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[187.189.51.144]) by smtp.gmail.com with ESMTPSA id l1sm522451ooi.48.2020.12.09.12.13.07 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Wed, 09 Dec 2020 12:13:09 -0800 (PST) Subject: Re: [PATCH v5 0/2] MTE support for KVM guest To: Catalin Marinas References: <0d0eb6da6a11f76d10e532c157181985@kernel.org> <20201207163405.GD1526@gaia> <874kkx5thq.wl-maz@kernel.org> <20201208172143.GB13960@gaia> <7ff14490e253878d0735633b792e1ea9@kernel.org> <20201209124443.GB13566@gaia> <20201209152741.GC13566@gaia> <8c39b104-39c3-7cca-82b9-2e47d7cb9a9a@linaro.org> <20201209183920.GI13566@gaia> From: Richard Henderson Message-ID: <6b9072fb-1232-e9fb-0b97-e69709980f99@linaro.org> Date: Wed, 9 Dec 2020 14:13:05 -0600 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:68.0) Gecko/20100101 Thunderbird/68.10.0 MIME-Version: 1.0 In-Reply-To: <20201209183920.GI13566@gaia> Content-Language: en-US X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20201209_151312_892569_048D0DE3 X-CRM114-Status: GOOD ( 14.86 ) 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: Peter Maydell , Juan Quintela , QEMU Developers , Marc Zyngier , lkml - Kernel Mailing List , Steven Price , arm-mail-list , Haibo Xu , Thomas Gleixner , Will Deacon , kvmarm , "Dr. David Alan Gilbert" , 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 On 12/9/20 12:39 PM, Catalin Marinas wrote: >> I would have thought that the best way is to use TCO, so that we don't have to >> have dual mappings (and however many MB of extra page tables that might imply). > > The problem appears when the VMM wants to use MTE itself (e.g. linked > against an MTE-aware glibc), toggling TCO is no longer generic enough, > especially when it comes to device emulation. But we do know exactly when we're manipulating guest memory -- we have special routines for that. So the special routines gain a toggle of TCO around the exact guest memory manipulation, not a blanket disable of MTE across large swaths of QEMU. r~ _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel