G650 pilot reported an aileron control failure during cruise flight and had to immediately descend to avoid a stall. The pilot diverted to an alternate airport and safely landed.

Narrative

Enroute from ZZZZ to ZZZ. Approximately 7 hours after takeoff. While in cruise flight at FL470; Mach .86. Aircraft jerked. Autopilot reverted to pitch and roll modes. Amber 'L Aileron Fail' CAS (Crew Alert System) message illuminated. Disengaged autopilot; yoke jerked hard to the left. Significant manual control force required to regain wings level flight. Displayed flight control synoptic. Left aileron showed full up deflection in synoptic. Left aileron Hydraulic Actuator and left aileron Emergency Backup Hydraulic Actuator were both boxed Amber (failed). Completed 'Aileron Fail' checklist. Flight Control Reset switch was ineffective. [Advised] ZZZZ Control.Required immediate descent to reduce pitch to avoid aerodynamic stall due to high drag created by deflected left aileron; and counteracting right aileron and spoilers. Diverted to ZZZZ1 for best wind and runway length. Performed controllability check. Landed without further incident. Recovery from this event would likely not be possible if it had occurred during takeoff or landing.