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

[Laurent Vivier]

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

> -        break;
> -    case POWERPC_MMU_REAL:
> -        cpu_abort(CPU(cpu), "No TLB for PowerPC 4xx in real mode\n");
> -        break;
> -    case POWERPC_MMU_MPC8xx:
> -        /* XXX: TODO */
> -        cpu_abort(CPU(cpu), "MPC8xx MMU model is not implemented\n");
> -        break;
>      case POWERPC_MMU_BOOKE:
>          /* XXX: TODO */
>          cpu_abort(CPU(cpu), "BookE MMU model is not implemented\n");
>          break;
> -    case POWERPC_MMU_BOOKE206:
> -        /* XXX: TODO */
> -        cpu_abort(CPU(cpu), "BookE 2.06 MMU model is not implemented\n");
> -        break;
>      case POWERPC_MMU_32B:
>      case POWERPC_MMU_601:
>          /* tlbie invalidate TLBs for all segments */
> @@ -2031,9 +2016,8 @@ void ppc_tlb_invalidate_one(CPUPPCState *env, 
> target_ulong addr)
>          break;
>  #endif /* defined(TARGET_PPC64) */
>      default:
> -        /* XXX: TODO */
> -        cpu_abort(CPU(cpu), "Unknown MMU model\n");
> -        break;
> +        /* Should never reach here with other MMU models */
> +        assert(0);
>      }
>  #else
>      ppc_tlb_invalidate_all(env);
>