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[173.198.77.218]) by smtp.gmail.com with ESMTPSA id c26-20020a6566da000000b004fb171df68fsm5641952pgw.7.2023.02.22.15.17.57 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Wed, 22 Feb 2023 15:17:58 -0800 (PST) Message-ID: Date: Wed, 22 Feb 2023 13:17:55 -1000 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:102.0) Gecko/20100101 Thunderbird/102.7.1 To: linux-arm-kernel@lists.infradead.org Content-Language: en-US From: Richard Henderson Subject: Feature request for enabling SCTLR_ELx.nAA Cc: =?UTF-8?Q?Alex_Benn=c3=a9e?= X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20230222_151802_820017_B0DD1239 X-CRM114-Status: UNSURE ( 9.53 ) X-CRM114-Notice: Please train this message. X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Transfer-Encoding: 7bit Content-Type: text/plain; charset="us-ascii"; Format="flowed" Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org Hi guys, It would be helpful to have a prctl for enabling nAA. Since we already have task->thread.sctlr_user, it would seem that this would not require any additional overhead during __switch_to(). My use case is the QEMU JIT, and being able to make use of LDAR/STLR instead of explicit DBM in some cases. At the moment, I can only make this replacement when the address is provably aligned, which is tricky to do with the time budget of a JIT, so the replacement rarely triggers. This ought to make a difference when emulating strongly ordered guests like x86. Thanks, r~ _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel