Re: [PATCH v10 24/26] KVM: s390: device attrs to enable/disable AP interpretation

David Hildenbrand
2018-09-17T08:51:08Z

Am 12.09.18 um 21:43 schrieb Tony Krowiak:
> From: Tony Krowiak <akrowiak@linux.ibm.com>
>
> Introduces two new VM crypto device attributes (KVM_S390_VM_CRYPTO)
> to enable or disable AP instruction interpretation from userspace
> via the KVM_SET_DEVICE_ATTR ioctl:
>
> * The KVM_S390_VM_CRYPTO_ENABLE_APIE attribute enables hardware
> interpretation of AP instructions executed on the guest.
>
> * The KVM_S390_VM_CRYPTO_DISABLE_APIE attribute disables hardware
> interpretation of AP instructions executed on the guest. In this
> case the instructions will be intercepted and pass through to
> the guest.
>
> Signed-off-by: Tony Krowiak <akrowiak@linux.ibm.com>
> ---
> arch/s390/include/asm/kvm_host.h | 1 +
> arch/s390/include/uapi/asm/kvm.h | 2 ++
> arch/s390/kvm/kvm-s390.c | 27 +++++++++++++++++++++++----
> 3 files changed, 26 insertions(+), 4 deletions(-)
>
> diff --git a/arch/s390/include/asm/kvm_host.h b/arch/s390/include/asm/kvm_host.h
> index b32bd1b..36d3531 100644
> --- a/arch/s390/include/asm/kvm_host.h
> +++ b/arch/s390/include/asm/kvm_host.h
> @@ -719,6 +719,7 @@ struct kvm_s390_crypto {
> __u32 crycbd;
> __u8 aes_kw;
> __u8 dea_kw;
> + __u8 apie;
> };
>
> #define APCB0_MASK_SIZE 1
> diff --git a/arch/s390/include/uapi/asm/kvm.h b/arch/s390/include/uapi/asm/kvm.h
> index 8c23afc..a8dbd90 100644
> --- a/arch/s390/include/uapi/asm/kvm.h
> +++ b/arch/s390/include/uapi/asm/kvm.h
> @@ -161,6 +161,8 @@ struct kvm_s390_vm_cpu_subfunc {
> #define KVM_S390_VM_CRYPTO_ENABLE_DEA_KW 1
> #define KVM_S390_VM_CRYPTO_DISABLE_AES_KW 2
> #define KVM_S390_VM_CRYPTO_DISABLE_DEA_KW 3
> +#define KVM_S390_VM_CRYPTO_ENABLE_APIE 4
> +#define KVM_S390_VM_CRYPTO_DISABLE_APIE 5
>
> /* kvm attributes for migration mode */
> #define KVM_S390_VM_MIGRATION_STOP 0
> diff --git a/arch/s390/kvm/kvm-s390.c b/arch/s390/kvm/kvm-s390.c
> index 2cdd980..286c2e0 100644
> --- a/arch/s390/kvm/kvm-s390.c
> +++ b/arch/s390/kvm/kvm-s390.c
> @@ -856,12 +856,11 @@ void kvm_s390_vcpu_crypto_reset_all(struct kvm *kvm)
>
> static int kvm_s390_vm_set_crypto(struct kvm *kvm, struct kvm_device_attr *attr)
> {
> - if (!test_kvm_facility(kvm, 76))
> - return -EINVAL;
> -
> mutex_lock(&kvm->lock);
> switch (attr->attr) {
> case KVM_S390_VM_CRYPTO_ENABLE_AES_KW:
> + if (!test_kvm_facility(kvm, 76))
> + return -EINVAL;
> get_random_bytes(
> kvm->arch.crypto.crycb->aes_wrapping_key_mask,
> sizeof(kvm->arch.crypto.crycb->aes_wrapping_key_mask));
> @@ -869,6 +868,8 @@ static int kvm_s390_vm_set_crypto(struct kvm *kvm, struct kvm_device_attr *attr)
> VM_EVENT(kvm, 3, "%s", "ENABLE: AES keywrapping support");
> break;
> case KVM_S390_VM_CRYPTO_ENABLE_DEA_KW:
> + if (!test_kvm_facility(kvm, 76))
> + return -EINVAL;
> get_random_bytes(
> kvm->arch.crypto.crycb->dea_wrapping_key_mask,
> sizeof(kvm->arch.crypto.crycb->dea_wrapping_key_mask));
> @@ -876,17 +877,31 @@ static int kvm_s390_vm_set_crypto(struct kvm *kvm, struct kvm_device_attr *attr)
> VM_EVENT(kvm, 3, "%s", "ENABLE: DEA keywrapping support");
> break;
> case KVM_S390_VM_CRYPTO_DISABLE_AES_KW:
> + if (!test_kvm_facility(kvm, 76))
> + return -EINVAL;
> kvm->arch.crypto.aes_kw = 0;
> memset(kvm->arch.crypto.crycb->aes_wrapping_key_mask, 0,
> sizeof(kvm->arch.crypto.crycb->aes_wrapping_key_mask));
> VM_EVENT(kvm, 3, "%s", "DISABLE: AES keywrapping support");
> break;
> case KVM_S390_VM_CRYPTO_DISABLE_DEA_KW:
> + if (!test_kvm_facility(kvm, 76))
> + return -EINVAL;
> kvm->arch.crypto.dea_kw = 0;
> memset(kvm->arch.crypto.crycb->dea_wrapping_key_mask, 0,
> sizeof(kvm->arch.crypto.crycb->dea_wrapping_key_mask));
> VM_EVENT(kvm, 3, "%s", "DISABLE: DEA keywrapping support");
> break;
> + case KVM_S390_VM_CRYPTO_ENABLE_APIE:
> + if (!ap_instructions_available()) {
> + mutex_unlock(&kvm->lock);
> + return -EOPNOTSUPP;
> + }
> + kvm->arch.crypto.apie = 1;
> + break;
> + case KVM_S390_VM_CRYPTO_DISABLE_APIE:
> + kvm->arch.crypto.apie = 0;
> + break;
> default:
> mutex_unlock(&kvm->lock);
> return -ENXIO;
> @@ -1493,6 +1508,8 @@ static int kvm_s390_vm_has_attr(struct kvm *kvm, struct kvm_device_attr *attr)
> case KVM_S390_VM_CRYPTO_ENABLE_DEA_KW:
> case KVM_S390_VM_CRYPTO_DISABLE_AES_KW:
> case KVM_S390_VM_CRYPTO_DISABLE_DEA_KW:
> + case KVM_S390_VM_CRYPTO_ENABLE_APIE:
> + case KVM_S390_VM_CRYPTO_DISABLE_APIE:

As also replied to the QEMU series, could we indicate
KVM_S390_VM_CRYPTO_ENABLE_APIE (and maybe
KVM_S390_VM_CRYPTO_DISABLE_APIE) only with ap_instructions_available(),
so we can avoid the additional KVM_S390_VM_CPU_FEAT_AP?

KVM_S390_VM_CPU_FEAT_AP is right now completely unused in KVM otherwise
(never checked, we only care about apie).

--

Thanks,

David / dhildenb