[libvirt] [Qemu-devel] [PATCH 0/9] i386: query-cpu-model-expansion test script

[Eduardo Habkost]

On Wed, Jan 18, 2017 at 12:09:28PM -0500, Jason J. Herne wrote:
> On 01/18/2017 12:00 PM, Eduardo Habkost wrote:
> > On Tue, Jan 17, 2017 at 10:22:10AM -0500, Jason J. Herne wrote:
> > > On 01/16/2017 08:01 PM, Eduardo Habkost wrote:
> > > > This is a follow-up to the series that implements
> > > > query-cpu-model-expansion. Before including the test script, the
> > > > series has some fixes to allow the results of
> > > > query-cpu-model-expansion to be used in the QEMU command-line.
> > > > 
> > > > The script probably will work on s390x too, but I couldn't test
> > > > it yet.
> > > > 
> > > 
> > > Eduardo,
> > > 
> > > This test seems to mostly work on s390. The only issue I ran into is
> > > querying host model using tcg only. s390 requires kvm to query the host
> > > model. Perhaps we could just skip the tcg host test case on s390?
> > 
> > We could still try to test "host", but add it to a greylist where
> > errors returned by query-cpu-model-expansion can be non-fatal.
> > query-cpu-model-expansion model="host" can also fail with KVM if
> > the host doesn't support CPU models.
> > 
> 
> David had the idea to just support -cpu host for tcg. We could do that.
> In the meantime, I'm ok with your greylist idea too. This would allow the
> script to work properly on s390 right from the start, and we can remove the
> greylist when s390 supports specifying -cpu host for tcg.

I believe we will still need to ignore query-cpu-model-expansion
errors on some cases, otherwise the test script will fail on
hosts where KVM doesn't support CPU models in KVM.

But we probably don't need a hardcoded greylist, anyway: we could
just make the error non-fatal in case the CPU model is not
reported as migration-safe in query-cpu-definitions.

But I was wondering:

1) Isn't "-cpu host" the default CPU model on s390x on KVM,
   even if the host doesn't support CPU models?

2) Is it really correct to return an error on
   "query-cpu-model-expansion model=host type=full" if the host
   doesn't support CPU models?

   What if it just returned { name: "host", props: {} }
   on those cases, meaning that the CPU model is valid and
   usable, but QEMU is unable to provide extra information about
   it.

-- 
Eduardo