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

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Date:   Tue, 09 Mar 2021 19:23:34 -0800 (PST)
From:   Palmer Dabbelt <palmer@...belt.com>
To:     atishp@...shpatra.org
CC:     anup@...infault.org, xypron.glpk@....de,
        Paul Walmsley <paul.walmsley@...ive.com>,
        aou@...s.berkeley.edu, Atish Patra <Atish.Patra@....com>,
        Anup Patel <Anup.Patel@....com>, wangkefeng.wang@...wei.com,
        linux-riscv@...ts.infradead.org, linux-kernel@...r.kernel.org,
        seanga2@...il.com
Subject:     Re: [PATCH 1/1] RISC-V: correct enum sbi_ext_rfence_fid

On Tue, 09 Mar 2021 11:28:39 PST (-0800), atishp@...shpatra.org wrote:
> 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.

Yes, agreed.  It's very important that we don't change the specs we said are 
frozen, that would be a huge mess.

This is on fixes.

Thanks!

>
>> 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

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