Re: [EXTERNAL] [PATCH 2/2] target/ppc: Fix ISA v3.0 (POWER9) slbia implementation

[David Gibson]

On Thu, Mar 19, 2020 at 07:46:54AM +1100, Benjamin Herrenschmidt wrote:
> On Wed, 2020-03-18 at 18:08 +0100, Cédric Le Goater wrote:
> > On 3/18/20 5:41 AM, Nicholas Piggin wrote:
> > > Linux using the hash MMU ("disable_radix" command line) on a POWER9
> > > machine quickly hits translation bugs due to using v3.0 slbia
> > > features that are not implemented in TCG. Add them.
> > 
> > I checked the ISA books and this looks OK but you are also modifying
> > slbie.
> 
> For the same reason, I believe slbie needs to invalidate caches even if
> the entry isn't present.
> 
> The kernel will under some circumstances overwrite SLB entries without
> invalidating (because the translation itself isn't invalid, it's just
> that the SLB is full, so anything cached in the ERAT is still
> technically ok).
> 
> However, when those things get really invalidated, they need to be
> taken out, even if they no longer have a corresponding SLB entry.

Right, the slbie change is certainly correct, but it doesn't match
what the commit message says this is doing.  Nick, can you split that
out please.

-- 
David Gibson                    | I'll have my music baroque, and my code
david AT gibson.dropbear.id.au  | minimalist, thank you.  NOT _the_ _other_
                                | _way_ _around_!
http://www.ozlabs.org/~dgibson

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