Re: [PATCH] UefiCpuPkg/MpInitLib: AP uses memory preceding IDT to store CpuMpData

[Laszlo Ersek <lersek@redhat.com>]

Hello Ray,

On 06/25/18 04:54, Ruiyu Ni wrote:
> Today's MpInitLib PEI implementation directly calls
> PeiServices->GetHobList() from AP which may cause racing issue.
>
> This patch fixes this issue by storing the CpuMpData to memory
> preceding IDT. Pointer to PeiServices pointer is stored there,
> so after AP procedure returns, the PeiServices pointer should be
> restored.
>
> Contributed-under: TianoCore Contribution Agreement 1.1
> Signed-off-by: Ruiyu Ni <ruiyu.ni@intel.com>
> Cc: Jeff Fan <vanjeff_919@hotmail.com>
> Cc: Eric Dong <eric.dong@intel.com>
> Cc: Jiewen Yao <jiewen.yao@intel.com>
> Cc: Fish Andrew <afish@apple.com>
> ---
>  UefiCpuPkg/Library/MpInitLib/DxeMpLib.c | 33 ++++++++++++++++++-
>  UefiCpuPkg/Library/MpInitLib/MpLib.c    |  8 +++++
>  UefiCpuPkg/Library/MpInitLib/MpLib.h    | 27 +++++++++++++++-
>  UefiCpuPkg/Library/MpInitLib/PeiMpLib.c | 56 +++++++++++++++++++++++++++++++--
>  4 files changed, 119 insertions(+), 5 deletions(-)
>
> diff --git a/UefiCpuPkg/Library/MpInitLib/DxeMpLib.c b/UefiCpuPkg/Library/MpInitLib/DxeMpLib.c
> index e7ed21c6cd..26fead2c66 100644
> --- a/UefiCpuPkg/Library/MpInitLib/DxeMpLib.c
> +++ b/UefiCpuPkg/Library/MpInitLib/DxeMpLib.c

[snip]

> +/**
> +  Pop the CpuMpData.
> +
> +  @param[in] Pointer  The pointer value which was stored in where the CPU MP Data is pushed.
> +  @param[in] Context  The context of push/pop operation.
> +**/
> +VOID
> +PopCpuMpData (
> +  IN VOID           *Pointer,
> +  IN VOID           *Context
> +  )
> +{

(1) When I applied this patch for regression-testing, "git am"
complained that the above line added two trailing space characters. Can
you please remove them?

(2) Other than that, I tested this patch with OVMF -- the patch breaks
OVMF. The last part of the log is:

> Loading PEIM [CpuMpPei]
> Loading PEIM at 0x000BFE81000 EntryPoint=0x000BFE86DC6 CpuMpPei.efi
> AP Loop Mode is 1
> WakeupBufferStart = 9F000, WakeupBufferSize = 1000
> TimedWaitForApFinish: reached FinishedApLimit=7 in 121 microseconds
> APIC MODE is 1
> MpInitLib: Find 8 processors in system.
> Does not find any stored CPU BIST information from PPI!
>   APICID - 0x00000000, BIST - 0x00000000
>   APICID - 0x00000001, BIST - 0x00000000
>   APICID - 0x00000002, BIST - 0x00000000
>   APICID - 0x00000003, BIST - 0x00000000
>   APICID - 0x00000004, BIST - 0x00000000
>   APICID - 0x00000005, BIST - 0x00000000
>   APICID - 0x00000006, BIST - 0x00000000
>   APICID - 0x00000007, BIST - 0x00000000
> Install PPI: [EfiSecPlatformInformation2Ppi]
> Install PPI: [EfiPeiMpServicesPpi]
> Notify: PPI Guid: [EfiPeiMpServicesPpi], Peim notify entry point: 8524F8
> PlatformPei: OnMpServicesAvailable

The last line is printed by OvmfPkg/PlatformPei, in
"OvmfPkg/PlatformPei/FeatureControl.c". OVMF uses
EFI_PEI_MP_SERVICES_PPI to write the Feature Control MSR on all CPUs.

https://github.com/tianocore/tianocore.github.io/wiki/Testing-SMM-with-QEMU,-KVM-and-libvirt#enable-nested-virtualization
https://github.com/tianocore/tianocore.github.io/wiki/Testing-SMM-with-QEMU,-KVM-and-libvirt#confirm-simple-multiprocessing-during-boot

Thanks,
Laszlo