Re: [PATCH v2] virtio: add VIRTIO_F_NOTIFICATION_DATA feature support

Michael S. Tsirkin
2023-03-21T09:08:40Z

On Tue, Mar 21, 2023 at 12:00:42PM +0300, Viktor Prutyanov wrote:
> On Tue, Mar 21, 2023 at 5:29 AM Jason Wang <jasowang@redhat.com> wrote:
> >
> > On Tue, Mar 21, 2023 at 7:21 AM Viktor Prutyanov <viktor@daynix.com> wrote:
> > >
> > > According to VirtIO spec v1.2, VIRTIO_F_NOTIFICATION_DATA feature
> > > indicates that the driver passes extra data along with the queue
> > > notifications.
> > >
> > > In a split queue case, the extra data is 16-bit available index. In a
> > > packed queue case, the extra data is 1-bit wrap counter and 15-bit
> > > available index.
> > >
> > > Add support for this feature for MMIO and PCI transports. Channel I/O
> > > transport will not accept this feature.
> > >
> > > Signed-off-by: Viktor Prutyanov <viktor@daynix.com>
> > > ---
> > >
> > > v2: reject the feature in virtio_ccw, replace __le32 with u32
> > >
> > > drivers/s390/virtio/virtio_ccw.c | 4 +---
> > > drivers/virtio/virtio_mmio.c | 15 ++++++++++++++-
> > > drivers/virtio/virtio_pci_common.c | 10 ++++++++++
> > > drivers/virtio/virtio_pci_common.h | 4 ++++
> > > drivers/virtio/virtio_pci_legacy.c | 2 +-
> > > drivers/virtio/virtio_pci_modern.c | 2 +-
> > > drivers/virtio/virtio_ring.c | 17 +++++++++++++++++
> > > include/linux/virtio_ring.h | 2 ++
> > > include/uapi/linux/virtio_config.h | 6 ++++++
> > > 9 files changed, 56 insertions(+), 6 deletions(-)
> > >
> > > diff --git a/drivers/s390/virtio/virtio_ccw.c b/drivers/s390/virtio/virtio_ccw.c
> > > index a10dbe632ef9..d72a59415527 100644
> > > --- a/drivers/s390/virtio/virtio_ccw.c
> > > +++ b/drivers/s390/virtio/virtio_ccw.c
> > > @@ -789,9 +789,7 @@ static u64 virtio_ccw_get_features(struct virtio_device *vdev)
> > >
> > > static void ccw_transport_features(struct virtio_device *vdev)
> > > {
> > > - /*
> > > - * Currently nothing to do here.
> > > - */
> > > + __virtio_clear_bit(vdev, VIRTIO_F_NOTIFICATION_DATA);
> >
> > Is there any restriction that prevents us from implementing
> > VIRTIO_F_NOTIFICATION_DATA? (Spec seems doesn't limit us from this)
>
> Most likely, nothing.

So pls code it up. It's the same format.

> >
> > > }
> > >
> > > static int virtio_ccw_finalize_features(struct virtio_device *vdev)
> > > diff --git a/drivers/virtio/virtio_mmio.c b/drivers/virtio/virtio_mmio.c
> > > index 3ff746e3f24a..0e13da17fe0a 100644
> > > --- a/drivers/virtio/virtio_mmio.c
> > > +++ b/drivers/virtio/virtio_mmio.c
> > > @@ -285,6 +285,19 @@ static bool vm_notify(struct virtqueue *vq)
> > > return true;
> > > }
> > >
> > > +static bool vm_notify_with_data(struct virtqueue *vq)
> > > +{
> > > + struct virtio_mmio_device *vm_dev = to_virtio_mmio_device(vq->vdev);
> > > + u32 data = vring_fill_notification_data(vq);
> >
> > Can we move this to the initialization?
>
> This data is new for each notification, because it helps to identify
> the next available index.
>
> >
> > Thanks
> >
>
> Thanks,
> Viktor Prutyanov