[PATCH 0/3] x86, pkeys: fix prefetch/pkeys interaction

[Dave Hansen]

The first two patches here are useful in any case, I think.

But, as for the third:  There are no known prefetch errata on
processors that support memory protection keys.  There have not
been any that I can find in any recent generations, either.

But, if there were a future erratum, we would need this.
Otherwise, apps who hit the theoretical erratum and used pkeys
would not be fixed up by the prefetch erratum detection code.

It also occurs to me that *if* there were an erratum on a modern
CPU, we might not know because we have so many workarounds in
place.

So, I'm submitting this, but I don't feel that strongly about it.
It doesn't fix a real problem, but it's also not that much code,
or in any kind of fast path.