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Violators will be prosecuted; (version=TLSv1/SSLv3 cipher=AES256-GCM-SHA384 bits=256/256) Thu, 11 Oct 2018 14:22:56 +0100 Received: from d06av25.portsmouth.uk.ibm.com (d06av25.portsmouth.uk.ibm.com [9.149.105.61]) by b06cxnps4076.portsmouth.uk.ibm.com (8.14.9/8.14.9/NCO v10.0) with ESMTP id w9BDMtmC65077462 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-GCM-SHA384 bits=256 verify=FAIL); Thu, 11 Oct 2018 13:22:55 GMT Received: from d06av25.portsmouth.uk.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id 47ECC11C050; Thu, 11 Oct 2018 16:22:28 +0100 (BST) Received: from d06av25.portsmouth.uk.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id D4F3711C052; Thu, 11 Oct 2018 16:22:26 +0100 (BST) Received: from aks.in.ibm.com (unknown [9.124.35.29]) by d06av25.portsmouth.uk.ibm.com (Postfix) with ESMTP; Thu, 11 Oct 2018 16:22:26 +0100 (BST) From: Akshay Adiga To: linux-kernel@vger.kernel.org, linuxppc-dev@lists.ozlabs.org Subject: [RFC PATCH v2 0/3] New device-tree format and Opal based idle save-restore Date: Thu, 11 Oct 2018 18:52:34 +0530 X-Mailer: git-send-email 2.17.1 X-TM-AS-GCONF: 00 x-cbid: 18101113-0008-0000-0000-0000027E2462 X-IBM-AV-DETECTION: SAVI=unused REMOTE=unused XFE=unused x-cbparentid: 18101113-0009-0000-0000-000021E76BE3 Message-Id: <20181011132237.14604-1-akshay.adiga@linux.vnet.ibm.com> X-Proofpoint-Virus-Version: vendor=fsecure engine=2.50.10434:, , definitions=2018-10-11_07:, , signatures=0 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 priorityscore=1501 malwarescore=0 suspectscore=0 phishscore=0 bulkscore=0 spamscore=0 clxscore=1011 lowpriorityscore=0 mlxscore=0 impostorscore=0 mlxlogscore=999 adultscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.0.1-1807170000 definitions=main-1810110130 X-BeenThere: linuxppc-dev@lists.ozlabs.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: ego@linux.vnet.ibm.com, npiggin@gmail.com, huntbag@linux.vnet.ibm.com, Akshay Adiga Errors-To: linuxppc-dev-bounces+linuxppc-dev=archiver.kernel.org@lists.ozlabs.org Sender: "Linuxppc-dev" Previously if a older kernel runs on a newer firmware, it may enable all available states irrespective of its capability of handling it. New device tree format adds a compatible flag, so that only kernel which has the capability to handle the version of stop state will enable it. Older kernel will still see stop0 and stop0_lite in older format and we will depricate it after some time. 1) Idea is to bump up the version string in firmware if we find a bug or regression in stop states. A fix will be provided in linux which would now know about the bumped up version of stop states, where as kernel without fixes would ignore the states. 2) Slowly deprecate cpuidle/cpuhotplug threshold which is hard-coded into cpuidle-powernv driver. Instead use compatible strings to indicate if idle state is suitable for cpuidle and hotplug. New idle state device tree format : power-mgt { ... ibm,enabled-stop-levels = <0xec000000>; ibm,cpu-idle-state-psscr-mask = <0x0 0x3003ff 0x0 0x3003ff>; ibm,cpu-idle-state-latencies-ns = <0x3e8 0x7d0>; ibm,cpu-idle-state-psscr = <0x0 0x330 0x0 0x300330>; ibm,cpu-idle-state-flags = <0x100000 0x101000>; ibm,cpu-idle-state-residency-ns = <0x2710 0x4e20>; ibm,idle-states { stop4 { flags = <0x207000>; compatible = "ibm,state-v1", "opal-support"; type = "cpuidle"; psscr-mask = <0x0 0x3003ff>; handle = <0x102>; latency-ns = <0x186a0>; residency-ns = <0x989680>; psscr = <0x0 0x300374>; }; ... stop11 { ... compatible = "ibm,state-v1", "opal-support"; type = "cpuoffline"; ... }; }; High-level parsing algorithm : Say Known version string = "ibm,state-v1" for each stop state node in device tree: if (compatible has known version string) kernel takes care of stop-transitions else if (compatible has "opal-support") OPAL takes care of stop-transitions else Skip All deeper states When a state does not have both version support and opal support, Its possible to exit from a shallower state. Hence skipping all deeper states. OPAL support for idle states ---------------------------- With this patch series, all the states that loose hypervisor state will be handled through opal_call. Patch 3 adds support for Saving/restoring of SPRs and resync-timebase in OPAL. Also all the decision making such as identifying first thread in the core and taking locks before restoring, etc are implemented in OPAL. How does it work ? ------------------- Consider a case that stop4 has a bug. We take the following steps to mitigate the problem. 1) Change compatible string for stop4 in OPAL to "ibm-state-v2" and remove "opal-supported". ship the new firmware. The kernel ignores stop4 and all deeper states. But we will still have shallower states. Prevents from completely disabling stop states. 2) Implement workaround in OPAL and add "opal-supported". Ship new firmware The kernel uses opal for stop-transtion , which has workaround implemented. We get stop4 and deeper states working without kernel changes and backports. (and considerably less time) 3) Implement workaround in kernel and add "ibm-state-v2" as known versions The kernel will now be able to handle stop4 and deeper states. Changes from v1 : - Code is rebased on Nick Piggin's v4 patch "powerpc/64s: reimplement book3s idle code in C" http://patchwork.ozlabs.org/patch/969596/ - All the states that loses hypervisor states will be handled by OPAL - All the decision making such as identifying first thread in the core and taking locks before restoring in such cases have also been moved to OPAL Abhishek Goel (1): cpuidle/powernv: save-restore sprs in opal Akshay Adiga (2): cpuidle/powernv: Add support for states with ibm,cpuidle-state-v1 powernv/cpuidle: Pass pointers instead of values to stop loop arch/powerpc/include/asm/cpuidle.h | 9 + arch/powerpc/include/asm/opal-api.h | 4 +- arch/powerpc/include/asm/opal.h | 3 + arch/powerpc/include/asm/processor.h | 8 +- arch/powerpc/kernel/idle_book3s.S | 6 +- arch/powerpc/platforms/powernv/idle.c | 247 ++++++++++++++---- .../powerpc/platforms/powernv/opal-wrappers.S | 2 + drivers/cpuidle/cpuidle-powernv.c | 46 ++-- 8 files changed, 251 insertions(+), 74 deletions(-) -- 2.17.1