linux-kernel - Re: [PATCH 1/1] RISC-V: correct enum sbi_ext_rfence_fid

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Message-ID: <CAOnJCULZFHPPXhL5ZyH9qNfb5BgUHos1PU2q6Khb7uT=N-7a3w@mail.gmail.com>
Date:   Tue, 9 Mar 2021 11:28:39 -0800
From:   Atish Patra <atishp@...shpatra.org>
To:     Anup Patel <anup@...infault.org>
Cc:     Heinrich Schuchardt <xypron.glpk@....de>,
        Paul Walmsley <paul.walmsley@...ive.com>,
        Palmer Dabbelt <palmer@...belt.com>,
        Albert Ou <aou@...s.berkeley.edu>,
        Atish Patra <atish.patra@....com>,
        Anup Patel <anup.patel@....com>,
        Kefeng Wang <wangkefeng.wang@...wei.com>,
        linux-riscv <linux-riscv@...ts.infradead.org>,
        "linux-kernel@...r.kernel.org List" <linux-kernel@...r.kernel.org>,
        Sean Anderson <seanga2@...il.com>
Subject: Re: [PATCH 1/1] RISC-V: correct enum sbi_ext_rfence_fid

On Mon, Mar 8, 2021 at 2:55 AM Anup Patel <anup@...infault.org> wrote:
>
> On Mon, Mar 8, 2021 at 1:19 PM Atish Patra <atishp@...shpatra.org> wrote:
> >
> > On Sat, Mar 6, 2021 at 4:12 AM Anup Patel <anup@...infault.org> wrote:
> > >
> > > On Sat, Mar 6, 2021 at 11:19 AM Heinrich Schuchardt <xypron.glpk@....de> wrote:
> > > >
> > > > The constants in enum sbi_ext_rfence_fid should match the SBI
> > > > specification. See
> > > > https://github.com/riscv/riscv-sbi-doc/blob/master/riscv-sbi.adoc#78-function-listing
> > > >
> > > > | Function Name               | FID | EID
> > > > | sbi_remote_fence_i          |   0 | 0x52464E43
> > > > | sbi_remote_sfence_vma       |   1 | 0x52464E43
> > > > | sbi_remote_sfence_vma_asid  |   2 | 0x52464E43
> > > > | sbi_remote_hfence_gvma_vmid |   3 | 0x52464E43
> > > > | sbi_remote_hfence_gvma      |   4 | 0x52464E43
> > > > | sbi_remote_hfence_vvma_asid |   5 | 0x52464E43
> > > > | sbi_remote_hfence_vvma      |   6 | 0x52464E43
> > > >
> > > > Fixes: ecbacc2a3efd ("RISC-V: Add SBI v0.2 extension definitions")
> > > > Reported-by: Sean Anderson <seanga2@...il.com>
> > > > Signed-off-by: Heinrich Schuchardt <xypron.glpk@....de>
> > >

Reviewed-by: Atish Patra <atish.patra@....com>

> > > Good catch.
> > >
> > > I guess we never saw any issues because these calls are only used by
> > > KVM RISC-V which is not merged yet. Further for KVM RISC-V, the HFENCE
> > > instruction is emulated as flush everything on FPGA, QEMU, and Spike so
> > > we did not notice any issue with KVM RISC-V too.
> > >
> >
> > OpenSBI & Xvisor also define the same order as Linux kernel. The
> > existing order(in Linux kernel)
> > makes more sense w.r.to Lexicographic order as well.
> >
> > Should we just fix the spec instead ?
>
> I would not recommend that because RFENCE is part of the released SBI v0.2 spec.
>

Fair enough.

> We have to be more careful in software to follow the spec correctly.
>

Agreed. Apologies for the slip up.

> Regards,
> Anup
>
> >
> > > Looks good to me.
> > >
> > > Reviewed-by: Anup Patel <anup@...infault.org>
> > >
> > > Regards,
> > > Anup
> > >
> > > > ---
> > > >  arch/riscv/include/asm/sbi.h | 4 ++--
> > > >  1 file changed, 2 insertions(+), 2 deletions(-)
> > > >
> > > > diff --git a/arch/riscv/include/asm/sbi.h b/arch/riscv/include/asm/sbi.h
> > > > index 99895d9c3bdd..d7027411dde8 100644
> > > > --- a/arch/riscv/include/asm/sbi.h
> > > > +++ b/arch/riscv/include/asm/sbi.h
> > > > @@ -51,10 +51,10 @@ enum sbi_ext_rfence_fid {
> > > >         SBI_EXT_RFENCE_REMOTE_FENCE_I = 0,
> > > >         SBI_EXT_RFENCE_REMOTE_SFENCE_VMA,
> > > >         SBI_EXT_RFENCE_REMOTE_SFENCE_VMA_ASID,
> > > > -       SBI_EXT_RFENCE_REMOTE_HFENCE_GVMA,
> > > >         SBI_EXT_RFENCE_REMOTE_HFENCE_GVMA_VMID,
> > > > -       SBI_EXT_RFENCE_REMOTE_HFENCE_VVMA,
> > > > +       SBI_EXT_RFENCE_REMOTE_HFENCE_GVMA,
> > > >         SBI_EXT_RFENCE_REMOTE_HFENCE_VVMA_ASID,
> > > > +       SBI_EXT_RFENCE_REMOTE_HFENCE_VVMA,
> > > >  };
> > > >
> > > >  enum sbi_ext_hsm_fid {
> > > > --
> > > > 2.30.1
> > > >
> > > >
> > > > _______________________________________________
> > > > linux-riscv mailing list
> > > > linux-riscv@...ts.infradead.org
> > > > http://lists.infradead.org/mailman/listinfo/linux-riscv
> > >
> > > _______________________________________________
> > > linux-riscv mailing list
> > > linux-riscv@...ts.infradead.org
> > > http://lists.infradead.org/mailman/listinfo/linux-riscv
> >
> >
> >
> > --
> > Regards,
> > Atish

-- 
Regards,
Atish

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