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=-4.0 required=3.0 tests=BAYES_00,MAILING_LIST_MULTI, SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED 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 D2937C4361B for ; Tue, 8 Dec 2020 10:02:44 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 99EEB217A0 for ; Tue, 8 Dec 2020 10:02:44 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728970AbgLHKCX (ORCPT ); Tue, 8 Dec 2020 05:02:23 -0500 Received: from mail.kernel.org ([198.145.29.99]:58180 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1728022AbgLHKCV (ORCPT ); Tue, 8 Dec 2020 05:02:21 -0500 Received: from disco-boy.misterjones.org (disco-boy.misterjones.org [51.254.78.96]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id 6E8F9217A0; Tue, 8 Dec 2020 10:01:40 +0000 (UTC) Received: from disco-boy.misterjones.org ([51.254.78.96] helo=www.loen.fr) by disco-boy.misterjones.org with esmtpsa (TLS1.2) tls TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256 (Exim 4.94) (envelope-from ) id 1kmZoQ-00H3In-Bb; Tue, 08 Dec 2020 10:01:38 +0000 MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII; format=flowed Content-Transfer-Encoding: 7bit Date: Tue, 08 Dec 2020 10:01:38 +0000 From: Marc Zyngier To: Haibo Xu Cc: Steven Price , Andrew Jones , Catalin Marinas , Juan Quintela , Richard Henderson , QEMU Developers , "Dr. David Alan Gilbert" , arm-mail-list , kvmarm , Thomas Gleixner , Will Deacon , Dave Martin , lkml - Kernel Mailing List Subject: Re: [PATCH v5 0/2] MTE support for KVM guest In-Reply-To: References: <20201119153901.53705-1-steven.price@arm.com> <20201119184248.4bycy6ouvaxqdiiy@kamzik.brq.redhat.com> <46fd98a2-ee39-0086-9159-b38c406935ab@arm.com> User-Agent: Roundcube Webmail/1.4.9 Message-ID: X-Sender: maz@kernel.org X-SA-Exim-Connect-IP: 51.254.78.96 X-SA-Exim-Rcpt-To: haibo.xu@linaro.org, steven.price@arm.com, drjones@redhat.com, catalin.marinas@arm.com, quintela@redhat.com, richard.henderson@linaro.org, qemu-devel@nongnu.org, dgilbert@redhat.com, linux-arm-kernel@lists.infradead.org, kvmarm@lists.cs.columbia.edu, tglx@linutronix.de, will@kernel.org, Dave.Martin@arm.com, linux-kernel@vger.kernel.org X-SA-Exim-Mail-From: maz@kernel.org X-SA-Exim-Scanned: No (on disco-boy.misterjones.org); SAEximRunCond expanded to false Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 2020-12-08 09:51, Haibo Xu wrote: > On Mon, 7 Dec 2020 at 22:48, Steven Price wrote: >> [...] >> Sounds like you are making good progress - thanks for the update. Have >> you thought about how the PROT_MTE mappings might work if QEMU itself >> were to use MTE? My worry is that we end up with MTE in a guest >> preventing QEMU from using MTE itself (because of the PROT_MTE >> mappings). I'm hoping QEMU can wrap its use of guest memory in a >> sequence which disables tag checking (something similar will be needed >> for the "protected VM" use case anyway), but this isn't something I've >> looked into. > > As far as I can see, to map all the guest memory with PROT_MTE in VMM > is a little weird, and lots of APIs have to be changed to include this > flag. > IMHO, it would be better if the KVM can provide new APIs to load/store > the > guest memory tag which may make it easier to enable the Qemu migration > support. On what granularity? To what storage? How do you plan to synchronise this with the dirty-log interface? Thanks, M. -- Jazz is not dead. It just smells funny...