[libvirt] [PATCH 0/4] qemu: Use host-model CPU on s390 by default

[Boris Fiuczynski]

Just a heads up.
After installing libvirt rpms of this branch all my existing kvm s390 
domains ended up with

   <cpu mode='custom' match='exact' check='none'>
     <model fallback='forbid'>qemu</model>
   </cpu>

Newly defined domains without specified cpu do so as well.


On 11/14/19 4:44 PM, Jiri Denemark wrote:
> On s390 machines host-passthrough and host-model CPUs result in the same
> guest ABI (with QEMU new enough to be able to tell us what "host" CPU is
> expanded to, which was implemented around 2.9.0). So instead of using
> host-passthrough CPU when there's no CPU specified in a domain XML we
> can safely use host-model and benefit from CPU compatibility checks
> during migration, snapshot restore and similar operations.
> 
> 
> This series applies on top of "qemu: Store default CPU in domain XML"
> which is already acked, but it's waiting for a QEMU patch to be applied
> to 4.2.0.
> 
> You can fetch both series at once using
> 
>      git fetch https://gitlab.com/jirkade/libvirt cpu-default-type
> 
> Jiri Denemark (4):
>    cpu_conf: Fix default value for CPU match attribute
>    cpu_conf: Don't format empty model for host-model CPUs
>    cpu_s390: Don't check match attribute for host-model CPUs
>    qemu: Use host-model CPU on s390 by default
> 
>   src/conf/cpu_conf.c                           | 25 ++++----------
>   src/conf/cpu_conf.h                           |  2 +-
>   src/cpu/cpu_s390.c                            | 18 +++++-----
>   src/qemu/qemu_domain.c                        | 33 ++++++++++++-------
>   .../ppc64-host+guest-compat-none.xml          |  4 +--
>   ...t-cpu-kvm-ccw-virtio-4.2.s390x-latest.args |  4 ++-
>   .../cpu-check-default-partial.xml             |  4 +--
>   .../cpu-host-model-features.xml               |  1 -
>   ...lt-cpu-kvm-ccw-virtio-4.2.s390x-latest.xml |  2 +-
>   9 files changed, 45 insertions(+), 48 deletions(-)
> 


-- 
Mit freundlichen Grüßen/Kind regards
    Boris Fiuczynski

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