linux-kernel - Re: [PATCH v2 08/13] platform/x86: hfi: add online and offline callback support

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Message-ID: <55ddb80c-abfa-f3e2-442a-65f270dadbf2@linux.intel.com>
Date: Mon, 14 Oct 2024 13:27:51 +0300 (EEST)
From: Ilpo Järvinen <ilpo.jarvinen@...ux.intel.com>
To: Mario Limonciello <mario.limonciello@....com>
cc: Borislav Petkov <bp@...en8.de>, Hans de Goede <hdegoede@...hat.com>, 
    x86@...nel.org, "Gautham R . Shenoy" <gautham.shenoy@....com>, 
    Perry Yuan <perry.yuan@....com>, LKML <linux-kernel@...r.kernel.org>, 
    linux-doc@...r.kernel.org, linux-pm@...r.kernel.org, 
    platform-driver-x86@...r.kernel.org, 
    Shyam Sundar S K <Shyam-sundar.S-k@....com>, 
    Perry Yuan <Perry.Yuan@....com>
Subject: Re: [PATCH v2 08/13] platform/x86: hfi: add online and offline
 callback support

On Thu, 10 Oct 2024, Mario Limonciello wrote:

> From: Perry Yuan <Perry.Yuan@....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.
> 
> Signed-off-by: Perry Yuan <Perry.Yuan@....com>
> Co-developed-by: Mario Limonciello <mario.limonciello@....com>
> Signed-off-by: Mario Limonciello <mario.limonciello@....com>
> ---
> v2:
>  * Rebase
> ---
>  drivers/platform/x86/amd/hfi/hfi.c | 90 +++++++++++++++++++++++++++++-
>  1 file changed, 89 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/platform/x86/amd/hfi/hfi.c b/drivers/platform/x86/amd/hfi/hfi.c
> index c0065ba0ed18..c969ee7ea5ee 100644
> --- a/drivers/platform/x86/amd/hfi/hfi.c
> +++ b/drivers/platform/x86/amd/hfi/hfi.c
> @@ -244,6 +244,89 @@ 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);
> +	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;
> +
> +	if (!zalloc_cpumask_var(&hfi_info->cpus, GFP_KERNEL))
> +		return -ENOMEM;
> +
> +	mutex_lock(&hfi_cpuinfo_lock);

Use guard()

> +	cpumask_set_cpu(cpu, hfi_info->cpus);
> +
> +	/*
> +	 * Check if @cpu as an associated, initialized and ranking data must be filled
> +	 */
> +	hfi_classes = hfi_info->amd_hfi_classes;
> +	if (!hfi_classes)
> +		goto unlock;
> +
> +	/* Enable the workload classification interface */
> +	ret = amd_hfi_set_state(cpu, true);
> +	if (ret)
> +		pr_err("wct enable failed for cpu %d\n", cpu);

CPU

Should wct too be capitalized?

Is it okay to return 0 when this error occurs?

> +
> +	mutex_unlock(&hfi_cpuinfo_lock);
> +	return 0;
> +
> +unlock:
> +	free_cpumask_var(hfi_info->cpus);
> +	mutex_unlock(&hfi_cpuinfo_lock);
> +	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;
> +
> +	mutex_lock(&hfi_cpuinfo_lock);

guard or scoped_guard.

> +
> +	/* Disable the workload classification interface */
> +	ret = amd_hfi_set_state(cpu, false);
> +	if (ret)
> +		pr_err("wct disable failed for cpu %d\n", cpu);
> +
> +	mutex_unlock(&hfi_cpuinfo_lock);
> +
> +	free_cpumask_var(hfi_info->cpus);
> +
> +	return 0;
> +}
> +
>  static int update_hfi_ipcc_scores(struct amd_hfi_data *amd_hfi_data)
>  {
>  	int cpu;
> @@ -362,8 +445,13 @@ static int amd_hfi_probe(struct platform_device *pdev)
>  	if (ret)
>  		goto out;
>  
> +	ret = cpuhp_setup_state(CPUHP_AP_ONLINE_DYN, "x86/amd_hfi:online",
> +				amd_hfi_online, amd_hfi_offline);
> +	if (ret < 0)
> +		goto out;

return ret;

> +
>  out:
> -	return ret;
> +	return ret < 0 ? ret : 0;
>  }
>  
>  static struct platform_driver amd_hfi_driver = {
> 

-- 
 i.