Re: [PATCH for 9.0 07/12] vdpa: set backend capabilities at vhost_vdpa_init

[Eugenio Perez Martin <eperezma@redhat.com>]

On Wed, Dec 20, 2023 at 5:34 AM Jason Wang <jasowang@redhat.com> wrote:
>
> On Sat, Dec 16, 2023 at 1:28 AM Eugenio Pérez <eperezma@redhat.com> wrote:
> >
> > The backend does not reset them until the vdpa file descriptor is closed
> > so there is no harm in doing it only once.
> >
> > This allows the destination of a live migration to premap memory in
> > batches, using VHOST_BACKEND_F_IOTLB_BATCH.
> >
> > Signed-off-by: Eugenio Pérez <eperezma@redhat.com>
> > ---
> >  hw/virtio/vhost-vdpa.c | 50 ++++++++++++++++--------------------------
> >  1 file changed, 19 insertions(+), 31 deletions(-)
> >
> > diff --git a/hw/virtio/vhost-vdpa.c b/hw/virtio/vhost-vdpa.c
> > index 449c3794b2..43f7c382b1 100644
> > --- a/hw/virtio/vhost-vdpa.c
> > +++ b/hw/virtio/vhost-vdpa.c
> > @@ -587,11 +587,25 @@ static int vhost_vdpa_init(struct vhost_dev *dev, void *opaque, Error **errp)
> >      struct vhost_vdpa *v = opaque;
> >      assert(dev->vhost_ops->backend_type == VHOST_BACKEND_TYPE_VDPA);
> >      trace_vhost_vdpa_init(dev, v->shared, opaque);
> > +    uint64_t backend_features;
> > +    uint64_t qemu_backend_features = 0x1ULL << VHOST_BACKEND_F_IOTLB_MSG_V2 |
> > +                                     0x1ULL << VHOST_BACKEND_F_IOTLB_BATCH |
> > +                                     0x1ULL << VHOST_BACKEND_F_IOTLB_ASID |
> > +                                     0x1ULL << VHOST_BACKEND_F_SUSPEND;
> >      int ret;
> >
> >      v->dev = dev;
> >      dev->opaque =  opaque ;
> >      v->shared->listener = vhost_vdpa_memory_listener;
> > +
> > +    if (vhost_vdpa_call(dev, VHOST_GET_BACKEND_FEATURES, &backend_features)) {
> > +        return -EFAULT;
> > +    }
> > +
> > +    backend_features &= qemu_backend_features;
> > +
> > +    dev->backend_cap = backend_features;
> > +    v->shared->backend_cap = backend_features;
> >      vhost_vdpa_init_svq(dev, v);
> >
> >      error_propagate(&dev->migration_blocker, v->migration_blocker);
> > @@ -599,6 +613,11 @@ static int vhost_vdpa_init(struct vhost_dev *dev, void *opaque, Error **errp)
> >          return 0;
> >      }
> >
> > +    ret = vhost_vdpa_call(dev, VHOST_SET_BACKEND_FEATURES, &backend_features);
> > +    if (ret) {
> > +        return -EFAULT;
> > +    }
> > +
> >      /*
> >       * If dev->shadow_vqs_enabled at initialization that means the device has
> >       * been started with x-svq=on, so don't block migration
> > @@ -829,36 +848,6 @@ static int vhost_vdpa_set_features(struct vhost_dev *dev,
> >      return vhost_vdpa_add_status(dev, VIRTIO_CONFIG_S_FEATURES_OK);
> >  }
> >
> > -static int vhost_vdpa_set_backend_cap(struct vhost_dev *dev)
>
> How about keeping this function but just calling it in vhost_vdpa_init()?
>

Sure, that is possible. I need to remove the VhostOps
vhost_set_backend_cap = vhost_vdpa_set_backend_cap, anyway, is that ok
for you?

Thanks!