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

[QingFeng Hao]

在 2017/7/3 16:21, Christian Borntraeger 写道:
> On 07/03/2017 10:08 AM, QingFeng Hao wrote:
> > 在 2017/7/3 15:41, Christian Borntraeger 写道:
> > > On 07/03/2017 09:38 AM, QingFeng Hao 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>
> > > cut'n'paste mistake of adding Stefans signoff?
> > >
> > > Otherwise it looks good.
> > I just want to mark that this patch is related with the former one from Stefan.
> > Is that ok to add this sign-off? thanks!
> No, sign-off indicates who passes the patch along for integration, so only 
> Stefan
> is allowed to add that - if he actually takes the patch. It is very important to
> not mangle the sign-off-chain as it is actually used to track how a patch moved 
> from
> the developer into the tree.
>
> You can give credit to Stefan in the patch description - e.g. by saying in the 
> patch
> description something like
>
> based on a similar patch from Stefan Hajnoczi - commit c324fd0a39c (" 
> virtio-pci: use
> ioeventfd even when KVM is disabled)
Thanks for your good explanation and I'll change the commit message.
> > > > ---
> > > >    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;
> > > > +    }
> > > >        if (!kvm_check_extension(kvm_state, KVM_CAP_IOEVENTFD)) {
> > > >            return -ENOSYS;
> > > >        }

--
Regards
QingFeng Hao