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[120.151.179.201]) by smtp.gmail.com with ESMTPSA id nk11sm1240093pjb.55.2022.01.25.14.05.13 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Tue, 25 Jan 2022 14:05:16 -0800 (PST) Subject: Re: [PATCH 2/2] target/arm: Bail out early on 0-length tlb range invalidate To: Idan Horowitz , qemu-arm@nongnu.org References: <20220110164754.1066025-1-idan.horowitz@gmail.com> <20220110164754.1066025-2-idan.horowitz@gmail.com> From: Richard Henderson Message-ID: <0f211c09-4b4d-2c82-cff6-64711563c6d8@linaro.org> Date: Wed, 26 Jan 2022 09:05:11 +1100 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:78.0) Gecko/20100101 Thunderbird/78.14.0 MIME-Version: 1.0 In-Reply-To: <20220110164754.1066025-2-idan.horowitz@gmail.com> Content-Type: text/plain; charset=utf-8; format=flowed Content-Language: en-US Content-Transfer-Encoding: 7bit X-Host-Lookup-Failed: Reverse DNS lookup failed for 2607:f8b0:4864:20::635 (failed) Received-SPF: pass client-ip=2607:f8b0:4864:20::635; envelope-from=richard.henderson@linaro.org; helo=mail-pl1-x635.google.com X-Spam_score_int: -12 X-Spam_score: -1.3 X-Spam_bar: - X-Spam_report: (-1.3 / 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, PDS_HP_HELO_NORDNS=0.001, RCVD_IN_DNSWL_NONE=-0.0001, RDNS_NONE=0.793, SPF_HELO_NONE=0.001, SPF_PASS=-0.001 autolearn=no 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: , Cc: peter.maydell@linaro.org, qemu-devel@nongnu.org, pbonzini@redhat.com Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" On 1/11/22 3:47 AM, Idan Horowitz wrote: > If the given range specifies no addresses to be flushed there's no reason > to schedule a function on all CPUs that does nothing. > > Signed-off-by: Idan Horowitz > --- > target/arm/helper.c | 4 ++++ > 1 file changed, 4 insertions(+) > > diff --git a/target/arm/helper.c b/target/arm/helper.c > index cfca0f5ba6..1e819835c2 100644 > --- a/target/arm/helper.c > +++ b/target/arm/helper.c > @@ -4564,6 +4564,10 @@ static void do_rvae_write(CPUARMState *env, uint64_t value, > length = tlbi_aa64_range_get_length(env, value); > bits = tlbbits_for_regime(env, one_idx, baseaddr); > > + if (length == 0) { > + return; > + } > + > if (synced) { > tlb_flush_range_by_mmuidx_all_cpus_synced(env_cpu(env), > baseaddr, > Looks good. I guess we could sort the extractions above so that we do length = ...; if (length == 0) { return; } addr = ... bits = ... Either way, Reviewed-by: Richard Henderson r~