linux-kernel - Re: [RESEND PATCH V3 2/2] riscv: add RISC-V Svpbmt extension supports

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Message-ID: <20211102060424.GA27015@lst.de>
Date:   Tue, 2 Nov 2021 07:04:24 +0100
From:   Christoph Hellwig <hch@....de>
To:     Wei Fu <wefu@...hat.com>
Cc:     Christoph Hellwig <hch@...radead.org>,
        Anup Patel <anup.patel@....com>,
        Atish Patra <atish.patra@....com>,
        Palmer Dabbelt <palmerdabbelt@...gle.com>, guoren@...nel.org,
        christoph.muellner@...ll.eu,
        Philipp Tomsich <philipp.tomsich@...ll.eu>,
        Christoph Hellwig <hch@....de>,
        Liu Shaohua <liush@...winnertech.com>,
        Wei Wu (吴伟) <lazyparser@...il.com>,
        Drew Fustini <drew@...gleboard.org>,
        linux-riscv@...ts.infradead.org, linux-kernel@...r.kernel.org,
        taiten.peng@...onical.com, aniket.ponkshe@...onical.com,
        heinrich.schuchardt@...onical.com, gordan.markus@...onical.com,
        guoren@...ux.alibaba.com, Arnd Bergmann <arnd@...db.de>,
        Chen-Yu Tsai <wens@...e.org>,
        Maxime Ripard <maxime@...no.tech>,
        Daniel Lustig <dlustig@...dia.com>,
        Greg Favor <gfavor@...tanamicro.com>,
        Andrea Mondelli <andrea.mondelli@...wei.com>,
        Jonathan Behrens <behrensj@....edu>,
        Xinhaoqu <xinhaoqu@...wei.com>,
        Bill Huffman <huffman@...ence.com>,
        Nick Kossifidis <mick@....forth.gr>,
        Allen Baum <allen.baum@...erantotech.com>,
        Josh Scheid <jscheid@...tanamicro.com>,
        Richard Trauben <rtrauben@...il.com>
Subject: Re: [RESEND PATCH V3 2/2] riscv: add RISC-V Svpbmt extension
 supports

On Mon, Oct 25, 2021 at 10:49:11PM +0800, Wei Fu wrote:
> > > +                                             >> _PAGE_PFN_SHIFT);
> >
> > >  static inline unsigned long _pmd_pfn(pmd_t pmd)
> > >  {
> > > -     return pmd_val(pmd) >> _PAGE_PFN_SHIFT;
> > > +     return (pmd_val(pmd) & _PAGE_CHG_MASK) >> _PAGE_PFN_SHIFT;
> > >  }
> >
> > The "(pud_val(pud) & _PAGE_CHG_MASK) >> _PAGE_PFN_SHIFT" expression begs
> > for readable and well-documented helper.
> 
> How about these:
> #define _chg_of_pmd(pmd)  (pmd_val(pmd) & _PAGE_CHG_MASK)
> #define _chg_of_pud(pud)  (pud_val(pud) & _PAGE_CHG_MASK)

I'd use inline functions instead of macros if possible, but otherwise
yes.

> How about :
> 
> extern unsigned long  _svpbmt_mask
> extern unsigned long _svpbmt_mt_pma
> extern unsigned long _svpbmt_mt_nc
> extern unsigned long _svpbmt_mt_io
> 
> #define _PAGE_MT_MASK              _svpbmt_mask
> #define _PAGE_MT_PMA        _svpbmt_mt_pma
> #define _PAGE_MT_NC          _svpbmt_mt_nc
> #define _PAGE_MT_IO           _svpbmt_mt_io

Looks much better.