linux-kernel - Re: [PATCH v1 2/8] powerpc: hugetlb: Convert set_huge_pte

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Message-ID: <0f2dd31a-a361-24ba-154d-4e614c0eff73@csgroup.eu>
Date:   Fri, 22 Sep 2023 06:56:43 +0000
From:   Christophe Leroy <christophe.leroy@...roup.eu>
To:     Ryan Roberts <ryan.roberts@....com>,
        Catalin Marinas <catalin.marinas@....com>,
        Will Deacon <will@...nel.org>,
        "James E.J. Bottomley" <James.Bottomley@...senPartnership.com>,
        Helge Deller <deller@....de>,
        Nicholas Piggin <npiggin@...il.com>,
        Paul Walmsley <paul.walmsley@...ive.com>,
        Palmer Dabbelt <palmer@...belt.com>,
        Albert Ou <aou@...s.berkeley.edu>,
        Heiko Carstens <hca@...ux.ibm.com>,
        Vasily Gorbik <gor@...ux.ibm.com>,
        Alexander Gordeev <agordeev@...ux.ibm.com>,
        Christian Borntraeger <borntraeger@...ux.ibm.com>,
        Sven Schnelle <svens@...ux.ibm.com>,
        Gerald Schaefer <gerald.schaefer@...ux.ibm.com>,
        "David S. Miller" <davem@...emloft.net>,
        Arnd Bergmann <arnd@...db.de>,
        Mike Kravetz <mike.kravetz@...cle.com>,
        Muchun Song <muchun.song@...ux.dev>,
        SeongJae Park <sj@...nel.org>,
        Andrew Morton <akpm@...ux-foundation.org>,
        Uladzislau Rezki <urezki@...il.com>,
        Christoph Hellwig <hch@...radead.org>,
        Lorenzo Stoakes <lstoakes@...il.com>,
        Anshuman Khandual <anshuman.khandual@....com>,
        Peter Xu <peterx@...hat.com>,
        Axel Rasmussen <axelrasmussen@...gle.com>,
        Qi Zheng <zhengqi.arch@...edance.com>
CC:     "linux-arm-kernel@...ts.infradead.org" 
        <linux-arm-kernel@...ts.infradead.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "linux-parisc@...r.kernel.org" <linux-parisc@...r.kernel.org>,
        "linuxppc-dev@...ts.ozlabs.org" <linuxppc-dev@...ts.ozlabs.org>,
        "linux-riscv@...ts.infradead.org" <linux-riscv@...ts.infradead.org>,
        "linux-s390@...r.kernel.org" <linux-s390@...r.kernel.org>,
        "sparclinux@...r.kernel.org" <sparclinux@...r.kernel.org>,
        "linux-mm@...ck.org" <linux-mm@...ck.org>,
        "stable@...r.kernel.org" <stable@...r.kernel.org>
Subject: Re: [PATCH v1 2/8] powerpc: hugetlb: Convert set_huge_pte_at() to
 take vma



Le 21/09/2023 à 18:20, Ryan Roberts a écrit :
> In order to fix a bug, arm64 needs access to the vma inside it's
> implementation of set_huge_pte_at(). Provide for this by converting the
> mm parameter to be a vma. Any implementations that require the mm can
> access it via vma->vm_mm.
> 
> This commit makes the required powerpc modifications. Separate commits
> update the other arches and core code, before the actual bug is fixed in
> arm64.
> 
> No behavioral changes intended.
> 
> Signed-off-by: Ryan Roberts <ryan.roberts@....com>
> ---
>   arch/powerpc/include/asm/nohash/32/hugetlb-8xx.h | 3 ++-
>   arch/powerpc/mm/book3s64/hugetlbpage.c           | 2 +-
>   arch/powerpc/mm/book3s64/radix_hugetlbpage.c     | 2 +-
>   arch/powerpc/mm/nohash/8xx.c                     | 2 +-
>   arch/powerpc/mm/pgtable.c                        | 7 ++++++-
>   5 files changed, 11 insertions(+), 5 deletions(-)
> 
> diff --git a/arch/powerpc/include/asm/nohash/32/hugetlb-8xx.h b/arch/powerpc/include/asm/nohash/32/hugetlb-8xx.h
> index de092b04ee1a..fff8cd726bc7 100644
> --- a/arch/powerpc/include/asm/nohash/32/hugetlb-8xx.h
> +++ b/arch/powerpc/include/asm/nohash/32/hugetlb-8xx.h
> @@ -46,7 +46,8 @@ static inline int check_and_get_huge_psize(int shift)
>   }
>   
>   #define __HAVE_ARCH_HUGE_SET_HUGE_PTE_AT
> -void set_huge_pte_at(struct mm_struct *mm, unsigned long addr, pte_t *ptep, pte_t pte);
> +void set_huge_pte_at(struct vm_area_struct *vma, unsigned long addr, pte_t *ptep, pte_t pte);
> +void __set_huge_pte_at(struct mm_struct *mm, unsigned long addr, pte_t *ptep, pte_t pte);

Don't add the burden of an additional function, see below

>   
>   #define __HAVE_ARCH_HUGE_PTE_CLEAR
>   static inline void huge_pte_clear(struct mm_struct *mm, unsigned long addr,
> diff --git a/arch/powerpc/mm/book3s64/hugetlbpage.c b/arch/powerpc/mm/book3s64/hugetlbpage.c
> index 3bc0eb21b2a0..ae7fd7c90eb8 100644
> --- a/arch/powerpc/mm/book3s64/hugetlbpage.c
> +++ b/arch/powerpc/mm/book3s64/hugetlbpage.c
> @@ -147,7 +147,7 @@ void huge_ptep_modify_prot_commit(struct vm_area_struct *vma, unsigned long addr
>   	if (radix_enabled())
>   		return radix__huge_ptep_modify_prot_commit(vma, addr, ptep,
>   							   old_pte, pte);
> -	set_huge_pte_at(vma->vm_mm, addr, ptep, pte);
> +	set_huge_pte_at(vma, addr, ptep, pte);
>   }
>   
>   void __init hugetlbpage_init_defaultsize(void)
> diff --git a/arch/powerpc/mm/book3s64/radix_hugetlbpage.c b/arch/powerpc/mm/book3s64/radix_hugetlbpage.c
> index 17075c78d4bc..7cd40a334c3a 100644
> --- a/arch/powerpc/mm/book3s64/radix_hugetlbpage.c
> +++ b/arch/powerpc/mm/book3s64/radix_hugetlbpage.c
> @@ -58,5 +58,5 @@ void radix__huge_ptep_modify_prot_commit(struct vm_area_struct *vma,
>   	    atomic_read(&mm->context.copros) > 0)
>   		radix__flush_hugetlb_page(vma, addr);
>   
> -	set_huge_pte_at(vma->vm_mm, addr, ptep, pte);
> +	set_huge_pte_at(vma, addr, ptep, pte);
>   }
> diff --git a/arch/powerpc/mm/nohash/8xx.c b/arch/powerpc/mm/nohash/8xx.c
> index dbbfe897455d..650a7a8496b6 100644
> --- a/arch/powerpc/mm/nohash/8xx.c
> +++ b/arch/powerpc/mm/nohash/8xx.c
> @@ -91,7 +91,7 @@ static int __ref __early_map_kernel_hugepage(unsigned long va, phys_addr_t pa,
>   	if (new && WARN_ON(pte_present(*ptep) && pgprot_val(prot)))
>   		return -EINVAL;
>   
> -	set_huge_pte_at(&init_mm, va, ptep, pte_mkhuge(pfn_pte(pa >> PAGE_SHIFT, prot)));
> +	__set_huge_pte_at(&init_mm, va, ptep, pte_mkhuge(pfn_pte(pa >> PAGE_SHIFT, prot)));

Call set_huge_pte_at() with a NULL vma instead.

>   
>   	return 0;
>   }
> diff --git a/arch/powerpc/mm/pgtable.c b/arch/powerpc/mm/pgtable.c
> index 3f86fd217690..9cbcb561a4d8 100644
> --- a/arch/powerpc/mm/pgtable.c
> +++ b/arch/powerpc/mm/pgtable.c
> @@ -288,7 +288,7 @@ int huge_ptep_set_access_flags(struct vm_area_struct *vma,
>   }
>   
>   #if defined(CONFIG_PPC_8xx)
> -void set_huge_pte_at(struct mm_struct *mm, unsigned long addr, pte_t *ptep, pte_t pte)
> +void __set_huge_pte_at(struct mm_struct *mm, unsigned long addr, pte_t *ptep, pte_t pte)

Keep it as set_huge_pte_at() with vma argument.

>   {
>   	pmd_t *pmd = pmd_off(mm, addr);

Change to:

	pmd_t *pmd = vma ? pmd_off(vma->vm_mm, addr) : pmd_off_k(addr);

>   	pte_basic_t val;
> @@ -310,6 +310,11 @@ void set_huge_pte_at(struct mm_struct *mm, unsigned long addr, pte_t *ptep, pte_
>   	for (i = 0; i < num; i++, entry++, val += SZ_4K)
>   		*entry = val;
>   }
> +
> +void set_huge_pte_at(struct vm_area_struct *vma, unsigned long addr, pte_t *ptep, pte_t pte)
> +{
> +	__set_huge_pte_at(vma->vm_mm, addr, ptep, pte);
> +}

Remove this burden.

>   #endif
>   #endif /* CONFIG_HUGETLB_PAGE */
>   


Christophe