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Subject: Re: [PATCH v2 05/19] riscv: add ISA extension parsing for vector
 crypto extensions
From:   Jerry Shih <jerry.shih@sifive.com>
In-Reply-To: <7626f978-e9ea-4f8f-b814-aeac02bd3712@rivosinc.com>
Date:   Fri, 20 Oct 2023 10:43:26 +0800
Cc:     Evan Green <evan@rivosinc.com>, linux-riscv@lists.infradead.org,
        devicetree@vger.kernel.org, linux-kernel@vger.kernel.org,
        linux-doc@vger.kernel.org, Palmer Dabbelt <palmer@rivosinc.com>,
        Paul Walmsley <paul.walmsley@sifive.com>,
        Rob Herring <robh+dt@kernel.org>,
        Krzysztof Kozlowski <krzysztof.kozlowski+dt@linaro.org>,
        Albert Ou <aou@eecs.berkeley.edu>,
        Jonathan Corbet <corbet@lwn.net>,
        Andrew Jones <ajones@ventanamicro.com>,
        Conor Dooley <conor@kernel.org>,
        Samuel Ortiz <sameo@rivosinc.com>
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References: <20231017131456.2053396-1-cleger@rivosinc.com>
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 <DA8B4610-D514-4733-B875-C247FFCCC7AA@sifive.com>
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To:     =?utf-8?B?Q2zDqW1lbnQgTMOpZ2Vy?= <cleger@rivosinc.com>
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On Oct 19, 2023, at 17:35, Cl=C3=A9ment L=C3=A9ger <cleger@rivosinc.com> =
wrote:
> On 18/10/2023 19:26, Evan Green wrote:
>> On Wed, Oct 18, 2023 at 5:53=E2=80=AFAM Cl=C3=A9ment L=C3=A9ger =
<cleger@rivosinc.com> wrote:
>>>=20
>>> On 18/10/2023 03:45, Jerry Shih wrote:
>>>>=20
>>>> The `Zvkb` is the subset of `Zvbb`[1]. So, the `Zvkb` should be =
bundled with `Zvbb`.
>>>=20
>>> Hi Jerry,
>>>=20
>>> Thanks for catching this, I think some other extensions will fall in
>>> this category as well then (Zvknha/Zvknhb). I will verify that.
>>=20
>> The bundling mechanism works well when an extension is a pure lasso
>> around other extensions. We'd have to tweak that code if we wanted to
>> support cases like this, where the extension is a superset of others,
>> but also contains loose change not present anywhere else (and
>> therefore also needs to stand as a separate bit).
>=20
> For Zvbb and Zvknhb, I used the following code:
>=20
> static const unsigned int riscv_zvbb_bundled_exts[] =3D {
> 	RISCV_ISA_EXT_ZVKB,
> 	RISCV_ISA_EXT_ZVBB
> };
>=20
> static const unsigned int riscv_zvknhb_bundled_exts[] =3D {
> 	RISCV_ISA_EXT_ZVKNHA,
> 	RISCV_ISA_EXT_ZVKNHB
> };
>=20
> Which correctly results in both extension (superset + base set) being
> enabled when only one is set. Is there something that I'm missing ?

We should not bundle zvknha and zvknhb together. They are exclusive.
Please check:
https://github.com/riscv/riscv-crypto/issues/364#issuecomment-1726782096

-Jerry