On 2024/07/18 21:07, Peter Maydell wrote:
On Tue, 16 Jul 2024 at 13:50, Akihiko Odaki <akihiko.odaki@xxxxxxxxxx> wrote:kvm_arm_get_host_cpu_features() used to add the PMU feature unconditionally, and kvm_arch_init_vcpu() removed it when it is actually not available. Conditionally add the PMU feature in kvm_arm_get_host_cpu_features() to save code. Signed-off-by: Akihiko Odaki <akihiko.odaki@xxxxxxxxxx> --- target/arm/kvm.c | 7 +------ 1 file changed, 1 insertion(+), 6 deletions(-) diff --git a/target/arm/kvm.c b/target/arm/kvm.c index 70f79eda33cd..849e2e21b304 100644 --- a/target/arm/kvm.c +++ b/target/arm/kvm.c @@ -280,6 +280,7 @@ static bool kvm_arm_get_host_cpu_features(ARMHostCPUFeatures *ahcf) if (kvm_arm_pmu_supported()) { init.features[0] |= 1 << KVM_ARM_VCPU_PMU_V3; pmu_supported = true; + features |= 1ULL << ARM_FEATURE_PMU; } if (!kvm_arm_create_scratch_host_vcpu(cpus_to_try, fdarray, &init)) { @@ -448,7 +449,6 @@ static bool kvm_arm_get_host_cpu_features(ARMHostCPUFeatures *ahcf) features |= 1ULL << ARM_FEATURE_V8; features |= 1ULL << ARM_FEATURE_NEON; features |= 1ULL << ARM_FEATURE_AARCH64; - features |= 1ULL << ARM_FEATURE_PMU; features |= 1ULL << ARM_FEATURE_GENERIC_TIMER; ahcf->features = features; @@ -1888,13 +1888,8 @@ int kvm_arch_init_vcpu(CPUState *cs) if (!arm_feature(env, ARM_FEATURE_AARCH64)) { cpu->kvm_init_features[0] |= 1 << KVM_ARM_VCPU_EL1_32BIT; } - if (!kvm_check_extension(cs->kvm_state, KVM_CAP_ARM_PMU_V3)) { - cpu->has_pmu = false; - } if (cpu->has_pmu) { cpu->kvm_init_features[0] |= 1 << KVM_ARM_VCPU_PMU_V3; - } else { - env->features &= ~(1ULL << ARM_FEATURE_PMU); } if (cpu_isar_feature(aa64_sve, cpu)) { assert(kvm_arm_sve_supported());Not every KVM CPU is necessarily the "host" CPU type. The "cortex-a57" and "cortex-a53" CPU types will work if you happen to be on a host of that CPU type, and they don't go through kvm_arm_get_host_cpu_features().
kvm_arm_vcpu_init() will emit an error in such a situation and I think it's better than silently removing a feature that the requested CPU type has. A user can still disable the feature if desired.
Regards, Akihiko Odaki
