Re: [PATCH] powercap/rapl: prevent overridding bits outside of the mask

[Jacob Pan <jacob.jun.pan@linux.intel.com>]

On Tue, 27 Jun 2017 02:17:32 +0200
"Rafael J. Wysocki" <rjw@rjwysocki.net> wrote:

> On Thursday, June 01, 2017 11:21:50 AM Adam Lessnau wrote:
> > Fixes wrong bits shift operation in the rapl_write_data_raw
> > function, which might cause overridding bits outside of the mask.
> > 
> > For example, writing new TIME_WINDOW1 value can override
> > POWER_LIMIT1.
> > 
> > Signed-off-by: Adam Lessnau <adam.lessnau@intel.com>  
> 
> Jacob, any comments?
> 
Looks like a good fix. Thanks.
> > ---
> >  drivers/powercap/intel_rapl.c | 4 +++-
> >  1 file changed, 3 insertions(+), 1 deletion(-)
> > 
> > diff --git a/drivers/powercap/intel_rapl.c
> > b/drivers/powercap/intel_rapl.c index 3c71f608b444..6dc27afb8527
> > 100644 --- a/drivers/powercap/intel_rapl.c
> > +++ b/drivers/powercap/intel_rapl.c
> > @@ -887,7 +887,9 @@ static int rapl_write_data_raw(struct
> > rapl_domain *rd, 
> >  	cpu = rd->rp->lead_cpu;
> >  	bits = rapl_unit_xlate(rd, rp->unit, value, 1);
> > -	bits |= bits << rp->shift;
> > +	bits <<= rp->shift;
> > +	bits &= rp->mask;
> > +
> >  	memset(&ma, 0, sizeof(ma));
> >  
> >  	ma.msr_no = rd->msrs[rp->id];
> >   
> 

[Jacob Pan]