回复: [edk2-devel] [PATCH v1 1/1] Fix AsmReadMsr64() and AsmWriteMsr64() with GCC toolchain

["gaoliming" <gaoliming@byosoft.com.cn>]

Create PR https://github.com/tianocore/edk2/pull/1562 for it. 

Thanks
Liming
> -----邮件原件-----
> 发件人: devel@edk2.groups.io <devel@edk2.groups.io> 代表 gaoliming
> 发送时间: 2021年4月13日 9:16
> 收件人: devel@edk2.groups.io; naitaku@gmail.com
> 抄送: 'Michael D Kinney' <michael.d.kinney@intel.com>; 'Zhiguang Liu'
> <zhiguang.liu@intel.com>
> 主题: 回复: [edk2-devel] [PATCH v1 1/1] Fix AsmReadMsr64() and
> AsmWriteMsr64() with GCC toolchain
> 
> Naito:
>   The fix is correct. Reviewed-by: Liming Gao <gaoliming@byosoft.com.cn>
> 
> Thanks
> Liming
> > -----邮件原件-----
> > 发件人: devel@edk2.groups.io <devel@edk2.groups.io> 代表 Takuto
> Naito
> > 发送时间: 2021年4月12日 23:07
> > 收件人: devel@edk2.groups.io
> > 抄送: Takuto Naito <naitaku@gmail.com>; Michael D Kinney
> > <michael.d.kinney@intel.com>; Liming Gao <gaoliming@byosoft.com.cn>;
> > Zhiguang Liu <zhiguang.liu@intel.com>
> > 主题: [edk2-devel] [PATCH v1 1/1] Fix AsmReadMsr64() and
> AsmWriteMsr64()
> > with GCC toolchain
> >
> > REF: https://bugzilla.tianocore.org/show_bug.cgi?id=3325
> >
> > 1. AsmReadMsr64() in X64/GccInlinePriv.c
> > AsmReadMsr64 can return uninitialized value if FilterBeforeMsrRead
> > returns False. This causes build error with the CLANG toolchain.
> >
> > 2. AsmWriteMsr64() in X64/GccInlinePriv.c
> > In the case that FilterBeforeMsrWrite changes Value and returns True,
> > The original Value, not the changed Value, is written to the MSR.
> > This behavior is different from the one of AsmWriteMsr64() in
> > X64/WriteMsr64.c for the MSFT toolchain.
> >
> > Signed-off-by: Takuto Naito <naitaku@gmail.com>
> > Cc: Michael D Kinney <michael.d.kinney@intel.com>
> > Cc: Liming Gao <gaoliming@byosoft.com.cn>
> > Cc: Zhiguang Liu <zhiguang.liu@intel.com>
> > ---
> >  MdePkg/Library/BaseLib/X64/GccInlinePriv.c | 7 +++----
> >  1 file changed, 3 insertions(+), 4 deletions(-)
> >
> > diff --git a/MdePkg/Library/BaseLib/X64/GccInlinePriv.c
> > b/MdePkg/Library/BaseLib/X64/GccInlinePriv.c
> > index e4920f2116..244bd62ee6 100644
> > --- a/MdePkg/Library/BaseLib/X64/GccInlinePriv.c
> > +++ b/MdePkg/Library/BaseLib/X64/GccInlinePriv.c
> > @@ -80,7 +80,7 @@ AsmReadMsr64 (
> >    }
> >    FilterAfterMsrRead (Index, &Value);
> >
> > -  return (((UINT64)HighData) << 32) | LowData;
> > +  return Value;
> >  }
> >
> >  /**
> > @@ -111,11 +111,10 @@ AsmWriteMsr64 (
> >    UINT32 HighData;
> >    BOOLEAN Flag;
> >
> > -  LowData  = (UINT32)(Value);
> > -  HighData = (UINT32)(Value >> 32);
> > -
> >    Flag = FilterBeforeMsrWrite (Index, &Value);
> >    if (Flag) {
> > +    LowData  = (UINT32)(Value);
> > +    HighData = (UINT32)(Value >> 32);
> >      __asm__ __volatile__ (
> >        "wrmsr"
> >        :
> > --
> > 2.31.1
> >
> >
> >
> >
> >
> 
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