Re: [RFC PATCH v4 13/20] vdpa: Save host and guest features

[Eugenio Perez Martin]

On Wed, Oct 13, 2021 at 5:57 AM Jason Wang <jasowang@redhat.com> wrote:
>
>
> 在 2021/10/1 下午3:05, Eugenio Pérez 写道:
> > Those are needed for SVQ: Host ones are needed to check if SVQ knows
> > how to talk with the device and for feature negotiation, and guest ones
> > to know if SVQ can talk with it.
> >
> > Signed-off-by: Eugenio Pérez <eperezma@redhat.com>
> > ---
> >   include/hw/virtio/vhost-vdpa.h |  2 ++
> >   hw/virtio/vhost-vdpa.c         | 31 ++++++++++++++++++++++++++++---
> >   2 files changed, 30 insertions(+), 3 deletions(-)
> >
> > diff --git a/include/hw/virtio/vhost-vdpa.h b/include/hw/virtio/vhost-vdpa.h
> > index fddac248b3..9044ae694b 100644
> > --- a/include/hw/virtio/vhost-vdpa.h
> > +++ b/include/hw/virtio/vhost-vdpa.h
> > @@ -26,6 +26,8 @@ typedef struct vhost_vdpa {
> >       int device_fd;
> >       uint32_t msg_type;
> >       MemoryListener listener;
> > +    uint64_t host_features;
> > +    uint64_t guest_features;
>
>
> Any reason that we can't use the features stored in VirtioDevice?
>
> Thanks
>

It was easier to handle the non standard _F_STOP feature flag in
vhost-vdpa but I think we can use VirtIODevice flags for the next
series.

Thanks!

>
> >       bool shadow_vqs_enabled;
> >       GPtrArray *shadow_vqs;
> >       struct vhost_dev *dev;
> > diff --git a/hw/virtio/vhost-vdpa.c b/hw/virtio/vhost-vdpa.c
> > index 6c5f4c98b8..a057e8277d 100644
> > --- a/hw/virtio/vhost-vdpa.c
> > +++ b/hw/virtio/vhost-vdpa.c
> > @@ -439,10 +439,19 @@ static int vhost_vdpa_set_mem_table(struct vhost_dev 
> > *dev,
> >       return 0;
> >   }
> >
> > -static int vhost_vdpa_set_features(struct vhost_dev *dev,
> > -                                   uint64_t features)
> > +/**
> > + * Internal set_features() that follows vhost/VirtIO protocol for that
> > + */
> > +static int vhost_vdpa_backend_set_features(struct vhost_dev *dev,
> > +                                           uint64_t features)
> >   {
> > +    struct vhost_vdpa *v = dev->opaque;
> > +
> >       int ret;
> > +    if (v->host_features & BIT_ULL(VIRTIO_F_QUEUE_STATE)) {
> > +        features |= BIT_ULL(VIRTIO_F_QUEUE_STATE);
> > +    }
> > +
> >       trace_vhost_vdpa_set_features(dev, features);
> >       ret = vhost_vdpa_call(dev, VHOST_SET_FEATURES, &features);
> >       uint8_t status = 0;
> > @@ -455,6 +464,17 @@ static int vhost_vdpa_set_features(struct vhost_dev 
> > *dev,
> >       return !(status & VIRTIO_CONFIG_S_FEATURES_OK);
> >   }
> >
> > +/**
> > + * Exposed vhost set features
> > + */
> > +static int vhost_vdpa_set_features(struct vhost_dev *dev,
> > +                                   uint64_t features)
> > +{
> > +    struct vhost_vdpa *v = dev->opaque;
> > +    v->guest_features = features;
> > +    return vhost_vdpa_backend_set_features(dev, features);
> > +}
> > +
> >   static int vhost_vdpa_set_backend_cap(struct vhost_dev *dev)
> >   {
> >       uint64_t features;
> > @@ -673,12 +693,17 @@ static int vhost_vdpa_set_vring_call(struct vhost_dev 
> > *dev,
> >   }
> >
> >   static int vhost_vdpa_get_features(struct vhost_dev *dev,
> > -                                     uint64_t *features)
> > +                                   uint64_t *features)
> >   {
> >       int ret;
> >
> >       ret = vhost_vdpa_call(dev, VHOST_GET_FEATURES, features);
> >       trace_vhost_vdpa_get_features(dev, *features);
> > +
> > +    if (ret == 0) {
> > +        struct vhost_vdpa *v = dev->opaque;
> > +        v->host_features = *features;
> > +    }
> >       return ret;
> >   }
> >
>