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=-5.3 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,NICE_REPLY_A,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 7FAC9C433E0 for ; Fri, 19 Mar 2021 08:20:01 +0000 (UTC) Received: from lists.gnu.org (lists.gnu.org [209.51.188.17]) (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 D2F9564F6A for ; Fri, 19 Mar 2021 08:20:00 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org D2F9564F6A Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=suse.de Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Received: from localhost ([::1]:54968 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1lNAMR-0002qx-RK for qemu-devel@archiver.kernel.org; Fri, 19 Mar 2021 04:19:59 -0400 Received: from eggs.gnu.org ([2001:470:142:3::10]:51792) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1lNALe-00023v-Kz; Fri, 19 Mar 2021 04:19:10 -0400 Received: from mx2.suse.de ([195.135.220.15]:39896) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1lNALc-0006Eo-Rp; Fri, 19 Mar 2021 04:19:10 -0400 X-Virus-Scanned: by amavisd-new at test-mx.suse.de Received: from relay2.suse.de (unknown [195.135.221.27]) by mx2.suse.de (Postfix) with ESMTP id B049AAB8C; Fri, 19 Mar 2021 08:19:03 +0000 (UTC) Subject: Re: arm_cpu_post_init (Was: Re: arm: "max" CPU class hierarchy changes possible?) To: Eduardo Habkost , Andrew Jones References: <2e6a5d98-e022-0b39-5f30-92eb74491d3b@redhat.com> <2277fdf5-ec92-476a-8fe5-0d4eee23dfef@suse.de> <20210311191046.ykcelkwq7orajyu7@kamzik.brq.redhat.com> <5467e45c-cc8e-6422-0c56-398405a7c331@suse.de> <20210318120837.cg4gfdpchjwiabav@kamzik.brq.redhat.com> <20210318125908.zwpm47ftlsuen3zo@kamzik.brq.redhat.com> <20210318131010.GT3139005@habkost.net> From: Claudio Fontana Message-ID: Date: Fri, 19 Mar 2021 09:19:02 +0100 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:68.0) Gecko/20100101 Thunderbird/68.12.0 MIME-Version: 1.0 In-Reply-To: <20210318131010.GT3139005@habkost.net> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit Received-SPF: pass client-ip=195.135.220.15; envelope-from=cfontana@suse.de; helo=mx2.suse.de X-Spam_score_int: -41 X-Spam_score: -4.2 X-Spam_bar: ---- X-Spam_report: (-4.2 / 5.0 requ) BAYES_00=-1.9, NICE_REPLY_A=-0.001, RCVD_IN_DNSWL_MED=-2.3, RCVD_IN_MSPIKE_H3=0.001, RCVD_IN_MSPIKE_WL=0.001, SPF_HELO_NONE=0.001, SPF_PASS=-0.001 autolearn=ham autolearn_force=no X-Spam_action: no action X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.23 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Peter Maydell , Richard Henderson , qemu-devel , =?UTF-8?Q?Philippe_Mathieu-Daud=c3=a9?= , qemu-arm , Paolo Bonzini Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" On 3/18/21 2:10 PM, Eduardo Habkost wrote: > On Thu, Mar 18, 2021 at 01:59:08PM +0100, Andrew Jones wrote: >> On Thu, Mar 18, 2021 at 01:42:36PM +0100, Claudio Fontana wrote: >>> On 3/18/21 1:08 PM, Andrew Jones wrote: >>>> On Thu, Mar 18, 2021 at 12:32:30PM +0100, Claudio Fontana wrote: >>>>> And why do we have a separate arm_cpu_finalize_features()? >>>> >>>> Separate, because it's not just called from arm_cpu_realizefn(). >>> >>> In particular it is also called by the monitor.c in qmp_query_cpu_model_expansion(), >>> >>> which basically creates an object of the cpu subclass, >>> and then calls arm_cpu_finalize_[features]() explicitly on the object. >>> >>> Is the qdev realize() method not called in this case? Should instead it be triggered, rather than initializing/realizing an incomplete object? >> >> Can you elaborate on what you mean by "triggered"? The QMP query does the >> least that it can get away with while still reusing the CPU model's >> feature initialization code. Any suggestions for improving that, >> preferably in the form of a patch, would be welcome. If it works well for >> Arm, then it could probably be applied to other architectures. The Arm QMP >> query is modeled off the others. > > This sound very similar to x86_cpu_expand_features(), so the > approach makes sense to me. Interesting, to me it sounds like a CPUClass method is hiding here, cc->cpu_expand_features(), I could help kickstart the implementation but would need a good description / comment of exactly which features are supposed to be expanded there. > > It wouldn't make sense to call realize() inside > qmp_query_cpu_model_expansion(). Realizing the CPU means > plugging it into the guest, and we would never want to do that > when executing a query command. > Makes sense, thanks for the explanation. Ciao, Claudio