On Mon, Oct 9, 2023 at 7:53 PM Samuel Holland <samuel.holland@xxxxxxxxxx> wrote:
>
> Hi Alex,
>
> On 2023-09-11 8:12 AM, 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. However, if the hugepage is a NAPOT region,
> > all PTEs that constitute this mapping must be invalidated, so the stride
> > size must actually be the size of the PTE.
> >
> > Note that THPs are directly handled by flush_pmd_tlb_range().
> >
> > Signed-off-by: Alexandre Ghiti <alexghiti@xxxxxxxxxxxx>
> > Reviewed-by: Andrew Jones <ajones@xxxxxxxxxxxxxxxx>
> > ---
> > arch/riscv/mm/tlbflush.c | 39 ++++++++++++++++++++++++++++++++++++++-
> > 1 file changed, 38 insertions(+), 1 deletion(-)
> >
> > diff --git a/arch/riscv/mm/tlbflush.c b/arch/riscv/mm/tlbflush.c
> > index fa03289853d8..5bda6d4fed90 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 +148,43 @@ 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_size;
> > +
> > + stride_size = is_vm_hugetlb_page(vma) ?
> > + huge_page_size(hstate_vma(vma)) :
> > + PAGE_SIZE;
> > +
> > +#ifdef CONFIG_RISCV_ISA_SVNAPOT
> > + /*
> > + * As stated in the privileged specification, every PTE in a NAPOT
> > + * region must be invalidated, so reset the stride in that case.
> > + */
> > + if (has_svnapot()) {
>
> This whole block should probably go inside the is_vm_hugetlb_page(vma) check,
> since we have to perform that check anyway.
Yes, you're right.
>
> > + unsigned long order, napot_size;
> > +
> > + for_each_napot_order(order) {
> > + napot_size = napot_cont_size(order);
> > +
> > + if (stride_size != napot_size)
> > + continue;
> > +
> > + if (napot_size >= PGDIR_SIZE)
>
> Can you check stride_size here directly, and drop the loop? We should be able to
> assume that the huge page size is valid. Non-NAPOT hugepages will hit one of the
> equal-to cases below, which is fine.
Yes, again, you're right.
I'll respin a new version now, let it go through our CI and send it tomorrow,
Thanks,
Alex
>
> Regards,
> Samuel
>
> > + stride_size = PGDIR_SIZE;
> > + else if (napot_size >= P4D_SIZE)
> > + stride_size = P4D_SIZE;
> > + else if (napot_size >= PUD_SIZE)
> > + stride_size = PUD_SIZE;
> > + else if (napot_size >= PMD_SIZE)
> > + stride_size = PMD_SIZE;
> > + else
> > + stride_size = PAGE_SIZE;
> > +
> > + break;
> > + }
> > + }
> > +#endif
> > +
> > + __flush_tlb_range(vma->vm_mm, start, end - start, stride_size);
> > }
> > #ifdef CONFIG_TRANSPARENT_HUGEPAGE
> > void flush_pmd_tlb_range(struct vm_area_struct *vma, unsigned long start,
>
