Re: [edk2-devel] Avoid split lock detection warnings triggered by OVMF?

["Friedrich Weber" <f.weber@proxmox.com>]

Thank you for your fast answer!

On 05/06/2025 09:04, Ard Biesheuvel wrote:
> Thanks for the elaborate report. Does the following help?
> 
> diff --git a/UefiCpuPkg/Library/MpInitLib/MpLib.h
> b/UefiCpuPkg/Library/MpInitLib/MpLib.h
> index a63bb81bef88..a9b3fa77e14d 100644
> --- a/UefiCpuPkg/Library/MpInitLib/MpLib.h
> +++ b/UefiCpuPkg/Library/MpInitLib/MpLib.h
> @@ -213,8 +213,6 @@ typedef struct {
>    UINTN              StackStart;
>    UINTN              StackSize;
>    UINTN              CFunction;
> -  IA32_DESCRIPTOR    GdtrProfile;
> -  IA32_DESCRIPTOR    IdtrProfile;
>    UINTN              BufferStart;
>    UINTN              ModeOffset;
>    UINTN              ApIndex;
> @@ -227,6 +225,8 @@ typedef struct {
>    UINTN              NumApsExecuting;
>    CPU_MP_DATA        *CpuMpData;
>    UINTN              InitializeFloatingPointUnitsAddress;
> +  IA32_DESCRIPTOR    GdtrProfile;
> +  IA32_DESCRIPTOR    IdtrProfile;
>    UINT32             ModeTransitionMemory;
>    UINT16             ModeTransitionSegment;
>    UINT32             ModeHighMemory;
> diff --git a/UefiCpuPkg/Library/MpInitLib/MpEqu.inc
> b/UefiCpuPkg/Library/MpInitLib/MpEqu.inc
> index d8ba9ea1246c..d67c4c923c82 100644
> --- a/UefiCpuPkg/Library/MpInitLib/MpEqu.inc
> +++ b/UefiCpuPkg/Library/MpInitLib/MpEqu.inc
> @@ -74,8 +74,6 @@ struc MP_CPU_EXCHANGE_INFO
>    .StackStart:                   CTYPE_UINTN 1
>    .StackSize:                    CTYPE_UINTN 1
>    .CFunction:                    CTYPE_UINTN 1
> -  .GdtrProfile:                  CTYPE_UINT8 IA32_DESCRIPTOR_size
> -  .IdtrProfile:                  CTYPE_UINT8 IA32_DESCRIPTOR_size
>    .BufferStart:                  CTYPE_UINTN 1
>    .ModeOffset:                   CTYPE_UINTN 1
>    .ApIndex:                      CTYPE_UINTN 1
> @@ -88,6 +86,8 @@ struc MP_CPU_EXCHANGE_INFO
>    .NumApsExecuting:              CTYPE_UINTN 1
>    .CpuMpData:                    CTYPE_UINTN 1
>    .InitializeFloatingPointUnits: CTYPE_UINTN 1
> +  .GdtrProfile:                  CTYPE_UINT8 IA32_DESCRIPTOR_size
> +  .IdtrProfile:                  CTYPE_UINT8 IA32_DESCRIPTOR_size
>    .ModeTransitionMemory:         CTYPE_UINT32 1
>    .ModeTransitionSegment:        CTYPE_UINT16 1
>    .ModeHighMemory:               CTYPE_UINT32 1

Applied this on top of 8c04bcc7ed, and the minimal reproducer doesn't
trigger any split lock warnings anymore. I also booted some
Linux+Windows test VMs with a patched firmware build and didn't see any
split lock warnings caused by OVMF (the Windows VMs seem to occasionally
trigger some when booted, but this is a different issue).



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