linux-kernel - Re: [PATCH 6/9] riscv: Fix set up of vector cpu hotplug callback

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Message-ID: <0a895286-2084-42d5-9d19-5a27d9cb6ef9@ghiti.fr>
Date: Thu, 13 Feb 2025 14:28:13 +0100
From: Alexandre Ghiti <alex@...ti.fr>
To: Andrew Jones <ajones@...tanamicro.com>, linux-riscv@...ts.infradead.org,
 linux-kernel@...r.kernel.org
Cc: paul.walmsley@...ive.com, palmer@...belt.com, charlie@...osinc.com,
 jesse@...osinc.com, Anup Patel <apatel@...tanamicro.com>
Subject: Re: [PATCH 6/9] riscv: Fix set up of vector cpu hotplug callback


On 07/02/2025 17:19, Andrew Jones wrote:
> Whether or not we have RISCV_PROBE_VECTOR_UNALIGNED_ACCESS we need to
> set up a cpu hotplug callback to check if we have vector at all,
> since, when we don't have vector, we need to set
> vector_misaligned_access to unsupported rather than leave it the
> default of unknown.
>
> Fixes: e7c9d66e313b ("RISC-V: Report vector unaligned access speed hwprobe")
> Signed-off-by: Andrew Jones <ajones@...tanamicro.com>
> ---
>   arch/riscv/kernel/unaligned_access_speed.c | 31 +++++++++++-----------
>   1 file changed, 16 insertions(+), 15 deletions(-)
>
> diff --git a/arch/riscv/kernel/unaligned_access_speed.c b/arch/riscv/kernel/unaligned_access_speed.c
> index c9d3237649bb..d9d4ca1fadc7 100644
> --- a/arch/riscv/kernel/unaligned_access_speed.c
> +++ b/arch/riscv/kernel/unaligned_access_speed.c
> @@ -356,6 +356,20 @@ static void check_vector_unaligned_access(struct work_struct *work __always_unus
>   	per_cpu(vector_misaligned_access, cpu) = speed;
>   }
>   
> +/* Measure unaligned access speed on all CPUs present at boot in parallel. */
> +static int __init vec_check_unaligned_access_speed_all_cpus(void *unused __always_unused)
> +{
> +	schedule_on_each_cpu(check_vector_unaligned_access);
> +
> +	return 0;
> +}
> +#else /* CONFIG_RISCV_PROBE_VECTOR_UNALIGNED_ACCESS */
> +static int __init vec_check_unaligned_access_speed_all_cpus(void *unused __always_unused)
> +{
> +	return 0;
> +}
> +#endif
> +
>   static int riscv_online_cpu_vec(unsigned int cpu)
>   {
>   	if (!has_vector()) {
> @@ -363,27 +377,16 @@ static int riscv_online_cpu_vec(unsigned int cpu)
>   		return 0;
>   	}
>   
> +#ifdef CONFIG_RISCV_PROBE_VECTOR_UNALIGNED_ACCESS
>   	if (per_cpu(vector_misaligned_access, cpu) != RISCV_HWPROBE_MISALIGNED_VECTOR_UNKNOWN)
>   		return 0;
>   
>   	check_vector_unaligned_access_emulated(NULL);
>   	check_vector_unaligned_access(NULL);
> -	return 0;
> -}
> -
> -/* Measure unaligned access speed on all CPUs present at boot in parallel. */
> -static int __init vec_check_unaligned_access_speed_all_cpus(void *unused __always_unused)
> -{
> -	schedule_on_each_cpu(check_vector_unaligned_access);
> +#endif
>   
>   	return 0;
>   }
> -#else /* CONFIG_RISCV_PROBE_VECTOR_UNALIGNED_ACCESS */
> -static int __init vec_check_unaligned_access_speed_all_cpus(void *unused __always_unused)
> -{
> -	return 0;
> -}
> -#endif
>   
>   static int __init check_unaligned_access_all_cpus(void)
>   {
> @@ -409,10 +412,8 @@ static int __init check_unaligned_access_all_cpus(void)
>   	cpuhp_setup_state_nocalls(CPUHP_AP_ONLINE_DYN, "riscv:online",
>   				  riscv_online_cpu, riscv_offline_cpu);
>   #endif
> -#ifdef CONFIG_RISCV_PROBE_VECTOR_UNALIGNED_ACCESS
>   	cpuhp_setup_state_nocalls(CPUHP_AP_ONLINE_DYN, "riscv:online",
>   				  riscv_online_cpu_vec, NULL);
> -#endif
>   
>   	return 0;
>   }

Reviewed-by: Alexandre Ghiti <alexghiti@...osinc.com>

Thanks,

Alex