linux-kernel - Re: [PATCH v7 07/11] powerpc/powernv: Add platform support for stop instruction

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Message-ID: <1467952040.13193.0.camel@neuling.org>
Date:	Fri, 08 Jul 2016 14:27:20 +1000
From:	Michael Neuling <mikey@...ling.org>
To:	Shreyas B Prabhu <shreyas@...ux.vnet.ibm.com>, mpe@...erman.id.au
Cc:	benh@....ibm.com, paulus@...abs.org, ego@...ux.vnet.ibm.com,
	linuxppc-dev@...ts.ozlabs.org, linux-kernel@...r.kernel.org,
	maddy@...ux.vnet.ibm.com
Subject: Re: [PATCH v7 07/11] powerpc/powernv: Add platform support for stop
 instruction


> > > 
> > > @@ -439,7 +540,18 @@ timebase_resync:
> > >  	 */
> > >  	bne	cr4,clear_lock
> > >  
> > > -	/* Restore per core state */
> > > +	/*
> > > +	 * First thread in the core to wake up and its waking up
> > > with
> > > +	 * complete hypervisor state loss. Restore per core
> > > hypervisor
> > > +	 * state.
> > > +	 */
> > > +BEGIN_FTR_SECTION
> > > +	ld	r4,_PTCR(r1)
> > > +	mtspr	SPRN_PTCR,r4
> > > +	ld	r4,_RPR(r1)
> > > +	mtspr	SPRN_RPR,r4
> > RPR looks wrong here.  This should be on POWER8 too.
> > 
> > This has changed since v6 and not noted in the v7 comments.  Why are
> > you
> > changing this now?
> > 
> RPR is a per-core resource in P9. So with this patch, RPR will continue
> to be restored per-subcore in P8 and will restored once per core in P9.

Ok, thanks for the explanation.

Mikey