Re: [PATCH v7 2/6] cpufreq: amd-pstate: initialize new core precision boost state

[Huang Rui <ray.huang@amd.com>]

On Tue, Apr 23, 2024 at 04:40:55PM +0800, Yuan, Perry wrote:
> From: Perry Yuan <Perry.Yuan@amd.com>
> 
> Add one global `global_params` to represent CPU Performance Boost(cpb)
> state for cpu frequency scaling, both active and passive modes all can
> support CPU cores frequency boosting control which is based on the BIOS
> setting, while BIOS turn on the "Core Performance Boost", it will
> allow OS control each core highest perf limitation from OS side.
> 
> The active, guided and passive modes of the amd-pstate driver can
> support frequency boost control when the "Core Performance Boost"
> (CPB) feature is enabled in the BIOS.  When enabled in BIOS, the user
> has an option at runtime to allow/disallow the cores from operating in
> the boost frequency range.
> 
> Add an amd_pstate_global_params object to record whether CPB is
> enabled in BIOS, and if it has been activated by the user
> 
> Reported-by: Artem S. Tashkinov" <aros@gmx.com>
> Cc: Oleksandr Natalenko <oleksandr@natalenko.name>
> Closes: https://bugzilla.kernel.org/show_bug.cgi?id=217931
> Signed-off-by: Perry Yuan <Perry.Yuan@amd.com>
> ---
>  drivers/cpufreq/amd-pstate.c | 39 +++++++++++++++++++++++++++---------
>  include/linux/amd-pstate.h   | 13 ++++++++++++
>  2 files changed, 42 insertions(+), 10 deletions(-)
> 
> diff --git a/drivers/cpufreq/amd-pstate.c b/drivers/cpufreq/amd-pstate.c
> index 83a29b257794..3d86cd7c9073 100644
> --- a/drivers/cpufreq/amd-pstate.c
> +++ b/drivers/cpufreq/amd-pstate.c
> @@ -68,6 +68,8 @@ static int cppc_state = AMD_PSTATE_UNDEFINED;
>  static bool cppc_enabled;
>  static bool amd_pstate_prefcore = true;
>  static struct quirk_entry *quirks;
> +struct amd_pstate_global_params amd_pstate_global_params;
> +EXPORT_SYMBOL_GPL(amd_pstate_global_params);
>  
>  /*
>   * AMD Energy Preference Performance (EPP)
> @@ -665,18 +667,27 @@ static int amd_pstate_set_boost(struct cpufreq_policy *policy, int state)
>  	return 0;
>  }
>  
> -static void amd_pstate_boost_init(struct amd_cpudata *cpudata)
> +static int amd_pstate_boost_init(struct amd_cpudata *cpudata)
>  {
> -	u32 highest_perf, nominal_perf;
> +	u64 boost_val;
> +	int ret;
>  
> -	highest_perf = READ_ONCE(cpudata->highest_perf);
> -	nominal_perf = READ_ONCE(cpudata->nominal_perf);
> +	ret = rdmsrl_on_cpu(cpudata->cpu, MSR_K7_HWCR, &boost_val);
> +	if (ret) {
> +		pr_err_once("failed to read initial CPU boost state!\n");
> +		return ret;
> +	}
>  
> -	if (highest_perf <= nominal_perf)
> -		return;
> +	amd_pstate_global_params.cpb_supported = !(boost_val & MSR_K7_HWCR_CPB_DIS);

We have a X86_FEATURE_CPB bit to indicate whether current processor to
support boost. It would better to add a check here if amd-pstate need
forward support.

Thanks,
Ray

> +
> +	if (amd_pstate_global_params.cpb_supported) {
> +		cpudata->boost_supported = true;
> +		current_pstate_driver->boost_enabled = true;
> +	}
>  
> -	cpudata->boost_supported = true;
> -	current_pstate_driver->boost_enabled = true;
> +	amd_pstate_global_params.cpb_boost = amd_pstate_global_params.cpb_supported;
> +
> +	return ret;
>  }
>  
>  static void amd_perf_ctl_reset(unsigned int cpu)
> @@ -900,6 +911,11 @@ static int amd_pstate_cpu_init(struct cpufreq_policy *policy)
>  
>  	amd_pstate_init_prefcore(cpudata);
>  
> +	/* initialize cpu cores boot state */
> +	ret = amd_pstate_boost_init(cpudata);
> +	if (ret)
> +		goto free_cpudata1;
> +
>  	ret = amd_pstate_init_perf(cpudata);
>  	if (ret)
>  		goto free_cpudata1;
> @@ -956,7 +972,6 @@ static int amd_pstate_cpu_init(struct cpufreq_policy *policy)
>  
>  	policy->driver_data = cpudata;
>  
> -	amd_pstate_boost_init(cpudata);
>  	if (!current_pstate_driver->adjust_perf)
>  		current_pstate_driver->adjust_perf = amd_pstate_adjust_perf;
>  
> @@ -1363,6 +1378,11 @@ static int amd_pstate_epp_cpu_init(struct cpufreq_policy *policy)
>  
>  	amd_pstate_init_prefcore(cpudata);
>  
> +	/* initialize cpu cores boot state */
> +	ret = amd_pstate_boost_init(cpudata);
> +	if (ret)
> +		goto free_cpudata1;
> +
>  	ret = amd_pstate_init_perf(cpudata);
>  	if (ret)
>  		goto free_cpudata1;
> @@ -1417,7 +1437,6 @@ static int amd_pstate_epp_cpu_init(struct cpufreq_policy *policy)
>  			return ret;
>  		WRITE_ONCE(cpudata->cppc_cap1_cached, value);
>  	}
> -	amd_pstate_boost_init(cpudata);
>  
>  	return 0;
>  
> diff --git a/include/linux/amd-pstate.h b/include/linux/amd-pstate.h
> index 6b832153a126..c5e41de65f70 100644
> --- a/include/linux/amd-pstate.h
> +++ b/include/linux/amd-pstate.h
> @@ -134,4 +134,17 @@ struct quirk_entry {
>  	u32 lowest_freq;
>  };
>  
> +/**
> + * struct amd_pstate_global_params - Global parameters, mostly tunable via sysfs.
> + * @cpb_boost:		Whether or not to use boost CPU P-states.
> + * @cpb_supported:	Whether or not CPU boost P-states are available
> + *			based on the MSR_K7_HWCR bit[25] state
> + */
> +struct amd_pstate_global_params {
> +	bool cpb_boost;
> +	bool cpb_supported;
> +};
> +
> +extern struct amd_pstate_global_params amd_pstate_global_params;
> +
>  #endif /* _LINUX_AMD_PSTATE_H */
> -- 
> 2.34.1
>