From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752546AbcFUGZa (ORCPT ); Tue, 21 Jun 2016 02:25:30 -0400 Received: from ozlabs.org ([103.22.144.67]:59993 "EHLO ozlabs.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751380AbcFUGZ1 convert rfc822-to-8bit (ORCPT ); Tue, 21 Jun 2016 02:25:27 -0400 Message-ID: <1466489657.25838.39.camel@neuling.org> Subject: Re: [v6, 08/11] powerpc/powernv: Add platform support for stop instruction From: Michael Neuling To: Shreyas B Prabhu , Michael Ellerman Cc: ego@linux.vnet.ibm.com, benh@au1.ibm.com, linux-kernel@vger.kernel.org, maddy@linux.vnet.ibm.com, linuxppc-dev@lists.ozlabs.org, Aneesh Kk Veetil Date: Tue, 21 Jun 2016 16:14:17 +1000 In-Reply-To: <5761518A.1040709@linux.vnet.ibm.com> References: <3rV3nm07hsz9t1V@ozlabs.org> <5761518A.1040709@linux.vnet.ibm.com> Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: 8BIT X-Mailer: Evolution 3.18.5.2-0ubuntu3 Mime-Version: 1.0 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org > > > +#define OPAL_PM_TIMEBASE_STOP 0x00000002 > > > +#define OPAL_PM_LOSE_HYP_CONTEXT 0x00002000 > > > +#define OPAL_PM_LOSE_FULL_CONTEXT 0x00004000 > > >  #define OPAL_PM_NAP_ENABLED 0x00010000 > > >  #define OPAL_PM_SLEEP_ENABLED 0x00020000 > > >  #define OPAL_PM_WINKLE_ENABLED 0x00040000 > > >  #define OPAL_PM_SLEEP_ENABLED_ER1 0x00080000 /* with > > > workaround */ > > > +#define OPAL_PM_STOP_INST_FAST 0x00100000 > > > +#define OPAL_PM_STOP_INST_DEEP 0x00200000 > > I don't see the above in skiboot yet? > I've posted it here - > http://patchwork.ozlabs.org/patch/617828/ FWIW, this is in now. https://github.com/open-power/skiboot/commit/952daa69baca407383bc900911f6c40718a0e289 > > > > > > > > > > diff --git a/arch/powerpc/include/asm/paca.h > > > b/arch/powerpc/include/asm/paca.h > > > index 546540b..ae91b44 100644 > > > --- a/arch/powerpc/include/asm/paca.h > > > +++ b/arch/powerpc/include/asm/paca.h > > > @@ -171,6 +171,8 @@ struct paca_struct { > > >   /* Mask to denote subcore sibling threads */ > > >   u8 subcore_sibling_mask; > > >  #endif > > > + /* Template for PSSCR with EC, ESL, TR, PSLL, MTL fields set > > > */ > > > + u64 thread_psscr; > > I'm not entirely clear on why that needs to be in the paca. Could it > > not be global? > > > While we use Requested Level (RL) field of PSSCR to request a stop > level, other fields in the SPR like EC, ESL, TR, PSLL, MTL can be > modified by individual threads less frequently to alter the behaviour of > stop. So the idea was to have a per-thread variable with all (except RL) > fields of PSSCR set appropriately. Threads at the time of entering idle, > can modify the RL field in the variable and execute stop instruction. But we don't do any of this currently? This is setup at init in pnv_init_idle_states() and only the RL is changed in power_stop(). So it can still be a global.  It could just be a constant currently even. >   .text > > >   > > >  /* > > > @@ -61,8 +75,19 @@ save_sprs_to_stack: > > >    * Note all register i.e per-core, per-subcore or per-thread > > > is saved > > >    * here since any thread in the core might wake up first > > >    */ > > > +BEGIN_FTR_SECTION > > > + mfspr r3,SPRN_PTCR > > > + std r3,_PTCR(r1) > > > + mfspr r3,SPRN_LMRR > > > + std r3,_LMRR(r1) > > > + mfspr r3,SPRN_LMSER > > > + std r3,_LMSER(r1) > > > + mfspr r3,SPRN_ASDR > > > + std r3,_ASDR(r1) > > > +FTR_SECTION_ELSE > > A comment here saying that SDR1 is removed in ISA 3.0 would be helpful. > > > Ok. I thought we decided we didn't need LMRR, LMSR,  https://lkml.org/lkml/2016/6/8/1121 or ASDR isn't actually used at all yet and is only valid for some page faults, so we don't need it here also. > +END_MMU_FTR_SECTION_IFCLR(MMU_FTR_RADIX) > > > + > > > + /* Restore per thread state */ > > > +BEGIN_FTR_SECTION > > > + bl      __restore_cpu_power9 > > > + > > > + ld r4,_LMRR(r1) > > > + mtspr SPRN_LMRR,r4 > > > + ld r4,_LMSER(r1) > > > + mtspr SPRN_LMSER,r4 > > > + ld r4,_ASDR(r1) > > > + mtspr SPRN_ASDR,r4 > > Should those be in __restore_cpu_power9 ? > I was not sure how these registers will be used, but after speaking to > Aneesh and Mikey I realized these registers will not need restoring. > LMRR and LMSER are associated with the context and ADSR will be consumed > before entering stop. So I'll be dropping the this hunk in next revision. Yep. >  > > >   pnv_alloc_idle_core_states(); > > >   > > > + if (supported_cpuidle_states & OPAL_PM_STOP_INST_FAST) > > > + for_each_possible_cpu(i) { > > > + > > > + u64 psscr_init_val = PSSCR_ESL | PSSCR_EC | > > > + PSSCR_PSLL_MASK | PSSCR_TR_MASK | > > > + PSSCR_MTL_MASK; > > > + > > > + paca[i].thread_psscr = psscr_init_val; This seems to be the only place you set this.  Why put it in the paca, why not just make this a constant?  Mikey