Air carrier crew reported GPS jamming at cruise; which resulted in a course deviation. The GPS remained inoperative until landing at destination.

Narrative

GPS Jamming. After returning from break; I was notified that the aircraft was subject to GPS jamming. Prior to break and subsequent crew change briefing; we had discussed the bulletin briefing of the procedures to employ prior to entry. Relief crew applied procedures and flight continued when GPS jamming occurred. Flight progressed without GPS for entire flight. Around the time we returned to the flight deck; ANP and RNP started to diverge and subsequently notified by Bahrain control of being off centerline. RNP was 2.0 and ANP was 2.7 and yellow. We subsequently used heading to steer back to right of magenta line approximately .5 miles and asked control if we were back on course. He said yes. I cycled the the NAV DATA-RAD NAV INHIBT to ON then OFF and within a few minutes ANP went back to normal. Also noted ADS-B OUT several times No further issues occurred. GPS never returned until on the ground in OMDB. We followed bulletin to turn on GPS and turn off RAD NAV INHIBT to on; wrote up GPS jamming at gate.