Re: [Qemu-devel] [PATCHv2 06/10] target-ppc: Remove unused mmu models from ppc_tlb_invalidate_one

[David Gibson]

On Wed, Jan 27, 2016 at 07:06:26PM +0100, Laurent Vivier wrote:
> On 27/01/2016 11:13, David Gibson wrote:
> > ppc_tlb_invalidate_one() has a big switch handling many different MMU
> > types.  However, most of those branches can never be reached:
> > 
> > It is called from 3 places: from remove_hpte() and h_protect() in
> > spapr_hcall.c (which always has a 64-bit hash MMU type), and from
> > helper_tlbie() in mmu_helper.c.
> > 
> > Calls to helper_tlbie() are generated from gen_tlbiel, gen_tlbiel and
> > gen_tlbiva.  The first two are only used with the PPC_MEM_TLBIE flag,
> > set only with 32-bit or 64-bit hash MMU models, and gen_tlbiva() is
> > used only on 440 and 460 models with the BookE mmu model.
> > 
> > These means the exhaustive list of MMU types which may call
> > ppc_tlb_invalidate_one() is: POWERPC_MMU_SOFT_6xx, POWERPC_MMU_601,
> > POWERPC_MMU_32B, POWERPC_MMU_SOFT_74xx, POWERPC_MMU_64B, POWERPC_MMU_2_03,
> > POWERPC_MMU_2_06, POWERPC_MMU_2_07 and POWERPC_MMU_BOOKE.
> > 
> > Clean up by removing logic for all other MMU types from
> > ppc_tlb_invalidate_one().
> > 
> > Signed-off-by: David Gibson <address@hidden>
> > ---
> >  target-ppc/mmu_helper.c | 20 ++------------------
> >  1 file changed, 2 insertions(+), 18 deletions(-)
> > 
> > diff --git a/target-ppc/mmu_helper.c b/target-ppc/mmu_helper.c
> > index c040b17..82ebe5d 100644
> > --- a/target-ppc/mmu_helper.c
> > +++ b/target-ppc/mmu_helper.c
> > @@ -1971,25 +1971,10 @@ void ppc_tlb_invalidate_one(CPUPPCState *env, 
> > target_ulong addr)
> >              ppc6xx_tlb_invalidate_virt(env, addr, 1);
> >          }
> >          break;
> > -    case POWERPC_MMU_SOFT_4xx:
> > -    case POWERPC_MMU_SOFT_4xx_Z:
> > -        ppc4xx_tlb_invalidate_virt(env, addr, env->spr[SPR_40x_PID]);
> 
> This function is now called by no one.

Ah, yes.  Well, actually it was already called by no one, but now it's obvious.

> Perhaps it should move to the
> next patch in helper_tlbiva() (according to your comments) ?

Uh... I'm not exactly sure what you're suggesting.  Moving it to the
next patch doesn't really make sense - this is about the 4xx MMU type
which is *not* the same as the BookE MMU type used on 44x and 46x
(yes, that's confusing - one of the dangers of using an "xx" name).

Hmm.. not sure what to do with this - ppc4xx_tlb_invalidate_virt()
should be removed, but I don't know that it's worth respinning the
whole series just for that.

-- 
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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