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Message-ID: <7bbceed4-c5f6-42d4-5d94-060032b73385@ghiti.fr>
Date:   Fri, 22 Sep 2023 09:54:21 +0200
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Subject: Re: [PATCH v1 3/8] riscv: hugetlb: Convert set_huge_pte_at() to take
 vma
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To:     Ryan Roberts <ryan.roberts@arm.com>,
        Catalin Marinas <catalin.marinas@arm.com>,
        Will Deacon <will@kernel.org>,
        "James E.J. Bottomley" <James.Bottomley@HansenPartnership.com>,
        Helge Deller <deller@gmx.de>,
        Nicholas Piggin <npiggin@gmail.com>,
        Christophe Leroy <christophe.leroy@csgroup.eu>,
        Paul Walmsley <paul.walmsley@sifive.com>,
        Palmer Dabbelt <palmer@dabbelt.com>,
        Albert Ou <aou@eecs.berkeley.edu>,
        Heiko Carstens <hca@linux.ibm.com>,
        Vasily Gorbik <gor@linux.ibm.com>,
        Alexander Gordeev <agordeev@linux.ibm.com>,
        Christian Borntraeger <borntraeger@linux.ibm.com>,
        Sven Schnelle <svens@linux.ibm.com>,
        Gerald Schaefer <gerald.schaefer@linux.ibm.com>,
        "David S. Miller" <davem@davemloft.net>,
        Arnd Bergmann <arnd@arndb.de>,
        Mike Kravetz <mike.kravetz@oracle.com>,
        Muchun Song <muchun.song@linux.dev>,
        SeongJae Park <sj@kernel.org>,
        Andrew Morton <akpm@linux-foundation.org>,
        Uladzislau Rezki <urezki@gmail.com>,
        Christoph Hellwig <hch@infradead.org>,
        Lorenzo Stoakes <lstoakes@gmail.com>,
        Anshuman Khandual <anshuman.khandual@arm.com>,
        Peter Xu <peterx@redhat.com>,
        Axel Rasmussen <axelrasmussen@google.com>,
        Qi Zheng <zhengqi.arch@bytedance.com>
Cc:     linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org,
        linux-parisc@vger.kernel.org, linuxppc-dev@lists.ozlabs.org,
        linux-riscv@lists.infradead.org, linux-s390@vger.kernel.org,
        sparclinux@vger.kernel.org, linux-mm@kvack.org,
        stable@vger.kernel.org
References: <20230921162007.1630149-1-ryan.roberts@arm.com>
 <20230921162007.1630149-4-ryan.roberts@arm.com>
From:   Alexandre Ghiti <alex@ghiti.fr>
In-Reply-To: <20230921162007.1630149-4-ryan.roberts@arm.com>
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Hi Ryan,

On 21/09/2023 18:20, Ryan Roberts wrote:
> 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 riscv 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@arm.com>
> ---
>   arch/riscv/include/asm/hugetlb.h | 2 +-
>   arch/riscv/mm/hugetlbpage.c      | 3 ++-
>   2 files changed, 3 insertions(+), 2 deletions(-)
>
> diff --git a/arch/riscv/include/asm/hugetlb.h b/arch/riscv/include/asm/hugetlb.h
> index 34e24f078cc1..be1ac8582bc2 100644
> --- a/arch/riscv/include/asm/hugetlb.h
> +++ b/arch/riscv/include/asm/hugetlb.h
> @@ -17,7 +17,7 @@ void huge_pte_clear(struct mm_struct *mm, unsigned long addr,
>   		    pte_t *ptep, unsigned long sz);
>   
>   #define __HAVE_ARCH_HUGE_SET_HUGE_PTE_AT
> -void set_huge_pte_at(struct mm_struct *mm,
> +void set_huge_pte_at(struct vm_area_struct *vma,
>   		     unsigned long addr, pte_t *ptep, pte_t pte);
>   
>   #define __HAVE_ARCH_HUGE_PTEP_GET_AND_CLEAR
> diff --git a/arch/riscv/mm/hugetlbpage.c b/arch/riscv/mm/hugetlbpage.c
> index 96225a8533ad..7cdbf0960772 100644
> --- a/arch/riscv/mm/hugetlbpage.c
> +++ b/arch/riscv/mm/hugetlbpage.c
> @@ -177,11 +177,12 @@ pte_t arch_make_huge_pte(pte_t entry, unsigned int shift, vm_flags_t flags)
>   	return entry;
>   }
>   
> -void set_huge_pte_at(struct mm_struct *mm,
> +void set_huge_pte_at(struct vm_area_struct *vma,
>   		     unsigned long addr,
>   		     pte_t *ptep,
>   		     pte_t pte)
>   {
> +	struct mm_struct *mm = vma->vm_mm;
>   	int i, pte_num;
>   
>   	if (!pte_napot(pte)) {


You can add:

Reviewed-by: Alexandre Ghiti <alexghiti@rivosinc.com>

I realize that we may have the same issue with our contig pte 
implementation (called napot in riscv) as we don't handle swap/migration 
entries at all. So I guess we need something similar, and I'll implement 
it (unless you want to do it of course, but I guess it's easier for me 
to test). One (maybe stupid) question though: wouldn't it be possible to 
extract the contig pte size from the value of ptep instead of using a vma?

Thanks,

Alex