Re: [PATCH v5 03/13] riscv: sbi: add FWFT extension interface

Andrew Jones
2025-04-24T12:50:53Z

On Thu, Apr 17, 2025 at 02:19:50PM +0200, Clément Léger wrote:
> This SBI extensions enables supervisor mode to control feature that are
> under M-mode control (For instance, Svadu menvcfg ADUE bit, Ssdbltrp
> DTE, etc). Add an interface to set local features for a specific cpu
> mask as well as for the online cpu mask.
>
> Signed-off-by: Clément Léger <cleger@rivosinc.com>
> Reviewed-by: Andrew Jones <ajones@ventanamicro.com>
> ---
> arch/riscv/include/asm/sbi.h | 17 +++++++++++
> arch/riscv/kernel/sbi.c | 57 ++++++++++++++++++++++++++++++++++++
> 2 files changed, 74 insertions(+)
>
> diff --git a/arch/riscv/include/asm/sbi.h b/arch/riscv/include/asm/sbi.h
> index 7ec249fea880..c8eab315c80e 100644
> --- a/arch/riscv/include/asm/sbi.h
> +++ b/arch/riscv/include/asm/sbi.h
> @@ -503,6 +503,23 @@ int sbi_remote_hfence_vvma_asid(const struct cpumask *cpu_mask,
> unsigned long asid);
> long sbi_probe_extension(int ext);
>
> +int sbi_fwft_set(u32 feature, unsigned long value, unsigned long flags);
> +int sbi_fwft_local_set_cpumask(const cpumask_t *mask, u32 feature,
> + unsigned long value, unsigned long flags);

I'm confused by the naming that includes 'local' and 'cpumask' together
and...

> +/**
> + * sbi_fwft_local_set() - Set a feature on all online cpus
> + * @feature: The feature to be set
> + * @value: The feature value to be set
> + * @flags: FWFT feature set flags
> + *
> + * Return: 0 on success, appropriate linux error code otherwise.
> + */
> +static inline int sbi_fwft_local_set(u32 feature, unsigned long value,
> + unsigned long flags)
> +{
> + return sbi_fwft_local_set_cpumask(cpu_online_mask, feature, value, flags);

...that something named with just 'local' is applied to all online cpus.
I've always considered 'local' functions to only affect the calling cpu.

Thanks,
drew