On 06/24/19 08:14, Zhichao Gao wrote:
> REF: https://bugzilla.tianocore.org/show_bug.cgi?id=1934
>
> Originally, the checksum part would done before verfiy the microcode
> data. Which meas the checksum would be done for a meaningless data.
> It would cause a incorrect TotalSize (the size of microcode data),
> then incorrect checksum and incorrect pointer increasing would happen.
> To fix this, move the checksum part 1 section in
> 'if (MicrocodeEntryPoint->HeaderVersion == 0x1)' section for a valid
> microcode data.
>
> Cc: Eric Dong <eric.d...@intel.com>
> Cc: Ray Ni <ray...@intel.com>
> Cc: Laszlo Ersek <ler...@redhat.com>
> Cc: Liming Gao <liming....@intel.com>
> Signed-off-by: Zhichao Gao <zhichao....@intel.com>
> ---
> UefiCpuPkg/Library/MpInitLib/Microcode.c | 52 ++++++++++++------------
> 1 file changed, 26 insertions(+), 26 deletions(-)
I'll defer on this patch to the (other) UefiCpuPkg reviewers /
maintainers. OVMF inherits the default zero value for
"PcdCpuMicrocodePatchRegionSize", from "UefiCpuPkg.dec". Therefore the
first check in MicrocodeDetect() evaluates to TRUE, and the function
exits immediately, in OVMF.
Thanks
Laszlo
> diff --git a/UefiCpuPkg/Library/MpInitLib/Microcode.c
> b/UefiCpuPkg/Library/MpInitLib/Microcode.c
> index 4763dcfebe..f1a42f2d4e 100644
> --- a/UefiCpuPkg/Library/MpInitLib/Microcode.c
> +++ b/UefiCpuPkg/Library/MpInitLib/Microcode.c
> @@ -1,7 +1,7 @@
> /** @file
> Implementation of loading microcode on processors.
>
> - Copyright (c) 2015 - 2018, Intel Corporation. All rights reserved.<BR>
> + Copyright (c) 2015 - 2019, Intel Corporation. All rights reserved.<BR>
> SPDX-License-Identifier: BSD-2-Clause-Patent
>
> **/
> @@ -160,34 +160,34 @@ MicrocodeDetect (
> //
> CorrectMicrocode = FALSE;
>
> - if (MicrocodeEntryPoint->DataSize == 0) {
> - TotalSize = sizeof (CPU_MICROCODE_HEADER) + 2000;
> - } else {
> - TotalSize = sizeof (CPU_MICROCODE_HEADER) +
> MicrocodeEntryPoint->DataSize;
> - }
> + if (MicrocodeEntryPoint->HeaderVersion == 0x1) {
> + if (MicrocodeEntryPoint->DataSize == 0) {
> + TotalSize = sizeof (CPU_MICROCODE_HEADER) + 2000;
> + } else {
> + TotalSize = sizeof (CPU_MICROCODE_HEADER) +
> MicrocodeEntryPoint->DataSize;
> + }
>
> - ///
> - /// Check overflow and whether TotalSize is aligned with 4 bytes.
> - ///
> - if ( ((UINTN)MicrocodeEntryPoint + TotalSize) > MicrocodeEnd ||
> - (TotalSize & 0x3) != 0
> - ) {
> - MicrocodeEntryPoint = (CPU_MICROCODE_HEADER *) (((UINTN)
> MicrocodeEntryPoint) + SIZE_1KB);
> - continue;
> - }
> + ///
> + /// Check overflow and whether TotalSize is aligned with 4 bytes.
> + ///
> + if ( ((UINTN)MicrocodeEntryPoint + TotalSize) > MicrocodeEnd ||
> + (TotalSize & 0x3) != 0
> + ) {
> + MicrocodeEntryPoint = (CPU_MICROCODE_HEADER *) (((UINTN)
> MicrocodeEntryPoint) + SIZE_1KB);
> + continue;
> + }
>
> - //
> - // Save an in-complete CheckSum32 from CheckSum Part1 for common parts.
> - //
> - InCompleteCheckSum32 = CalculateSum32 (
> - (UINT32 *) MicrocodeEntryPoint,
> - TotalSize
> - );
> - InCompleteCheckSum32 -= MicrocodeEntryPoint->ProcessorSignature.Uint32;
> - InCompleteCheckSum32 -= MicrocodeEntryPoint->ProcessorFlags;
> - InCompleteCheckSum32 -= MicrocodeEntryPoint->Checksum;
> + //
> + // Save an in-complete CheckSum32 from CheckSum Part1 for common parts.
> + //
> + InCompleteCheckSum32 = CalculateSum32 (
> + (UINT32 *) MicrocodeEntryPoint,
> + TotalSize
> + );
> + InCompleteCheckSum32 -= MicrocodeEntryPoint->ProcessorSignature.Uint32;
> + InCompleteCheckSum32 -= MicrocodeEntryPoint->ProcessorFlags;
> + InCompleteCheckSum32 -= MicrocodeEntryPoint->Checksum;
>
> - if (MicrocodeEntryPoint->HeaderVersion == 0x1) {
> //
> // It is the microcode header. It is not the padding data between
> microcode patches
> // because the padding data should not include 0x00000001 and it
> should be the repeated
>
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