Re: [PATCH] riscv: Implement missing huge_ptep_get

[Petko Manolov <petko.manolov@konsulko.com>]

On 23-07-24 10:30:20, Alexandre Ghiti wrote:
> Hi Petko,
> 
> On Sun, Jul 23, 2023 at 3:48 PM Petko Manolov
> <petko.manolov@konsulko.com> wrote:
> >
> > From: Alexandre Ghiti <alexghiti@rivosinc.com>
> >
> > huge_ptep_get must be reimplemented in order to go through all the PTEs
> > of a NAPOT region: this is needed because the HW can update the A/D bits
> > of any of the PTE that constitutes the NAPOT region.
> >
> > Fixes: 82a1a1f3bfb6 ("riscv: mm: support Svnapot in hugetlb page")
> > Signed-off-by: Alexandre Ghiti <alexghiti@rivosinc.com>
> > Reviewed-by: Andrew Jones <ajones@ventanamicro.com>
> > Link: https://lore.kernel.org/r/20230428120120.21620-2-alexghiti@rivosinc.com
> > Cc: stable@vger.kernel.org
> > Signed-off-by: Palmer Dabbelt <palmer@rivosinc.com>
> > Signed-off-by: Petko Manolov <petko.manolov@konsulko.com>
> > ---
> >  arch/riscv/include/asm/hugetlb.h |  3 +++
> >  arch/riscv/mm/hugetlbpage.c      | 24 ++++++++++++++++++++++++
> >  2 files changed, 27 insertions(+)
> >
> > diff --git a/arch/riscv/include/asm/hugetlb.h b/arch/riscv/include/asm/hugetlb.h
> > index fe6f23006641..ce1ebda1a49a 100644
> > --- a/arch/riscv/include/asm/hugetlb.h
> > +++ b/arch/riscv/include/asm/hugetlb.h
> > @@ -36,6 +36,9 @@ int huge_ptep_set_access_flags(struct vm_area_struct *vma,
> >                                unsigned long addr, pte_t *ptep,
> >                                pte_t pte, int dirty);
> >
> > +#define __HAVE_ARCH_HUGE_PTEP_GET
> > +pte_t huge_ptep_get(pte_t *ptep);
> > +
> >  pte_t arch_make_huge_pte(pte_t entry, unsigned int shift, vm_flags_t flags);
> >  #define arch_make_huge_pte arch_make_huge_pte
> >
> > diff --git a/arch/riscv/mm/hugetlbpage.c b/arch/riscv/mm/hugetlbpage.c
> > index 238d00bdac14..e0ef56dc57b9 100644
> > --- a/arch/riscv/mm/hugetlbpage.c
> > +++ b/arch/riscv/mm/hugetlbpage.c
> > @@ -3,6 +3,30 @@
> >  #include <linux/err.h>
> >
> >  #ifdef CONFIG_RISCV_ISA_SVNAPOT
> > +pte_t huge_ptep_get(pte_t *ptep)
> > +{
> > +       unsigned long pte_num;
> > +       int i;
> > +       pte_t orig_pte = ptep_get(ptep);
> > +
> > +       if (!pte_present(orig_pte) || !pte_napot(orig_pte))
> > +               return orig_pte;
> > +
> > +       pte_num = napot_pte_num(napot_cont_order(orig_pte));
> > +
> > +       for (i = 0; i < pte_num; i++, ptep++) {
> > +               pte_t pte = ptep_get(ptep);
> > +
> > +               if (pte_dirty(pte))
> > +                       orig_pte = pte_mkdirty(orig_pte);
> > +
> > +               if (pte_young(pte))
> > +                       orig_pte = pte_mkyoung(orig_pte);
> > +       }
> > +
> > +       return orig_pte;
> > +}
> > +
> >  pte_t *huge_pte_alloc(struct mm_struct *mm,
> >                       struct vm_area_struct *vma,
> >                       unsigned long addr,
> > --
> > 2.39.2
> >
> 
> Not sure I understand why you propose this patch to stable since svnapot
> support was introduced in 6.4 and this fix (and another one) was merged in 6.4
> too. Am I missing something?

Hey there.  I've no idea how "Signed-off" with my email address appeared in this
patch.  I most certainly have not done so, nor i am in any way related to this
code.  Weird.


		Petko