linux-kernel - Re: [PATCH] mips: define pud_index() regardless of page table folding

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Message-ID: <CAAhV-H7+swFnqoVk9VS=4UoM+OVW4PX5G0mqSPAbM1WfXC44rA@mail.gmail.com>
Date:   Mon, 13 Apr 2020 14:21:38 +0800
From:   Huacai Chen <chenhuacai@...il.com>
To:     Mike Rapoport <rppt@...nel.org>
Cc:     Thomas Bogendoerfer <tsbogend@...ha.franken.de>,
        Paolo Bonzini <pbonzini@...hat.com>,
        Peter Xu <peterx@...hat.com>, maobibo <maobibo@...ngson.cn>,
        Sergei Shtylyov <sergei.shtylyov@...entembedded.com>,
        "open list:MIPS" <linux-mips@...r.kernel.org>, kvm@...r.kernel.org,
        LKML <linux-kernel@...r.kernel.org>,
        Mike Rapoport <rppt@...ux.ibm.com>
Subject: Re: [PATCH] mips: define pud_index() regardless of page table folding

Tested-by: Huacai Chen <chenhc@...ote.com>

On Thu, Apr 2, 2020 at 4:17 PM Mike Rapoport <rppt@...nel.org> wrote:
>
> From: Mike Rapoport <rppt@...ux.ibm.com>
>
> Commit 31168f033e37 ("mips: drop __pXd_offset() macros that duplicate
> pXd_index() ones") is correct that pud_index() & __pud_offset() are the
> same when pud_index() is actually provided, however it does not take into
> account the __PAGETABLE_PUD_FOLDED case. This has broken MIPS KVM
> compilation because it relied on availability of pud_index().
>
> Define pud_index() regardless of page table folded. It will evaluate to
> actual index for 4-level pagetables and to 0 for folded PUD level.
>
> Link: https://lore.kernel.org/lkml/20200331154749.5457-1-pbonzini@redhat.com
> Reported-by: Paolo Bonzini <pbonzini@...hat.com>
> Signed-off-by: Mike Rapoport <rppt@...ux.ibm.com>
> ---
>  arch/mips/include/asm/pgtable-64.h | 4 ++--
>  1 file changed, 2 insertions(+), 2 deletions(-)
>
> diff --git a/arch/mips/include/asm/pgtable-64.h b/arch/mips/include/asm/pgtable-64.h
> index f92716cfa4f4..ee5dc0c145b9 100644
> --- a/arch/mips/include/asm/pgtable-64.h
> +++ b/arch/mips/include/asm/pgtable-64.h
> @@ -172,6 +172,8 @@
>
>  extern pte_t invalid_pte_table[PTRS_PER_PTE];
>
> +#define pud_index(address)     (((address) >> PUD_SHIFT) & (PTRS_PER_PUD - 1))
> +
>  #ifndef __PAGETABLE_PUD_FOLDED
>  /*
>   * For 4-level pagetables we defines these ourselves, for 3-level the
> @@ -210,8 +212,6 @@ static inline void p4d_clear(p4d_t *p4dp)
>         p4d_val(*p4dp) = (unsigned long)invalid_pud_table;
>  }
>
> -#define pud_index(address)     (((address) >> PUD_SHIFT) & (PTRS_PER_PUD - 1))
> -
>  static inline unsigned long p4d_page_vaddr(p4d_t p4d)
>  {
>         return p4d_val(p4d);
> --
> 2.25.1
>