Re: [PATCH 3/3] powerpc/mm: call H_BLOCK_REMOVE when supported

[Laurent Dufour]

Le 12/09/2019 Ã 16:20, Aneesh Kumar K.V a ÃcritÂ:
> 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?

Yes that's correct.

I think I should also put the warning message displayed when reading the 
characteristic in that commit and explicitly mentioned that we only support 
8 entries size block for this hcall.
This way the limitation is limited to this commit.

> > 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@xxxxxxxxxxxxx>
> > ---
> > Â arch/powerpc/platforms/pseries/lpar.c | 11 +++++++++--
> > Â 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,
> > ÂÂÂÂÂ if (lock_tlbie)
> > ÂÂÂÂÂÂÂÂÂ spin_lock_irqsave(&pSeries_lpar_tlbie_lock, flags);
> > -ÂÂÂ if (firmware_has_feature(FW_FEATURE_BLOCK_REMOVE))
> > +ÂÂÂ /*
> > +ÂÂÂÂ * Assuming THP size is 16M, and we only support 8 bytes size buffer
> > +ÂÂÂÂ * for the momment.
> > +ÂÂÂÂ */
> > +ÂÂÂ if (mmu_psize_defs[psize].hblk[MMU_PAGE_16M] == 8)
> > ÂÂÂÂÂÂÂÂÂ hugepage_block_invalidate(slot, vpn, count, psize, ssize);
> > ÂÂÂÂÂ else
> > ÂÂÂÂÂÂÂÂÂ hugepage_bulk_invalidate(slot, vpn, count, psize, ssize);
>
>
>
> So we don't use block invalidate if blocksize is != 8.

yes

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