I can successfully attach disks to a running KVM instance using
virsh attach-disk node-1 /dev/vg_lunsr/lun1 vdb Disk attached successfully
...but these new devices aren't seen by the guest without a reboot, which almost defeats the purpose of dynamic attachment. If these were SCSI devices I would use e.g.
/sys/class/scsi_host/host0/scan to request the SCSI drivers to scan for new devices. Is there an equivalent capability for the virtio block driver?