Re: [qemu-s390x] [PATCH v2 2/6] s390x/vfio: ap: Use the APdevice as a child of the APBus

[Pierre Morel]

On 29/11/2018 21:42, Tony Krowiak wrote:
> On 11/22/18 11:35 AM, Pierre Morel wrote:
> > Two good reasons to use the base device as a child of the
> > AP BUS:
> > - We can easily find the device without traversing the qtree.
> > - In case we have different APdevice instantiation, VFIO with
> >    interception or emulation, we will need the APDevice as
> >    a parent device.
> >
> > Signed-off-by: Pierre Morel <address@hidden>
> > ---
> >   hw/s390x/ap-device.c         | 22 ++++++++++++++++++++++
> >   hw/vfio/ap.c                 | 16 ++++++----------
> >   include/hw/s390x/ap-device.h |  2 ++
> >   3 files changed, 30 insertions(+), 10 deletions(-)
> >
> > diff --git a/hw/s390x/ap-device.c b/hw/s390x/ap-device.c
> > index f5ac8db..554d5aa 100644
> > --- a/hw/s390x/ap-device.c
> > +++ b/hw/s390x/ap-device.c
> > @@ -11,13 +11,35 @@
> >   #include "qemu/module.h"
> >   #include "qapi/error.h"
> >   #include "hw/qdev.h"
> > +#include "hw/s390x/ap-bridge.h"
> >   #include "hw/s390x/ap-device.h"
> > +APDevice *s390_get_ap(void)
>
> How about ap_get_device(void)?

Yes, keep same conventions.

> > +{
> > +    static DeviceState *apb;
>
> Why static if you call s390_get_ap_bridge()
> to retrieve it without first checking for NULL?

static are initialized as NULL.

> > +    BusState *bus;
> > +    BusChild *child;
> > +    static APDevice *ap;
> > +
> > +    if (ap) {
> > +        return ap;
> > +    }
> > +
> > +    apb = s390_get_ap_bridge();
> > +    /* We have only a single child on the BUS */
> > +    bus = qdev_get_child_bus(apb, TYPE_AP_BUS
> > +    child = QTAILQ_FIRST(&bus->children);
> > +    assert(child != NULL);
> > +    ap = DO_UPCAST(APDevice, parent_obj, child->child);
>
> I received a comment from Thomas Huth in Message ID
> <address@hidden>
> that DO_UPCAST should be avoided in new code. You should
> create an AP_DEVICE macro for this in ap-device.h

Thanks I will do.

Regards,
Pierre


--
Pierre Morel
Linux/KVM/QEMU in Böblingen - Germany