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Message-Id: <E78B3BF9-8E49-417B-A89E-05F72690A92F@sifive.com> Date: Wed, 29 Nov 2023 10:39:56 +0800 From: Jerry Shih <jerry.shih@...ive.com> To: Eric Biggers <ebiggers@...nel.org> Cc: Conor Dooley <conor@...nel.org>, Paul Walmsley <paul.walmsley@...ive.com>, palmer@...belt.com, aou@...s.berkeley.edu, herbert@...dor.apana.org.au, davem@...emloft.net, conor.dooley@...rochip.com, ardb@...nel.org, heiko@...ech.de, phoebe.chen@...ive.com, hongrong.hsu@...ive.com, linux-riscv@...ts.infradead.org, linux-kernel@...r.kernel.org, linux-crypto@...r.kernel.org Subject: Re: [PATCH v2 04/13] RISC-V: crypto: add Zvkned accelerated AES implementation On Nov 29, 2023, at 04:12, Eric Biggers <ebiggers@...nel.org> wrote: > On Tue, Nov 28, 2023 at 05:54:49PM +0000, Conor Dooley wrote: >>> +static inline bool check_aes_ext(void) >>> +{ >>> + return riscv_isa_extension_available(NULL, ZVKNED) && >>> + riscv_vector_vlen() >= 128; >>> +} >> >> I'm not keen on this construct, where you are checking vlen greater than >> 128 and the presence of Zvkned without checking for the presence of V >> itself. Can you use "has_vector()" in any places where you depend on the >> presence of vector please? > > Shouldn't both of those things imply vector support already? The vector crypto extensions imply `V` extension. Should we still need to check the `V` explicitly? https://github.com/riscv/riscv-crypto/blob/main/doc/vector/riscv-crypto-spec-vector.adoc#1-extensions-overview >> Also, there are potentially a lot of places in this drivers where you >> can replace "riscv_isa_extension_available()" with >> "riscv_has_extension_likely()". The latter is optimised with >> alternatives, so in places that are going to be evaluated frequently it >> may be beneficial for you. > > These extension checks are only executed in module_init functions, so they're > not performance critical. All `riscv_isa_extension_available()` calls in crypto drivers are called once in the module init calls. Should we still need that `riscv_has_extension_likely()` with a little more code size? > - Eric
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