From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-2.5 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,USER_AGENT_SANE_1 autolearn=no autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 6965BC433DF for ; Fri, 26 Jun 2020 07:29:13 +0000 (UTC) Received: from lists.ozlabs.org (lists.ozlabs.org [203.11.71.2]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id C3C1D2076E for ; Fri, 26 Jun 2020 07:29:12 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org C3C1D2076E Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=kaod.org Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=linuxppc-dev-bounces+linuxppc-dev=archiver.kernel.org@lists.ozlabs.org Received: from bilbo.ozlabs.org (lists.ozlabs.org [IPv6:2401:3900:2:1::3]) by lists.ozlabs.org (Postfix) with ESMTP id 49tT5z0PdmzDr1c for ; Fri, 26 Jun 2020 17:29:11 +1000 (AEST) Authentication-Results: lists.ozlabs.org; spf=pass (sender SPF authorized) smtp.mailfrom=kaod.org (client-ip=46.105.72.44; helo=9.mo173.mail-out.ovh.net; envelope-from=clg@kaod.org; receiver=) Authentication-Results: lists.ozlabs.org; dmarc=none (p=none dis=none) header.from=kaod.org Received: from 9.mo173.mail-out.ovh.net (9.mo173.mail-out.ovh.net [46.105.72.44]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by lists.ozlabs.org (Postfix) with ESMTPS id 49tT3b6fqfzDqv8 for ; Fri, 26 Jun 2020 17:27:07 +1000 (AEST) Received: from player734.ha.ovh.net (unknown [10.108.35.90]) by mo173.mail-out.ovh.net (Postfix) with ESMTP id 71BC6143960 for ; Fri, 26 Jun 2020 09:27:03 +0200 (CEST) Received: from kaod.org (lfbn-tou-1-921-245.w86-210.abo.wanadoo.fr [86.210.152.245]) (Authenticated sender: clg@kaod.org) by player734.ha.ovh.net (Postfix) with ESMTPSA id 4F79413A000E6; Fri, 26 Jun 2020 07:26:52 +0000 (UTC) Authentication-Results: garm.ovh; auth=pass (GARM-95G0018ba46917-0696-40ce-8ee4-92facd6b3767,4AA08B4753365576F5C892DCFEC488B61DD07F5F) smtp.auth=clg@kaod.org Subject: Re: [PATCH] powerpc/pseries: Use doorbells even if XIVE is available From: =?UTF-8?Q?C=c3=a9dric_Le_Goater?= To: Michael Ellerman , Nicholas Piggin , linuxppc-dev@lists.ozlabs.org References: <20200624134724.2343007-1-npiggin@gmail.com> <87r1u4aqzm.fsf@mpe.ellerman.id.au> Message-ID: Date: Fri, 26 Jun 2020 09:26:52 +0200 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:68.0) Gecko/20100101 Thunderbird/68.9.0 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit X-Ovh-Tracer-Id: 11765372554848930790 X-VR-SPAMSTATE: OK X-VR-SPAMSCORE: -100 X-VR-SPAMCAUSE: gggruggvucftvghtrhhoucdtuddrgeduhedrudeltddguddulecutefuodetggdotefrodftvfcurfhrohhfihhlvgemucfqggfjpdevjffgvefmvefgnecuuegrihhlohhuthemucehtddtnecusecvtfgvtghiphhivghnthhsucdlqddutddtmdenucfjughrpefuhffvfhfkffgfgggjtgfgsehtjeertddtfeejnecuhfhrohhmpeevrogurhhitggpnfgvpgfiohgrthgvrhcuoegtlhhgsehkrghougdrohhrgheqnecuggftrfgrthhtvghrnhepheevheejjefhtedvueeghfeiffduleeijeehteeuvdfgheeikeevffeghfeviefhnecukfhppedtrddtrddtrddtpdekiedrvddutddrudehvddrvdegheenucevlhhushhtvghrufhiiigvpedtnecurfgrrhgrmhepmhhouggvpehsmhhtphdqohhuthdphhgvlhhopehplhgrhigvrhejfeegrdhhrgdrohhvhhdrnhgvthdpihhnvghtpedtrddtrddtrddtpdhmrghilhhfrhhomheptghlgheskhgrohgurdhorhhgpdhrtghpthhtoheplhhinhhugihpphgtqdguvghvsehlihhsthhsrdhoiihlrggsshdrohhrgh 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: Anton Blanchard , kvm-ppc@vger.kernel.org, David Gibson Errors-To: linuxppc-dev-bounces+linuxppc-dev=archiver.kernel.org@lists.ozlabs.org Sender: "Linuxppc-dev" [ ... ] >>> An option vector (or dt-cpu-ftrs) could be defined to disable msgsndp >>> to get KVM performance back. > > An option vector would require a PAPR change. Unless the architecture > reserves some bits for the implementation, but I don't think so. Same > for CAS. > >> Qemu/KVM populates /proc/device-tree/hypervisor, so we *could* look at >> that. Though adding PowerVM/KVM specific hacks is obviously a very >> slippery slope. > > QEMU could advertise a property "emulated-msgsndp", or something similar, > which would be interpreted by Linux as a CPU feature and taken into account > when doing the IPIs. This is really a PowerVM optimization. > The CPU setup for XIVE needs a cleanup also. There is no need to allocate > interrupts for IPIs anymore in that case. We need to keep these for the other cores. The XIVE layer is unchanged. C.