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([2602:47:d49d:ec01:b651:a70f:2852:70f5]) by smtp.gmail.com with ESMTPSA id b191-20020a621bc8000000b0052d2b55be32sm4425693pfb.171.2022.08.19.22.21.46 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Fri, 19 Aug 2022 22:21:46 -0700 (PDT) Message-ID: <5b2694b7-a1bf-504a-5af6-8ac95d34d5ee@linaro.org> Date: Fri, 19 Aug 2022 22:21:44 -0700 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:91.0) Gecko/20100101 Thunderbird/91.11.0 Subject: Re: [PATCH 5/6] target/arm: Advertise FEAT_ETS for '-cpu max' Content-Language: en-US To: Peter Maydell , qemu-arm@nongnu.org, qemu-devel@nongnu.org References: <20220819110052.2942289-1-peter.maydell@linaro.org> <20220819110052.2942289-6-peter.maydell@linaro.org> From: Richard Henderson In-Reply-To: <20220819110052.2942289-6-peter.maydell@linaro.org> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 8bit Received-SPF: pass client-ip=2607:f8b0:4864:20::634; envelope-from=richard.henderson@linaro.org; helo=mail-pl1-x634.google.com X-Spam_score_int: -20 X-Spam_score: -2.1 X-Spam_bar: -- X-Spam_report: (-2.1 / 5.0 requ) BAYES_00=-1.9, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, NICE_REPLY_A=-0.001, RCVD_IN_DNSWL_NONE=-0.0001, SPF_HELO_NONE=0.001, SPF_PASS=-0.001, T_SCC_BODY_TEXT_LINE=-0.01 autolearn=unavailable autolearn_force=no X-Spam_action: no action X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" On 8/19/22 04:00, Peter Maydell wrote: > The architectural feature FEAT_ETS (Enhanced Translation > Synchronization) is a set of tightened guarantees about memory > ordering involving translation table walks: > > * if memory access RW1 is ordered-before memory access RW2 then it > is also ordered-before any translation table walk generated by RW2 > that generates a translation fault, address size fault or access > fault > > * TLB maintenance on non-exec-permission translations is guaranteed > complete after a DSB (ie it does not need the context > synchronization event that you have to have if you don’t have > FEAT_ETS) > > For QEMU’s implementation we don’t reorder translation table walk > accesses, and we guarantee to finish the TLB maintenance as soon as > the TLB op is done (the tlb_flush functions will complete at the end > of the TLB, and TLB ops always end the TB because they’re sysreg First TLB on this line should be TB. Reviewed-by: Richard Henderson r~