Re: [PATCH 1/2] UefiCpuPkg/PiSmmCpuDxeSmm: drop support for obsolete processors

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

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

> -----Original Message-----
> From: Gerd Hoffmann <kraxel@redhat.com>
> Sent: Friday, March 10, 2023 8:49 PM
> To: devel@edk2.groups.io
> Cc: Ni, Ray <ray.ni@intel.com>; Oliver Steffen <osteffen@redhat.com>; Gerd
> Hoffmann <kraxel@redhat.com>; Kumar, Rahul R
> <rahul.r.kumar@intel.com>; Pawel Polawski <ppolawsk@redhat.com>;
> Dong, Eric <eric.dong@intel.com>
> Subject: [PATCH 1/2] UefiCpuPkg/PiSmmCpuDxeSmm: drop support for
> obsolete processors
> 
> It's highly unlikely the code ever runs on processors which are
> almost 30 years old.  Drop the code handling them.
> 
> Bugzilla: https://bugzilla.tianocore.org/show_bug.cgi?id=4345
> Signed-off-by: Gerd Hoffmann <kraxel@redhat.com>
> ---
>  UefiCpuPkg/PiSmmCpuDxeSmm/PiSmmCpuDxeSmm.c | 20 +++++---------------
>  1 file changed, 5 insertions(+), 15 deletions(-)
> 
> diff --git a/UefiCpuPkg/PiSmmCpuDxeSmm/PiSmmCpuDxeSmm.c
> b/UefiCpuPkg/PiSmmCpuDxeSmm/PiSmmCpuDxeSmm.c
> index d2d0950f3b42..55a9f79da8eb 100644
> --- a/UefiCpuPkg/PiSmmCpuDxeSmm/PiSmmCpuDxeSmm.c
> +++ b/UefiCpuPkg/PiSmmCpuDxeSmm/PiSmmCpuDxeSmm.c
> @@ -871,24 +871,14 @@ PiCpuSmmEntry (
>      //
>      DEBUG ((DEBUG_INFO, "PiCpuSmmEntry: gSmmBaseHobGuid not
> found!\n"));
>      //
> +    // very old processors (i486 + pentium) need 32k not 4k alignment,
> exclude them.
> +    //
> +    ASSERT (FamilyId >= 6);
> +    //
>      // Allocate buffer for all of the tiles.
>      //
> -    // Intel(R) 64 and IA-32 Architectures Software Developer's Manual
> -    // Volume 3C, Section 34.11 SMBASE Relocation
> -    //   For Pentium and Intel486 processors, the SMBASE values must be
> -    //   aligned on a 32-KByte boundary or the processor will enter shutdown
> -    //   state during the execution of a RSM instruction.
> -    //
> -    // Intel486 processors: FamilyId is 4
> -    // Pentium processors : FamilyId is 5
> -    //
>      BufferPages = EFI_SIZE_TO_PAGES (SIZE_32KB + TileSize *
> (mMaxNumberOfCpus - 1));
> -    if ((FamilyId == 4) || (FamilyId == 5)) {
> -      Buffer = AllocateAlignedCodePages (BufferPages, SIZE_32KB);
> -    } else {
> -      Buffer = AllocateAlignedCodePages (BufferPages, SIZE_4KB);
> -    }
> -
> +    Buffer      = AllocateAlignedCodePages (BufferPages, SIZE_4KB);
>      ASSERT (Buffer != NULL);
>      DEBUG ((DEBUG_INFO, "New Allcoated SMRAM SaveState Buffer (0x%08x,
> 0x%08x)\n", Buffer, EFI_PAGES_TO_SIZE (BufferPages)));
>    }
> --
> 2.39.2