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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
Date: Tue, 1 Aug 2023 16:28:33 +0100	[thread overview]
Message-ID: <ZMkkoVl+q4Iljoy1@arm.com> (raw)
In-Reply-To: <20230801135616.165067-1-wangkefeng.wang@huawei.com>

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

_______________________________________________
linux-arm-kernel mailing list
linux-arm-kernel@lists.infradead.org
http://lists.infradead.org/mailman/listinfo/linux-arm-kernel

WARNING: multiple messages have this Message-ID (diff)
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
Date: Tue, 1 Aug 2023 16:28:33 +0100	[thread overview]
Message-ID: <ZMkkoVl+q4Iljoy1@arm.com> (raw)
In-Reply-To: <20230801135616.165067-1-wangkefeng.wang@huawei.com>

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


  reply	other threads:[~2023-08-01 15:29 UTC|newest]

Thread overview: 24+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2023-08-01  2:31 [PATCH v2 0/2] mm: hugetlb: fix mremap tlb flush Kefeng Wang
2023-08-01  2:31 ` Kefeng Wang
2023-08-01  2:31 ` [PATCH v2 1/2] mm: hugetlb: use flush_hugetlb_tlb_range() in move_hugetlb_page_tables() Kefeng Wang
2023-08-01  2:31   ` Kefeng Wang
2023-08-01  2:31 ` [PATCH v2 2/2] arm64: hugetlb: enable __HAVE_ARCH_FLUSH_HUGETLB_TLB_RANGE Kefeng Wang
2023-08-01  2:31   ` Kefeng Wang
2023-08-01  2:31   ` Muchun Song
2023-08-01  2:31     ` Muchun Song
2023-08-01 11:09   ` Catalin Marinas
2023-08-01 11:09     ` Catalin Marinas
2023-08-01 11:22     ` Kefeng Wang
2023-08-01 11:22       ` Kefeng Wang
2023-08-01 13:36       ` Kefeng Wang
2023-08-01 13:36         ` Kefeng Wang
2023-08-01 13:56   ` [PATCH v3] " Kefeng Wang
2023-08-01 13:56     ` Kefeng Wang
2023-08-01 15:28     ` Catalin Marinas [this message]
2023-08-01 15:28       ` Catalin Marinas
2023-08-02  1:27     ` [PATCH v4] " Kefeng Wang
2023-08-02  1:27       ` Kefeng Wang
2023-08-02  1:40       ` Muchun Song
2023-08-02  1:40         ` Muchun Song
2023-08-02 10:41       ` Catalin Marinas
2023-08-02 10:41         ` Catalin Marinas

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