> -----Original Message-----
> From: Michael S. Tsirkin <m...@redhat.com>
> Sent: Monday, February 19, 2024 3:15 PM
> To: Srujana Challa <scha...@marvell.com>
> Cc: qemu-devel@nongnu.org; Vamsi Krishna Attunuru
> <vattun...@marvell.com>; Jerin Jacob <jer...@marvell.com>; Jason Wang
> <jasow...@redhat.com>
> 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 <scha...@marvell.com>
> > ---
> > 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
