Re: [PATCH] tlb: hugetlb: Add arm64 contiguous hint awareness

[Steve Capper <steve.capper@arm.com>]

On 24/03/2022 15:58, Peter Zijlstra wrote:
> On Thu, Mar 24, 2022 at 02:35:44PM +0000, Steve Capper wrote:
>>> It occurs to me that perhaps this can be written like:
>>>
>>> 	unsigned long _sz = huge_page_size(h);
>>> 	if (_sz >= P4D_SIZE)
>>> 		tlb_flush_p4d_range(tlb, address, _sz);
>>> 	else if (_sz >= PUD_SIZE)
>>> 		tlb_flush_pud_range(tlb, address, _sz);
>>> 	else if (_sz >= PMD_SIZE)
>>> 		tlb_flush_pmd_range(tlb, address, _sz);
>>> 	else
>>> 		tlb_flush_pte_range(tlb, address, _sz);
>>> 	__tlb_remove_tlb_entry(tlb, ptep, address);
>>>
>>> And then it can still be generic..
>>
>> Thanks Peter,
>> My concern with that would be the CONT_PMD_SIZE case would result in a call
>> to tlb_flush_pte_range rather than tlb_flush_pmd_range causing some of the
>> level parameters to be different.
> 
> arch/arm64/include/asm/pgtable-hwdef.h:#define CONT_PMD_SIZE            (CONT_PMDS * PMD_SIZE)
> 
> Seems to imply CONT_PMD_SIZE >= PMD_SIZE, and would thus tickle:
> 
>>> 	else if (_sz >= PMD_SIZE)
>>> 		tlb_flush_pmd_range(tlb, address, _sz);
> 
> Or am I confused?

Nope, it was me who was confused :-).
I misread one of the the lines sorry.
Yeah this should be fine for arm64.

Cheers,
-- 
Steve