hyperv_guid2str
int hyperv_guid2str(const struct hyperv_guid *, char *,
n = hyperv_guid2str(vmbus_chan_guid_inst(chan), buf,
hyperv_guid2str(&chan->ch_guid_type, guidbuf, sizeof(guidbuf));
hyperv_guid2str(&chan->ch_guid_inst, guidbuf, sizeof(guidbuf));