Re: [PATCH] UefiCpuPkg: Check invalid RegisterCpuFeature parameter

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

> -----Original Message-----
> From: Song, BinX
> Sent: Monday, December 11, 2017 6:00 PM
> To: Ni, Ruiyu <ruiyu.ni@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
> 
> 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.
The original function name IsXXXXCheck() is not good. Please do not follow the
same naming style. 

> 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.
I didn't mean to define a new MAX macro.
You just need to update the comments. 
> 
> 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