Re: [Qemu-devel] [PATCH v2 1/2] s390x/ais: enable ais when migration is available

[Yi Min Zhao]

在 2017/9/26 下午10:06, Christian Borntraeger 写道:
> On 09/26/2017 03:43 PM, David Hildenbrand wrote:
> > > +    /* try enable the AIS facility */
> > > +    test_attr.group = KVM_DEV_FLIC_AISM_ALL;
> > > +    if (!ioctl(flic_state->fd, KVM_HAS_DEVICE_ATTR, test_attr)) {
> > > +            kvm_vm_enable_cap(kvm_state, KVM_CAP_S390_AIS, 0);
> > > +    }
> > > +
> > >       return;
> > >   fail:
> > >       error_propagate(errp, errp_local);
> > > @@ -578,7 +584,7 @@ static void kvm_s390_flic_reset(DeviceState *dev)
> > >   
> > >       flic_disable_wait_pfault(flic);
> > >   
> > > -    if (fs->ais_supported) {
> > > +    if (s390_has_feat(S390_FEAT_ADAPTER_INT_SUPPRESSION)) {
> > I don't remember if a reset is trigger on realization. Most probably
> > not, but it could be.
> >
> > Would it hurt if the following code would not get called if the flic
> > hasn't been used yet? (possible reset before cpu model has been
> > initialized) - are kvm_s390_modify_ais_mode() calls required before ais
> > can be used for the first time?
> Hmm, simm/nimm should default to zero in the kernel I guess. So I think it would
> not hurt. Yi Min, correct?
Yes, the default mode is all interruption mode, IOW simm = 0 and nimm = 0.
> Anyway it seems that reset is NOT called during realize, the first
> call is
>
>                  #0  0x00000000010e5178 kvm_s390_flic_reset (qemu-system-s390x)
>                  #1  0x000000000124bbc4 device_reset (qemu-system-s390x)
>                  #2  0x0000000001248cd0 qdev_reset_one (qemu-system-s390x)
>                  #3  0x0000000001249ea4 qdev_walk_children (qemu-system-s390x)
>                  #4  0x000000000124fd3a qbus_walk_children (qemu-system-s390x)
>                  #5  0x0000000001248e6c qbus_reset_all (qemu-system-s390x)
>                  #6  0x0000000001248eae qbus_reset_all_fn (qemu-system-s390x)
>                  #7  0x0000000001250a60 qemu_devices_reset (qemu-system-s390x)
>                  #8  0x0000000001143c80 s390_machine_reset (qemu-system-s390x)
>                  #9  0x00000000011c5b72 qemu_system_reset (qemu-system-s390x)
>                  #10 0x00000000011ceb8e main (qemu-system-s390x)
>                  #11 0x000003ff947a289a __libc_start_main (libc.so.6)
>                  #12 0x0000000001017646 _start (qemu-system-s390x)