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

Yuan, Perry
2024-02-08T04:19:09Z

[AMD Official Use Only - General]

> -----Original Message-----
> From: Oleksandr Natalenko <oleksandr@natalenko.name>
> Sent: Wednesday, February 7, 2024 10:45 PM
> To: rafael.j.wysocki@intel.com; Limonciello, Mario
> <Mario.Limonciello@amd.com>; viresh.kumar@linaro.org; Huang, Ray
> <Ray.Huang@amd.com>; Shenoy, Gautham Ranjal
> <gautham.shenoy@amd.com>; Petkov, Borislav
> <Borislav.Petkov@amd.com>; Yuan, Perry <Perry.Yuan@amd.com>
> Cc: Deucher, Alexander <Alexander.Deucher@amd.com>; Huang, Shimmer
> <Shimmer.Huang@amd.com>; Du, Xiaojian <Xiaojian.Du@amd.com>; Meng,
> Li (Jassmine) <Li.Meng@amd.com>; linux-pm@vger.kernel.org; linux-
> kernel@vger.kernel.org
> Subject: Re: [PATCH v3 1/7] cpufreq: amd-pstate: initialize new core precision
> boost state
>
> 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:
>

Will check this with v6.8 as well.

> ```
> 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.

Let me optimize and rename the struct definition and var name.

Thanks for the feedback.
Perry.

>
> >
> > /*
> > * 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)