Re: [qemu-s390x] [PATCH v3 4/7] s390x/kvm: interface to interpret AP instructions

[Tony Krowiak]

On 03/15/2018 07:24 PM, Tony Krowiak wrote:
> The VFIO AP device exploits interpretive execution of AP
> instructions (APIE). APIE is enabled by setting a device attribute
> via the KVM_SET_DEVICE_ATTR ioctl.
>
> Signed-off-by: Tony Krowiak <address@hidden>
> ---
>   target/s390x/kvm.c       |   16 ++++++++++++++++
>   target/s390x/kvm_s390x.h |    2 ++
>   2 files changed, 18 insertions(+), 0 deletions(-)
>
> diff --git a/target/s390x/kvm.c b/target/s390x/kvm.c
> index 33e5ec3..2812e28 100644
> --- a/target/s390x/kvm.c
> +++ b/target/s390x/kvm.c
> @@ -277,6 +277,22 @@ static void kvm_s390_init_dea_kw(void)
>       }
>   }
>
> +int kvm_s390_set_interpret_ap(uint8_t enable)
> +{
> +    struct kvm_device_attr attribute = {
> +        .group = KVM_S390_VM_CRYPTO,
> +        .attr  = KVM_S390_VM_CRYPTO_INTERPRET_AP,
> +        .addr = 1,
> +    };
> +
> +    if (!kvm_vm_check_attr(kvm_state, KVM_S390_VM_CRYPTO,
> +                           KVM_S390_VM_CRYPTO_INTERPRET_AP)) {
> +        return -EOPNOTSUPP;
> +    }
> +
> +    return kvm_vm_ioctl(kvm_state, KVM_SET_DEVICE_ATTR, &attribute);
> +}
I proposed removing the KVM_S390_VM_CRYPTO_INTERPRET_AP device attribute 
from the kernel in
Message ID <address@hidden> on 
the kernel mailing list
and proposed setting interpretive execution for AP instructions via the 
mdev open callback. That
would eliminate the need for this patch.
> +
>   void kvm_s390_crypto_reset(void)
>   {
>       if (s390_has_feat(S390_FEAT_MSA_EXT_3)) {
> diff --git a/target/s390x/kvm_s390x.h b/target/s390x/kvm_s390x.h
> index 34ee7e7..0d6c6e7 100644
> --- a/target/s390x/kvm_s390x.h
> +++ b/target/s390x/kvm_s390x.h
> @@ -40,4 +40,6 @@ void kvm_s390_crypto_reset(void);
>   void kvm_s390_restart_interrupt(S390CPU *cpu);
>   void kvm_s390_stop_interrupt(S390CPU *cpu);
>
> +int kvm_s390_set_interpret_ap(uint8_t enable);
> +
>   #endif /* KVM_S390X_H */