Re: [PATCH 1/2] powerpc: Add mask of possible MMU features

["Aneesh Kumar K.V" <aneesh.kumar@linux.vnet.ibm.com>]

Michael Ellerman <mpe@ellerman.id.au> writes:

> Follow the example of the cpu feature code, and add a mask of possible
> MMU features, MMU_FTRS_POSSIBLE.
>
> This is used in mmu_has_feature(), which allows the possible mask to act
> as a shortcut for any features that are not possible, but still allows
> the feature bit itself to be defined.
>
> We will use this feature in the next commit to fix a bug with the
> recently add MMU_FTR_RADIX.
>
> Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>

Reviewed-by: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>

> ---
>  arch/powerpc/include/asm/mmu.h | 14 +++++++++++++-
>  1 file changed, 13 insertions(+), 1 deletion(-)
>
> diff --git a/arch/powerpc/include/asm/mmu.h b/arch/powerpc/include/asm/mmu.h
> index d91dc886c90f..a5e37c93700b 100644
> --- a/arch/powerpc/include/asm/mmu.h
> +++ b/arch/powerpc/include/asm/mmu.h
> @@ -119,9 +119,21 @@
>  DECLARE_PER_CPU(int, next_tlbcam_idx);
>  #endif
>
> +enum {
> +	MMU_FTRS_POSSIBLE = MMU_FTR_HPTE_TABLE | MMU_FTR_TYPE_8xx |
> +		MMU_FTR_TYPE_40x | MMU_FTR_TYPE_44x | MMU_FTR_TYPE_FSL_E |
> +		MMU_FTR_TYPE_47x | MMU_FTR_USE_HIGH_BATS | MMU_FTR_BIG_PHYS |
> +		MMU_FTR_USE_TLBIVAX_BCAST | MMU_FTR_USE_TLBILX |
> +		MMU_FTR_LOCK_BCAST_INVAL | MMU_FTR_NEED_DTLB_SW_LRU |
> +		MMU_FTR_USE_TLBRSRV | MMU_FTR_USE_PAIRED_MAS |
> +		MMU_FTR_NO_SLBIE_B | MMU_FTR_16M_PAGE | MMU_FTR_TLBIEL |
> +		MMU_FTR_LOCKLESS_TLBIE | MMU_FTR_CI_LARGE_PAGE |
> +		MMU_FTR_1T_SEGMENT | MMU_FTR_RADIX,
> +};
> +
>  static inline int mmu_has_feature(unsigned long feature)
>  {
> -	return (cur_cpu_spec->mmu_features & feature);
> +	return (MMU_FTRS_POSSIBLE & cur_cpu_spec->mmu_features & feature);
>  }
>
>  static inline void mmu_clear_feature(unsigned long feature)
> -- 
> 2.5.0