RE: [PATCH v11 4/9] cpufreq: amd-pstate: initialize new core precision boost state

From: Yuan, Perry
Date: Thu Jun 13 2024 - 23:32:43 EST

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[AMD Official Use Only - AMD Internal Distribution Only]

> -----Original Message-----
> From: Limonciello, Mario <Mario.Limonciello@xxxxxxx>
> Sent: Friday, June 14, 2024 1:55 AM
> To: Yuan, Perry <Perry.Yuan@xxxxxxx>; Shenoy, Gautham Ranjal
> <gautham.shenoy@xxxxxxx>; Petkov, Borislav <Borislav.Petkov@xxxxxxx>
> Cc: rafael.j.wysocki@xxxxxxxxx; viresh.kumar@xxxxxxxxxx; Deucher, Alexander
> <Alexander.Deucher@xxxxxxx>; Huang, Shimmer
> <Shimmer.Huang@xxxxxxx>; Du, Xiaojian <Xiaojian.Du@xxxxxxx>; Meng,
> Li (Jassmine) <Li.Meng@xxxxxxx>; linux-pm@xxxxxxxxxxxxxxx; linux-
> kernel@xxxxxxxxxxxxxxx
> Subject: Re: [PATCH v11 4/9] cpufreq: amd-pstate: initialize new core
> precision boost state
>
> On 6/13/2024 02:25, Perry Yuan wrote:
> > From: Perry Yuan <Perry.Yuan@xxxxxxx>
> >
> > 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@xxxxxxx>
> > Cc: Oleksandr Natalenko <oleksandr@xxxxxxxxxxxxxx>
> > Closes: https://bugzilla.kernel.org/show_bug.cgi?id=217931
> > Signed-off-by: Perry Yuan <Perry.Yuan@xxxxxxx>
> > ---
> > drivers/cpufreq/amd-pstate.c | 59 +++++++++++++++++++++++++++++-----
> --
> > drivers/cpufreq/amd-pstate.h | 13 ++++++++
> > 2 files changed, 61 insertions(+), 11 deletions(-)
> >
> > diff --git a/drivers/cpufreq/amd-pstate.c
> > b/drivers/cpufreq/amd-pstate.c index fda8f86c90e0..9f42524074a9 100644
> > --- a/drivers/cpufreq/amd-pstate.c
> > +++ b/drivers/cpufreq/amd-pstate.c
> > @@ -102,6 +102,8 @@ 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) @@ -696,7 +698,7 @@
> > static int amd_pstate_set_boost(struct cpufreq_policy *policy, int
> > state)
> >
> > if (!cpudata->boost_supported) {
> > pr_err("Boost mode is not supported by this processor or
> SBIOS\n");
> > - return -EINVAL;
> > + return -ENOTSUPP;
> > }
> >
> > if (state)
> > @@ -714,18 +716,38 @@ 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_set(struct amd_cpudata *cpudata)
> > {
> > - u32 highest_perf, nominal_perf;
> > + u64 boost_val;
> > + int ret = -1;
> >
> > - highest_perf = READ_ONCE(cpudata->highest_perf);
> > - nominal_perf = READ_ONCE(cpudata->nominal_perf);
> > + if (!cpu_feature_enabled(X86_FEATURE_CPB)) {
> > + pr_debug_once("Boost CPB capabilities not present in the
> processor\n");
> > + ret = -EOPNOTSUPP;
> > + goto exit_err;
> > + }
> >
> > - if (highest_perf <= nominal_perf)
> > - return;
> > + ret = rdmsrl_on_cpu(cpudata->cpu, MSR_K7_HWCR, &boost_val);
> > + if (ret) {
> > + pr_err_once("failed to read initial CPU boost state!\n");
> > + ret = -EIO;
> > + goto exit_err;
> > + }
> > +
> > + amd_pstate_global_params.cpb_supported = !(boost_val &
> MSR_K7_HWCR_CPB_DIS);
> > + if (amd_pstate_global_params.cpb_supported) {
> > + current_pstate_driver->boost_enabled = true;
> > + WRITE_ONCE(cpudata->boost_supported, true);
> > + }
> >
> > - cpudata->boost_supported = true;
> > - current_pstate_driver->boost_enabled = true;
> > + amd_pstate_global_params.cpb_boost =
> amd_pstate_global_params.cpb_supported;
> > + return 0;
> > +
> > +exit_err:
> > + WRITE_ONCE(cpudata->boost_supported, false);
> > + current_pstate_driver->boost_enabled = false;
> > + amd_pstate_global_params.cpb_boost = false;
> > + return ret;
> > }
> >
> > static void amd_perf_ctl_reset(unsigned int cpu) @@ -1007,7 +1029,6
> > @@ 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;
> >
> > @@ -1389,6 +1410,21 @@ static bool
> amd_pstate_acpi_pm_profile_undefined(void)
> > return false;
> > }
> >
> > +static int amd_pstate_init_boost(struct cpufreq_policy *policy) {
> > + struct amd_cpudata *cpudata = policy->driver_data;
> > + int ret;
> > +
> > + /* initialize cpu cores boot state */
> > + ret = amd_pstate_boost_set(cpudata);
> > + if (ret)
> > + return ret;
> > +
> > + policy->boost_enabled = READ_ONCE(cpudata->boost_supported);
>
> Because of the change I suggested in patch 3/9, I believe you should move
> the check for
>
> if (!cpudata->boost_supported)
>
> from amd_pstate_boost_set() to the beginning of amd_pstate_init_boost().
> Something like this:

cpudata->boost_supported will be initialized in amd_pstate_init_boost(), if system is identified to support boost control, then each CPU will mark boost_supported to be true.

In the next, the set_boost callback will check boost mode is not supported or not before it do real boost switching operation.

amd_pstate_init_boost() was added to initialize everything that control needs, the below function will set “cpudata->boost_supported” value when it returns.

static int amd_pstate_init_boost(struct cpufreq_policy *policy)
{
struct amd_cpudata *cpudata = policy->driver_data;
int ret;

/* initialize cpu cores boot state */
ret = amd_pstate_boost_set(cpudata);<<<<------- “cpudata->boost_supported” will be set to true or false.
if (ret)
return ret;

policy->boost_enabled = READ_ONCE(cpudata->boost_state);

return 0;
}

>
> static int amd_pstate_init_boost(struct cpufreq_policy *policy) {
> struct amd_cpudata *cpudata = policy->driver_data;
> int ret;
>
> if (!cpudata->boost_supported) {
> policy->boost_enabled = false;
> return 0;
> }
> ret = amd_pstate_boost_set(cpudata);
> if (ret)
> return ret;
>
> policy->boost_enabled = true;
>
> return ret;
> }
>
> > +
> > + return 0;
> > +}
> > +
> > static int amd_pstate_epp_cpu_init(struct cpufreq_policy *policy)
> > {
> > int min_freq, max_freq, nominal_freq, ret; @@ -1467,7 +1503,6 @@
> > 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;
> >
> > @@ -1706,6 +1741,7 @@ static struct cpufreq_driver amd_pstate_driver =
> {
> > .exit = amd_pstate_cpu_exit,
> > .suspend = amd_pstate_cpu_suspend,
> > .resume = amd_pstate_cpu_resume,
> > + .init_boost = amd_pstate_init_boost,
> > .set_boost = amd_pstate_set_boost,
> > .update_limits = amd_pstate_update_limits,
> > .name = "amd-pstate",
> > @@ -1723,6 +1759,7 @@ static struct cpufreq_driver
> amd_pstate_epp_driver = {
> > .suspend = amd_pstate_epp_suspend,
> > .resume = amd_pstate_epp_resume,
> > .update_limits = amd_pstate_update_limits,
> > + .init_boost = amd_pstate_init_boost,
> > .name = "amd-pstate-epp",
> > .attr = amd_pstate_epp_attr,
> > };
> > diff --git a/drivers/cpufreq/amd-pstate.h
> > b/drivers/cpufreq/amd-pstate.h index e6a28e7f4dbf..0b75a6267fca 100644
> > --- a/drivers/cpufreq/amd-pstate.h
> > +++ b/drivers/cpufreq/amd-pstate.h
> > @@ -101,4 +101,17 @@ struct amd_cpudata {
> > bool suspended;
> > };
> >
> > +/**
> > + * 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 */

Next message: Qi Zheng: "Re: [RFC PATCH 0/3] asynchronously scan and free empty user PTE pages"
Previous message: Duan, Zhenzhong: "RE: [PATCH v4 3/3] PCI/AER: Clear UNCOR_STATUS bits that might be ANFE"
In reply to: Mario Limonciello: "Re: [PATCH v11 4/9] cpufreq: amd-pstate: initialize new core precision boost state"
Next in thread: Perry Yuan: "[PATCH v11 5/9] cpufreq: amd-pstate: implement cpb_boost sysfs entry for boost control"
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