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

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Date:   Tue, 1 Aug 2023 19:22:09 +0800
From:   Kefeng Wang <wangkefeng.wang@...wei.com>
To:     Catalin Marinas <catalin.marinas@....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 2023/8/1 19:09, Catalin Marinas wrote:
> 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).
> 

How about this way, not involved with thp ？

diff --git a/arch/arm64/include/asm/hugetlb.h 
b/arch/arm64/include/asm/hugetlb.h
index e5c2e3dd9cf0..a7ce59d3388e 100644
--- a/arch/arm64/include/asm/hugetlb.h
+++ b/arch/arm64/include/asm/hugetlb.h
@@ -66,10 +66,22 @@ static inline void flush_hugetlb_tlb_range(struct 
vm_area_struct *vma,
                                            unsigned long end)
  {
         unsigned long stride = huge_page_size(hstate_vma(vma));
+       int tlb_level = 0;

-       if (stride != PMD_SIZE && stride != PUD_SIZE)
+       switch (stride) {
+#ifndef __PAGETABLE_PMD_FOLDED
+       case PUD_SIZE:
+               tlb_level = 1;
+               break;
+#endif
+       case PMD_SIZE:
+               tlb_level = 2;
+               break;
+       default:
                 stride = PAGE_SIZE;
-       __flush_tlb_range(vma, start, end, stride, false, 0);
+       }
+
+       __flush_tlb_range(vma, start, end, stride, false, tlb_level);
  }