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[37.158.132.66]) by smtp.gmail.com with ESMTPSA id 5b1f17b1804b1-477a7cb24dfsm22092785e9.14.2025.11.17.07.26.16 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Mon, 17 Nov 2025 07:26:16 -0800 (PST) Message-ID: <9b2de87c-b7d8-4a64-8c7b-bf94e3233275@linaro.org> Date: Mon, 17 Nov 2025 16:26:14 +0100 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH RFC v2 04/10] target/arm: add FEAT_MTE_STORE_ONLY logic To: Gabriel Brookman , qemu-devel@nongnu.org Cc: Peter Maydell , Gustavo Romero , qemu-arm@nongnu.org References: <20251116-feat-mte4-v2-0-9a7122b7fa76@gmail.com> <20251116-feat-mte4-v2-4-9a7122b7fa76@gmail.com> From: Richard Henderson Content-Language: en-US In-Reply-To: <20251116-feat-mte4-v2-4-9a7122b7fa76@gmail.com> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit Received-SPF: pass client-ip=2a00:1450:4864:20::334; envelope-from=richard.henderson@linaro.org; helo=mail-wm1-x334.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, RCVD_IN_DNSWL_NONE=-0.0001, SPF_HELO_NONE=0.001, SPF_PASS=-0.001 autolearn=ham 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-bounces+qemu-devel=archiver.kernel.org@nongnu.org On 11/17/25 02:40, Gabriel Brookman wrote: > This feature automatically succeeds tag checks on load instructions when > the appropriate SCTLR_TCSO register for the current exception level is > set. Find information on this feature in the "Tag Checking" section of > the ARM ARM, Memory Tagging Extension chapter. > > Signed-off-by: Gabriel Brookman > --- > target/arm/tcg/mte_helper.c | 22 ++++++++++++++++++++++ > 1 file changed, 22 insertions(+) > > diff --git a/target/arm/tcg/mte_helper.c b/target/arm/tcg/mte_helper.c > index bb48fe359b..f9fd6fd408 100644 > --- a/target/arm/tcg/mte_helper.c > +++ b/target/arm/tcg/mte_helper.c > @@ -865,8 +865,30 @@ static int mte_probe_int(CPUARMState *env, uint32_t desc, uint64_t ptr, > return 0; > } > > +static bool mte_store_only_active(CPUARMState *env) > +{ > + int el = arm_current_el(env); > + if (el) { > + if (SCTLR_TCSO & env->cp15.sctlr_el[el]) { > + return true; > + } > + } else { > + if ((HCR_E2H & env->cp15.hcr_el2) &&' You can't test hcr_el2 directly, because SecEL2 might not exist when (Non-secure) EL2 does. However, this can be simplified using arm_sctlr(): uint64_t sctlr = arm_sctlr(env, el); uint64_t test = el ? SCTLR_TCSO : SCTLR_TCSO0; return sctlr & test; That said, we should cache this in TBFLAGS so that we don't generate the mte_check function call at runtime for reads. See target/arm/tcg/hflags.c, s/MTE_ACTIVE/. r~