Messages in this thread | | | Date | Thu, 11 Apr 2024 11:44:58 +0100 | From | Will Deacon <> | Subject | Re: [PATCH v3 3/3] arm64: tlb: Allow range operation for MAX_TLBI_RANGE_PAGES |
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On Wed, Apr 10, 2024 at 09:50:20AM +0100, Marc Zyngier wrote: > On Mon, 08 Apr 2024 09:43:44 +0100, > Ryan Roberts <ryan.roberts@arm.com> wrote: > > > > On 05/04/2024 04:58, Gavin Shan wrote: > > > MAX_TLBI_RANGE_PAGES pages is covered by SCALE#3 and NUM#31 and it's > > > supported now. Allow TLBI RANGE operation when the number of pages is > > > equal to MAX_TLBI_RANGE_PAGES in __flush_tlb_range_nosync(). > > > > > > Suggested-by: Marc Zyngier <maz@kernel.org> > > > Signed-off-by: Gavin Shan <gshan@redhat.com> > > > > Reviewed-by: Ryan Roberts <ryan.roberts@arm.com> > > > > > --- > > > arch/arm64/include/asm/tlbflush.h | 4 ++-- > > > 1 file changed, 2 insertions(+), 2 deletions(-) > > > > > > diff --git a/arch/arm64/include/asm/tlbflush.h b/arch/arm64/include/asm/tlbflush.h > > > index 243d71f7bc1f..95fbc8c05607 100644 > > > --- a/arch/arm64/include/asm/tlbflush.h > > > +++ b/arch/arm64/include/asm/tlbflush.h > > > @@ -446,11 +446,11 @@ static inline void __flush_tlb_range_nosync(struct vm_area_struct *vma, > > > * When not uses TLB range ops, we can handle up to > > > * (MAX_DVM_OPS - 1) pages; > > > * When uses TLB range ops, we can handle up to > > > - * (MAX_TLBI_RANGE_PAGES - 1) pages. > > > + * MAX_TLBI_RANGE_PAGES pages. > > > */ > > > if ((!system_supports_tlb_range() && > > > (end - start) >= (MAX_DVM_OPS * stride)) || > > > - pages >= MAX_TLBI_RANGE_PAGES) { > > > + pages > MAX_TLBI_RANGE_PAGES) { > > > > As a further enhancement, I wonder if it might be better to test: > > > > pages * 4 / MAX_TLBI_RANGE_PAGES > MAX_DVM_OPS > > > > Then add an extra loop over __flush_tlb_range_op(), like KVM does. > > > > The math is trying to express that there are a maximum of 4 tlbi range > > instructions for MAX_TLBI_RANGE_PAGES pages (1 per scale) and we only need to > > fall back to flushing the whole mm if it could generate more than MAX_DVM_OPS ops. > > That'd be a good enhancement indeed, although I wonder if that occurs > as often as we see it on the KVM side. But in any case, adding > consistency amongst the users of __flush_tlb_range_op() can only be > beneficial.
I'll pick patches 2 & 3 up for 6.10, but feel free to send stuff on top if you want to tweak this.
Will
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