vhost-user: do not send RESET_OWNER on device reset

vhost-user: do not send RESET_OWNER on device reset

The VHOST_USER_RESET_OWNER message is deprecated in the spec:

   This is no longer used. Used to be sent to request disabling all
   rings, but some back-ends interpreted it to also discard connection
   state (this interpretation would lead to bugs).  It is recommended
   that back-ends either ignore this message, or use it to disable all
   rings.

The only caller of vhost_user_reset_device() is vhost_user_scsi_reset().
It checks that F_RESET_DEVICE was negotiated before calling it:

  static void vhost_user_scsi_reset(VirtIODevice *vdev)
  {
      VHostSCSICommon *vsc = VHOST_SCSI_COMMON(vdev);
      struct vhost_dev *dev = &vsc->dev;

      /*
       * Historically, reset was not implemented so only reset devices
       * that are expecting it.
       */
      if (!virtio_has_feature(dev->protocol_features,
                              VHOST_USER_PROTOCOL_F_RESET_DEVICE)) {
          return;
      }

      if (dev->vhost_ops->vhost_reset_device) {
          dev->vhost_ops->vhost_reset_device(dev);
      }
  }

Therefore VHOST_USER_RESET_OWNER is actually never sent by
vhost_user_reset_device(). Remove the dead code. This effectively moves
the vhost-user protocol specific code from vhost-user-scsi.c into
vhost-user.c where it belongs.

Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
Message-Id: <20231004014532.1228637-2-stefanha@redhat.com>
Reviewed-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
Reviewed-by: Raphael Norwitz <raphael.norwitz@nutanix.com>