Ping.
> Subject: RE: [EXT] Re: [PATCH] vhost_net: add NOTIFICATION_DATA and
> IN_ORDER feature bits to vdpa_feature_bits
>
>
>
> > -----Original Message-----
> > From: Michael S. Tsirkin <[email protected]>
> > Sent: Monday, February 19, 2024 3:15 PM
> > To: Srujana Challa <[email protected]>
> > Cc: [email protected]; Vamsi Krishna Attunuru
> > <[email protected]>; Jerin Jacob <[email protected]>; Jason Wang
> > <[email protected]>
> > Subject: [EXT] Re: [PATCH] vhost_net: add NOTIFICATION_DATA and
> > IN_ORDER feature bits to vdpa_feature_bits
> >
> > External Email
> >
> > ----------------------------------------------------------------------
> > On Tue, Jan 02, 2024 at 04:44:32PM +0530, Srujana Challa wrote:
> > > Enables VIRTIO_F_NOTIFICATION_DATA and VIRTIO_F_IN_ORDER feature
> > bits
> > > for vhost vdpa backend. Also adds code to consider all feature bits
> > > supported by vhost net client type for feature negotiation, so that
> > > vhost backend device supported features can be negotiated with guest.
> > >
> > > Signed-off-by: Srujana Challa <[email protected]>
> > > ---
> > > hw/net/vhost_net.c | 10 ++++++++++
> > > net/vhost-vdpa.c | 2 ++
> > > 2 files changed, 12 insertions(+)
> > >
> > > diff --git a/hw/net/vhost_net.c b/hw/net/vhost_net.c index
> > > e8e1661646..65ae8bcece 100644
> > > --- a/hw/net/vhost_net.c
> > > +++ b/hw/net/vhost_net.c
> > > @@ -117,6 +117,16 @@ static const int
> > > *vhost_net_get_feature_bits(struct vhost_net *net)
> > >
> > > uint64_t vhost_net_get_features(struct vhost_net *net, uint64_t
> > > features) {
> > > + const int *bit = vhost_net_get_feature_bits(net);
> > > +
> > > + /*
> > > + * Consider all feature bits for feature negotiation with vhost
> > > backend,
> > > + * so that all backend device supported features can be negotiated.
> > > + */
> > > + while (*bit != VHOST_INVALID_FEATURE_BIT) {
> > > + features |= (1ULL << *bit);
> > > + bit++;
> > > + }
> > > return vhost_get_features(&net->dev, vhost_net_get_feature_bits(net),
> > > features);
> > > }
> >
> > I don't think we should do this part. With vdpa QEMU is in control of
> > which features are exposed and that is intentional since features are
> > often tied to other behaviour.
>
> Vdpa Qemu can negotiate all the features which vdpa backend device supports
> with the guest right?
> Guest drivers (it could be userspace or kernel drivers) will negotiate their
> own
> features, so that
> frontend supported features will get the precedence.
>
> >
> > > diff --git a/net/vhost-vdpa.c b/net/vhost-vdpa.c index
> > > 3726ee5d67..51334fcfe2 100644
> > > --- a/net/vhost-vdpa.c
> > > +++ b/net/vhost-vdpa.c
> > > @@ -57,7 +57,9 @@ typedef struct VhostVDPAState {
> > > */
> > > const int vdpa_feature_bits[] = {
> > > VIRTIO_F_ANY_LAYOUT,
> > > + VIRTIO_F_IN_ORDER,
> > > VIRTIO_F_IOMMU_PLATFORM,
> > > + VIRTIO_F_NOTIFICATION_DATA,
> > > VIRTIO_F_NOTIFY_ON_EMPTY,
> > > VIRTIO_F_RING_PACKED,
> > > VIRTIO_F_RING_RESET,
> > > --
> > > 2.25.1
