CPU mode feature policy settings

[Adam Dyess]

with the cpu-model-extra-flags argument you can set nova.conf -- cpu_model_extra_flags. However nova will only set features. the default policy for a feature is 'required'

for instance)
   juju config nova-compute cpu-model-extra-flags="feature-1 feature-2"

creates nova.conf
   cpu_model_extra_flags = feature-1, feature-2

in libvirt xml

<cpu>
  <feature name="feature-1/>
  <feature name="feature-2/>
</cpu>

the default policy attribute above is 'require'
<cpu>
  <feature policy="require" name="feature-1/>
  <feature policy="require" name="feature-2/>
</cpu>

I have a circumstance where i'd like to control the policy flag in this XML

https://www.berrange.com/posts/2010/02/15/guest-cpu-model-configuration-in-libvirt-with-qemukvm/
The next enhancement is that the <feature> elements can each have an extra “policy” attribute with possible values

    policy=”force” – expose the feature to the guest even if the host does not have it. This is kind of crazy, except in the case of software emulation.
    policy=”require” – expose the feature to the guest and fail if the host does not have it. This is the sensible default.
    policy=”optional” – expose the feature to the guest if it happens to support it.
    policy=”disable” – if the host has this feature, then hide it from the guest
    policy=”forbid” – if the host has this feature, then fail and refuse to start the guest

Could you push upstream to add this feature?