Re: [PATCH v5 15/17] riscv: cpufeature: Introduce ISA bases bitmap and rva23u64 detection

[sashiko-bot@kernel.org]

Thank you for your contribution! Sashiko AI review found 1 potential issue(s) to consider:
- [Medium] The RVA23U64 base detection wrongly mandates the legacy broad `B` extension superset instead of its required bitmanip constituent extensions (`Zba`, `Zbb`, `Zbs`).
--

commit e73d8757f0ce7270b4b39989368d4e83e5a355fc
Author: Guodong Xu <docular.xu@gmail.com>

riscv: cpufeature: Introduce ISA bases bitmap and rva23u64 detection

This commit introduces a per-hart and host-wide bitmap of conformant ISA
profile bases, such as IMA and RVA23U64. The bitmap is computed during
init by riscv_init_isa_bases() and registered as a subsys_initcall.

> diff --git a/arch/riscv/kernel/cpufeature.c b/arch/riscv/kernel/cpufeature.c
> index 4c3bf813af052..fa8471aef42ee 100644
> --- a/arch/riscv/kernel/cpufeature.c
> +++ b/arch/riscv/kernel/cpufeature.c

[ ... ]

> @@ -1304,3 +1307,90 @@ void __init_or_module riscv_cpufeature_patch_func(struct alt_entry *begin,
>  	}
>  }
>  #endif

[ ... ]

> +	/* RVA23U64 */
> +
> +	/* Supm with PMLEN=7 */
> +	if (!riscv_have_user_pmlen(7))
> +		return;
> +
> +	__set_bit(RISCV_ISA_EXT_F, ext_mask);
> +	__set_bit(RISCV_ISA_EXT_D, ext_mask);
> +	__set_bit(RISCV_ISA_EXT_C, ext_mask);
> +	__set_bit(RISCV_ISA_EXT_B, ext_mask);

[Severity: Medium]
Does this incorrectly mandate the legacy broad B extension for RVA23U64?

If a RISC-V device tree advertises the RVA23U64 constituent bitmanip
extensions (e.g., zba, zbb, zbs) but omits the legacy unratified 'b'
string, it appears this check will fail because RISCV_ISA_EXT_B won't be
synthesized. Should this instead check for the individual constituent
extensions required by the profile?

> +	__set_bit(RISCV_ISA_EXT_ZICSR, ext_mask);
> +	__set_bit(RISCV_ISA_EXT_ZICNTR, ext_mask);
> +	__set_bit(RISCV_ISA_EXT_ZIHPM, ext_mask);

[ ... ]

-- 
Sashiko AI review · https://sashiko.dev/#/patchset/20260701-rva23u64-hwprobe-v2-v5-0-2c61f94a695a@gmail.com?part=15