Hi Zhenyu, On Sat, May 30, 2020 at 06:24:21PM +0800, Zhenyu Ye wrote: > On 2020/5/26 22:52, Catalin Marinas wrote: > > On Mon, May 25, 2020 at 03:19:42PM +0800, Zhenyu Ye wrote: > >> tlb_flush_##_pxx##_range() is used to set tlb->cleared_*, > >> flush_##_pxx##_tlb_range() will actually flush the TLB entry. > >> > >> In arch64, tlb_flush_p?d_range() is defined as: > >> > >> #define flush_pmd_tlb_range(vma, addr, end) flush_tlb_range(vma, addr, end) > >> #define flush_pud_tlb_range(vma, addr, end) flush_tlb_range(vma, addr, end) > > > > Currently, flush_p??_tlb_range() are generic and defined as above. I > > think in the generic code they can remain an alias for > > flush_tlb_range(). > > > > On arm64, we can redefine them as: > > > > #define flush_pte_tlb_range(vma, addr, end) __flush_tlb_range(vma, addr, end, 3) > > #define flush_pmd_tlb_range(vma, addr, end) __flush_tlb_range(vma, addr, end, 2) > > #define flush_pud_tlb_range(vma, addr, end) __flush_tlb_range(vma, addr, end, 1) > > #define flush_p4d_tlb_range(vma, addr, end) __flush_tlb_range(vma, addr, end, 0) > > > > (unless the compiler optimises away all the mmu_gather stuff in your > > macro above but they don't look trivial to me) > > I changed generic code before considering that other structures may also > use this feature, such as Power9. And Peter may want to replace all > flush_tlb_range() by tlb_flush() in the future, see [1] for details. > > If only enable this feature on aarch64, your codes are better. > > [1] https://lore.kernel.org/linux-arm-kernel/20200402163849.GM20713@xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx/ But we change the semantics slightly if we implement these as mmu_gather. For example, tlb_end_vma() -> tlb_flush_mmu_tlbonly() ends up calling mmu_notifier_invalidate_range() which it didn't before. I think we end up invoking the notifier unnecessarily in some cases (see the comment in __split_huge_pmd()) or we end up calling the notifier twice (e.g. pmdp_huge_clear_flush_notify()). > > Also, I don't see the new flush_pte_* and flush_p4d_* macros used > > anywhere and I don't think they are needed. The pte equivalent is > > flush_tlb_page() (we need to make sure it's not used on a pmd in the > > hugetlb context). > > flush_tlb_page() is used to flush only one page. If we add the > flush_pte_tlb_range(), then we can use it to flush a range of pages in > the future. If we know flush_tlb_page() is only called on a small page, could we add TTL information here as well? > But flush_pte_* and flush_p4d_* macros are really not used anywhere. I > will remove them in next version of series, and add them if someone > needs. I think it makes sense. -- Catalin
