[PATCH] powerpc/powernv/nvram: opal_nvram_write handle unknown OPAL errors

[Nicholas Piggin]

On Tue, 27 Mar 2018 23:13:00 +1100
Michael Ellerman <mpe at ellerman.id.au> wrote:

> Nicholas Piggin <npiggin at gmail.com> writes:
> 
> > opal_nvram_write currently just assumes success if it encounters an
> > error other than OPAL_BUSY or OPAL_BUSY_EVENT. Have it return -EIO
> > on other errors instead.  
> 
> Does that ever happen with current skiboot?

I can now even using the mambo fake flash driver that never returns
failure, because skiboot will return OPAL_INTERNAL_ERROR if we try
to re-enter it. So I hit it when testing sreset-in-opal cases (the
crash path wants to write something to nvram).

Not sure about the skiboot flash layer. Aside from programming
errors, it looks like perhaps ECC and BMC failure or unresponsive
could cause errors to come back here.

> Even if it doesn't I think I'm inclined to tag this for stable.

It's turning some relatively minor types of errors into a system
hang, so it seems like it could go in stable. I've hit the -EIO case
in these basic tests and it hasn't had obvious bugs.

Thanks,
Nick