From mboxrd@z Thu Jan 1 00:00:00 1970 From: Gautham R Shenoy Subject: Re: [PATCH 5/5] powernv:idle: Disable LOSE_FULL_CONTEXT states when stop-api fails. Date: Fri, 7 Jul 2017 23:07:10 +0530 Message-ID: <20170707173710.GE8913@in.ibm.com> References: <1499272696-28751-1-git-send-email-ego@linux.vnet.ibm.com> <1499272696-28751-6-git-send-email-ego@linux.vnet.ibm.com> <20170707012916.215ed32a@roar.ozlabs.ibm.com> Reply-To: ego@linux.vnet.ibm.com Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Return-path: Received: from mx0b-001b2d01.pphosted.com ([148.163.158.5]:35665 "EHLO mx0a-001b2d01.pphosted.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1751915AbdGGRhc (ORCPT ); Fri, 7 Jul 2017 13:37:32 -0400 Received: from pps.filterd (m0098420.ppops.net [127.0.0.1]) by mx0b-001b2d01.pphosted.com (8.16.0.20/8.16.0.20) with SMTP id v67HNeme055684 for ; Fri, 7 Jul 2017 13:37:31 -0400 Received: from e37.co.us.ibm.com (e37.co.us.ibm.com [32.97.110.158]) by mx0b-001b2d01.pphosted.com with ESMTP id 2bjcmjd6bn-1 (version=TLSv1.2 cipher=AES256-SHA bits=256 verify=NOT) for ; Fri, 07 Jul 2017 13:37:31 -0400 Received: from localhost by e37.co.us.ibm.com with IBM ESMTP SMTP Gateway: Authorized Use Only! Violators will be prosecuted for from ; Fri, 7 Jul 2017 11:37:30 -0600 Content-Disposition: inline In-Reply-To: <20170707012916.215ed32a@roar.ozlabs.ibm.com> Sender: linux-pm-owner@vger.kernel.org List-Id: linux-pm@vger.kernel.org To: Nicholas Piggin Cc: "Gautham R. Shenoy" , Michael Ellerman , Michael Neuling , Vaidyanathan Srinivasan , Shilpasri G Bhat , "Rafael J. Wysocki" , Akshay Adiga , linuxppc-dev@lists.ozlabs.org, linux-kernel@vger.kernel.org, linux-pm@vger.kernel.org On Fri, Jul 07, 2017 at 01:29:16AM +1000, Nicholas Piggin wrote: > On Wed, 5 Jul 2017 22:08:16 +0530 > "Gautham R. Shenoy" wrote: > > > From: "Gautham R. Shenoy" > > > > Currently, we use the opal call opal_slw_set_reg() to inform the that > > the Sleep-Winkle Engine (SLW) to restore the contents of some of the > > Hypervisor state on wakeup from deep idle states that lose full > > hypervisor context (characterized by the flag > > OPAL_PM_LOSE_FULL_CONTEXT). > > > > However, the current code has a bug in that if opal_slw_set_reg() > > fails, we don't disable the use of these deep states (winkle on > > POWER8, stop4 onwards on POWER9). > > > > This patch fixes this bug by ensuring that if the the sleep winkle > > engine is unable to restore the hypervisor states in > > pnv_save_sprs_for_deep_states(), then we mark as invalid the states > > which lose full context. > > > > As a side-effect, since supported_cpuidle_states in > > pnv_probe_idle_states() consists of flags of only the valid states, > > this patch will ensure that no other subsystem in the kernel can use > > the states which lose full context on stop-api failures. > > Looks good. Is there something minimal we can do for stable here? > > Aside question, do we need to restore LPCR at all with the SLW engine? > It gets set up again when by the idle wakeup code. > > And does POWER9 really need MSR and PSSCR restored by SLW? (going a bit > off topic here, I'm just curious) MSR is needed to be restored so that we wakeup with the right endianness and with the IR,DR disabled. PSSCR is set to a value so that in case of a special wakeup for a deep-stop, the SLW can program the core to go back to the stop level provided by the PSSCR value via the stop-api. > > Thanks, > Nick > -- Thanks and Regards gautham.