Re: [qemu-s390x] [PATCH v2 1/6] s390x/vfio: ap: Finding the AP bridge

[Pierre Morel]

On 29/11/2018 21:30, Tony Krowiak wrote:
> On 11/22/18 11:35 AM, Pierre Morel wrote:
> > In the case we will enter QEMU through interception of instructions,
> > we will need to retrieve the AP devices.
> > The base device is the AP bridge.
> >
> > Let us implement a way to retrieve the AP Bridge from qtree.
> >
> > Signed-off-by: Pierre Morel <address@hidden>
> > ---
> >   hw/s390x/ap-bridge.c         | 12 ++++++++++++
> >   include/hw/s390x/ap-bridge.h |  1 +
> >   2 files changed, 13 insertions(+)
> >
> > diff --git a/hw/s390x/ap-bridge.c b/hw/s390x/ap-bridge.c
> > index 3795d30..831ad5d 100644
> > --- a/hw/s390x/ap-bridge.c
> > +++ b/hw/s390x/ap-bridge.c
> > @@ -14,6 +14,18 @@
> >   #include "hw/s390x/ap-bridge.h"
> >   #include "cpu.h"
> > +DeviceState *s390_get_ap_bridge(void)
> > +{
> > +    static DeviceState *apb;
>
> Since you are caching a reference to the bridge after
> retrieving it, why not make apb a global scope variable
> and initialize it in s390_init_ap() when the bridge is
> created. You can then declare it as an extern in the
> ap-bridge.h header file and you eliminate the need for
> this function. If you do make it a global var, I would
> name it ap_bridge;

We already had this discussion when implementing zPCI.
I use a similar solution as it was decided at that time.


Regards,
Pierre


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