Re: [Qemu-devel] [PATCH 9/9] tests: Test case for query-cpu-model-expansion

[Eduardo Habkost]

On Wed, Jan 18, 2017 at 10:39:46AM +0100, David Hildenbrand wrote:
> Am 17.01.2017 um 02:02 schrieb Eduardo Habkost:
> > +    def checkExpansions(self, model, msg):
> > +        """Perform multiple expansion operations on model, validate results
> > +
> > +        @model is a CpuModelExpansionInfo struct, with some extra keys:
> > +        * model['runnable'] should be set to True if the CPU model is
> > +          runnable on this host
> > +        * model['qom-props'] will be set to the full list of properties for
> > +          the CPU, if the model is runnable
> > +        """
> > +        exp_s = self.checkOneExpansion(model, 'static',
> > +                                       '%s.static' % (msg))
> > +        exp_f = self.checkOneExpansion(model, 'full',
> > +                                       '%s.full' % (msg))
> > +        exp_ss = self.checkOneExpansion(exp_s, 'static',
> > +                                        '%s.static.static' % (msg))
> > +        exp_sf = self.checkOneExpansion(exp_s, 'full',
> > +                                        '%s.static.full' % (msg))
> > +        exp_ff = self.checkOneExpansion(exp_f, 'full',
> > +                                        '%s.full.full' % (msg))
> > +
> > +        # static expansion twice should result in the same data:
> > +        self.assertEquals(exp_s, exp_ss, '%s: static != static+static' % 
> > (msg))
> > +        # full expansion twice should also result in the same data:
> > +        self.assertEquals(exp_f, exp_ff, '%s: full != full+full' % (msg))
> > +
> > +        # migration-safe CPU models have an extra feature:
> > +        # their static expansion should be equivalent to the full
> > +        # expansion (as their static expansion is also precise)
> 
> This is not true for s390x:
> 
> "z13-base" is both, static and migration-safe.
> 
> Doing a full expansion will expand all features (so your check against
> QOM properties should succeed)
> 
> Doing a static expansion will expand no features, as z13-base is
> already static, so there are no features to expand (no delta changes).
> 
> "z13" is only migration-safe.
> 
> Doing a full expansion will expand all features.
> 
> Doing a static expansion will only expand the features different to
> "z13-base". (Remember, delta changes only to minimize reported
> features).

I think my comment was confusing. By "equivalent" I don't mean
having the same expansion, but resulting in the same set of
features.

This is not comparing full_expansion(model) and
static_expansion(model). It is comparing full_expansion(model)
full_expansion(static_expansion(model)).

In other words, absolutely no feature should be lost or changed
during static expansion, and we verify that by doing a full
expansion after the static expansion (exp_sf) and comparing the
results with the full expansion (exp_f).

I believe this is true on s390x too, isn't it?

> 
> 
> And I wonder if that is also true for x86? This should only be true if
> the "base" model contains absolutely no features.

This is true on x86, but temporarily. "base" still contains no
features, but I plan to add extra information to type=full that
can't appear on type=static.

> 
> > +        if self.isMigrationSafe(model['model']):
> > +            self.assertEquals(exp_sf['model']['props'], 
> > exp_f['model']['props'],
> > +                              '%s: props: static+full != full' % (msg))
> > +            self.assertEquals(exp_sf.get('qom-props'), 
> > exp_f.get('qom-props'),
> > +                              '%s: qom-props: static+full != full' % (msg))
> 
> 
> -- 
> 
> David

-- 
Eduardo