Re: [PATCH v4 04/12] RISC-V: add vector crypto extension detection

[Eric Biggers]

On Tue, Jul 11, 2023 at 05:37:35PM +0200, Heiko Stuebner wrote:
> From: Heiko Stuebner <heiko.stuebner@xxxxxxxx>
> 
> Add detection for some extensions of the vector-crypto specification:
> - Zvkb: Vector Bit-manipulation used in Cryptography
> - Zvkg: Vector GCM/GMAC
> - Zvknha and Zvknhb: NIST Algorithm Suite
> - Zvkns: AES-128, AES-256 Single Round Suite
> - Zvksed: ShangMi Algorithm Suite
> - Zvksh: ShangMi Algorithm Suite
> 
> As their use is very specific and will likely be limited to special places
> we expect current code to just pre-encode those instructions, so right now
> we don't introduce toolchain requirements.
> 
> Signed-off-by: Heiko Stuebner <heiko.stuebner@xxxxxxxx>
> ---
>  arch/riscv/include/asm/hwcap.h |  9 ++++++
>  arch/riscv/kernel/cpu.c        |  8 ++++++
>  arch/riscv/kernel/cpufeature.c | 50 ++++++++++++++++++++++++++++++++++
>  3 files changed, 67 insertions(+)
> 
> diff --git a/arch/riscv/include/asm/hwcap.h b/arch/riscv/include/asm/hwcap.h
> index b80ca6e77088..0f5172fa87b0 100644
> --- a/arch/riscv/include/asm/hwcap.h
> +++ b/arch/riscv/include/asm/hwcap.h
> @@ -64,6 +64,15 @@
>  #define RISCV_ISA_EXT_ZKSED		51
>  #define RISCV_ISA_EXT_ZKSH		52
>  #define RISCV_ISA_EXT_ZKT		53
> +#define RISCV_ISA_EXT_ZVBB		54
> +#define RISCV_ISA_EXT_ZVBC		55
> +#define RISCV_ISA_EXT_ZVKG		56
> +#define RISCV_ISA_EXT_ZVKNED		57
> +#define RISCV_ISA_EXT_ZVKNHA		58
> +#define RISCV_ISA_EXT_ZVKNHB		59
> +#define RISCV_ISA_EXT_ZVKSED		60
> +#define RISCV_ISA_EXT_ZVKSH		61
> +#define RISCV_ISA_EXT_ZVKT		62

It would be helpful if each RISCV_ISA_EXT_* definition had a comment that spells
out what it stands for, similar to what arch/x86/include/asm/cpufeatures.h does.
I know they can all be looked up, and they're sort of mnemonic, but it would be
helpful.

- Eric