It probably would be possible to add a new instruction that causes the processor to flush all state in exchange for sacrificing task switching speed. Of course it might still have bugs, but you could imagine that it would be easier to get right.

Of course, it’s not doing much for the billions of devices that exist.

I would hope that we could find a software solution that web browsers can implement so that devices can be patched.

Either way, I would want such a solution to not compromise performance in the case where code is running in the same security context.

This is what I don’t like about existing mitigations. It’s making computers slower in many contexts where they don’t need to be.