Re: [Qemu-devel] [PATCH v2 2/2] s390x/ais: disable ais for compat machines

[David Hildenbrand]

On 26.09.2017 15:36, Christian Borntraeger wrote:
> With newer kernels that do support the ais feature (4.13) a qemu 2.11
> will not only enable the ais feature for the 2.11 machine, but also
> for a <=2.10 compat machine. As this feature is not available in
> QEMU <=2.9 (and QEMU 2.10.1), this guest will fail to migrate
> back to an older qemu like 2.9 with:
> 
> _snip_
> error while loading state for instance 0x0 of device 's390-flic'
> _snip_
> 
> making the whole compat machine dis-functional. As a permanent fix, we
> need to fence the ais feature for machines <= 2.10
> 
> Due to ais being enabled on 2.10.0 (fixed in 2.10.1) this will prevent
> migration of ais-enabled guests from 2.10.0 with
> 
> _snip_
> qemu-system-s390x: Failed to load s390-flic/ais:tmp
> qemu-system-s390x: error while loading state for instance 0x0 of device 
> 's390-flic'
> qemu-system-s390x: load of migration failed: Function not implemented
> _snip_
> 
> Signed-off-by: Christian Borntraeger <address@hidden>
> Cc: Yi Min Zhao <address@hidden>
> Cc: Dr. David Alan Gilbert <address@hidden>
> ---
>  hw/intc/s390_flic_kvm.c            |  4 +++-


As discussed, I think we should use cpu_model_allowed() instead.

-- 

Thanks,

David