Light aircraft flight instructor reported an airspace violation occurred when they departed from their cruise altitude after experiencing GPS jamming in the HSV area.

Narrative

My student and I were cruising direct to ZZZ at 3000ft MSL with advisory services speaking to Huntsville Approach. We were flying through the Huntsville airspace from the northeast on a southwest course that had us briefly flying over R-2104C. We were flying with ATC advisory services (flight following) and ATC had cleared us direct on a course that would take us through R-2104C and told us to remain at or above 3;000ft MSL. The autopilot was flying the aircraft and we crossed over the R-2104C at ~3;020ft. We had the local altimeter setting at Huntsville. There was also some light turbulence at the time. Upon overflying R-2104C; our AHARS and GPS failed and the autopilot disconnected. We believe GPS spoofing/ jamming activity in the vicinity of our aircraft caused the system malfunction. While this happened; we were VMC and looking out the window; so it took a couple seconds to realize the issue. Upon seeing the crew alerting system messages on the G1000 panel; turbulence -- combined with not having hands on the yoke as the AP (Autopilot) was assumed to be flying -- caused us to lose altitude. I immediately disabled the autopilot and began hand flying the aircraft; trying to regain the lost altitude and heading while also investigating/ troubleshooting the issue. While I can't be certain; it's possible that during this time of regaining control of the aircraft; I may have briefly descended below the 3;000ft over R-2104C. Our altimeter was just on the cusp of descending below 3;000ft. Shortly after we were given a vector by ATC to turn to a heading of 270; taking us out of R-2104C to west. After leaving R-2104C; the affected systems returned to functioning normally.