linux-kernel - Re: [PATCH -fixes 2/2] riscv: Implement missing huge_ptep

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Date:   Fri, 28 Apr 2023 14:40:28 +0200
From:   Andrew Jones <ajones@...tanamicro.com>
To:     Alexandre Ghiti <alexghiti@...osinc.com>
Cc:     Paul Walmsley <paul.walmsley@...ive.com>,
        Palmer Dabbelt <palmer@...belt.com>,
        Albert Ou <aou@...s.berkeley.edu>,
        Qinglin Pan <panqinglin2020@...as.ac.cn>,
        linux-riscv@...ts.infradead.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH -fixes 2/2] riscv: Implement missing huge_ptep_get

On Fri, Apr 28, 2023 at 02:01:20PM +0200, Alexandre Ghiti wrote:
> 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: f2aeb0118ddd ("riscv: mm: support Svnapot in hugetlb page")
> Signed-off-by: Alexandre Ghiti <alexghiti@...osinc.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,
> -- 
> 2.37.2
>

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