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Date: Tue, 23 Apr 2024 18:51:52 +0800
From: Huang Rui <ray.huang@....com>
To: "Yuan, Perry" <Perry.Yuan@....com>
Cc: "rafael.j.wysocki@...el.com" <rafael.j.wysocki@...el.com>,
"Limonciello, Mario" <Mario.Limonciello@....com>,
"viresh.kumar@...aro.org" <viresh.kumar@...aro.org>,
"Shenoy, Gautham Ranjal" <gautham.shenoy@....com>,
"Petkov, Borislav" <Borislav.Petkov@....com>,
"Deucher, Alexander" <Alexander.Deucher@....com>,
"Huang, Shimmer" <Shimmer.Huang@....com>,
"oleksandr@...alenko.name" <oleksandr@...alenko.name>,
"Du, Xiaojian" <Xiaojian.Du@....com>,
"Meng, Li (Jassmine)" <Li.Meng@....com>,
"linux-pm@...r.kernel.org" <linux-pm@...r.kernel.org>,
"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH v7 2/6] cpufreq: amd-pstate: initialize new core
precision boost state
On Tue, Apr 23, 2024 at 04:40:55PM +0800, Yuan, Perry wrote:
> From: Perry Yuan <Perry.Yuan@....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@....com>
> Cc: Oleksandr Natalenko <oleksandr@...alenko.name>
> Closes: https://bugzilla.kernel.org/show_bug.cgi?id=217931
> Signed-off-by: Perry Yuan <Perry.Yuan@....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
>
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