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-rw-r--r--drivers/cpufreq/Kconfig2
-rw-r--r--drivers/cpufreq/Kconfig.x8617
-rw-r--r--drivers/cpufreq/amd-pstate.c131
-rw-r--r--drivers/cpufreq/cpufreq.c3
-rw-r--r--drivers/cpufreq/intel_pstate.c2
-rw-r--r--drivers/idle/intel_idle.c231
-rw-r--r--include/acpi/actbl.h3
-rw-r--r--include/linux/amd-pstate.h4
-rw-r--r--include/linux/cpufreq.h5
9 files changed, 341 insertions, 57 deletions
diff --git a/drivers/cpufreq/Kconfig b/drivers/cpufreq/Kconfig
index 2c839bd2b051..a1c51abddbc5 100644
--- a/drivers/cpufreq/Kconfig
+++ b/drivers/cpufreq/Kconfig
@@ -38,7 +38,7 @@ choice
prompt "Default CPUFreq governor"
default CPU_FREQ_DEFAULT_GOV_USERSPACE if ARM_SA1110_CPUFREQ
default CPU_FREQ_DEFAULT_GOV_SCHEDUTIL if ARM64 || ARM
- default CPU_FREQ_DEFAULT_GOV_SCHEDUTIL if X86_INTEL_PSTATE && SMP
+ default CPU_FREQ_DEFAULT_GOV_SCHEDUTIL if (X86_INTEL_PSTATE || X86_AMD_PSTATE) && SMP
default CPU_FREQ_DEFAULT_GOV_PERFORMANCE
help
This option sets which CPUFreq governor shall be loaded at
diff --git a/drivers/cpufreq/Kconfig.x86 b/drivers/cpufreq/Kconfig.x86
index 00476e94db90..438c9e75a04d 100644
--- a/drivers/cpufreq/Kconfig.x86
+++ b/drivers/cpufreq/Kconfig.x86
@@ -51,6 +51,23 @@ config X86_AMD_PSTATE
If in doubt, say N.
+config X86_AMD_PSTATE_DEFAULT_MODE
+ int "AMD Processor P-State default mode"
+ depends on X86_AMD_PSTATE
+ default 3 if X86_AMD_PSTATE
+ range 1 4
+ help
+ Select the default mode the amd-pstate driver will use on
+ supported hardware.
+ The value set has the following meanings:
+ 1 -> Disabled
+ 2 -> Passive
+ 3 -> Active (EPP)
+ 4 -> Guided
+
+ For details, take a look at:
+ <file:Documentation/admin-guide/pm/amd-pstate.rst>.
+
config X86_AMD_PSTATE_UT
tristate "selftest for AMD Processor P-State driver"
depends on X86 && ACPI_PROCESSOR
diff --git a/drivers/cpufreq/amd-pstate.c b/drivers/cpufreq/amd-pstate.c
index ddd346a239e0..81fba0dcbee9 100644
--- a/drivers/cpufreq/amd-pstate.c
+++ b/drivers/cpufreq/amd-pstate.c
@@ -62,7 +62,8 @@
static struct cpufreq_driver *current_pstate_driver;
static struct cpufreq_driver amd_pstate_driver;
static struct cpufreq_driver amd_pstate_epp_driver;
-static int cppc_state = AMD_PSTATE_DISABLE;
+static int cppc_state = AMD_PSTATE_UNDEFINED;
+static bool cppc_enabled;
/*
* AMD Energy Preference Performance (EPP)
@@ -228,7 +229,28 @@ static int amd_pstate_set_energy_pref_index(struct amd_cpudata *cpudata,
static inline int pstate_enable(bool enable)
{
- return wrmsrl_safe(MSR_AMD_CPPC_ENABLE, enable);
+ int ret, cpu;
+ unsigned long logical_proc_id_mask = 0;
+
+ if (enable == cppc_enabled)
+ return 0;
+
+ for_each_present_cpu(cpu) {
+ unsigned long logical_id = topology_logical_die_id(cpu);
+
+ if (test_bit(logical_id, &logical_proc_id_mask))
+ continue;
+
+ set_bit(logical_id, &logical_proc_id_mask);
+
+ ret = wrmsrl_safe_on_cpu(cpu, MSR_AMD_CPPC_ENABLE,
+ enable);
+ if (ret)
+ return ret;
+ }
+
+ cppc_enabled = enable;
+ return 0;
}
static int cppc_enable(bool enable)
@@ -236,6 +258,9 @@ static int cppc_enable(bool enable)
int cpu, ret = 0;
struct cppc_perf_ctrls perf_ctrls;
+ if (enable == cppc_enabled)
+ return 0;
+
for_each_present_cpu(cpu) {
ret = cppc_set_enable(cpu, enable);
if (ret)
@@ -251,6 +276,7 @@ static int cppc_enable(bool enable)
}
}
+ cppc_enabled = enable;
return ret;
}
@@ -1045,6 +1071,26 @@ static const struct attribute_group amd_pstate_global_attr_group = {
.attrs = pstate_global_attributes,
};
+static bool amd_pstate_acpi_pm_profile_server(void)
+{
+ switch (acpi_gbl_FADT.preferred_profile) {
+ case PM_ENTERPRISE_SERVER:
+ case PM_SOHO_SERVER:
+ case PM_PERFORMANCE_SERVER:
+ return true;
+ }
+ return false;
+}
+
+static bool amd_pstate_acpi_pm_profile_undefined(void)
+{
+ if (acpi_gbl_FADT.preferred_profile == PM_UNSPECIFIED)
+ return true;
+ if (acpi_gbl_FADT.preferred_profile >= NR_PM_PROFILES)
+ return true;
+ return false;
+}
+
static int amd_pstate_epp_cpu_init(struct cpufreq_policy *policy)
{
int min_freq, max_freq, nominal_freq, lowest_nonlinear_freq, ret;
@@ -1102,10 +1148,14 @@ static int amd_pstate_epp_cpu_init(struct cpufreq_policy *policy)
policy->max = policy->cpuinfo.max_freq;
/*
- * Set the policy to powersave to provide a valid fallback value in case
+ * Set the policy to provide a valid fallback value in case
* the default cpufreq governor is neither powersave nor performance.
*/
- policy->policy = CPUFREQ_POLICY_POWERSAVE;
+ if (amd_pstate_acpi_pm_profile_server() ||
+ amd_pstate_acpi_pm_profile_undefined())
+ policy->policy = CPUFREQ_POLICY_PERFORMANCE;
+ else
+ policy->policy = CPUFREQ_POLICY_POWERSAVE;
if (boot_cpu_has(X86_FEATURE_CPPC)) {
ret = rdmsrl_on_cpu(cpudata->cpu, MSR_AMD_CPPC_REQ, &value);
@@ -1356,10 +1406,29 @@ static struct cpufreq_driver amd_pstate_epp_driver = {
.online = amd_pstate_epp_cpu_online,
.suspend = amd_pstate_epp_suspend,
.resume = amd_pstate_epp_resume,
- .name = "amd_pstate_epp",
+ .name = "amd-pstate-epp",
.attr = amd_pstate_epp_attr,
};
+static int __init amd_pstate_set_driver(int mode_idx)
+{
+ if (mode_idx >= AMD_PSTATE_DISABLE && mode_idx < AMD_PSTATE_MAX) {
+ cppc_state = mode_idx;
+ if (cppc_state == AMD_PSTATE_DISABLE)
+ pr_info("driver is explicitly disabled\n");
+
+ if (cppc_state == AMD_PSTATE_ACTIVE)
+ current_pstate_driver = &amd_pstate_epp_driver;
+
+ if (cppc_state == AMD_PSTATE_PASSIVE || cppc_state == AMD_PSTATE_GUIDED)
+ current_pstate_driver = &amd_pstate_driver;
+
+ return 0;
+ }
+
+ return -EINVAL;
+}
+
static int __init amd_pstate_init(void)
{
struct device *dev_root;
@@ -1367,15 +1436,6 @@ static int __init amd_pstate_init(void)
if (boot_cpu_data.x86_vendor != X86_VENDOR_AMD)
return -ENODEV;
- /*
- * by default the pstate driver is disabled to load
- * enable the amd_pstate passive mode driver explicitly
- * with amd_pstate=passive or other modes in kernel command line
- */
- if (cppc_state == AMD_PSTATE_DISABLE) {
- pr_info("driver load is disabled, boot with specific mode to enable this\n");
- return -ENODEV;
- }
if (!acpi_cpc_valid()) {
pr_warn_once("the _CPC object is not present in SBIOS or ACPI disabled\n");
@@ -1386,6 +1446,33 @@ static int __init amd_pstate_init(void)
if (cpufreq_get_current_driver())
return -EEXIST;
+ switch (cppc_state) {
+ case AMD_PSTATE_UNDEFINED:
+ /* Disable on the following configs by default:
+ * 1. Undefined platforms
+ * 2. Server platforms
+ * 3. Shared memory designs
+ */
+ if (amd_pstate_acpi_pm_profile_undefined() ||
+ amd_pstate_acpi_pm_profile_server() ||
+ !boot_cpu_has(X86_FEATURE_CPPC)) {
+ pr_info("driver load is disabled, boot with specific mode to enable this\n");
+ return -ENODEV;
+ }
+ ret = amd_pstate_set_driver(CONFIG_X86_AMD_PSTATE_DEFAULT_MODE);
+ if (ret)
+ return ret;
+ break;
+ case AMD_PSTATE_DISABLE:
+ return -ENODEV;
+ case AMD_PSTATE_PASSIVE:
+ case AMD_PSTATE_ACTIVE:
+ case AMD_PSTATE_GUIDED:
+ break;
+ default:
+ return -EINVAL;
+ }
+
/* capability check */
if (boot_cpu_has(X86_FEATURE_CPPC)) {
pr_debug("AMD CPPC MSR based functionality is supported\n");
@@ -1438,21 +1525,7 @@ static int __init amd_pstate_param(char *str)
size = strlen(str);
mode_idx = get_mode_idx_from_str(str, size);
- if (mode_idx >= AMD_PSTATE_DISABLE && mode_idx < AMD_PSTATE_MAX) {
- cppc_state = mode_idx;
- if (cppc_state == AMD_PSTATE_DISABLE)
- pr_info("driver is explicitly disabled\n");
-
- if (cppc_state == AMD_PSTATE_ACTIVE)
- current_pstate_driver = &amd_pstate_epp_driver;
-
- if (cppc_state == AMD_PSTATE_PASSIVE || cppc_state == AMD_PSTATE_GUIDED)
- current_pstate_driver = &amd_pstate_driver;
-
- return 0;
- }
-
- return -EINVAL;
+ return amd_pstate_set_driver(mode_idx);
}
early_param("amd_pstate", amd_pstate_param);
diff --git a/drivers/cpufreq/cpufreq.c b/drivers/cpufreq/cpufreq.c
index 6b52ebe5a890..50bbc969ffe5 100644
--- a/drivers/cpufreq/cpufreq.c
+++ b/drivers/cpufreq/cpufreq.c
@@ -2828,7 +2828,8 @@ int cpufreq_register_driver(struct cpufreq_driver *driver_data)
(driver_data->setpolicy && (driver_data->target_index ||
driver_data->target)) ||
(!driver_data->get_intermediate != !driver_data->target_intermediate) ||
- (!driver_data->online != !driver_data->offline))
+ (!driver_data->online != !driver_data->offline) ||
+ (driver_data->adjust_perf && !driver_data->fast_switch))
return -EINVAL;
pr_debug("trying to register driver %s\n", driver_data->name);
diff --git a/drivers/cpufreq/intel_pstate.c b/drivers/cpufreq/intel_pstate.c
index 2548ec92faa2..f29182512b98 100644
--- a/drivers/cpufreq/intel_pstate.c
+++ b/drivers/cpufreq/intel_pstate.c
@@ -824,6 +824,8 @@ static ssize_t store_energy_performance_preference(
err = cpufreq_start_governor(policy);
if (!ret)
ret = err;
+ } else {
+ ret = 0;
}
}
diff --git a/drivers/idle/intel_idle.c b/drivers/idle/intel_idle.c
index aa2d19db2b1d..34201d7ef33e 100644
--- a/drivers/idle/intel_idle.c
+++ b/drivers/idle/intel_idle.c
@@ -199,6 +199,43 @@ static __cpuidle int intel_idle_xstate(struct cpuidle_device *dev,
return __intel_idle(dev, drv, index);
}
+static __always_inline int __intel_idle_hlt(struct cpuidle_device *dev,
+ struct cpuidle_driver *drv, int index)
+{
+ raw_safe_halt();
+ raw_local_irq_disable();
+ return index;
+}
+
+/**
+ * intel_idle_hlt - Ask the processor to enter the given idle state using hlt.
+ * @dev: cpuidle device of the target CPU.
+ * @drv: cpuidle driver (assumed to point to intel_idle_driver).
+ * @index: Target idle state index.
+ *
+ * Use the HLT instruction to notify the processor that the CPU represented by
+ * @dev is idle and it can try to enter the idle state corresponding to @index.
+ *
+ * Must be called under local_irq_disable().
+ */
+static __cpuidle int intel_idle_hlt(struct cpuidle_device *dev,
+ struct cpuidle_driver *drv, int index)
+{
+ return __intel_idle_hlt(dev, drv, index);
+}
+
+static __cpuidle int intel_idle_hlt_irq_on(struct cpuidle_device *dev,
+ struct cpuidle_driver *drv, int index)
+{
+ int ret;
+
+ raw_local_irq_enable();
+ ret = __intel_idle_hlt(dev, drv, index);
+ raw_local_irq_disable();
+
+ return ret;
+}
+
/**
* intel_idle_s2idle - Ask the processor to enter the given idle state.
* @dev: cpuidle device of the target CPU.
@@ -1242,6 +1279,25 @@ static struct cpuidle_state snr_cstates[] __initdata = {
.enter = NULL }
};
+static struct cpuidle_state vmguest_cstates[] __initdata = {
+ {
+ .name = "C1",
+ .desc = "HLT",
+ .flags = MWAIT2flg(0x00) | CPUIDLE_FLAG_IRQ_ENABLE,
+ .exit_latency = 5,
+ .target_residency = 10,
+ .enter = &intel_idle_hlt, },
+ {
+ .name = "C1L",
+ .desc = "Long HLT",
+ .flags = MWAIT2flg(0x00) | CPUIDLE_FLAG_TLB_FLUSHED,
+ .exit_latency = 5,
+ .target_residency = 200,
+ .enter = &intel_idle_hlt, },
+ {
+ .enter = NULL }
+};
+
static const struct idle_cpu idle_cpu_nehalem __initconst = {
.state_table = nehalem_cstates,
.auto_demotion_disable_flags = NHM_C1_AUTO_DEMOTE | NHM_C3_AUTO_DEMOTE,
@@ -1839,6 +1895,66 @@ static bool __init intel_idle_verify_cstate(unsigned int mwait_hint)
return true;
}
+static void state_update_enter_method(struct cpuidle_state *state, int cstate)
+{
+ if (state->enter == intel_idle_hlt) {
+ if (force_irq_on) {
+ pr_info("forced intel_idle_irq for state %d\n", cstate);
+ state->enter = intel_idle_hlt_irq_on;
+ }
+ return;
+ }
+ if (state->enter == intel_idle_hlt_irq_on)
+ return; /* no update scenarios */
+
+ if (state->flags & CPUIDLE_FLAG_INIT_XSTATE) {
+ /*
+ * Combining with XSTATE with IBRS or IRQ_ENABLE flags
+ * is not currently supported but this driver.
+ */
+ WARN_ON_ONCE(state->flags & CPUIDLE_FLAG_IBRS);
+ WARN_ON_ONCE(state->flags & CPUIDLE_FLAG_IRQ_ENABLE);
+ state->enter = intel_idle_xstate;
+ return;
+ }
+
+ if (cpu_feature_enabled(X86_FEATURE_KERNEL_IBRS) &&
+ state->flags & CPUIDLE_FLAG_IBRS) {
+ /*
+ * IBRS mitigation requires that C-states are entered
+ * with interrupts disabled.
+ */
+ WARN_ON_ONCE(state->flags & CPUIDLE_FLAG_IRQ_ENABLE);
+ state->enter = intel_idle_ibrs;
+ return;
+ }
+
+ if (state->flags & CPUIDLE_FLAG_IRQ_ENABLE) {
+ state->enter = intel_idle_irq;
+ return;
+ }
+
+ if (force_irq_on) {
+ pr_info("forced intel_idle_irq for state %d\n", cstate);
+ state->enter = intel_idle_irq;
+ }
+}
+
+/*
+ * For mwait based states, we want to verify the cpuid data to see if the state
+ * is actually supported by this specific CPU.
+ * For non-mwait based states, this check should be skipped.
+ */
+static bool should_verify_mwait(struct cpuidle_state *state)
+{
+ if (state->enter == intel_idle_hlt)
+ return false;
+ if (state->enter == intel_idle_hlt_irq_on)
+ return false;
+
+ return true;
+}
+
static void __init intel_idle_init_cstates_icpu(struct cpuidle_driver *drv)
{
int cstate;
@@ -1887,35 +2003,15 @@ static void __init intel_idle_init_cstates_icpu(struct cpuidle_driver *drv)
}
mwait_hint = flg2MWAIT(cpuidle_state_table[cstate].flags);
- if (!intel_idle_verify_cstate(mwait_hint))
+ if (should_verify_mwait(&cpuidle_state_table[cstate]) && !intel_idle_verify_cstate(mwait_hint))
continue;
/* Structure copy. */
drv->states[drv->state_count] = cpuidle_state_table[cstate];
state = &drv->states[drv->state_count];
- if (state->flags & CPUIDLE_FLAG_INIT_XSTATE) {
- /*
- * Combining with XSTATE with IBRS or IRQ_ENABLE flags
- * is not currently supported but this driver.
- */
- WARN_ON_ONCE(state->flags & CPUIDLE_FLAG_IBRS);
- WARN_ON_ONCE(state->flags & CPUIDLE_FLAG_IRQ_ENABLE);
- state->enter = intel_idle_xstate;
- } else if (cpu_feature_enabled(X86_FEATURE_KERNEL_IBRS) &&
- state->flags & CPUIDLE_FLAG_IBRS) {
- /*
- * IBRS mitigation requires that C-states are entered
- * with interrupts disabled.
- */
- WARN_ON_ONCE(state->flags & CPUIDLE_FLAG_IRQ_ENABLE);
- state->enter = intel_idle_ibrs;
- } else if (state->flags & CPUIDLE_FLAG_IRQ_ENABLE) {
- state->enter = intel_idle_irq;
- } else if (force_irq_on) {
- pr_info("forced intel_idle_irq for state %d\n", cstate);
- state->enter = intel_idle_irq;
- }
+ state_update_enter_method(state, cstate);
+
if ((disabled_states_mask & BIT(drv->state_count)) ||
((icpu->use_acpi || force_use_acpi) &&
@@ -2041,6 +2137,93 @@ static void __init intel_idle_cpuidle_devices_uninit(void)
cpuidle_unregister_device(per_cpu_ptr(intel_idle_cpuidle_devices, i));
}
+/*
+ * Match up the latency and break even point of the bare metal (cpu based)
+ * states with the deepest VM available state.
+ *
+ * We only want to do this for the deepest state, the ones that has
+ * the TLB_FLUSHED flag set on the .
+ *
+ * All our short idle states are dominated by vmexit/vmenter latencies,
+ * not the underlying hardware latencies so we keep our values for these.
+ */
+static void matchup_vm_state_with_baremetal(void)
+{
+ int cstate;
+
+ for (cstate = 0; cstate < CPUIDLE_STATE_MAX; ++cstate) {
+ int matching_cstate;
+
+ if (intel_idle_max_cstate_reached(cstate))
+ break;
+
+ if (!cpuidle_state_table[cstate].enter)
+ break;
+
+ if (!(cpuidle_state_table[cstate].flags & CPUIDLE_FLAG_TLB_FLUSHED))
+ continue;
+
+ for (matching_cstate = 0; matching_cstate < CPUIDLE_STATE_MAX; ++matching_cstate) {
+ if (!icpu->state_table[matching_cstate].enter)
+ break;
+ if (icpu->state_table[matching_cstate].exit_latency > cpuidle_state_table[cstate].exit_latency) {
+ cpuidle_state_table[cstate].exit_latency = icpu->state_table[matching_cstate].exit_latency;
+ cpuidle_state_table[cstate].target_residency = icpu->state_table[matching_cstate].target_residency;
+ }
+ }
+
+ }
+}
+
+
+static int __init intel_idle_vminit(const struct x86_cpu_id *id)
+{
+ int retval;
+
+ cpuidle_state_table = vmguest_cstates;
+
+ icpu = (const struct idle_cpu *)id->driver_data;
+
+ pr_debug("v" INTEL_IDLE_VERSION " model 0x%X\n",
+ boot_cpu_data.x86_model);
+
+ intel_idle_cpuidle_devices = alloc_percpu(struct cpuidle_device);
+ if (!intel_idle_cpuidle_devices)
+ return -ENOMEM;
+
+ /*
+ * We don't know exactly what the host will do when we go idle, but as a worst estimate
+ * we can assume that the exit latency of the deepest host state will be hit for our
+ * deep (long duration) guest idle state.
+ * The same logic applies to the break even point for the long duration guest idle state.
+ * So lets copy these two properties from the table we found for the host CPU type.
+ */
+ matchup_vm_state_with_baremetal();
+
+ intel_idle_cpuidle_driver_init(&intel_idle_driver);
+
+ retval = cpuidle_register_driver(&intel_idle_driver);
+ if (retval) {
+ struct cpuidle_driver *drv = cpuidle_get_driver();
+ printk(KERN_DEBUG pr_fmt("intel_idle yielding to %s\n"),
+ drv ? drv->name : "none");
+ goto init_driver_fail;
+ }
+
+ retval = cpuhp_setup_state(CPUHP_AP_ONLINE_DYN, "idle/intel:online",
+ intel_idle_cpu_online, NULL);
+ if (retval < 0)
+ goto hp_setup_fail;
+
+ return 0;
+hp_setup_fail:
+ intel_idle_cpuidle_devices_uninit();
+ cpuidle_unregister_driver(&intel_idle_driver);
+init_driver_fail:
+ free_percpu(intel_idle_cpuidle_devices);
+ return retval;
+}
+
static int __init intel_idle_init(void)
{
const struct x86_cpu_id *id;
@@ -2059,6 +2242,8 @@ static int __init intel_idle_init(void)
id = x86_match_cpu(intel_idle_ids);
if (id) {
if (!boot_cpu_has(X86_FEATURE_MWAIT)) {
+ if (boot_cpu_has(X86_FEATURE_HYPERVISOR))
+ return intel_idle_vminit(id);
pr_debug("Please enable MWAIT in BIOS SETUP\n");
return -ENODEV;
}
diff --git a/include/acpi/actbl.h b/include/acpi/actbl.h
index e5dfb6f4de52..451f6276da49 100644
--- a/include/acpi/actbl.h
+++ b/include/acpi/actbl.h
@@ -307,7 +307,8 @@ enum acpi_preferred_pm_profiles {
PM_SOHO_SERVER = 5,
PM_APPLIANCE_PC = 6,
PM_PERFORMANCE_SERVER = 7,
- PM_TABLET = 8
+ PM_TABLET = 8,
+ NR_PM_PROFILES = 9
};
/* Values for sleep_status and sleep_control registers (V5+ FADT) */
diff --git a/include/linux/amd-pstate.h b/include/linux/amd-pstate.h
index c10ebf8c42e6..446394f84606 100644
--- a/include/linux/amd-pstate.h
+++ b/include/linux/amd-pstate.h
@@ -94,7 +94,8 @@ struct amd_cpudata {
* enum amd_pstate_mode - driver working mode of amd pstate
*/
enum amd_pstate_mode {
- AMD_PSTATE_DISABLE = 0,
+ AMD_PSTATE_UNDEFINED = 0,
+ AMD_PSTATE_DISABLE,
AMD_PSTATE_PASSIVE,
AMD_PSTATE_ACTIVE,
AMD_PSTATE_GUIDED,
@@ -102,6 +103,7 @@ enum amd_pstate_mode {
};
static const char * const amd_pstate_mode_string[] = {
+ [AMD_PSTATE_UNDEFINED] = "undefined",
[AMD_PSTATE_DISABLE] = "disable",
[AMD_PSTATE_PASSIVE] = "passive",
[AMD_PSTATE_ACTIVE] = "active",
diff --git a/include/linux/cpufreq.h b/include/linux/cpufreq.h
index 26e2eb399484..172ff51c1b2a 100644
--- a/include/linux/cpufreq.h
+++ b/include/linux/cpufreq.h
@@ -340,7 +340,10 @@ struct cpufreq_driver {
/*
* ->fast_switch() replacement for drivers that use an internal
* representation of performance levels and can pass hints other than
- * the target performance level to the hardware.
+ * the target performance level to the hardware. This can only be set
+ * if ->fast_switch is set too, because in those cases (under specific
+ * conditions) scale invariance can be disabled, which causes the
+ * schedutil governor to fall back to the latter.
*/
void (*adjust_perf)(unsigned int cpu,
unsigned long min_perf,