Pull powerpc fixes from Michael Ellerman:
 "One fix for a bug in our context id handling on 64-bit hash CPUs,
  which can lead to unrelated processes being able to read/write to each
  other's virtual memory. See the commit for full details.

  That is the fix for CVE-2019-12817.

  This also adds a kernel selftest for the bug"

* tag 'powerpc-5.2-6' of git://git.kernel.org/pub/scm/linux/kernel/git/powerpc/linux:
  selftests/powerpc: Add test of fork with mapping above 512TB
  powerpc/mm/64s/hash: Reallocate context ids on fork