Re: [PATCH v6 11/18] arm64/mm: Split __flush_tlb_range() to elide trailing DSB

Mark Rutland
2024-02-15T11:24:25Z

On Thu, Feb 15, 2024 at 10:31:58AM +0000, Ryan Roberts wrote:
> Split __flush_tlb_range() into __flush_tlb_range_nosync() +
> __flush_tlb_range(), in the same way as the existing flush_tlb_page()
> arrangement. This allows calling __flush_tlb_range_nosync() to elide the
> trailing DSB. Forthcoming "contpte" code will take advantage of this
> when clearing the young bit from a contiguous range of ptes.
>
> Ordering between dsb and mmu_notifier_arch_invalidate_secondary_tlbs()
> has changed, but now aligns with the ordering of __flush_tlb_page(). It
> has been discussed that __flush_tlb_page() may be wrong though.
> Regardless, both will be resolved separately if needed.
>
> Reviewed-by: David Hildenbrand <david@redhat.com>
> Tested-by: John Hubbard <jhubbard@nvidia.com>
> Signed-off-by: Ryan Roberts <ryan.roberts@arm.com>

Acked-by: Mark Rutland <mark.rutland@arm.com>

Mark.

> ---
> arch/arm64/include/asm/tlbflush.h | 13 +++++++++++--
> 1 file changed, 11 insertions(+), 2 deletions(-)
>
> diff --git a/arch/arm64/include/asm/tlbflush.h b/arch/arm64/include/asm/tlbflush.h
> index 1deb5d789c2e..3b0e8248e1a4 100644
> --- a/arch/arm64/include/asm/tlbflush.h
> +++ b/arch/arm64/include/asm/tlbflush.h
> @@ -422,7 +422,7 @@ do { \
> #define __flush_s2_tlb_range_op(op, start, pages, stride, tlb_level) \
> __flush_tlb_range_op(op, start, pages, stride, 0, tlb_level, false, kvm_lpa2_is_enabled());
>
> -static inline void __flush_tlb_range(struct vm_area_struct *vma,
> +static inline void __flush_tlb_range_nosync(struct vm_area_struct *vma,
> unsigned long start, unsigned long end,
> unsigned long stride, bool last_level,
> int tlb_level)
> @@ -456,10 +456,19 @@ static inline void __flush_tlb_range(struct vm_area_struct *vma,
> __flush_tlb_range_op(vae1is, start, pages, stride, asid,
> tlb_level, true, lpa2_is_enabled());
>
> - dsb(ish);
> mmu_notifier_arch_invalidate_secondary_tlbs(vma->vm_mm, start, end);
> }
>
> +static inline void __flush_tlb_range(struct vm_area_struct *vma,
> + unsigned long start, unsigned long end,
> + unsigned long stride, bool last_level,
> + int tlb_level)
> +{
> + __flush_tlb_range_nosync(vma, start, end, stride,
> + last_level, tlb_level);
> + dsb(ish);
> +}
> +
> static inline void flush_tlb_range(struct vm_area_struct *vma,
> unsigned long start, unsigned long end)
> {
> --
> 2.25.1
>