[PATCH] powerpc/powernv: Fix opal entry/exit MSR_RI coverage

[Nicholas Piggin]

On Mon, 24 Apr 2017 11:47:48 +1000
Benjamin Herrenschmidt <benh at kernel.crashing.org> wrote:

> On Thu, 2017-03-30 at 22:10 +1000, Nicholas Piggin wrote:
> > There are some windows in opal entry/exit that can not recover from a
> > re-entrant interrupt (e.g., machine check) due to using SRR registers,
> > but they currently do not have MSR_RI clear.
> > 
> > These were found by machine check injection coverage tests using the
> > powerpc system simulator (Mambo).  
> 
> So you make us enter/exit OPAL with RI off with your patch.

It should hrfid to opal with MSR_RI set. It seems to be doing the right
thing when stepping through it with the simulator.

> 
> OPAL currently won't re-enable it (which is a problem... we need to
> deal with MCEs happening while in OPAL, especially the ones with
> the special recovery table).
> 
> So if we do that we need to make OPAL turn it back on. In that case
> I would suggest making OPAL also turn it back off, thus avoiding
> touching FIXUP_ENDIAN...