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SubjectRe: [PATCH 3/3] powerpc/mm: call H_BLOCK_REMOVE when supported
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On 8/30/19 5:37 PM, Laurent Dufour wrote:
> Instead of calling H_BLOCK_REMOVE all the time when the feature is
> exhibited, call this hcall only when the couple base page size, page size
> is supported as reported by the TLB Invalidate Characteristics.
>

supported is not actually what we are checking here. We are checking
whether the base page size actual page size remove can be done in chunks
of 8 blocks. If we don't support 8 block you fallback to bulk
invalidate. May be update the commit message accordingly?


> For regular pages and hugetlb, the assumption is made that the page size is
> equal to the base page size. For THP the page size is assumed to be 16M.
>
> Signed-off-by: Laurent Dufour <ldufour@linux.ibm.com>
> ---
> arch/powerpc/platforms/pseries/lpar.c | 11 +++++++++--
> 1 file changed, 9 insertions(+), 2 deletions(-)
>
> diff --git a/arch/powerpc/platforms/pseries/lpar.c b/arch/powerpc/platforms/pseries/lpar.c
> index 375e19b3cf53..ef3dbf108a65 100644
> --- a/arch/powerpc/platforms/pseries/lpar.c
> +++ b/arch/powerpc/platforms/pseries/lpar.c
> @@ -1143,7 +1143,11 @@ static inline void __pSeries_lpar_hugepage_invalidate(unsigned long *slot,
> if (lock_tlbie)
> spin_lock_irqsave(&pSeries_lpar_tlbie_lock, flags);
>
> - if (firmware_has_feature(FW_FEATURE_BLOCK_REMOVE))
> + /*
> + * Assuming THP size is 16M, and we only support 8 bytes size buffer
> + * for the momment.
> + */
> + if (mmu_psize_defs[psize].hblk[MMU_PAGE_16M] == 8)
> hugepage_block_invalidate(slot, vpn, count, psize, ssize);
> else
> hugepage_bulk_invalidate(slot, vpn, count, psize, ssize);



So we don't use block invalidate if blocksize is != 8.


> @@ -1437,7 +1441,10 @@ static void pSeries_lpar_flush_hash_range(unsigned long number, int local)
> if (lock_tlbie)
> spin_lock_irqsave(&pSeries_lpar_tlbie_lock, flags);
>
> - if (firmware_has_feature(FW_FEATURE_BLOCK_REMOVE)) {
> + /*
> + * Currently, we only support 8 bytes size buffer in do_block_remove().
> + */
> + if (mmu_psize_defs[batch->psize].hblk[batch->psize] == 8) {
> do_block_remove(number, batch, param);
> goto out;
> }
>

-aneesh

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