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[174.21.142.130]) by smtp.gmail.com with ESMTPSA id l5-20020a056a0016c500b004f768db4c94sm20137260pfc.212.2022.04.27.08.39.47 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Wed, 27 Apr 2022 08:39:47 -0700 (PDT) Message-ID: Date: Wed, 27 Apr 2022 08:39:45 -0700 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:91.0) Gecko/20100101 Thunderbird/91.8.0 Subject: Re: [PATCH v2] target/arm: Disable cryptographic instructions when neon is disabled Content-Language: en-US To: Damien Hedde , qemu-devel@nongnu.org References: <20220427090117.6954-1-damien.hedde@greensocs.com> From: Richard Henderson In-Reply-To: <20220427090117.6954-1-damien.hedde@greensocs.com> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit 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: -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: , Cc: Peter Maydell , "open list:ARM TCG CPUs" Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" On 4/27/22 02:01, Damien Hedde wrote: > As of now, cryptographic instructions ISAR fields are never cleared so > we can end up with a cpu with cryptographic instructions but no > floating-point/neon instructions which is not a possible configuration > according to ARM specifications. > > In QEMU, we have 3 kinds of cpus regarding cryptographic instructions: > + no support > + cortex-a57/a72: cryptographic extension is optional, > floating-point/neon is not. > + cortex-a53: crytographic extension is optional as well as > floationg-point/neon. But cryptographic requires > floating-point/neon support. > > Therefore we can safely clear the ISAR fields when neon is disabled. > > Note that other arm cpus seem to follow this. For example cortex-a55 is > like cortex-a53 and cortex-a76/cortex-a710 are like cortex-a57/a72. > > Signed-off-by: Damien Hedde > --- > > v2: also clear SHA3 / SM3 / SM4 (Richard) > --- > target/arm/cpu.c | 9 +++++++++ > 1 file changed, 9 insertions(+) Reviewed-by: Richard Henderson r~