Re: [PATCH v8 07/13] platform/x86: hfi: add online and offline callback support

["Ilpo Järvinen" <ilpo.jarvinen@linux.intel.com>]

On Tue, 18 Feb 2025, Mario Limonciello wrote:

> From: Perry Yuan <Perry.Yuan@amd.com>
> 
> There are some firmware parameters that need to be configured
> when a CPU core is brought online or offline.
> 
> when CPU is online, it will initialize the workload classification
> parameters to CPU firmware which will trigger the workload class ID
> updating function.
> 
> Once the CPU is going to offline, it will need to disable the workload
> classification function and clear the history.
> 
> Reviewed-by: Gautham R. Shenoy <gautham.shenoy@amd.com>
> Signed-off-by: Perry Yuan <Perry.Yuan@amd.com>
> Co-developed-by: Mario Limonciello <mario.limonciello@amd.com>
> Signed-off-by: Mario Limonciello <mario.limonciello@amd.com>
> ---
> v8:
>  * Move cpus member to this patch
>  * Add comment about online
> v7:
>  * move mutex to this patch
> ---
>  drivers/platform/x86/amd/hfi/hfi.c | 87 ++++++++++++++++++++++++++++++
>  1 file changed, 87 insertions(+)
> 
> diff --git a/drivers/platform/x86/amd/hfi/hfi.c b/drivers/platform/x86/amd/hfi/hfi.c
> index e1550f4463275..90b57175ccd97 100644
> --- a/drivers/platform/x86/amd/hfi/hfi.c
> +++ b/drivers/platform/x86/amd/hfi/hfi.c
> @@ -93,6 +93,7 @@ struct amd_hfi_classes {
>   * struct amd_hfi_cpuinfo - HFI workload class info per CPU
>   * @cpu:		cpu index
>   * @apic_id:		apic id of the current cpu
> + * @cpus:		mask of cpus associated with amd_hfi_cpuinfo
>   * @class_index:	workload class ID index
>   * @nr_class:		max number of workload class supported
>   * @ipcc_scores:	ipcc scores for each class
> @@ -103,6 +104,7 @@ struct amd_hfi_classes {
>  struct amd_hfi_cpuinfo {
>  	int		cpu;
>  	u32		apic_id;
> +	cpumask_var_t	cpus;
>  	s16		class_index;
>  	u8		nr_class;
>  	int		*ipcc_scores;
> @@ -111,6 +113,8 @@ struct amd_hfi_cpuinfo {
>  
>  static DEFINE_PER_CPU(struct amd_hfi_cpuinfo, amd_hfi_cpuinfo) = {.class_index = -1};
>  
> +static DEFINE_MUTEX(hfi_cpuinfo_lock);

Please mention what this protects.

> +
>  static int find_cpu_index_by_apicid(unsigned int target_apicid)
>  {
>  	int cpu_index;
> @@ -234,6 +238,80 @@ static int amd_set_hfi_ipcc_score(struct amd_hfi_cpuinfo *hfi_cpuinfo, int cpu)
>  	return 0;
>  }
>  
> +static int amd_hfi_set_state(unsigned int cpu, bool state)
> +{
> +	int ret;
> +
> +	ret = wrmsrl_on_cpu(cpu, AMD_WORKLOAD_CLASS_CONFIG, state);

I'd prefer bool -> u64 conversion be done explicitly, eg. ,with ?: 
operator.

> +	if (ret)
> +		return ret;
> +
> +	return wrmsrl_on_cpu(cpu, AMD_WORKLOAD_HRST, 0x1);
> +}
> +
> +/**
> + * amd_hfi_online() - Enable workload classification on @cpu
> + * @cpu: CPU in which the workload classification will be enabled
> + *
> + * Return: 0 on success, negative error code on failure
> + */
> +static int amd_hfi_online(unsigned int cpu)
> +{
> +	struct amd_hfi_cpuinfo *hfi_info = per_cpu_ptr(&amd_hfi_cpuinfo, cpu);
> +	struct amd_hfi_classes *hfi_classes;
> +	int ret;
> +
> +	if (WARN_ON_ONCE(!hfi_info))
> +		return -EINVAL;
> +
> +	/*
> +	 * Check if @cpu as an associated, initialized and ranking data must be filled

Please fold to 80 characters.

> +	 */
> +	hfi_classes = hfi_info->amd_hfi_classes;
> +	if (!hfi_classes)
> +		return -EINVAL;
> +
> +	guard(mutex)(&hfi_cpuinfo_lock);
> +
> +	if (!zalloc_cpumask_var(&hfi_info->cpus, GFP_KERNEL))
> +		return -ENOMEM;
> +
> +	cpumask_set_cpu(cpu, hfi_info->cpus);
> +
> +	ret = amd_hfi_set_state(cpu, true);
> +	if (ret)
> +		pr_err("WCT enable failed for CPU %d\n", cpu);

%u

> +
> +	return ret;
> +}
> +
> +/**
> + * amd_hfi_offline() - Disable workload classification on @cpu
> + * @cpu: CPU in which the workload classification will be disabled
> + *
> + * Remove @cpu from those covered by its HFI instance.
> + *
> + * Return: 0 on success, negative error code on failure
> + */
> +static int amd_hfi_offline(unsigned int cpu)
> +{
> +	struct amd_hfi_cpuinfo *hfi_info = &per_cpu(amd_hfi_cpuinfo, cpu);
> +	int ret;
> +
> +	if (WARN_ON_ONCE(!hfi_info))
> +		return -EINVAL;
> +
> +	guard(mutex)(&hfi_cpuinfo_lock);
> +
> +	ret = amd_hfi_set_state(cpu, false);
> +	if (ret)
> +		pr_err("WCT disable failed for CPU %d\n", cpu);

%u

> +
> +	free_cpumask_var(hfi_info->cpus);
> +
> +	return ret;
> +}
> +
>  static int update_hfi_ipcc_scores(void)
>  {
>  	int cpu;
> @@ -339,6 +417,15 @@ static int amd_hfi_probe(struct platform_device *pdev)
>  	if (ret)
>  		return ret;
>  
> +	/*
> +	 * Tasks will already be running at the time this happens. This is
> +	 * OK because rankings will be adjusted by the callbacks.
> +	 */
> +	ret = cpuhp_setup_state(CPUHP_AP_ONLINE_DYN, "x86/amd_hfi:online",
> +				amd_hfi_online, amd_hfi_offline);
> +	if (ret < 0)
> +		return ret;
> +
>  	return 0;
>  }
>  
> 

-- 
 i.