MT_WTBL_W0_KEY_IDX
w0 &= ~(MT_WTBL_W0_RX_KEY_VALID | MT_WTBL_W0_KEY_IDX);
w0 &= ~MT_WTBL_W0_KEY_IDX;
w0 |= FIELD_PREP(MT_WTBL_W0_KEY_IDX, keyidx);