Re: [PATCH] UefiCpuPkg/MtrrLib: Fix MtrrDebugPrintAllMtrrsWorker to avoid hang

["Ni, Ruiyu" <ruiyu.ni@intel.com>]

Thanks Steven.

All,
I will check in this patch ASAP.
Because it's just a bug fix in a corner of implementation and it may cause all system hang.


-----Original Message-----
From: Shi, Steven 
Sent: Tuesday, October 17, 2017 10:04 AM
To: Ni, Ruiyu <ruiyu.ni@intel.com>; edk2-devel@lists.01.org
Cc: Laszlo Ersek <lersek@redhat.com>
Subject: RE: [PATCH] UefiCpuPkg/MtrrLib: Fix MtrrDebugPrintAllMtrrsWorker to avoid hang

Reviewed-by: Steven Shi <steven.shi@intel.com>


Steven Shi
Intel\SSG\STO\UEFI Firmware

Tel: +86 021-61166522
iNet: 821-6522


> -----Original Message-----
> From: Ni, Ruiyu
> Sent: Tuesday, October 17, 2017 9:47 AM
> To: edk2-devel@lists.01.org
> Cc: Shi, Steven <steven.shi@intel.com>; Laszlo Ersek 
> <lersek@redhat.com>
> Subject: [PATCH] UefiCpuPkg/MtrrLib: Fix MtrrDebugPrintAllMtrrsWorker 
> to avoid hang
> 
> ARRAY_SIZE(Mtrrs->Variables.Mtrr) was used in
> MtrrDebugPrintAllMtrrsWorker() to parse the MTRR registers.
> Instead, the actual variable MTRR count should be used.
> Otherwise, the uninitialized random data in MtrrSetting may cause
> MtrrLibSetMemoryType() hang.
> 
> Steven Shi found this bug in QEMU when using Q35 chip.
> 
> Contributed-under: TianoCore Contribution Agreement 1.1
> Signed-off-by: Ruiyu Ni <ruiyu.ni@intel.com>
> Cc: Steven Shi <steven.shi@intel.com>
> Cc: Laszlo Ersek <lersek@redhat.com>
> ---
>  UefiCpuPkg/Library/MtrrLib/MtrrLib.c | 9 ++++++---
>  1 file changed, 6 insertions(+), 3 deletions(-)
> 
> diff --git a/UefiCpuPkg/Library/MtrrLib/MtrrLib.c
> b/UefiCpuPkg/Library/MtrrLib/MtrrLib.c
> index 2fd1d0153e..cb22558103 100644
> --- a/UefiCpuPkg/Library/MtrrLib/MtrrLib.c
> +++ b/UefiCpuPkg/Library/MtrrLib/MtrrLib.c
> @@ -2776,6 +2776,7 @@ MtrrDebugPrintAllMtrrsWorker (
>      UINTN             RangeCount;
>      UINT64            MtrrValidBitsMask;
>      UINT64            MtrrValidAddressMask;
> +    UINT32            VariableMtrrCount;
>      MTRR_MEMORY_RANGE Ranges[
>        ARRAY_SIZE (mMtrrLibFixedMtrrTable) * sizeof (UINT64) + 2 * 
> ARRAY_SIZE (Mtrrs->Variables.Mtrr) + 1
>        ];
> @@ -2785,6 +2786,8 @@ MtrrDebugPrintAllMtrrsWorker (
>        return;
>      }
> 
> +    VariableMtrrCount = GetVariableMtrrCountWorker ();
> +
>      if (MtrrSetting != NULL) {
>        Mtrrs = MtrrSetting;
>      } else {
> @@ -2802,7 +2805,7 @@ MtrrDebugPrintAllMtrrsWorker (
>        DEBUG((DEBUG_CACHE, "Fixed MTRR[%02d]   : %016lx\n", Index, Mtrrs-
> >Fixed.Mtrr[Index]));
>      }
> 
> -    for (Index = 0; Index < ARRAY_SIZE (Mtrrs->Variables.Mtrr); Index++) {
> +    for (Index = 0; Index < VariableMtrrCount; Index++) {
>        if (((MSR_IA32_MTRR_PHYSMASK_REGISTER *)&Mtrrs-
> >Variables.Mtrr[Index].Mask)->Bits.V == 0) {
>          //
>          // If mask is not valid, then do not display range @@ 
> -2829,11 +2832,11 @@ MtrrDebugPrintAllMtrrsWorker (
>      RangeCount = 1;
> 
>      MtrrLibGetRawVariableRanges (
> -      &Mtrrs->Variables, ARRAY_SIZE (Mtrrs->Variables.Mtrr),
> +      &Mtrrs->Variables, VariableMtrrCount,
>        MtrrValidBitsMask, MtrrValidAddressMask, RawVariableRanges
>        );
>      MtrrLibApplyVariableMtrrs (
> -      RawVariableRanges, ARRAY_SIZE (RawVariableRanges),
> +      RawVariableRanges, VariableMtrrCount,
>        Ranges, ARRAY_SIZE (Ranges), &RangeCount
>        );
> 
> --
> 2.12.2.windows.2