Reviewed-by: <michael.d.kin...@intel.com>
Mike
> -----Original Message-----
> From: Fan, Jeff
> Sent: Tuesday, March 1, 2016 11:37 PM
> To: edk2-devel@lists.01.org
> Cc: Tian, Feng <feng.t...@intel.com>; Kinney, Michael D
> <michael.d.kin...@intel.com>
> Subject: [Patch v2] UefiCpuPkg/CpuMpPei: Load microcode if found newer
> revision
>
> Current implementation only loads the latest revision if there is no microcode
> loaded. Per IA32 User Manual, we should load the newer revision by comparing
> the existing microcode loaded with the updating revision.
>
> Cc: Feng Tian <feng.t...@intel.com>
> Cc: Michael Kinney <michael.d.kin...@intel.com>
> Contributed-under: TianoCore Contribution Agreement 1.0
> Signed-off-by: Jeff Fan <jeff....@intel.com>
> ---
> UefiCpuPkg/CpuMpPei/Microcode.c | 18 ++++++++++--------
> 1 file changed, 10 insertions(+), 8 deletions(-)
>
> diff --git a/UefiCpuPkg/CpuMpPei/Microcode.c b/UefiCpuPkg/CpuMpPei/Microcode.c
> index 70e149b..9dcbf99 100644
> --- a/UefiCpuPkg/CpuMpPei/Microcode.c
> +++ b/UefiCpuPkg/CpuMpPei/Microcode.c
> @@ -1,7 +1,7 @@
> /** @file
> Implementation of loading microcode on processors.
>
> - Copyright (c) 2015, Intel Corporation. All rights reserved.<BR>
> + Copyright (c) 2015 - 2016, Intel Corporation. All rights reserved.<BR>
> This program and the accompanying materials
> are licensed and made available under the terms and conditions of the BSD
> License
> which accompanies this distribution. The full text of the license may be
> found at
> @@ -57,7 +57,6 @@ MicrocodeDetect (
> UINTN TotalSize;
> UINT32 CheckSum32;
> BOOLEAN CorrectMicrocode;
> - INT32 CurrentSignature;
> MICROCODE_INFO MicrocodeInfo;
>
> ZeroMem (&MicrocodeInfo, sizeof (MICROCODE_INFO));
> @@ -181,17 +180,20 @@ MicrocodeDetect (
>
> if (LatestRevision > 0) {
> //
> - // Get microcode update signature of currently loaded microcode update
> + // BIOS only authenticate updates that contain a numerically larger
> revision
> + // than the currently loaded revision, where Current Signature < New
> Update
> + // Revision. A processor with no loaded update is considered to have a
> + // revision equal to zero.
> //
> - CurrentSignature = GetCurrentMicrocodeSignature ();
> - //
> - // If no microcode update has been loaded, then trigger microcode load.
> - //
> - if (CurrentSignature == 0) {
> + if (LatestRevision > GetCurrentMicrocodeSignature ()) {
> AsmWriteMsr64 (
> EFI_MSR_IA32_BIOS_UPDT_TRIG,
> (UINT64) (UINTN) MicrocodeInfo.MicrocodeData
> );
> + //
> + // Get and verify new microcode signature
> + //
> + ASSERT (LatestRevision == GetCurrentMicrocodeSignature ());
> MicrocodeInfo.Load = TRUE;
> } else {
> MicrocodeInfo.Load = FALSE;
> --
> 1.9.5.msysgit.0
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