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[187.189.51.144]) by smtp.gmail.com with ESMTPSA id a14sm13143044qkc.47.2021.03.15.11.42.36 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Mon, 15 Mar 2021 11:42:37 -0700 (PDT) Subject: Re: [PATCH v3 1/3] target/arm: Add support for FEAT_TLBIRANGE To: Rebecca Cran , Peter Maydell , qemu-arm@nongnu.org References: <20210310002917.8876-1-rebecca@nuviainc.com> <20210310002917.8876-2-rebecca@nuviainc.com> <3930c2d8-8972-0acf-7a48-71803072a559@linaro.org> From: Richard Henderson Message-ID: <6edef34b-215c-6c18-1400-16dea21f4555@linaro.org> Date: Mon, 15 Mar 2021 12:42:34 -0600 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:78.0) Gecko/20100101 Thunderbird/78.7.1 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset=utf-8; format=flowed Content-Language: en-US Content-Transfer-Encoding: 8bit Received-SPF: pass client-ip=2607:f8b0:4864:20::735; envelope-from=richard.henderson@linaro.org; helo=mail-qk1-x735.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 autolearn=unavailable autolearn_force=no X-Spam_action: no action X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.23 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: qemu-devel@nongnu.org Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" On 3/15/21 12:34 PM, Rebecca Cran wrote: > On 3/10/21 12:24 PM, Richard Henderson wrote: >> On 3/9/21 6:29 PM, Rebecca Cran wrote: >>> +void tlb_flush_page_range_by_mmuidx(CPUState *cpu, target_ulong addr, >>> +                                    unsigned int num_pages, uint16_t idxmap) >> >> I am not keen on this interface.  I think you should take either start+end >> addresses (inclusive) or start+length (in bytes). >> >> Using num_pages, and as an unsigned int, seems too easy to fail when applied >> to a different guest. > > Do you mean pushing the knowledge of the number of pages to invalidate down to > cputlb.c? Yes. In particular, your interface does not allow a single call to invalidate 1/2 of the total address space. Because the type for num_pages isn't large enough. There's nothing else in the cputlb interface that is page-based, except for "flush one page", and I thought that either target_ulong addr, target_ulong length, unsigned bits would be a clearer interface to use. > Because I'm thinking there has to be a loop somewhere that > invalidates each page if a full flush isn't being done? Certainly. r~