than the switchin functions to guarantee that we're operating with the
correct tlb entry.
- Remove the post copy/zero tlb invalidations. It is faster to invalidate
an entry that is known to exist and so it is faster to invalidate after
use. However, some architectures implement speculative page table
prefetching so we can not be guaranteed that the invalidated entry is still
invalid when we re-enter any of these functions. As a result of this we
must always invalidate before use to be safe.
f67fdc737e