Pushing Intel to provide the drivers or at least documentation would be the best solution - the BIOS lock would become irrelevant. However, I don't agree with

Pushing Intel to provide the drivers or at least documentation would be the best solution - the BIOS lock would become irrelevant. However, I don't agree with conclusion that Lenovo isn't to blame. They went out of their way to ensure that even power users playing with EFI shell won't be able to switch to AHCI mode. I don't care about Microsoft here. Lenovo showed its bad side and I probably won't be buying their devices anymore - which is a pity, as I'm writing this on my Yoga 2 Pro, with my company's Yoga 900 (fortunately older, unblocked revision) nearby and I liked those devices.