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Mon, 23 Nov 2020 07:16:20 -0500 X-MC-Unique: OjmxZbq0PEacCG4qpdCK8w-1 Received: from smtp.corp.redhat.com (int-mx04.intmail.prod.int.phx2.redhat.com [10.5.11.14]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id CBE4A8AEA40; Mon, 23 Nov 2020 12:16:17 +0000 (UTC) Received: from work-vm (ovpn-114-158.ams2.redhat.com [10.36.114.158]) by smtp.corp.redhat.com (Postfix) with ESMTPS id CC31B5D9CC; Mon, 23 Nov 2020 12:16:13 +0000 (UTC) Date: Mon, 23 Nov 2020 12:16:11 +0000 From: "Dr. David Alan Gilbert" To: Peter Maydell Subject: Re: [PATCH v5 0/2] MTE support for KVM guest Message-ID: <20201123121611.GG3022@work-vm> References: <20201119153901.53705-1-steven.price@arm.com> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.14.6 (2020-07-11) X-Scanned-By: MIMEDefang 2.79 on 10.5.11.14 X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20201123_071820_253190_BBE3F164 X-CRM114-Status: GOOD ( 22.66 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Mark Rutland , Andrew Jones , Haibo Xu , Suzuki K Poulose , QEMU Developers , Catalin Marinas , Juan Quintela , Richard Henderson , lkml - Kernel Mailing List , Steven Price , James Morse , arm-mail-list , Marc Zyngier , Thomas Gleixner , Will Deacon , kvmarm , Julien Thierry , Dave Martin Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org * Peter Maydell (peter.maydell@linaro.org) wrote: > On Thu, 19 Nov 2020 at 15:39, Steven Price wrote: > > This series adds support for Arm's Memory Tagging Extension (MTE) to > > KVM, allowing KVM guests to make use of it. This builds on the existing > > user space support already in v5.10-rc1, see [1] for an overview. > > > The change to require the VMM to map all guest memory PROT_MTE is > > significant as it means that the VMM has to deal with the MTE tags even > > if it doesn't care about them (e.g. for virtual devices or if the VMM > > doesn't support migration). Also unfortunately because the VMM can > > change the memory layout at any time the check for PROT_MTE/VM_MTE has > > to be done very late (at the point of faulting pages into stage 2). > > I'm a bit dubious about requring the VMM to map the guest memory > PROT_MTE unless somebody's done at least a sketch of the design > for how this would work on the QEMU side. Currently QEMU just > assumes the guest memory is guest memory and it can access it > without special precautions... Although that is also changing because of the encrypted/protected memory in things like SEV. Dave > thanks > -- PMM > -- Dr. David Alan Gilbert / dgilbert@redhat.com / Manchester, UK _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel