Re: [PATCH v3 1/7] cpufreq: amd-pstate: initialize new core precision boost state

Oleksandr Natalenko
2024-02-07T14:45:34Z

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On středa 7. února 2024 10:21:52 CET Perry Yuan wrote:
> From: Perry Yuan <Perry.Yuan@amd.com>
>
> Add gloal global_params to represent current 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.
>
> If core performance boost is disabled while a core is in a boosted P-state,
> the core transitions to the highest performance non-boosted P-state,
> that is the same as the nominal frequency limit.
>
> Reported-by: Artem S. Tashkinov" <aros@gmx.com>
> Closes: https://bugzilla.kernel.org/show_bug.cgi?id=217931
> Signed-off-by: Perry Yuan <Perry.Yuan@amd.com>
> ---
> drivers/cpufreq/amd-pstate.c | 49 ++++++++++++------------------------
> include/linux/amd-pstate.h | 14 +++++++++++
> 2 files changed, 30 insertions(+), 33 deletions(-)
>
> diff --git a/drivers/cpufreq/amd-pstate.c b/drivers/cpufreq/amd-pstate.c
> index 08e112444c27..3772f71f525f 100644
> --- a/drivers/cpufreq/amd-pstate.c
> +++ b/drivers/cpufreq/amd-pstate.c
> @@ -67,6 +67,7 @@ static struct cpufreq_driver amd_pstate_epp_driver;
> static int cppc_state = AMD_PSTATE_UNDEFINED;
> static bool cppc_enabled;
> static bool amd_pstate_prefcore = true;
> +struct global_params global;

Doesn't this require `EXPORT_SYMBOL_GPL(global)` then? Otherwise with v6.8 I get this:

```
ERROR: modpost: "global" [drivers/cpufreq/amd-pstate-ut.ko] undefined!
```

If so, I'd pretty mush rename this to be less generic, say, `amd_pstate_global_params_struct` for the struct name itself and `amd_pstate_global_params` for the actual variable name.

>
> /*
> * AMD Energy Preference Performance (EPP)
> @@ -669,43 +670,21 @@ static int amd_get_lowest_nonlinear_freq(struct amd_cpudata *cpudata)
> return lowest_nonlinear_freq * 1000;
> }
>
> -static int amd_pstate_set_boost(struct cpufreq_policy *policy, int state)
> +static int amd_pstate_boost_init(struct amd_cpudata *cpudata)
> {
> - struct amd_cpudata *cpudata = policy->driver_data;
> + u64 boost_val;
> int ret;
>
> - if (!cpudata->boost_supported) {
> - pr_err("Boost mode is not supported by this processor or SBIOS\n");
> - return -EINVAL;
> - }
> -
> - if (state)
> - policy->cpuinfo.max_freq = cpudata->max_freq;
> - else
> - policy->cpuinfo.max_freq = cpudata->nominal_freq;
> -
> - policy->max = policy->cpuinfo.max_freq;
> -
> - ret = freq_qos_update_request(&cpudata->req[1],
> - policy->cpuinfo.max_freq);
> - if (ret < 0)
> + 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;
> + }
>
> - return 0;
> -}
> -
> -static void amd_pstate_boost_init(struct amd_cpudata *cpudata)
> -{
> - u32 highest_perf, nominal_perf;
> -
> - highest_perf = READ_ONCE(cpudata->highest_perf);
> - nominal_perf = READ_ONCE(cpudata->nominal_perf);
> -
> - if (highest_perf <= nominal_perf)
> - return;
> + global.cpb_supported = !((boost_val >> 25) & 0x1);
> + global.cpb_boost = global.cpb_supported;
>
> - cpudata->boost_supported = true;
> - current_pstate_driver->boost_enabled = true;
> + return ret;
> }
>
> static void amd_perf_ctl_reset(unsigned int cpu)
> @@ -848,6 +827,9 @@ static int amd_pstate_cpu_init(struct cpufreq_policy *policy)
> if (ret)
> goto free_cpudata1;
>
> + /* initialize cpu cores boot state */
> + amd_pstate_boost_init(cpudata);
> +
> min_freq = amd_get_min_freq(cpudata);
> max_freq = amd_get_max_freq(cpudata);
> nominal_freq = amd_get_nominal_freq(cpudata);
> @@ -899,7 +881,6 @@ 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;
>
> @@ -1310,6 +1291,9 @@ static int amd_pstate_epp_cpu_init(struct cpufreq_policy *policy)
> if (ret)
> goto free_cpudata1;
>
> + /* initialize cpu cores boot state */
> + amd_pstate_boost_init(cpudata);
> +
> min_freq = amd_get_min_freq(cpudata);
> max_freq = amd_get_max_freq(cpudata);
> nominal_freq = amd_get_nominal_freq(cpudata);
> @@ -1360,7 +1344,6 @@ 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 d21838835abd..465e9295a60c 100644
> --- a/include/linux/amd-pstate.h
> +++ b/include/linux/amd-pstate.h
> @@ -124,4 +124,18 @@ static const char * const amd_pstate_mode_string[] = {
> [AMD_PSTATE_GUIDED] = "guided",
> NULL,
> };
> +
> +/**
> + * struct 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 global_params {
> + bool cpb_boost;
> + bool cpb_supported;
> +};
> +
> +extern struct global_params global;
> +
> #endif /* _LINUX_AMD_PSTATE_H */
>

--
Oleksandr Natalenko (post-factum)

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