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Date:   Tue, 1 Aug 2023 16:28:33 +0100
From:   Catalin Marinas <catalin.marinas@arm.com>
To:     Kefeng Wang <wangkefeng.wang@huawei.com>
Cc:     Andrew Morton <akpm@linux-foundation.org>,
        Will Deacon <will@kernel.org>,
        Mike Kravetz <mike.kravetz@oracle.com>,
        Muchun Song <muchun.song@linux.dev>,
        Mina Almasry <almasrymina@google.com>, kirill@shutemov.name,
        joel@joelfernandes.org, william.kucharski@oracle.com,
        kaleshsingh@google.com, linux-mm@kvack.org,
        linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org,
        21cnbao@gmail.com
Subject: Re: [PATCH v3] arm64: hugetlb: enable
 __HAVE_ARCH_FLUSH_HUGETLB_TLB_RANGE
Message-ID: <ZMkkoVl+q4Iljoy1@arm.com>
References: <20230801023145.17026-3-wangkefeng.wang@huawei.com>
 <20230801135616.165067-1-wangkefeng.wang@huawei.com>
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On Tue, Aug 01, 2023 at 09:56:16PM +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));
> +
> +	switch (stride) {
> +#ifndef __PAGETABLE_PMD_FOLDED
> +	case PUD_SIZE:
> +		flush_pud_tlb_range(vma, start, end);
> +		break;
> +#endif
> +	case PMD_SIZE:
> +		flush_pmd_tlb_range(vma, start, end);
> +		break;
> +	default:
> +		__flush_tlb_range(vma, start, end, PAGE_SIZE, false, 0);
> +	}
> +}

I think we should be consistent and either use __flush_tlb_range()
everywhere or flush_p*d_tlb_range() together with flush_tlb_range().
Maybe using __flush_tlb_range() for the pmd/pud is not too bad, smaller
patch.

That said, I'd avoid the #ifndef and just go for an if/else statement:

	if (stride == PMD_SIZE)
		__flush_tlb_range(vma, start, end, stride, false, 2);
	else if (stride == PUD_SIZE)
		__flush_tlb_range(vma, start, end, stride, false, 1);
	else
		__flush_tlb_range(vma, start, end, PAGE_SIZE, 0);

With the pmd folded, the P*D_SIZE is the same and the compiler should
eliminate the second branch.

-- 
Catalin