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=-2.3 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 782A4C35247 for ; Thu, 6 Feb 2020 01:46:39 +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 4A03620658 for ; Thu, 6 Feb 2020 01:46:39 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 4A03620658 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=huawei.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Received: from localhost ([::1]:59594 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1izWFZ-0003xl-EG for qemu-devel@archiver.kernel.org; Wed, 05 Feb 2020 20:46:37 -0500 Received: from eggs.gnu.org ([2001:470:142:3::10]:55852) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1izVqO-0003Ss-Ht for qemu-devel@nongnu.org; Wed, 05 Feb 2020 20:20:37 -0500 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1izVqN-0002Jq-FR for qemu-devel@nongnu.org; Wed, 05 Feb 2020 20:20:36 -0500 Received: from szxga04-in.huawei.com ([45.249.212.190]:2697 helo=huawei.com) by eggs.gnu.org with esmtps (TLS1.0:DHE_RSA_AES_256_CBC_SHA1:32) (Exim 4.71) (envelope-from ) id 1izVqL-0001Xg-1P; Wed, 05 Feb 2020 20:20:33 -0500 Received: from DGGEMS411-HUB.china.huawei.com (unknown [172.30.72.59]) by Forcepoint Email with ESMTP id 371BABC200ABA29A102D; Thu, 6 Feb 2020 09:20:28 +0800 (CST) Received: from [127.0.0.1] (10.173.221.228) by DGGEMS411-HUB.china.huawei.com (10.3.19.211) with Microsoft SMTP Server id 14.3.439.0; Thu, 6 Feb 2020 09:20:20 +0800 Subject: Re: [RFC v2 00/14] Add SDEI support for arm64 To: Marc Zyngier References: <20191105091056.9541-1-guoheyi@huawei.com> <5aece614-4341-35e5-53a6-2f3d788e6e8d@huawei.com> <350aa4ca1b57a466ed882236caf23051@kernel.org> From: Heyi Guo Message-ID: Date: Thu, 6 Feb 2020 09:20:19 +0800 User-Agent: Mozilla/5.0 (Windows NT 10.0; WOW64; rv:68.0) Gecko/20100101 Thunderbird/68.2.2 MIME-Version: 1.0 In-Reply-To: <350aa4ca1b57a466ed882236caf23051@kernel.org> Content-Type: text/plain; charset="utf-8"; format=flowed X-Originating-IP: [10.173.221.228] X-CFilter-Loop: Reflected Content-Transfer-Encoding: quoted-printable X-detected-operating-system: by eggs.gnu.org: GNU/Linux 2.2.x-3.x [generic] [fuzzy] X-Received-From: 45.249.212.190 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: Mark Rutland , Peter Maydell , Gavin Shan , "Michael S. Tsirkin" , Cornelia Huck , QEMU Developers , Shannon Zhao , Igor Mammedov , qemu-arm , James Morse , Paolo Bonzini , wanghaibin.wang@huawei.com, Dave Martin Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" Hi Marc, On 2020/2/5 21:15, Marc Zyngier wrote: > Hi Heyi, > > On 2020-02-04 08:26, Heyi Guo wrote: >> Update Marc's email address. >> >> +cc Gavin as he is posting a RFC for ARM NMI. >> >> Hi Marc, >> >> Really sorry for missing to update your email address, for the initial >> topic was raised long time ago and I forgot to update the Cc list in >> the commit message of the patches. >> >> Thanks Gavin for forwarding current discussion on ARM NMI to me. >> >> For you said SDEI is "horrible", does it mean we'd better never >> implement SDEI in virtual world? Or do you have any advice on how to >> implement it? > > My concern is that SDEI implies having EL3. EL3 not being virtualizable > with KVM, you end-up baking SDEI in *hardware*. Of course, this hardwar= e > is actually software (it is QEMU), but this isn't the way it was=20 > intended. > > It's not the first time we've done that (PSCI is another example), but=20 > the > logic behind SDEI looks much more invasive. Thanks for your comments. Thinking about them for quite a while, below is my understanding, please=20 correct me if I'm wrong: So should the KVM based virtual machine be treated as one with CPUs only=20 having NS-EL1 and NS-EL0, ideally? And SDEI messes up this model, isn't i= t? PSCI only contains some one-shot operations, so it is much less invasive=20 than SDEI. I've another question. The origin of "virtual" SDEI requirement comes=20 from the lack of hard lockup detector in VM. We can have some kind of=20 watchdog, but how can the watchdog trigger the VM OS to panic and run=20 kdump, even in irq-off state? Thanks, Heyi > > =C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0 M.