We perform ab initio QED calculations of energy levels for the n=1 and n=2 states of He-like ions with the nuclear charge in the range Z=12-100. The complete set of two-electron QED corrections is evaluated to all orders in the parameter αZ. Uncalculated contributions to energy levels come through orders α3(αZ)2, α2(αZ)7, and higher. A significant improvement in accuracy of theoretical predictions is achieved, especially in the high-Z region.