On Wed, Mar 15, 2023 at 02:11:57PM +0530, rhythm.m.mahajan@xxxxxxxxxx wrote:
>
>
> On 15/03/23 1:27 pm, Greg KH wrote:
> > On Tue, Mar 14, 2023 at 04:11:59AM -0700, Rhythm Mahajan wrote:
> > > The commit: 3f235279828c ("x86/cpu: Restore AMD's DE_CFG MSR after resume")
> > > renamed the MSR_F10H_DECFG_LFENCE_SERIALIZE macro to
> > > MSR_AMD64_DE_CFG_LFENCE_SERIALIZE.
> > > The fix changed MSR_F10H_DECFG_LFENCE_SERIALIZE to
> > > MSR_AMD64_DE_CFG_LFENCE_SERIALIZE_BIT in the init_amd() function,
> > > but should have used MSR_AMD64_DE_CFG_LFENCE_SERIALIZE.
> > > This causes a discrepancy in the LFENCE serialization
> > > check in the init_amd() function.
> > >
> > > This causes a ~16% sysbench memory regression, when running:
> > > sysbench --test=memory run
> > >
> > > Fixes: 3f235279828c2a8aff3164fef08d58f7af2d64fc("x86/cpu: Restore AMD's DE_CFG MSR after resume
> > > ")
> >
> > Odd line-wrapping :(
> >
> > And please use the proper way to reference SHA1 as documented in the
> > kernel documentation.
> Thanks, I will send a v2 for this.
> >
> > And why is this only needed in 4.14.y? What about Linus's tree and all
> > of the other stable trees?
> The regression was introduced after the backport of 2632daebafd0 ("x86/cpu:
> Restore AMD's DE_CFG MSR after resume") for 4.14.y and 4.9.y.
> Mainline and other stable don't have this regression.
> The fix is only needed for 4.14.y and 4.9.y.
Ah, then please make this more obvious in your changelog text that this
is a problem that is only caused by the backport and is not relevant
anywhere else.
thanks,
greg k-h
