Re: [Qemu-devel] [PATCH v4 3/5] s390x: Add I/O adapter registration.

[Cornelia Huck <cornelia.huck@de.ibm.com>]

On Wed, 09 Apr 2014 16:05:00 +0200
Alexander Graf <agraf@suse.de> wrote:

> 
> On 09.04.14 13:34, Cornelia Huck wrote:
> > Register an I/O adapter interrupt source for when virtio-ccw devices start
> > using adapter interrupts.
> >
> > Reviewed-by: Thomas Huth <thuth@linux.vnet.ibm.com>
> > Signed-off-by: Cornelia Huck <cornelia.huck@de.ibm.com>
> > ---
> >   hw/intc/s390_flic.c   |   59 +++++++++++++++++++++++++++++++++++++++++++++++++
> >   hw/s390x/css.c        |   51 ++++++++++++++++++++++++++++++++++++++++++
> >   hw/s390x/css.h        |    4 ++++
> >   hw/s390x/virtio-ccw.c |    4 ++++
> >   hw/s390x/virtio-ccw.h |    1 +
> >   target-s390x/cpu.h    |   33 +++++++++++++++++++++++++++
> >   6 files changed, 152 insertions(+)
> >

> > diff --git a/hw/s390x/virtio-ccw.c b/hw/s390x/virtio-ccw.c
> > index 2bf0af8..1193682 100644
> > --- a/hw/s390x/virtio-ccw.c
> > +++ b/hw/s390x/virtio-ccw.c
> > @@ -522,6 +522,10 @@ static int virtio_ccw_cb(SubchDev *sch, CCW1 ccw)
> >                   dev->thinint_isc = thinint->isc;
> >                   dev->ind_bit = thinint->ind_bit;
> >                   cpu_physical_memory_unmap(thinint, hw_len, 0, hw_len);
> > +                ret = css_register_io_adapter(CSS_IO_ADAPTER_VIRTIO,
> > +                                              dev->thinint_isc, true, false,
> > +                                              &dev->adapter_id);
> 
> In all other machines the machine file is the one creating the link 
> between a device and the interrupt controller. Can we do something 
> similar for s390?

Hm. This would imply we'd need to add a virtio I/O adapter for each isc
(0-7) at startup, regardless whether the guest enables adapter
interrupts on any of those iscs. Moreover, we'd need to do the same for
each type (on each isc) if we add more types of I/O adapters later
(should we want to support one of the other adapter-interrupt using
devices). I'd prefer to add an I/O adapter only when needed.