Ah, you're proposing a solution for Meltdown rather than Spectre. The difference is that with Meltdown there is speculative access to memory that isn't even map

Ah, you're proposing a solution for Meltdown rather than Spectre. The difference is that with Meltdown there is speculative access to memory that isn't even mapped to the original process. Memory encryption might work as a way to solve that, but we already know how to solve that -- do what AMD and others have been doing the whole time and don't continue speculative execution through a page fault.