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    SubjectRe: [PATCH v2 2/4] riscv: Improve flush_tlb_range() for hugetlb pages
    On Thu, Jul 27, 2023 at 08:55:51PM +0200, Alexandre Ghiti wrote:
    > flush_tlb_range() uses a fixed stride of PAGE_SIZE and in its current form,
    > when a hugetlb mapping needs to be flushed, flush_tlb_range() flushes the
    > whole tlb: so set a stride of the size of the hugetlb mapping in order to
    > only flush the hugetlb mapping.
    >
    > Note that THPs are directly handled by flush_pmd_tlb_range().
    >
    > Signed-off-by: Alexandre Ghiti <alexghiti@rivosinc.com>
    > ---
    > arch/riscv/mm/tlbflush.c | 10 +++++++++-
    > 1 file changed, 9 insertions(+), 1 deletion(-)
    >
    > diff --git a/arch/riscv/mm/tlbflush.c b/arch/riscv/mm/tlbflush.c
    > index fa03289853d8..3e4acef1f6bc 100644
    > --- a/arch/riscv/mm/tlbflush.c
    > +++ b/arch/riscv/mm/tlbflush.c
    > @@ -3,6 +3,7 @@
    > #include <linux/mm.h>
    > #include <linux/smp.h>
    > #include <linux/sched.h>
    > +#include <linux/hugetlb.h>
    > #include <asm/sbi.h>
    > #include <asm/mmu_context.h>
    >
    > @@ -147,7 +148,14 @@ void flush_tlb_page(struct vm_area_struct *vma, unsigned long addr)
    > void flush_tlb_range(struct vm_area_struct *vma, unsigned long start,
    > unsigned long end)
    > {
    > - __flush_tlb_range(vma->vm_mm, start, end - start, PAGE_SIZE);
    > + unsigned long stride_shift;
    > +
    > + stride_shift = is_vm_hugetlb_page(vma) ?
    > + huge_page_shift(hstate_vma(vma)) :
    > + PAGE_SHIFT;

    We want the size below instead of the shift, so we can just use
    huge_page_size() and PAGE_SIZE here.

    > +
    > + __flush_tlb_range(vma->vm_mm,
    > + start, end - start, 1 << stride_shift);

    Shouldn't need to wrap this line.

    > }
    > #ifdef CONFIG_TRANSPARENT_HUGEPAGE
    > void flush_pmd_tlb_range(struct vm_area_struct *vma, unsigned long start,
    > --
    > 2.39.2
    >

    Otherwise,

    Reviewed-by: Andrew Jones <ajones@ventanamicro.com>

    Thanks,
    drew

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