Re: [PATCH v2] UefiCpuPkg/DxeMpLib: Allocate below 4GB mem for AsmRelocateApLoopFunc

["Fan, Jeff" <jeff.fan@intel.com>]

Laszlo,

Good catch before I push this serial of patch. I will remove sizeof() when I push the patch.

Thanks!
Jeff

-----Original Message-----
From: Laszlo Ersek [mailto:lersek@redhat.com] 
Sent: Tuesday, November 15, 2016 9:40 AM
To: Fan, Jeff; edk2-devel@ml01.01.org
Cc: Kinney, Michael D; Paolo Bonzini; Yao, Jiewen
Subject: Re: [edk2] [PATCH v2] UefiCpuPkg/DxeMpLib: Allocate below 4GB mem for AsmRelocateApLoopFunc

Jeff,

independently from the other discussion, I found a small mistake in this patch (after I reviewed, tested, and committed it for you...):

On 11/11/16 09:56, Jeff Fan wrote:
> Current implementation just allocates reserve memory for AsmRelocateApLoopFunc.
> It not be safe because APs will be placed into 32bit protected mode on 
> long mode DXE. This reserve memory must be located below 4GB memory.
> 
> This fix is to allocate < 4GB memory for AsmRelocateApLoopFunc.
> 
> Cc: Laszlo Ersek <lersek@redhat.com>
> Cc: Paolo Bonzini <pbonzini@redhat.com>
> Cc: Jiewen Yao <jiewen.yao@intel.com>
> Cc: Michael D Kinney <michael.d.kinney@intel.com>
> Contributed-under: TianoCore Contribution Agreement 1.0
> Signed-off-by: Jeff Fan <jeff.fan@intel.com>
> ---
>  UefiCpuPkg/Library/MpInitLib/DxeMpLib.c | 27 
> ++++++++++++++++++++-------
>  1 file changed, 20 insertions(+), 7 deletions(-)
> 
> diff --git a/UefiCpuPkg/Library/MpInitLib/DxeMpLib.c 
> b/UefiCpuPkg/Library/MpInitLib/DxeMpLib.c
> index eb36d6f..4b929ff 100644
> --- a/UefiCpuPkg/Library/MpInitLib/DxeMpLib.c
> +++ b/UefiCpuPkg/Library/MpInitLib/DxeMpLib.c
> @@ -286,7 +286,8 @@ InitMpGlobalData (
>    IN CPU_MP_DATA               *CpuMpData
>    )
>  {
> -  EFI_STATUS     Status;
> +  EFI_STATUS                 Status;
> +  EFI_PHYSICAL_ADDRESS       Address;
>  
>    SaveCpuMpData (CpuMpData);
>  
> @@ -298,16 +299,28 @@ InitMpGlobalData (
>    }
>  
>    //
> -  // Avoid APs access invalid buff data which allocated by 
> BootServices,
> -  // so we will allocate reserved data for AP loop code.
> +  // Avoid APs access invalid buffer data which allocated by 
> + BootServices,  // so we will allocate reserved data for AP loop 
> + code. We also need to  // allocate this buffer below 4GB due to APs 
> + may be transferred to 32bit  // protected mode on long mode DXE.
>    // Allocating it in advance since memory services are not available in
>    // Exit Boot Services callback function.
>    //
> -  mReservedApLoopFunc = AllocateReservedCopyPool (
> -                          CpuMpData->AddressMap.RelocateApLoopFuncSize,
> -                          CpuMpData->AddressMap.RelocateApLoopFuncAddress
> -                          );
> +  Address = BASE_4GB - 1;
> +  Status  = gBS->AllocatePages (
> +                   AllocateMaxAddress,
> +                   EfiReservedMemoryType,
> +                   EFI_SIZE_TO_PAGES (sizeof 
> + (CpuMpData->AddressMap.RelocateApLoopFuncSize)),

The "sizeof" operator should be unnecessary here.

(It is no problem in practice because the function size is really small, so it gets rounded up to 1 page anyway.)

Sorry for not noticing this earlier.

Thanks
Laszlo

> +                   &Address
> +                   );
> +  ASSERT_EFI_ERROR (Status);
> +  mReservedApLoopFunc = (VOID *) (UINTN) Address;
>    ASSERT (mReservedApLoopFunc != NULL);
> +  CopyMem (
> +    mReservedApLoopFunc,
> +    CpuMpData->AddressMap.RelocateApLoopFuncAddress,
> +    CpuMpData->AddressMap.RelocateApLoopFuncSize
> +    );
>  
>    Status = gBS->CreateEvent (
>                    EVT_TIMER | EVT_NOTIFY_SIGNAL,
>