Hi Peter,
On 7/4/25 2:14 PM, Peter Maydell wrote:
> On Wed, 2 Jul 2025 at 17:31, Eric Auger <eric.au...@redhat.com> wrote:
>> From: Haibo Xu <haibo...@linaro.org>
>>
>> KVM_CAP_ARM_EL2 must be supported by the cpu to enable ARM_FEATURE_EL2.
>> In case the host does support NV, expose the feature.
>>
>> Signed-off-by: Haibo Xu <haibo...@linaro.org>
>> Signed-off-by: Miguel Luis <miguel.l...@oracle.com>
>> Signed-off-by: Eric Auger <eric.au...@redhat.com>
>> Reviewed-by: Richard Henderson <richard.hender...@linaro.org>
>>
>> ---
>> v2 -> v3:
>> - check pmu->has_el2 on kvm_arch_init_vcpu() when setting
>> KVM_ARM_VCPU_HAS_EL2 feature (Peter)
>>
>> v1 -> v2:
>> - remove isar_feature_aa64_aa32_el2 modif in target/arm/cpu.h
>> [Richard] and use el2_supported in kvm_arch_init_vcpu
>> ---
>> target/arm/kvm.c | 16 ++++++++++++++++
>> 1 file changed, 16 insertions(+)
>>
>> diff --git a/target/arm/kvm.c b/target/arm/kvm.c
>> index e5708e54ae..46e5f19637 100644
>> --- a/target/arm/kvm.c
>> +++ b/target/arm/kvm.c
>> @@ -250,6 +250,7 @@ static bool
>> kvm_arm_get_host_cpu_features(ARMHostCPUFeatures *ahcf)
>> */
>> int fdarray[3];
>> bool sve_supported;
>> + bool el2_supported;
>> bool pmu_supported = false;
>> uint64_t features = 0;
>> int err;
>> @@ -269,6 +270,14 @@ static bool
>> kvm_arm_get_host_cpu_features(ARMHostCPUFeatures *ahcf)
>> init.features[0] |= 1 << KVM_ARM_VCPU_SVE;
>> }
>>
>> + /*
>> + * Ask for EL2 if supported.
>> + */
>> + el2_supported = kvm_arm_el2_supported();
>> + if (el2_supported) {
>> + init.features[0] |= 1 << KVM_ARM_VCPU_HAS_EL2;
>> + }
>> +
>> /*
>> * Ask for Pointer Authentication if supported, so that we get
>> * the unsanitized field values for AA64ISAR1_EL1.
>> @@ -422,6 +431,10 @@ static bool
>> kvm_arm_get_host_cpu_features(ARMHostCPUFeatures *ahcf)
>> features |= 1ULL << ARM_FEATURE_AARCH64;
>> features |= 1ULL << ARM_FEATURE_GENERIC_TIMER;
>>
>> + if (el2_supported) {
>> + features |= 1ULL << ARM_FEATURE_EL2;
>> + }
>> +
>> ahcf->features = features;
>>
>> return true;
>> @@ -1887,6 +1900,9 @@ int kvm_arch_init_vcpu(CPUState *cs)
>> cpu->kvm_init_features[0] |= (1 << KVM_ARM_VCPU_PTRAUTH_ADDRESS |
>> 1 << KVM_ARM_VCPU_PTRAUTH_GENERIC);
>> }
>> + if (cpu->has_el2 && kvm_arm_el2_supported()) {
>> + cpu->kvm_init_features[0] |= 1 << KVM_ARM_VCPU_HAS_EL2;
>> + }
>>
>> /* Do KVM_ARM_VCPU_INIT ioctl */
>> ret = kvm_arm_vcpu_init(cpu);
>> --
> How does this interact with creating an aarch32 VM with
> "-cpu host,aarch64=off" ? Looking at the kernel, it will
> fail vcpu_init if you ask for a vcpu with both EL1_32BIT
> and HAS_EL2. I guess since the virt board will only request
> HAS_EL2 if you say virtualization=on this is fine. Do we
> give a sensible error message if the user tries
> -accel kvm -M virt,virtualization=on -cpu host,aarch64=off ?
Not yet. I will add one.
Thanks!
Eric
>
> -- PMM
>
