Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753222AbdGSITH (ORCPT ); Wed, 19 Jul 2017 04:19:07 -0400 Received: from mx0b-001b2d01.pphosted.com ([148.163.158.5]:47793 "EHLO mx0a-001b2d01.pphosted.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1752190AbdGSITD (ORCPT ); Wed, 19 Jul 2017 04:19:03 -0400 From: "Gautham R. Shenoy" To: Michael Ellerman , Michael Neuling , Nicholas Piggin , Vaidyanathan Srinivasan , Shilpasri G Bhat , Akshay Adiga Cc: linuxppc-dev@lists.ozlabs.org, linux-kernel@vger.kernel.org, "Gautham R. Shenoy" Subject: [v2 PATCH 0/2] powerpc: powernv: Enable stop4 via cpuidle Date: Wed, 19 Jul 2017 13:48:48 +0530 X-Mailer: git-send-email 1.8.3.1 X-TM-AS-GCONF: 00 x-cbid: 17071908-0024-0000-0000-000002B27438 X-IBM-SpamModules-Scores: X-IBM-SpamModules-Versions: BY=3.00007385; HX=3.00000241; KW=3.00000007; PH=3.00000004; SC=3.00000214; SDB=6.00889713; UDB=6.00444442; IPR=6.00669885; BA=6.00005479; NDR=6.00000001; ZLA=6.00000005; ZF=6.00000009; ZB=6.00000000; ZP=6.00000000; ZH=6.00000000; ZU=6.00000002; MB=3.00016272; XFM=3.00000015; UTC=2017-07-19 08:19:01 X-IBM-AV-DETECTION: SAVI=unused REMOTE=unused XFE=unused x-cbparentid: 17071908-0025-0000-0000-000044CD9F5B Message-Id: X-Proofpoint-Virus-Version: vendor=fsecure engine=2.50.10432:,, definitions=2017-07-19_05:,, signatures=0 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 spamscore=0 suspectscore=0 malwarescore=0 phishscore=0 adultscore=0 bulkscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.0.1-1706020000 definitions=main-1707190136 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2076 Lines: 50 From: "Gautham R. Shenoy" Hi, This is the second iteration of the patchset to enable exploitation of stop4 idle state on POWER9 via cpuidle. The earlier version can be found here : https://lkml.org/lkml/2017/7/18/691 The change from the first version is to the second patch titled " powernv/powerpc: Clear PECE1 in LPCR via stop-api only on Hotplug" where all the LPCR manipulations for CPU-Hotplug are moved into arch/powerpc/platforms/powernv/idle.c as per Nicholas Piggin's suggestion. ====== Description =========================== The stop4 idle state on POWER9 is a deep idle state which loses hypervisor resources, but whose latency is low enough that it can be exposed via cpuidle. Until now, the deep idle states which lose hypervisor resources (eg: winkle) were only exposed via CPU-Hotplug. Hence currently on wakeup from such states, barring a few SPRs which need to be restored to their older value, rest of the SPRS are reinitialized to their values corresponding to that at boot time. When stop4 is used in the context of cpuidle, we want these additional SPRs to be restored to their older value, to ensure that the context on the CPU coming back from idle is same as it was before going idle. Additionally, the CPU which is in stop4 while idling can be woken up by the decrementer interrupts. So we need to ensure that the LPCR is programmed with PECE1 bit cleared via the stop-api only for the CPU-Hotplug case and not for cpuidle. The two patches in the series address this problem. Gautham R. Shenoy (2): powernv/powerpc:Save/Restore additional SPRs for stop4 cpuidle powernv/powerpc: Clear PECE1 in LPCR via stop-api only on Hotplug arch/powerpc/include/asm/paca.h | 7 ++++++ arch/powerpc/kernel/asm-offsets.c | 12 +++++++++ arch/powerpc/kernel/idle_book3s.S | 46 +++++++++++++++++++++++++++++++++-- arch/powerpc/platforms/powernv/idle.c | 45 +++++++++++++++++++++++++++++++++- arch/powerpc/platforms/powernv/smp.c | 10 -------- 5 files changed, 107 insertions(+), 13 deletions(-) -- 1.9.4