CTX_RING_TAIL
ce->lrc_reg_state[CTX_RING_TAIL + 1] = ce->ring->tail;
CTX_REG(regs, CTX_RING_TAIL, RING_TAIL(base), 0);
regs[CTX_RING_TAIL + 1] = ce->ring->tail;
reg_state[CTX_RING_TAIL+1] = intel_ring_set_tail(rq->ring, rq->tail);