Re: [PATCH] UefiCpuPkg: Check invalid RegisterCpuFeature parameter

["Song, BinX" <binx.song@intel.com>]

Hi Ray,

Below is my opinions for your 2 questions:
1. Can we rename this function name to "RegisterCpuFeatureLibIsFeatureValid"?
[Bell]: In content of RegisterCpuFeaturesLib.c, there is a function named IsBitMaskMatchCheck(), it's my function's base, they have similar function - a small valid/invalid check,
So I think it is better to keep them align.
2. Can we just say "CPU_FEATURE_PROC_TRACE" is the MAX feature we support?
[Bell]: Discussed with Eric before, we should not define this as a MAX feature for future extension purpose.

Best Regards,
Bell Song


> -----Original Message-----
> From: Ni, Ruiyu
> Sent: Monday, December 11, 2017 5:40 PM
> To: Song, BinX <binx.song@intel.com>; edk2-devel@lists.01.org
> Cc: lersek@redhat.com; Dong, Eric <eric.dong@intel.com>
> Subject: Re: [edk2] [PATCH] UefiCpuPkg: Check invalid RegisterCpuFeature
> parameter
> 
> On 12/11/2017 4:16 PM, Song, BinX wrote:
> > Check and assert invalid RegisterCpuFeature function parameter
> >
> > Cc: Eric Dong <eric.dong@intel.com>
> > Cc: Laszlo Ersek <lersek@redhat.com>
> > Contributed-under: TianoCore Contribution Agreement 1.1
> > Signed-off-by: Bell Song <binx.song@intel.com>
> > ---
> >   .../Include/Library/RegisterCpuFeaturesLib.h       |  4 ++++
> >   .../RegisterCpuFeaturesLib.c                       | 28 ++++++++++++++++++++++
> >   2 files changed, 32 insertions(+)
> >
> > diff --git a/UefiCpuPkg/Include/Library/RegisterCpuFeaturesLib.h
> b/UefiCpuPkg/Include/Library/RegisterCpuFeaturesLib.h
> > index 9331e49..54244cd 100644
> > --- a/UefiCpuPkg/Include/Library/RegisterCpuFeaturesLib.h
> > +++ b/UefiCpuPkg/Include/Library/RegisterCpuFeaturesLib.h
> > @@ -72,6 +72,10 @@
> >   #define CPU_FEATURE_ENERGY_PERFORMANCE_BIAS         (32+10)
> >   #define CPU_FEATURE_PPIN                            (32+11)
> > +//
> > +// When you add new CPU features, please also replace the minor CPU
> feature
> > +// with the max CPU feature in the IsFeatureValidCheck() function.
> > +//
> >   #define CPU_FEATURE_PROC_TRACE                      (32+12)
> >
> >   #define CPU_FEATURE_BEFORE_ALL                      BIT27
> >   #define CPU_FEATURE_AFTER_ALL                       BIT28
> > diff --git
> a/UefiCpuPkg/Library/RegisterCpuFeaturesLib/RegisterCpuFeaturesLib.c
> b/UefiCpuPkg/Library/RegisterCpuFeaturesLib/RegisterCpuFeaturesLib.c
> > index dd6a82b..f75d900 100644
> > ---
> a/UefiCpuPkg/Library/RegisterCpuFeaturesLib/RegisterCpuFeaturesLib.c
> > +++
> b/UefiCpuPkg/Library/RegisterCpuFeaturesLib/RegisterCpuFeaturesLib.c
> > @@ -81,6 +81,33 @@ DumpCpuFeature (
> >   }
> >
> >   /**
> > +  Determines if the CPU feature is valid.
> > +
> > +  @param[in]  Feature        Pointer to CPU feature
> > +
> > +  @retval TRUE  The CPU feature is valid.
> > +  @retval FALSE The CPU feature is invalid.
> > +**/
> > +BOOLEAN
> > +IsFeatureValidCheck (
> Can we rename this function name to
> "RegisterCpuFeatureLibIsFeatureValid"?
> 
> 
> > +  IN UINT32        Feature
> > +  )
> > +{
> > +  UINT32      Data;
> > +
> > +  Data = Feature;
> > +  Data &= ~(CPU_FEATURE_BEFORE | CPU_FEATURE_AFTER |
> CPU_FEATURE_BEFORE_ALL | CPU_FEATURE_AFTER_ALL);
> > +  //
> > +  // Please replace CPU feature below with the MAX one if have.
> Can we just say "CPU_FEATURE_PROC_TRACE" is the MAX feature we
> support?
> 
> 
> > +  //
> > +  if (Data > CPU_FEATURE_PROC_TRACE) {
> > +    DEBUG ((DEBUG_ERROR, "Invalid CPU feature: 0x%x ", Feature));
> > +    return FALSE;
> > +  }
> > +  return TRUE;
> > +}
> > +
> > +/**
> >     Determines if the feature bit mask is in dependent CPU feature bit mask
> buffer.
> >
> >     @param[in]  FeatureMask        Pointer to CPU feature bit mask
> > @@ -444,6 +471,7 @@ RegisterCpuFeature (
> >
> >     VA_START (Marker, InitializeFunc);
> >     Feature = VA_ARG (Marker, UINT32);
> > +  ASSERT (IsFeatureValidCheck(Feature));
> >     while (Feature != CPU_FEATURE_END) {
> >       ASSERT ((Feature & (CPU_FEATURE_BEFORE | CPU_FEATURE_AFTER))
> >                       != (CPU_FEATURE_BEFORE | CPU_FEATURE_AFTER));
> >
> 
> 
> --
> Thanks,
> Ray