linux-kernel - Re: [PATCH v2 2/2] arm64: hugetlb: enable __HAVE_ARCH_FLUSH_HUGETLB_TLB

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Message-ID: <ZMjn+68gKrdQSjMD@arm.com>
Date:   Tue, 1 Aug 2023 12:09:47 +0100
From:   Catalin Marinas <catalin.marinas@....com>
To:     Kefeng Wang <wangkefeng.wang@...wei.com>
Cc:     Andrew Morton <akpm@...ux-foundation.org>,
        Will Deacon <will@...nel.org>,
        Mike Kravetz <mike.kravetz@...cle.com>,
        Muchun Song <muchun.song@...ux.dev>,
        Mina Almasry <almasrymina@...gle.com>, kirill@...temov.name,
        joel@...lfernandes.org, william.kucharski@...cle.com,
        kaleshsingh@...gle.com, linux-mm@...ck.org,
        linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org,
        21cnbao@...il.com
Subject: Re: [PATCH v2 2/2] arm64: hugetlb: enable
 __HAVE_ARCH_FLUSH_HUGETLB_TLB_RANGE

On Tue, Aug 01, 2023 at 10:31:45AM +0800, Kefeng Wang wrote:
> +#define __HAVE_ARCH_FLUSH_HUGETLB_TLB_RANGE
> +static inline void flush_hugetlb_tlb_range(struct vm_area_struct *vma,
> +					   unsigned long start,
> +					   unsigned long end)
> +{
> +	unsigned long stride = huge_page_size(hstate_vma(vma));
> +
> +	if (stride != PMD_SIZE && stride != PUD_SIZE)
> +		stride = PAGE_SIZE;
> +	__flush_tlb_range(vma, start, end, stride, false, 0);

We could use some hints here for the tlb_level (2 for pmd, 1 for pud).
Regarding the last_level argument to __flush_tlb_range(), I think it
needs to stay false since this function is also called on the
hugetlb_unshare_pmds() path where the pud is cleared and needs
invalidating.

That said, maybe you can rewrite it as a switch statement and call
flush_pmd_tlb_range() or flush_pud_tlb_range() (just make sure these are
defined when CONFIG_HUGETLBFS is enabled).

-- 
Catalin