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Date: Mon, 7 Aug 2017 11:52:09 +0200
From: Cornelia Huck <cohuck@redhat.com>
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Subject: Re: [Qemu-devel] [PATCH v4 7/9] s390x/pci: fence off instructions
 for non-pci
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To: David Hildenbrand <david@redhat.com>
Cc: qemu-devel@nongnu.org, borntraeger@de.ibm.com, agraf@suse.de, thuth@redhat.com, pmorel@linux.vnet.ibm.com, zyimin@linux.vnet.ibm.com

On Fri, 4 Aug 2017 15:17:25 +0200
David Hildenbrand <david@redhat.com> wrote:

> On 04.08.2017 13:29, Cornelia Huck wrote:
> > If a guest running on a machine without zpci issues a pci instruction,
> > throw them an exception.
> > 
> > Reviewed-by: Thomas Huth <thuth@redhat.com>
> > Signed-off-by: Cornelia Huck <cohuck@redhat.com>
> > ---
> >  target/s390x/kvm.c | 54 +++++++++++++++++++++++++++++++++++++++++-------------
> >  1 file changed, 41 insertions(+), 13 deletions(-)
> > 
> > diff --git a/target/s390x/kvm.c b/target/s390x/kvm.c
> > index bc62bba5b7..9de165d8b1 100644
> > --- a/target/s390x/kvm.c
> > +++ b/target/s390x/kvm.c
> > @@ -1191,7 +1191,11 @@ static int kvm_clp_service_call(S390CPU *cpu, struct kvm_run *run)
> >  {
> >      uint8_t r2 = (run->s390_sieic.ipb & 0x000f0000) >> 16;
> >  
> > -    return clp_service_call(cpu, r2);
> > +    if (s390_has_feat(S390_FEAT_ZPCI)) {
> > +        return clp_service_call(cpu, r2);
> > +    } else {
> > +        return -1;
> > +    }  
> 
> I am a fan of dropping these else case and returning directly. But that
> is just my opinion.
> 
> (applies to all changes in this patch)
> 
> 

You are not the first to say that :)

I do prefer this way around, though, and if there aren't strong
objections, I'll keep it like this.