Re: [Qemu-block] [Qemu-devel] [PATCH 1/1] virtio-scsi-ccw: use ioeventfd even when KVM is disabled

[QingFeng Hao]

在 2017/7/3 19:48, Cornelia Huck 写道:
> On Mon,  3 Jul 2017 09:38:36 +0200
> QingFeng Hao <address@hidden> wrote:
>
> > Do not check kvm_eventfds_enabled() when KVM is disabled since it
> > always returns 0.  Since commit
> > 8c56c1a592b5092d91da8d8943c17777d6462a6f ("memory: emulate
> > ioeventfd") it has been possible to use ioeventfds in qtest or TCG
> > mode.
> >
> > This patch makes -device virtio-scsi-ccw,iothread=iothread0 work even
> > when KVM is disabled.
> >
> > I have tested that virtio-scsi-ccw works under tcg both with and
> > without iothread.
> >
> > This patch fixes qemu-iotests 068, which was accidentally merged early
> > despite the dependency on ioeventfd.
> >
> > Signed-off-by: QingFeng Hao <address@hidden>
> > Signed-off-by: Stefan Hajnoczi <address@hidden>
> > ---
> >   hw/s390x/virtio-ccw.c | 2 +-
> >   target/s390x/kvm.c    | 3 +++
> >   2 files changed, 4 insertions(+), 1 deletion(-)
> >
> > diff --git a/hw/s390x/virtio-ccw.c b/hw/s390x/virtio-ccw.c
> > index 90d37cb9ff..35896eb007 100644
> > --- a/hw/s390x/virtio-ccw.c
> > +++ b/hw/s390x/virtio-ccw.c
> > @@ -711,7 +711,7 @@ static void
> > virtio_ccw_device_realize(VirtioCcwDevice *dev, Error **errp)
> > sch->cssid, sch->ssid, sch->schid, sch->devno, ccw_dev->devno.valid ?
> > "user-configured" : "auto-configured");
> > -    if (!kvm_eventfds_enabled()) {
> > +    if (kvm_enabled() && !kvm_eventfds_enabled()) {
> >           dev->flags &= ~VIRTIO_CCW_FLAG_USE_IOEVENTFD;
> >       }
> >   
> > diff --git a/target/s390x/kvm.c b/target/s390x/kvm.c
> > index a3d00196f4..c37f9c3b9e 100644
> > --- a/target/s390x/kvm.c
> > +++ b/target/s390x/kvm.c
> > @@ -2220,6 +2220,9 @@ int
> > kvm_s390_assign_subch_ioeventfd(EventNotifier *notifier, uint32_t
> > sch, .addr = sch, .len = 8,
> >       };
> > +    if (!kvm_enabled()) {
> > +        return 0;
> > +    }
> I'd prefer if you moved the kvm_enabled() check into
> s390_assign_subch_ioeventfd().
Thanks and I'll change it just as Christian's comment.
> >       if (!kvm_check_extension(kvm_state, KVM_CAP_IOEVENTFD)) {
> >           return -ENOSYS;
> >       }

--
Regards
QingFeng Hao