linux-kernel - Re: [PATCH v4 03/18] riscv: sbi: add FWFT extension interface

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Message-ID: <20250322-a87faa18fe5b54b7cb61b353@orel>
Date: Sat, 22 Mar 2025 13:11:28 +0100
From: Andrew Jones <ajones@...tanamicro.com>
To: Clément Léger <cleger@...osinc.com>
Cc: Paul Walmsley <paul.walmsley@...ive.com>, 
	Palmer Dabbelt <palmer@...belt.com>, Anup Patel <anup@...infault.org>, 
	Atish Patra <atishp@...shpatra.org>, Shuah Khan <shuah@...nel.org>, Jonathan Corbet <corbet@....net>, 
	linux-riscv@...ts.infradead.org, linux-kernel@...r.kernel.org, linux-doc@...r.kernel.org, 
	kvm@...r.kernel.org, kvm-riscv@...ts.infradead.org, linux-kselftest@...r.kernel.org, 
	Samuel Holland <samuel.holland@...ive.com>
Subject: Re: [PATCH v4 03/18] riscv: sbi: add FWFT extension interface

On Mon, Mar 17, 2025 at 06:06:09PM +0100, 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@...osinc.com>
> ---
>  arch/riscv/include/asm/sbi.h | 20 +++++++++++
>  arch/riscv/kernel/sbi.c      | 69 ++++++++++++++++++++++++++++++++++++
>  2 files changed, 89 insertions(+)
> 
> diff --git a/arch/riscv/include/asm/sbi.h b/arch/riscv/include/asm/sbi.h
> index d11d22717b49..1cecfa82c2e5 100644
> --- a/arch/riscv/include/asm/sbi.h
> +++ b/arch/riscv/include/asm/sbi.h
> @@ -503,6 +503,26 @@ int sbi_remote_hfence_vvma_asid(const struct cpumask *cpu_mask,
>  				unsigned long asid);
>  long sbi_probe_extension(int ext);
>  
> +int sbi_fwft_local_set_cpumask(const cpumask_t *mask, u32 feature,
> +			       unsigned long value, unsigned long flags);
> +/**
> + * 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);

Let flags stick out. We have 100 chars.

> + }
> +
> +int sbi_fwft_get(u32 feature, unsigned long *value);
> +int sbi_fwft_set(u32 feature, unsigned long value, unsigned long flags);
> +
>  /* Check if current SBI specification version is 0.1 or not */
>  static inline int sbi_spec_is_0_1(void)
>  {
> diff --git a/arch/riscv/kernel/sbi.c b/arch/riscv/kernel/sbi.c
> index 1989b8cade1b..d41a5642be24 100644
> --- a/arch/riscv/kernel/sbi.c
> +++ b/arch/riscv/kernel/sbi.c
> @@ -299,6 +299,75 @@ static int __sbi_rfence_v02(int fid, const struct cpumask *cpu_mask,
>  	return 0;
>  }
>  
> +/**
> + * sbi_fwft_get() - Get a feature for the local hart
> + * @feature: The feature ID to be set
> + * @value: Will contain the feature value on success
> + *
> + * Return: 0 on success, appropriate linux error code otherwise.
> + */
> +int sbi_fwft_get(u32 feature, unsigned long *value)
> +{
> +	return -EOPNOTSUPP;
> +}
> +
> +/**
> + * sbi_fwft_set() - Set a feature on the local hart
> + * @feature: The feature ID to be set
> + * @value: The feature value to be set
> + * @flags: FWFT feature set flags
> + *
> + * Return: 0 on success, appropriate linux error code otherwise.
> + */
> +int sbi_fwft_set(u32 feature, unsigned long value, unsigned long flags)
> +{
> +	return -EOPNOTSUPP;
> +}
> +
> +struct fwft_set_req {
> +	u32 feature;
> +	unsigned long value;
> +	unsigned long flags;
> +	atomic_t error;
> +};
> +
> +static void cpu_sbi_fwft_set(void *arg)
> +{
> +	struct fwft_set_req *req = arg;
> +	int ret;
> +
> +	ret = sbi_fwft_set(req->feature, req->value, req->flags);
> +	if (ret)
> +		atomic_set(&req->error, ret);
> +}
> +
> +/**
> + * sbi_fwft_local_set() - Set a feature for the specified cpumask

sbi_fwft_local_set_cpumask

> + * @mask: CPU mask of cpus that need the feature to be set
> + * @feature: The feature ID to be set
> + * @value: The feature value to be set
> + * @flags: FWFT feature set flags
> + *
> + * Return: 0 on success, appropriate linux error code otherwise.
> + */
> +int sbi_fwft_local_set_cpumask(const cpumask_t *mask, u32 feature,
> +			       unsigned long value, unsigned long flags)
> +{
> +	struct fwft_set_req req = {
> +		.feature = feature,
> +		.value = value,
> +		.flags = flags,
> +		.error = ATOMIC_INIT(0),
> +	};
> +
> +	if (feature & SBI_FWFT_GLOBAL_FEATURE_BIT)
> +		return -EINVAL;
> +
> +	on_each_cpu_mask(mask, cpu_sbi_fwft_set, &req, 1);
> +
> +	return atomic_read(&req.error);
> +}
> +
>  /**
>   * sbi_set_timer() - Program the timer for next timer event.
>   * @stime_value: The value after which next timer event should fire.
> -- 
> 2.47.2
>

Otherwise,

Reviewed-by: Andrew Jones <ajones@...tanamicro.com>