Re: [PATCH v1 02/13] riscv: add ISA extension probing for Zv* extensions

From: Clément Léger
Date: Thu Oct 12 2023 - 09:17:22 EST




On 11/10/2023 13:14, Clément Léger wrote:
> Add probing of some Zv* ISA extensions that are mentioned in "RISC-V
> Cryptography Extensions Volume II" [1]. These ISA extensions are the
> following:
>
> - Zvbb: Vector Basic Bit-manipulation
> - Zvbc: Vector Carryless Multiplication
> - Zvkb: Vector Cryptography Bit-manipulation
> - Zvkg: Vector GCM/GMAC.
> - Zvkned: NIST Suite: Vector AES Block Cipher
> - Zvknh[ab]: NIST Suite: Vector SHA-2 Secure Hash
> - Zvksed: ShangMi Suite: SM4 Block Cipher
> - Zvksh: ShangMi Suite: SM3 Secure Hash
> - Zvkn: NIST Algorithm Suite
> - Zvknc: NIST Algorithm Suite with carryless multiply
> - Zvkng: NIST Algorithm Suite with GCM.
> - Zvks: ShangMi Algorithm Suite
> - Zvksc: ShangMi Algorithm Suite with carryless multiplication
> - Zvksg: ShangMi Algorithm Suite with GCM.
> - Zvkt: Vector Data-Independent Execution Latency.
>
> [1] https://drive.google.com/file/d/1gb9OLH-DhbCgWp7VwpPOVrrY6f3oSJLL/view
>
> Signed-off-by: Clément Léger <cleger@xxxxxxxxxxxx>
> ---
> arch/riscv/include/asm/hwcap.h | 16 ++++++++++++++++
> arch/riscv/kernel/cpufeature.c | 16 ++++++++++++++++
> 2 files changed, 32 insertions(+)
>
> diff --git a/arch/riscv/include/asm/hwcap.h b/arch/riscv/include/asm/hwcap.h
> index b7b58258f6c7..4e46981ac6c8 100644
> --- a/arch/riscv/include/asm/hwcap.h
> +++ b/arch/riscv/include/asm/hwcap.h
> @@ -58,6 +58,22 @@
> #define RISCV_ISA_EXT_ZICSR 40
> #define RISCV_ISA_EXT_ZIFENCEI 41
> #define RISCV_ISA_EXT_ZIHPM 42
> +#define RISCV_ISA_EXT_ZVBB 43
> +#define RISCV_ISA_EXT_ZVBC 44
> +#define RISCV_ISA_EXT_ZVKB 45
> +#define RISCV_ISA_EXT_ZVKG 46
> +#define RISCV_ISA_EXT_ZVKN 47
> +#define RISCV_ISA_EXT_ZVKNC 48
> +#define RISCV_ISA_EXT_ZVKNED 49
> +#define RISCV_ISA_EXT_ZVKNG 50
> +#define RISCV_ISA_EXT_ZVKNHA 51
> +#define RISCV_ISA_EXT_ZVKNHB 52
> +#define RISCV_ISA_EXT_ZVKS 53
> +#define RISCV_ISA_EXT_ZVKSC 54
> +#define RISCV_ISA_EXT_ZVKSED 55
> +#define RISCV_ISA_EXT_ZVKSH 56
> +#define RISCV_ISA_EXT_ZVKSG 57

About Zvks/Zvkn, these extensions are actually shorthand for a few other
sub-extensions, it is still not clear if it should be parsed as is.
There are multiple solutions:

- Handle them as-is, simply enable the extension, if reported through
hwprobe, userspace will be responsible to detect the sub-extensions
(current approach)

- "Unfold" the extension in order to enable all the sub-extensions and
keep the main one (for instance for Zvkn, enable Zvkned, Zvknhb, Zvkb,
Zvkt, Zvkn)

- "Unfold" but don't keep the extension "shorthand" in the ISA extension
list (for instance for Zvkn, enable Zvkned, Zvknhb, Zvkb, Zvkt)

Thanks,

Clément

> +#define RISCV_ISA_EXT_ZVKT 58
>
> #define RISCV_ISA_EXT_MAX 64
>
> diff --git a/arch/riscv/kernel/cpufeature.c b/arch/riscv/kernel/cpufeature.c
> index 1cfbba65d11a..859d647f3ced 100644
> --- a/arch/riscv/kernel/cpufeature.c
> +++ b/arch/riscv/kernel/cpufeature.c
> @@ -174,6 +174,22 @@ const struct riscv_isa_ext_data riscv_isa_ext[] = {
> __RISCV_ISA_EXT_DATA(zba, RISCV_ISA_EXT_ZBA),
> __RISCV_ISA_EXT_DATA(zbb, RISCV_ISA_EXT_ZBB),
> __RISCV_ISA_EXT_DATA(zbs, RISCV_ISA_EXT_ZBS),
> + __RISCV_ISA_EXT_DATA(zvbb, RISCV_ISA_EXT_ZVBB),
> + __RISCV_ISA_EXT_DATA(zvbc, RISCV_ISA_EXT_ZVBC),
> + __RISCV_ISA_EXT_DATA(zvkb, RISCV_ISA_EXT_ZVKB),
> + __RISCV_ISA_EXT_DATA(zvkg, RISCV_ISA_EXT_ZVKG),
> + __RISCV_ISA_EXT_DATA(zvkn, RISCV_ISA_EXT_ZVKN),
> + __RISCV_ISA_EXT_DATA(zvknc, RISCV_ISA_EXT_ZVKNC),
> + __RISCV_ISA_EXT_DATA(zvkned, RISCV_ISA_EXT_ZVKNED),
> + __RISCV_ISA_EXT_DATA(zvkng, RISCV_ISA_EXT_ZVKNG),
> + __RISCV_ISA_EXT_DATA(zvknha, RISCV_ISA_EXT_ZVKNHA),
> + __RISCV_ISA_EXT_DATA(zvknhb, RISCV_ISA_EXT_ZVKNHB),
> + __RISCV_ISA_EXT_DATA(zvks, RISCV_ISA_EXT_ZVKS),
> + __RISCV_ISA_EXT_DATA(zvksc, RISCV_ISA_EXT_ZVKSC),
> + __RISCV_ISA_EXT_DATA(zvksed, RISCV_ISA_EXT_ZVKSED),
> + __RISCV_ISA_EXT_DATA(zvksh, RISCV_ISA_EXT_ZVKSH),
> + __RISCV_ISA_EXT_DATA(zvksg, RISCV_ISA_EXT_ZVKSG),
> + __RISCV_ISA_EXT_DATA(zvkt, RISCV_ISA_EXT_ZVKT),
> __RISCV_ISA_EXT_DATA(smaia, RISCV_ISA_EXT_SMAIA),
> __RISCV_ISA_EXT_DATA(ssaia, RISCV_ISA_EXT_SSAIA),
> __RISCV_ISA_EXT_DATA(sscofpmf, RISCV_ISA_EXT_SSCOFPMF),