linux-kernel - Re: [PATCH 1/3] riscv: Fixup _PAGE_GLOBAL in _PAGE

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Message-ID: <CAJF2gTQOimKQR8nL3SKgC6OP8OcsagFCADfehg4TEt96D9xVpQ@mail.gmail.com>
Date:   Mon, 24 May 2021 16:22:49 +0800
From:   Guo Ren <guoren@...nel.org>
To:     Anup Patel <anup@...infault.org>
Cc:     Anup Patel <anup.patel@....com>,
        Palmer Dabbelt <palmerdabbelt@...gle.com>,
        Arnd Bergmann <arnd@...db.de>,
        linux-riscv <linux-riscv@...ts.infradead.org>,
        "linux-kernel@...r.kernel.org List" <linux-kernel@...r.kernel.org>,
        linux-arch <linux-arch@...r.kernel.org>,
        linux-sunxi@...ts.linux.dev, Guo Ren <guoren@...ux.alibaba.com>
Subject: Re: [PATCH 1/3] riscv: Fixup _PAGE_GLOBAL in _PAGE_KERNEL

Hi Anup,

On Mon, May 24, 2021 at 4:03 PM Anup Patel <anup@...infault.org> wrote:
>
> On Mon, May 24, 2021 at 12:22 PM <guoren@...nel.org> wrote:
> >
> > From: Guo Ren <guoren@...ux.alibaba.com>
> >
> > Kernel virtual address translation should avoid care asid or it'll
> > cause more TLB-miss and TLB-refill. Because the current asid in satp
> > belongs to the current process, but the target kernel va TLB entry's
> > asid still belongs to the previous process.
> >
> > Signed-off-by: Guo Ren <guoren@...ux.alibaba.com>
> > Cc: Anup Patel <anup.patel@....com>
> > Cc: Palmer Dabbelt <palmerdabbelt@...gle.com>
>
> First of all thanks for doing this series, I had similar changes in mind
> as follow-up to the ASID allocator.
>
> I went through all three patches and at least I don't see any
> obvious issue but I think we should try testing it more on a few
> existing platforms.
We've tested it on Allwinner D1 C906 and C910 SMP*4 for a long time,
just hope it won't affect u540.

(In fact, C910 has used ASID allocator for more than two years with
our own kernel-tree. I remember we've talked about it in 2019
plumber.)

>
> Reviewed-by: Anup Patel <anup@...infault.org>
>
> Regards,
> Anup
>
> > ---
> >  arch/riscv/include/asm/pgtable.h | 1 +
> >  1 file changed, 1 insertion(+)
> >
> > diff --git a/arch/riscv/include/asm/pgtable.h b/arch/riscv/include/asm/pgtable.h
> > index 78f2323..017da15 100644
> > --- a/arch/riscv/include/asm/pgtable.h
> > +++ b/arch/riscv/include/asm/pgtable.h
> > @@ -135,6 +135,7 @@
> >                                 | _PAGE_PRESENT \
> >                                 | _PAGE_ACCESSED \
> >                                 | _PAGE_DIRTY \
> > +                               | _PAGE_GLOBAL \
> >                                 | _PAGE_CACHE)
> >
> >  #define PAGE_KERNEL            __pgprot(_PAGE_KERNEL)
> > --
> > 2.7.4
> >



-- 
Best Regards
 Guo Ren

ML: https://lore.kernel.org/linux-csky/