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Re: [Qemu-devel] [qemu-s390x] [PATCH v8 3/6] s390x/kvm: enable/disable A
From: |
David Hildenbrand |
Subject: |
Re: [Qemu-devel] [qemu-s390x] [PATCH v8 3/6] s390x/kvm: enable/disable AP instruction interpretation for guest |
Date: |
Mon, 17 Sep 2018 10:43:11 +0200 |
User-agent: |
Mozilla/5.0 (X11; Linux x86_64; rv:60.0) Gecko/20100101 Thunderbird/60.0 |
Am 12.09.18 um 22:08 schrieb Tony Krowiak:
> From: Tony Krowiak <address@hidden>
>
> Let's use the KVM_SET_DEVICE_ATTR ioctl to enable or disable
> hardware interpretation of AP instructions executed on the guest.
> If the S390_FEAT_AP feature is installed, AP instructions will
> be interpreted by default; otherwise, they will be intercepted.
> This attribute setting may be overridden by a device. For example,
> a device may want to provide AP instructions to the guest (i.e.,
> S390_FEAT_AP turned on), but it may want to emulate them. In this
> case, the AP instructions executed on the guest must be
> intercepted; so when the device is realized, it must disable
> interpretation.
>
> Signed-off-by: Tony Krowiak <address@hidden>
> ---
> target/s390x/kvm.c | 16 ++++++++++++++++
> 1 files changed, 16 insertions(+), 0 deletions(-)
>
> diff --git a/target/s390x/kvm.c b/target/s390x/kvm.c
> index c4bd84d..28a3900 100644
> --- a/target/s390x/kvm.c
> +++ b/target/s390x/kvm.c
> @@ -2297,6 +2297,19 @@ void kvm_s390_get_host_cpu_model(S390CPUModel *model,
> Error **errp)
> S390_FEAT_MAX);
> }
>
> +static void kvm_s390_configure_apie(int interpret)
> +{
> + uint64_t attr = KVM_S390_VM_CRYPTO_DISABLE_APIE;
> +
> + if (interpret) {
> + attr = KVM_S390_VM_CRYPTO_ENABLE_APIE;
> + }
> +
> + if (kvm_vm_check_attr(kvm_state, KVM_S390_VM_CRYPTO, attr)) {
> + kvm_s390_set_attr(attr);
> + }
> +}
> +
> void kvm_s390_apply_cpu_model(const S390CPUModel *model, Error **errp)
> {
> struct kvm_s390_vm_cpu_processor prop = {
> @@ -2346,6 +2359,9 @@ void kvm_s390_apply_cpu_model(const S390CPUModel
> *model, Error **errp)
> if (test_bit(S390_FEAT_CMM, model->features)) {
> kvm_s390_enable_cmma();
> }
> +
> + /* configure hardware interpretation of AP instructions */
> + kvm_s390_configure_apie(test_bit(S390_FEAT_AP, model->features));
> }
>
As it is off as default,
if (test_bit(S390_FEAT_AP, model->features)) {
kvm_s390_configure_apie(true, model->features));
}
will save one ioctl without AP when starting a guest.
As mentioned as replay to patch #2, instead of KVM_S390_VM_CPU_FEAT_AP,
I think we can simply do the following in kvm_s390_get_host_cpu_model()
/* for now, we can only provide the AP feature with HW support */
if (kvm_vm_check_attr(kvm_state, KVM_S390_VM_CRYPTO,
KVM_S390_VM_CRYPTO_ENABLE_APIE)) {
set_bit(S390_FEAT_AP, model->features);
}
Apart from that, looks good to me.
--
Thanks,
David / dhildenb
Re: [Qemu-devel] [PATCH v8 3/6] s390x/kvm: enable/disable AP instruction interpretation for guest, Cornelia Huck, 2018/09/20
[Qemu-devel] [PATCH v8 4/6] s390x/ap: base Adjunct Processor (AP) object model, Tony Krowiak, 2018/09/12