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Subject: Re: [PATCH 06/12] RISC-V: crypto: add accelerated AES-CBC/CTR/ECB/XTS
 implementations
From:   Jerry Shih <jerry.shih@sifive.com>
In-Reply-To: <20231102051639.GF1498@sol.localdomain>
Date:   Tue, 7 Nov 2023 16:53:13 +0800
Cc:     Paul Walmsley <paul.walmsley@sifive.com>, palmer@dabbelt.com,
        Albert Ou <aou@eecs.berkeley.edu>, herbert@gondor.apana.org.au,
        davem@davemloft.net, andy.chiu@sifive.com, greentime.hu@sifive.com,
        conor.dooley@microchip.com, guoren@kernel.org, bjorn@rivosinc.com,
        heiko@sntech.de, ardb@kernel.org, phoebe.chen@sifive.com,
        hongrong.hsu@sifive.com, linux-riscv@lists.infradead.org,
        linux-kernel@vger.kernel.org, linux-crypto@vger.kernel.org
Reply-To: 20231102051639.GF1498@sol.localdomain
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References: <20231025183644.8735-1-jerry.shih@sifive.com>
 <20231025183644.8735-7-jerry.shih@sifive.com>
 <20231102051639.GF1498@sol.localdomain>
To:     Eric Biggers <ebiggers@kernel.org>
Precedence: bulk

On Nov 2, 2023, at 13:16, Eric Biggers <ebiggers@kernel.org> wrote:
> On Thu, Oct 26, 2023 at 02:36:38AM +0800, Jerry Shih wrote:
>> +static int ecb_encrypt(struct skcipher_request *req)
>> +{
>> +	struct crypto_skcipher *tfm =3D crypto_skcipher_reqtfm(req);
>> +	const struct riscv64_aes_ctx *ctx =3D crypto_skcipher_ctx(tfm);
>> +	struct skcipher_walk walk;
>> +	unsigned int nbytes;
>> +	int err;
>> +
>> +	/* If we have error here, the `nbytes` will be zero. */
>> +	err =3D skcipher_walk_virt(&walk, req, false);
>> +	while ((nbytes =3D walk.nbytes)) {
>> +		kernel_vector_begin();
>> +		rv64i_zvkned_ecb_encrypt(walk.src.virt.addr, =
walk.dst.virt.addr,
>> +					 nbytes & =
AES_BLOCK_VALID_SIZE_MASK,
>> +					 &ctx->key);
>> +		kernel_vector_end();
>> +		err =3D skcipher_walk_done(
>> +			&walk, nbytes & AES_BLOCK_REMAINING_SIZE_MASK);
>> +	}
>> +
>> +	return err;
>> +}
>=20
> There's no fallback for !crypto_simd_usable() here.  I really like it =
this way.
> However, for it to work (for skciphers and aeads), RISC-V needs to =
allow the
> vector registers to be used in softirq context.  Is that already the =
case?

The kernel-mode-vector could be enabled in softirq, but we don't have =
nesting
vector contexts. Will we have the case that kernel needs to jump to =
softirq for
encryptions during the regular crypto function? If yes, we need to have =
fallbacks
for all algorithms.

-Jerry=