Re: [edk2-devel] [PATCH 1/1] UefiCpuPkg/MpInitLib: Always initialize the DoDecrement variable

["Liming Gao" <liming.gao@intel.com>]

Laszlo:

> -----Original Message-----
> From: devel@edk2.groups.io <devel@edk2.groups.io> On Behalf Of Laszlo Ersek
> Sent: Wednesday, August 19, 2020 5:24 PM
> To: Tom Lendacky <thomas.lendacky@amd.com>; devel@edk2.groups.io
> Cc: Gao, Liming <liming.gao@intel.com>; Dong, Eric <eric.dong@intel.com>; Ni, Ray <ray.ni@intel.com>; Kumar, Rahul1
> <rahul1.kumar@intel.com>
> Subject: Re: [edk2-devel] [PATCH 1/1] UefiCpuPkg/MpInitLib: Always initialize the DoDecrement variable
> 
> On 08/18/20 15:10, Tom Lendacky wrote:
> > From: Tom Lendacky <thomas.lendacky@amd.com>
> >
> > REF: https://bugzilla.tianocore.org/show_bug.cgi?id=2901
> >
> > The DoDecrement variable in ApWakeupFunction () wasn't always being
> > initialized. Update the code to always fully initialize it.
> >
> > Cc: Eric Dong <eric.dong@intel.com>
> > Cc: Ray Ni <ray.ni@intel.com>
> > Cc: Laszlo Ersek <lersek@redhat.com>
> > Cc: Rahul Kumar <rahul1.kumar@intel.com>
> > Signed-off-by: Tom Lendacky <thomas.lendacky@amd.com>
> > ---
> >  UefiCpuPkg/Library/MpInitLib/MpLib.c | 4 +---
> >  1 file changed, 1 insertion(+), 3 deletions(-)
> >
> > diff --git a/UefiCpuPkg/Library/MpInitLib/MpLib.c b/UefiCpuPkg/Library/MpInitLib/MpLib.c
> > index 90416c81b616..e24bdc64f930 100644
> > --- a/UefiCpuPkg/Library/MpInitLib/MpLib.c
> > +++ b/UefiCpuPkg/Library/MpInitLib/MpLib.c
> > @@ -885,9 +885,7 @@ ApWakeupFunction (
> >            UINT64                    Status;
> >            BOOLEAN                   DoDecrement;
> >
> > -          if (CpuMpData->InitFlag == ApInitConfig) {
> > -            DoDecrement = TRUE;
> > -          }
> > +          DoDecrement = (CpuMpData->InitFlag == ApInitConfig) ? TRUE : FALSE;
> >
> >            while (TRUE) {
> >              Msr.GhcbPhysicalAddress = AsmReadMsr64 (MSR_SEV_ES_GHCB);
> >
> 
> Not that I want to obsess about style, but
> 
>   (condition) ? TRUE : FALSE
> 
> is an anti-patter that's similar to
> 
>   (condition) == TRUE
> 
> Instead, I suggest:
> 
>   DoDecrement = (BOOLEAN)(CpuMpData->InitFlag == ApInitConfig);
> 
> (The (BOOLEAN) cast is necessary, or at least used to be necessary,
> becasue the == operator returns "int" (INT32), but BOOLEAN (i.e., the
> type of "DoDecrement") is UINT8 -- and some VS toolchains perceive (or
> used to perceive) this implicit conversion as a "potential loss of
> precision". That warning is of course bogus, as the == operator only
> produces 0 or 1, each of which values fits comfortably into a UINT8. But
> still the explicit (BOOLEAN) cast is how we suppress the warning.)

I agree this style is simpler than before. 
> 
> Different question: who's supposed to merge (v2 of) this? Per
> "Maintainers.txt", it should be Eric or Ray; OTOH, maybe the fix is
> urgent (build failure with CLANGPDB) and anyone with push access could
> qualify.
This fix needs to catch this stable tag. Once the package maintainer reviews it, I will merge it. 

Thanks
Liming
> 
> Thanks,
> Laszlo
> 
> 
>