powerpc: Add a cpu feature CPU_FTR_PMAO_BUG

Some power8 revisions have a hardware bug where we can lose a
Performance Monitor (PMU) exception under certain circumstances.

We will be adding a workaround for this case, see the next commit for
details. The observed behaviour is that writing PMAO doesn't cause an
exception as we would expect, hence the name of the feature.

Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
This commit is contained in:
Michael Ellerman 2014-03-14 16:00:28 +11:00 • committed by Benjamin Herrenschmidt
commit 68f2f0d431
2 changed files with 5 additions and 3 deletions