Re: [PATCH v2 5/6] mm: tlb: Provide flush_*_tlb_range wrappers

From: Catalin Marinas <catalin.marinas@arm.com>
To: Zhenyu Ye <yezhenyu2@huawei.com>
Cc: peterz@infradead.org, mark.rutland@arm.com, will@kernel.org,
	aneesh.kumar@linux.ibm.com, akpm@linux-foundation.org,
	npiggin@gmail.com, arnd@arndb.de, rostedt@goodmis.org,
	maz@kernel.org, suzuki.poulose@arm.com, tglx@linutronix.de,
	yuzhao@google.com, Dave.Martin@arm.com, steven.price@arm.com,
	broonie@kernel.org, guohanjun@huawei.com,
	linux-arm-kernel@lists.infradead.org,
	linux-kernel@vger.kernel.org, linux-arch@vger.kernel.org,
	linux-mm@kvack.org, arm@kernel.org, xiexiangyou@huawei.com,
	prime.zeng@hisilicon.com, zhangshaokun@hisilicon.com,
	kuhn.chenqun@huawei.com
Subject: Re: [PATCH v2 5/6] mm: tlb: Provide flush_*_tlb_range wrappers
Date: Fri, 22 May 2020 16:42:55 +0100	[thread overview]
Message-ID: <20200522154254.GD26492@gaia> (raw)
In-Reply-To: <20200423135656.2712-6-yezhenyu2@huawei.com>

On Thu, Apr 23, 2020 at 09:56:55PM +0800, Zhenyu Ye wrote:
> diff --git a/mm/pgtable-generic.c b/mm/pgtable-generic.c
> index 3d7c01e76efc..3eff199d3507 100644
> --- a/mm/pgtable-generic.c
> +++ b/mm/pgtable-generic.c
> @@ -101,6 +101,28 @@ pte_t ptep_clear_flush(struct vm_area_struct *vma, unsigned long address,
>  
>  #ifdef CONFIG_TRANSPARENT_HUGEPAGE
>  
> +#ifndef __HAVE_ARCH_FLUSH_PMD_TLB_RANGE
> +
> +#define FLUSH_Pxx_TLB_RANGE(_pxx)					\
> +void flush_##_pxx##_tlb_range(struct vm_area_struct *vma,		\
> +			      unsigned long addr, unsigned long end)	\
> +{									\
> +		struct mmu_gather tlb;					\
> +									\
> +		tlb_gather_mmu(&tlb, vma->vm_mm, addr, end);		\
> +		tlb_start_vma(&tlb, vma);				\
> +		tlb_flush_##_pxx##_range(&tlb, addr, end - addr);	\
> +		tlb_end_vma(&tlb, vma);					\
> +		tlb_finish_mmu(&tlb, addr, end);			\
> +}

I may have confused myself (flush_p??_tlb_* vs. tlb_flush_p??_*) but do
actually need this whole tlb_gather thing here? IIUC (by grep'ing),
flush_p?d_tlb_range() is only called on huge pages, so we should know
the level already.

-- 
Catalin