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[88.187.86.199]) by smtp.gmail.com with ESMTPSA id 5b1f17b1804b1-458953eb7acsm525015225e9.28.2025.08.12.00.33.10 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Tue, 12 Aug 2025 00:33:11 -0700 (PDT) Message-ID: Date: Tue, 12 Aug 2025 09:33:10 +0200 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [RFC PATCH 07/11] target/arm: Replace kvm_arm_pmu_supported by host_cpu_feature_supported From: =?UTF-8?Q?Philippe_Mathieu-Daud=C3=A9?= To: Richard Henderson , qemu-devel@nongnu.org Cc: Miguel Luis , kvm@vger.kernel.org, Peter Maydell , Paolo Bonzini , Haibo Xu , Mohamed Mediouni , Mark Burton , Alexander Graf , Claudio Fontana , =?UTF-8?Q?Alex_Benn=C3=A9e?= , Mads Ynddal , Eric Auger , qemu-arm@nongnu.org, Cameron Esfahani References: <20250811170611.37482-1-philmd@linaro.org> <20250811170611.37482-8-philmd@linaro.org> <8efcc809-f548-4383-b742-e435d622da73@linaro.org> <14d7d948-e840-4ae7-ae93-122755d6a421@linaro.org> <3d88ea9c-9cfe-4cd4-a282-2f467f2a502f@linaro.org> Content-Language: en-US In-Reply-To: <3d88ea9c-9cfe-4cd4-a282-2f467f2a502f@linaro.org> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 8bit Received-SPF: pass client-ip=2a00:1450:4864:20::32b; envelope-from=philmd@linaro.org; helo=mail-wm1-x32b.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=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-bounces+qemu-devel=archiver.kernel.org@nongnu.org On 12/8/25 08:03, Philippe Mathieu-Daudé wrote: > On 12/8/25 06:49, Philippe Mathieu-Daudé wrote: >> On 12/8/25 02:48, Richard Henderson wrote: >>> On 8/12/25 03:06, Philippe Mathieu-Daudé wrote: >>>> +++ b/target/arm/kvm.c >>>> @@ -288,7 +288,7 @@ static bool >>>> kvm_arm_get_host_cpu_features(ARMHostCPUFeatures *ahcf) >>>>                                1 << KVM_ARM_VCPU_PTRAUTH_GENERIC); >>>>       } >>>> -    if (kvm_arm_pmu_supported()) { >>>> +    if (host_cpu_feature_supported(ARM_FEATURE_PMU, false)) { >>> >>> Why is false correct here?  Alternately, in the next patch, why is it >>> correct to pass true for the EL2 test? >> >> I think I copied to KVM the HVF use, adapted on top of: >> https://lore.kernel.org/qemu-devel/20250808070137.48716-12- >> mohamed@unpredictable.fr/ >> >>> >>> What is the purpose of the can_emulate parameter at all? >> >> When using split-accel on pre-M3, we might emulate EL2: >> >>         |   feat            |    can_emulate   |    retval >>         +   ----            +      -----       +     ---- > > M1/M2  |  ARM_FEATURE_EL2         false            false> M1/M2  | > ARM_FEATURE_EL2         true             true >> M3/M4  |  ARM_FEATURE_EL2         any              true > > For example in hvf.c: > > static bool hvf_arm_get_host_cpu_features(ARMHostCPUFeatures *ahcf) > { >     ... >     if (host_cpu_feature_supported(ARM_FEATURE_EL2, true)) { >         ahcf->features |= 1ULL << ARM_FEATURE_EL2; >     } > > and then only when split-accel is not enabled: > > hv_return_t hvf_arch_vm_create(MachineState *ms, uint32_t pa_range) > { >     ... >     if (host_cpu_feature_supported(ARM_FEATURE_EL2, false)) { >         ret = hv_vm_config_set_el2_enabled(config, true); >         if (ret != HV_SUCCESS) { >             goto cleanup; >         } >     } > What I'm looking for: - Is this feature supported BY HW? -> hw_init_feature - Is this feature supported BY SW? -> sw_init_feature - Is this feature supported BY ANY? -> do smth with feature With split-accel, this isn't specific to HVF/ARM. I can use a tri-state enum { ANY, HW, SW }.