linux-kernel - Re: [PATCH v6 05/14] riscv: sbi: add SBI FWFT extension calls

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Message-ID: <4032b00c-1194-45b1-b1e5-4e9237ed7948@linux.dev>
Date: Thu, 8 May 2025 16:01:12 -0700
From: Atish Patra <atish.patra@...ux.dev>
To: Clément Léger <cleger@...osinc.com>,
 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
Cc: Samuel Holland <samuel.holland@...ive.com>,
 Andrew Jones <ajones@...tanamicro.com>, Deepak Gupta <debug@...osinc.com>
Subject: Re: [PATCH v6 05/14] riscv: sbi: add SBI FWFT extension calls

On 4/24/25 10:31 AM, ClÃ©ment LÃ©ger wrote:
> Add FWFT extension calls. This will be ratified in SBI V3.0 hence, it is
> provided as a separate commit that can be left out if needed.
> 
> Signed-off-by: Clément Léger <cleger@...osinc.com>
> Reviewed-by: Andrew Jones <ajones@...tanamicro.com>
> ---
>   arch/riscv/kernel/sbi.c | 20 +++++++++++++++++++-
>   1 file changed, 19 insertions(+), 1 deletion(-)
> 
> diff --git a/arch/riscv/kernel/sbi.c b/arch/riscv/kernel/sbi.c
> index d57e4dae7dac..070014ff35d4 100644
> --- a/arch/riscv/kernel/sbi.c
> +++ b/arch/riscv/kernel/sbi.c
> @@ -299,6 +299,8 @@ static int __sbi_rfence_v02(int fid, const struct cpumask *cpu_mask,
>   	return 0;
>   }
>   
> +static bool sbi_fwft_supported;
> +

super nit: Can declare this along with struct fwft_set_req so that they 
are together ? You can move the sbi_fwft_set to below the struct 
fwft_set_req.

>   /**
>    * sbi_fwft_set() - Set a feature on the local hart
>    * @feature: The feature ID to be set
> @@ -309,7 +311,15 @@ static int __sbi_rfence_v02(int fid, const struct cpumask *cpu_mask,
>    */
>   int sbi_fwft_set(u32 feature, unsigned long value, unsigned long flags)
>   {
> -	return -EOPNOTSUPP;
> +	struct sbiret ret;
> +
> +	if (!sbi_fwft_supported)
> +		return -EOPNOTSUPP;
> +
> +	ret = sbi_ecall(SBI_EXT_FWFT, SBI_EXT_FWFT_SET,
> +			feature, value, flags, 0, 0, 0);
> +
> +	return sbi_err_map_linux_errno(ret.error);
>   }
>   
>   struct fwft_set_req {
> @@ -348,6 +358,9 @@ int sbi_fwft_set_cpumask(const cpumask_t *mask, u32 feature,
>   		.error = ATOMIC_INIT(0),
>   	};
>   
> +	if (!sbi_fwft_supported)
> +		return -EOPNOTSUPP;
> +
>   	if (feature & SBI_FWFT_GLOBAL_FEATURE_BIT)
>   		return -EINVAL;
>   
> @@ -679,6 +692,11 @@ void __init sbi_init(void)
>   			pr_info("SBI DBCN extension detected\n");
>   			sbi_debug_console_available = true;
>   		}
> +		if (sbi_spec_version >= sbi_mk_version(3, 0) &&
> +		    sbi_probe_extension(SBI_EXT_FWFT)) {
> +			pr_info("SBI FWFT extension detected\n");
> +			sbi_fwft_supported = true;
> +		}
>   	} else {
>   		__sbi_set_timer = __sbi_set_timer_v01;
>   		__sbi_send_ipi	= __sbi_send_ipi_v01;

Otherwise, LGTM.

Reviewed-by: Atish Patra <atishp@...osinc.com>