Re: [Qemu-devel] [PATCH 19/25] spapr: add hcalls support for the XIVE interrupt mode

[Benjamin Herrenschmidt]

On Wed, 2017-12-06 at 20:20 +1100, David Gibson wrote:
> On Tue, Dec 05, 2017 at 08:50:26AM -0600, Benjamin Herrenschmidt wrote:
> > On Tue, 2017-12-05 at 18:00 +1100, David Gibson wrote:
> > > > The CPU revision. But we won't introduce XIVE exploitation mode on 
> > > > anything else than DD2.0 which has full XIVE support. Even STORE_EOI 
> > > > that we should be adding.
> > > 
> > > Hrm.  Host CPU?  That's a problem - if guest visible properties like
> > > this vary with the host CPU, migration breaks.
> > 
> > I don't think this is going to be a problem in practice. The
> > availability of trigger comes from OPAL but in practice, all virtual
> > interrupts are going to support it always,
> 
> Ok.  It still makes me nervous to derive guest visible features from
> the host.  I'd prefer to just hardwire the XIVE model to always/never
> advertise it and simply fail if that isn't workable for the host kernel.

We could fail loudly if we see an migratable interrupt that doesn't
have the flag.

Cheers,
Ben.