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Message-ID:
<CYYPR12MB865534CC49D3AB044FF373AF9CC22@CYYPR12MB8655.namprd12.prod.outlook.com>
Date: Fri, 14 Jun 2024 02:32:34 +0000
From: "Yuan, Perry" <Perry.Yuan@....com>
To: "Limonciello, Mario" <Mario.Limonciello@....com>, "Shenoy, Gautham Ranjal"
<gautham.shenoy@....com>, "Petkov, Borislav" <Borislav.Petkov@....com>
CC: "rafael.j.wysocki@...el.com" <rafael.j.wysocki@...el.com>,
"viresh.kumar@...aro.org" <viresh.kumar@...aro.org>, "Deucher, Alexander"
<Alexander.Deucher@....com>, "Huang, Shimmer" <Shimmer.Huang@....com>, "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 v11 5/9] cpufreq: amd-pstate: implement cpb_boost sysfs
entry for boost control
[AMD Official Use Only - AMD Internal Distribution Only]
> -----Original Message-----
> From: Limonciello, Mario <Mario.Limonciello@....com>
> Sent: Friday, June 14, 2024 1:55 AM
> To: Yuan, Perry <Perry.Yuan@....com>; Shenoy, Gautham Ranjal
> <gautham.shenoy@....com>; Petkov, Borislav <Borislav.Petkov@....com>
> Cc: rafael.j.wysocki@...el.com; viresh.kumar@...aro.org; Deucher, Alexander
> <Alexander.Deucher@....com>; Huang, Shimmer
> <Shimmer.Huang@....com>; Du, Xiaojian <Xiaojian.Du@....com>; Meng,
> Li (Jassmine) <Li.Meng@....com>; linux-pm@...r.kernel.org; linux-
> kernel@...r.kernel.org
> Subject: Re: [PATCH v11 5/9] cpufreq: amd-pstate: implement cpb_boost
> sysfs entry for boost control
>
> On 6/13/2024 02:25, Perry Yuan wrote:
> > From: Perry Yuan <Perry.Yuan@....com>
> >
> > With this new sysfs entry `cpb_boost`created, user can change CPU
> > boost state dynamically under `active`, `guided` and `passive` modes.
> > And the highest perf and frequency will also be updated as the boost
> > state changing.
> >
> > 0): check current boost state
> > cat /sys/devices/system/cpu/amd_pstate/cpb_boost
> >
> > 1): disable CPU boost
> > sudo bash -c "echo 0 > /sys/devices/system/cpu/amd_pstate/cpb_boost"
> >
> > 2): enable CPU boost
> > sudo bash -c "echo 1 > /sys/devices/system/cpu/amd_pstate/cpb_boost"
> >
> > Link: https://bugzilla.kernel.org/show_bug.cgi?id=217931
> > Link: https://bugzilla.kernel.org/show_bug.cgi?id=217618
> > Signed-off-by: Perry Yuan <Perry.Yuan@....com>
> > ---
> > drivers/cpufreq/amd-pstate-ut.c | 2 +-
> > drivers/cpufreq/amd-pstate.c | 117
> +++++++++++++++++++++++++++++++-
> > drivers/cpufreq/amd-pstate.h | 1 +
> > 3 files changed, 118 insertions(+), 2 deletions(-)
> >
> > diff --git a/drivers/cpufreq/amd-pstate-ut.c
> > b/drivers/cpufreq/amd-pstate-ut.c index fc275d41d51e..b528f198f4c3
> > 100644
> > --- a/drivers/cpufreq/amd-pstate-ut.c
> > +++ b/drivers/cpufreq/amd-pstate-ut.c
> > @@ -227,7 +227,7 @@ static void amd_pstate_ut_check_freq(u32 index)
> > goto skip_test;
> > }
> >
> > - if (cpudata->boost_supported) {
> > + if (amd_pstate_global_params.cpb_boost) {
> > if ((policy->max == cpudata->max_freq) ||
> > (policy->max == cpudata-
> >nominal_freq))
> > amd_pstate_ut_cases[index].result =
> AMD_PSTATE_UT_RESULT_PASS;
> > diff --git a/drivers/cpufreq/amd-pstate.c
> > b/drivers/cpufreq/amd-pstate.c index 9f42524074a9..fe7c9d3562c5 100644
> > --- a/drivers/cpufreq/amd-pstate.c
> > +++ b/drivers/cpufreq/amd-pstate.c
> > @@ -104,6 +104,7 @@ 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);
> > +static int amd_pstate_cpu_boost(int cpu, bool state);
> >
> > /*
> > * AMD Energy Preference Performance (EPP) @@ -738,6 +739,7 @@
> > static int amd_pstate_boost_set(struct amd_cpudata *cpudata)
> > if (amd_pstate_global_params.cpb_supported) {
> > current_pstate_driver->boost_enabled = true;
> > WRITE_ONCE(cpudata->boost_supported, true);
> > + WRITE_ONCE(cpudata->boost_state, true);
> > }
> >
> > amd_pstate_global_params.cpb_boost =
> > amd_pstate_global_params.cpb_supported;
> > @@ -745,6 +747,7 @@ static int amd_pstate_boost_set(struct
> amd_cpudata
> > *cpudata)
> >
> > exit_err:
> > WRITE_ONCE(cpudata->boost_supported, false);
> > + WRITE_ONCE(cpudata->boost_state, false);
> > current_pstate_driver->boost_enabled = false;
> > amd_pstate_global_params.cpb_boost = false;
> > return ret;
> > @@ -1348,6 +1351,116 @@ static ssize_t prefcore_show(struct device
> *dev,
> > return sysfs_emit(buf, "%s\n",
> str_enabled_disabled(amd_pstate_prefcore));
> > }
> >
> > +static int amd_pstate_cpu_boost_update(struct cpufreq_policy *policy,
> > +bool on) {
> > + struct amd_cpudata *cpudata = policy->driver_data;
> > + struct cppc_perf_ctrls perf_ctrls;
> > + u32 highest_perf, nominal_perf, nominal_freq, max_freq;
> > + int ret;
> > +
> > + if (!policy) {
> > + pr_err("policy is null\n");
> > + return -ENODATA;
> > + }
>
> This is dead code that can't possibly be hit, because there would be a NULL
> pointer dereference above for this line:
>
> struct amd_cpudata *cpudata = policy->driver_data;
>
> Furthermore, the caller for this function, amd_pstate_cpu_boost() has the
> same check already.
>
> So drop the check here.
Will improve the checking code in v12.
Thanks for the feedback.
>
> > +
> > + highest_perf = READ_ONCE(cpudata->highest_perf);
> > + nominal_perf = READ_ONCE(cpudata->nominal_perf);
> > + nominal_freq = READ_ONCE(cpudata->nominal_freq);
> > + max_freq = READ_ONCE(cpudata->max_freq);
> > +
> > + if (boot_cpu_has(X86_FEATURE_CPPC)) {
> > + u64 value = READ_ONCE(cpudata->cppc_req_cached);
> > +
> > + value &= ~GENMASK_ULL(7, 0);
> > + value |= on ? highest_perf : nominal_perf;
> > + WRITE_ONCE(cpudata->cppc_req_cached, value);
> > +
> > + wrmsrl_on_cpu(cpudata->cpu, MSR_AMD_CPPC_REQ, value);
> > + } else {
> > + perf_ctrls.max_perf = on ? highest_perf : nominal_perf;
> > + ret = cppc_set_epp_perf(cpudata->cpu, &perf_ctrls, 1);
> > + if (ret) {
> > + cpufreq_cpu_release(policy);
> > + pr_debug("failed to set energy perf value (%d)\n",
> ret);
> > + return ret;
> > + }
> > + }
> > +
> > + if (on)
> > + policy->cpuinfo.max_freq = max_freq;
> > + else
> > + policy->cpuinfo.max_freq = nominal_freq * 1000;
> > +
> > + policy->max = policy->cpuinfo.max_freq;
> > +
> > + if (cppc_state == AMD_PSTATE_PASSIVE) {
> > + ret = freq_qos_update_request(&cpudata->req[1], policy-
> >cpuinfo.max_freq);
> > + if (ret < 0)
> > + pr_debug("Failed to update freq constraint:
> CPU%d\n", cpudata->cpu);
> > + }
> > +
> > + return ret < 0 ? ret : 0;
> > +}
> > +
> > +static int amd_pstate_cpu_boost(int cpu, bool state) {
> > + int ret;
> > + struct cpufreq_policy *policy = cpufreq_cpu_get(cpu);
> > + struct amd_cpudata *cpudata = policy->driver_data;
> > +
> > + if (!policy) {
> > + pr_err("policy is NULL\n");
> > + ret = -ENODATA;
> > + goto err_exit;
> > + }
> > +
> > + ret = amd_pstate_cpu_boost_update(policy, state);
> > + refresh_frequency_limits(policy);
> > + WRITE_ONCE(cpudata->boost_state, state);
> > + policy->boost_enabled = state;
> > +
> > +err_exit:
> > + cpufreq_cpu_put(policy);
> > + return ret < 0 ? ret : 0;
> > +}
> > +
> > +static ssize_t cpb_boost_show(struct device *dev,
> > + struct device_attribute *attr, char *buf) {
> > + return sysfs_emit(buf, "%u\n",
> amd_pstate_global_params.cpb_boost);
> > +}
> > +
> > +static ssize_t cpb_boost_store(struct device *dev, struct device_attribute
> *b,
> > + const char *buf, size_t count) {
> > + bool new_state;
> > + ssize_t ret;
> > + int cpu;
> > +
> > + if (!amd_pstate_global_params.cpb_supported) {
> > + pr_err("Boost mode is not supported by this processor or
> SBIOS\n");
> > + return -EINVAL;
> > + }
> > +
> > + ret = kstrtobool(buf, &new_state);
> > + if (ret)
> > + return ret;
> > +
> > + mutex_lock(&amd_pstate_driver_lock);
> > + for_each_present_cpu(cpu) {
> > + ret = amd_pstate_cpu_boost(cpu, new_state);
> > + if (ret < 0) {
> > + pr_warn("failed to update cpu boost for CPU%d
> (%zd)\n", cpu, ret);
> > + goto err_exit;
> > + }
> > + }
> > + amd_pstate_global_params.cpb_boost = !!new_state;
> > +
> > +err_exit:
> > + mutex_unlock(&amd_pstate_driver_lock);
> > + return ret < 0 ? ret : count;
> > +}
> > +
> > cpufreq_freq_attr_ro(amd_pstate_max_freq);
> > cpufreq_freq_attr_ro(amd_pstate_lowest_nonlinear_freq);
> >
> > @@ -1358,6 +1471,7 @@
> cpufreq_freq_attr_rw(energy_performance_preference);
> > cpufreq_freq_attr_ro(energy_performance_available_preferences);
> > static DEVICE_ATTR_RW(status);
> > static DEVICE_ATTR_RO(prefcore);
> > +static DEVICE_ATTR_RW(cpb_boost);
> >
> > static struct freq_attr *amd_pstate_attr[] = {
> > &amd_pstate_max_freq,
> > @@ -1382,6 +1496,7 @@ static struct freq_attr *amd_pstate_epp_attr[] = {
> > static struct attribute *pstate_global_attributes[] = {
> > &dev_attr_status.attr,
> > &dev_attr_prefcore.attr,
> > + &dev_attr_cpb_boost.attr,
> > NULL
> > };
> >
> > @@ -1420,7 +1535,7 @@ static int amd_pstate_init_boost(struct
> cpufreq_policy *policy)
> > if (ret)
> > return ret;
> >
> > - policy->boost_enabled = READ_ONCE(cpudata->boost_supported);
> > + policy->boost_enabled = READ_ONCE(cpudata->boost_state);
> >
> > return 0;
> > }
> > diff --git a/drivers/cpufreq/amd-pstate.h
> > b/drivers/cpufreq/amd-pstate.h index 0b75a6267fca..9eba854ab7d3
> 100644
> > --- a/drivers/cpufreq/amd-pstate.h
> > +++ b/drivers/cpufreq/amd-pstate.h
> > @@ -99,6 +99,7 @@ struct amd_cpudata {
> > u32 policy;
> > u64 cppc_cap1_cached;
> > bool suspended;
> > + bool boost_state;
> > };
> >
> > /**
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