionLength     = REGION_LENGTH (Level);
> +  RegionMask       = RegionLength - 1;
> +
>    //
>    // ParentPagingEntry ONLY is deferenced for checking Present and
> MustBeOne bits
>    // when Modify is FALSE.
> @@ -353,8 +362,7 @@ PageTableLibMapInLevel (
>        //
>        PageTableLibSetPnle (&ParentPagingEntry->Pnle, &NopAttribute,
> &AllOneMask);
> 
> -      RegionLength = REGION_LENGTH (Level);
> -      PagingEntry  = (IA32_PAGING_ENTRY
> *)(UINTN)IA32_PNLE_PAGE_TABLE_BASE_ADDRESS (&ParentPagingEntry-
> >Pnle);
> +      PagingEntry = (IA32_PAGING_ENTRY
> *)(UINTN)IA32_PNLE_PAGE_TABLE_BASE_ADDRESS (&ParentPagingEntry-
> >Pnle);
>        for (SubOffset = 0, Index = 0; Index < 512; Index++) {
>          PagingEntry[Index].Uint64 = OneOfPagingEntry.Uint64 + SubOffset;
>          SubOffset                += RegionLength;
> @@ -425,15 +433,10 @@ PageTableLibMapInLevel (
>    }
> 
>    //
> -  // RegionLength: 256T (1 << 48) 512G (1 << 39), 1G (1 << 30), 2M (1 << 21) or
> 4K (1 << 12).
>    // RegionStart:  points to the linear address that's aligned on RegionLength
> and lower than (LinearAddress + Offset).
>    //
> -  BitStart     = 12 + (Level - 1) * 9;
> -  Index        = (UINTN)BitFieldRead64 (LinearAddress + Offset, BitStart,
> BitStart + 9 - 1);
> -  RegionLength = LShiftU64 (1, BitStart);
> -  RegionMask   = RegionLength - 1;
> -  RegionStart  = (LinearAddress + Offset) & ~RegionMask;
> -
> +  Index                   = PagingEntryIndex;
> +  RegionStart             = (LinearAddress + Offset) & ~RegionMask;
>    ParentAttribute->Uint64 = PageTableLibGetPnleMapAttribute
> (&ParentPagingEntry->Pnle, ParentAttribute);
> 
>    //
> --
> 2.31.1.windows.1