[PATCH] powerpc/book3s64/radix/tlb: Determine hugepage flush correctly

[Nicholas Piggin]

Excerpts from Aneesh Kumar K.V's message of May 13, 2020 1:06 pm:
> With a 64K page size flush with start and end value as below
> (start, end) = (721f680d0000, 721f680e0000) results in
> (hstart, hend) = (721f68200000, 721f68000000)
> 
> Avoid doing a __tlbie_va_range with the wrong hstart and hend value in this
> case.
> 
> __tlbie_va_range will skip the actual tlbie operation for start > end.
> But we still end up doing the tlbie fixup.

Hm, good catch.

> Reported-by: Bharata B Rao <bharata at linux.ibm.com>
> Signed-off-by: Aneesh Kumar K.V <aneesh.kumar at linux.ibm.com>
> ---
>  arch/powerpc/mm/book3s64/radix_tlb.c | 6 +++---
>  1 file changed, 3 insertions(+), 3 deletions(-)
> 
> diff --git a/arch/powerpc/mm/book3s64/radix_tlb.c b/arch/powerpc/mm/book3s64/radix_tlb.c
> index 758ade2c2b6e..d592f9e1c037 100644
> --- a/arch/powerpc/mm/book3s64/radix_tlb.c
> +++ b/arch/powerpc/mm/book3s64/radix_tlb.c
> @@ -884,10 +884,10 @@ static inline void __radix__flush_tlb_range(struct mm_struct *mm,
>  		if (IS_ENABLED(CONFIG_TRANSPARENT_HUGEPAGE)) {
>  			hstart = (start + PMD_SIZE - 1) & PMD_MASK;
>  			hend = end & PMD_MASK;
> -			if (hstart == hend)
> -				hflush = false;
> -			else
> +			if (hstart < hend)
>  				hflush = true;
> +			else
> +				hflush = false;

We can probably get rid of the else part since it is already false.

Otherwise

Reviewed-by: Nicholas Piggin <npiggin at gmail.com>