[PATCH V11 3/7] cpufreq: amd-pstate: Enable amd-pstate preferred core supporting.

Meng Li
2023-11-29T06:55:20Z

amd-pstate driver utilizes the functions and data structures
provided by the ITMT architecture to enable the scheduler to
favor scheduling on cores which can be get a higher frequency
with lower voltage. We call it amd-pstate preferrred core.

Here sched_set_itmt_core_prio() is called to set priorities and
sched_set_itmt_support() is called to enable ITMT feature.
amd-pstate driver uses the highest performance value to indicate
the priority of CPU. The higher value has a higher priority.

The initial core rankings are set up by amd-pstate when the
system boots.

Add a variable hw_prefcore in cpudata structure. It will check
if the processor and power firmware support preferred core
feature.

Add one new early parameter `disable` to allow user to disable
the preferred core.

Only when hardware supports preferred core and user set `enabled`
in early parameter, amd pstate driver supports preferred core featue.

Tested-by: Oleksandr Natalenko <oleksandr@natalenko.name>
Reviewed-by: Huang Rui <ray.huang@amd.com>
Reviewed-by: Wyes Karny <wyes.karny@amd.com>
Reviewed-by: Mario Limonciello <mario.limonciello@amd.com>
Co-developed-by: Perry Yuan <Perry.Yuan@amd.com>
Signed-off-by: Perry Yuan <Perry.Yuan@amd.com>
Signed-off-by: Meng Li <li.meng@amd.com>
---
drivers/cpufreq/amd-pstate.c | 141 +++++++++++++++++++++++++++++++----
include/linux/amd-pstate.h | 4 +
2 files changed, 129 insertions(+), 16 deletions(-)

diff --git a/drivers/cpufreq/amd-pstate.c b/drivers/cpufreq/amd-pstate.c
index 9a1e194d5cf8..74dcf63d75f9 100644
--- a/drivers/cpufreq/amd-pstate.c
+++ b/drivers/cpufreq/amd-pstate.c
@@ -37,6 +37,7 @@
#include <linux/uaccess.h>
#include <linux/static_call.h>
#include <linux/amd-pstate.h>
+#include <linux/topology.h>

#include <acpi/processor.h>
#include <acpi/cppc_acpi.h>
@@ -49,6 +50,7 @@

#define AMD_PSTATE_TRANSITION_LATENCY 20000
#define AMD_PSTATE_TRANSITION_DELAY 1000
+#define AMD_PSTATE_PREFCORE_THRESHOLD 166

/*
* TODO: We need more time to fine tune processors with shared memory solution
@@ -64,6 +66,7 @@ static struct cpufreq_driver amd_pstate_driver;
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;

/*
* AMD Energy Preference Performance (EPP)
@@ -290,23 +293,21 @@ static inline int amd_pstate_enable(bool enable)
static int pstate_init_perf(struct amd_cpudata *cpudata)
{
u64 cap1;
- u32 highest_perf;

int ret = rdmsrl_safe_on_cpu(cpudata->cpu, MSR_AMD_CPPC_CAP1,
&cap1);
if (ret)
return ret;

- /*
- * TODO: Introduce AMD specific power feature.
- *
- * CPPC entry doesn't indicate the highest performance in some ASICs.
+ /* For platforms that do not support the preferred core feature, the
+ * highest_pef may be configured with 166 or 255, to avoid max frequency
+ * calculated wrongly. we take the AMD_CPPC_HIGHEST_PERF(cap1) value as
+ * the default max perf.
*/
- highest_perf = amd_get_highest_perf();
- if (highest_perf > AMD_CPPC_HIGHEST_PERF(cap1))
- highest_perf = AMD_CPPC_HIGHEST_PERF(cap1);
-
- WRITE_ONCE(cpudata->highest_perf, highest_perf);
+ if (cpudata->hw_prefcore)
+ WRITE_ONCE(cpudata->highest_perf, AMD_PSTATE_PREFCORE_THRESHOLD);
+ else
+ WRITE_ONCE(cpudata->highest_perf, AMD_CPPC_HIGHEST_PERF(cap1));

WRITE_ONCE(cpudata->nominal_perf, AMD_CPPC_NOMINAL_PERF(cap1));
WRITE_ONCE(cpudata->lowest_nonlinear_perf, AMD_CPPC_LOWNONLIN_PERF(cap1));
@@ -318,17 +319,15 @@ static int pstate_init_perf(struct amd_cpudata *cpudata)
static int cppc_init_perf(struct amd_cpudata *cpudata)
{
struct cppc_perf_caps cppc_perf;
- u32 highest_perf;

int ret = cppc_get_perf_caps(cpudata->cpu, &cppc_perf);
if (ret)
return ret;

- highest_perf = amd_get_highest_perf();
- if (highest_perf > cppc_perf.highest_perf)
- highest_perf = cppc_perf.highest_perf;
-
- WRITE_ONCE(cpudata->highest_perf, highest_perf);
+ if (cpudata->hw_prefcore)
+ WRITE_ONCE(cpudata->highest_perf, AMD_PSTATE_PREFCORE_THRESHOLD);
+ else
+ WRITE_ONCE(cpudata->highest_perf, cppc_perf.highest_perf);

WRITE_ONCE(cpudata->nominal_perf, cppc_perf.nominal_perf);
WRITE_ONCE(cpudata->lowest_nonlinear_perf,
@@ -676,6 +675,80 @@ static void amd_perf_ctl_reset(unsigned int cpu)
wrmsrl_on_cpu(cpu, MSR_AMD_PERF_CTL, 0);
}

+/*
+ * Set amd-pstate preferred core enable can't be done directly from cpufreq callbacks
+ * due to locking, so queue the work for later.
+ */
+static void amd_pstste_sched_prefcore_workfn(struct work_struct *work)
+{
+ sched_set_itmt_support();
+}
+static DECLARE_WORK(sched_prefcore_work, amd_pstste_sched_prefcore_workfn);
+
+/*
+ * Get the highest performance register value.
+ * @cpu: CPU from which to get highest performance.
+ * @highest_perf: Return address.
+ *
+ * Return: 0 for success, -EIO otherwise.
+ */
+static int amd_pstate_get_highest_perf(int cpu, u32 *highest_perf)
+{
+ int ret;
+
+ if (boot_cpu_has(X86_FEATURE_CPPC)) {
+ u64 cap1;
+
+ ret = rdmsrl_safe_on_cpu(cpu, MSR_AMD_CPPC_CAP1, &cap1);
+ if (ret)
+ return ret;
+ WRITE_ONCE(*highest_perf, AMD_CPPC_HIGHEST_PERF(cap1));
+ } else {
+ u64 cppc_highest_perf;
+
+ ret = cppc_get_highest_perf(cpu, &cppc_highest_perf);
+ if (ret)
+ return ret;
+ WRITE_ONCE(*highest_perf, cppc_highest_perf);
+ }
+
+ return (ret);
+}
+
+#define CPPC_MAX_PERF U8_MAX
+
+static void amd_pstate_init_prefcore(struct amd_cpudata *cpudata)
+{
+ int ret, prio;
+ u32 highest_perf;
+
+ ret = amd_pstate_get_highest_perf(cpudata->cpu, &highest_perf);
+ if (ret)
+ return;
+
+ cpudata->hw_prefcore = true;
+ /* check if CPPC preferred core feature is enabled*/
+ if (highest_perf < CPPC_MAX_PERF)
+ prio = (int)highest_perf;
+ else {
+ pr_debug("AMD CPPC preferred core is unsupported!\n");
+ cpudata->hw_prefcore = false;
+ return;
+ }
+
+ if (!amd_pstate_prefcore)
+ return;
+
+ /*
+ * The priorities can be set regardless of whether or not
+ * sched_set_itmt_support(true) has been called and it is valid to
+ * update them at any time after it has been called.
+ */
+ sched_set_itmt_core_prio(prio, cpudata->cpu);
+
+ schedule_work(&sched_prefcore_work);
+}
+
static int amd_pstate_cpu_init(struct cpufreq_policy *policy)
{
int min_freq, max_freq, nominal_freq, lowest_nonlinear_freq, ret;
@@ -697,6 +770,8 @@ static int amd_pstate_cpu_init(struct cpufreq_policy *policy)

cpudata->cpu = policy->cpu;

+ amd_pstate_init_prefcore(cpudata);
+
ret = amd_pstate_init_perf(cpudata);
if (ret)
goto free_cpudata1;
@@ -845,6 +920,17 @@ static ssize_t show_amd_pstate_highest_perf(struct cpufreq_policy *policy,
return sysfs_emit(buf, "%u\n", perf);
}

+static ssize_t show_amd_pstate_hw_prefcore(struct cpufreq_policy *policy,
+ char *buf)
+{
+ bool hw_prefcore;
+ struct amd_cpudata *cpudata = policy->driver_data;
+
+ hw_prefcore = READ_ONCE(cpudata->hw_prefcore);
+
+ return sysfs_emit(buf, "%s\n", str_enabled_disabled(hw_prefcore));
+}
+
static ssize_t show_energy_performance_available_preferences(
struct cpufreq_policy *policy, char *buf)
{
@@ -1037,18 +1123,27 @@ static ssize_t status_store(struct device *a, struct device_attribute *b,
return ret < 0 ? ret : count;
}

+static ssize_t prefcore_show(struct device *dev,
+ struct device_attribute *attr, char *buf)
+{
+ return sysfs_emit(buf, "%s\n", str_enabled_disabled(amd_pstate_prefcore));
+}
+
cpufreq_freq_attr_ro(amd_pstate_max_freq);
cpufreq_freq_attr_ro(amd_pstate_lowest_nonlinear_freq);

cpufreq_freq_attr_ro(amd_pstate_highest_perf);
+cpufreq_freq_attr_ro(amd_pstate_hw_prefcore);
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 struct freq_attr *amd_pstate_attr[] = {
&amd_pstate_max_freq,
&amd_pstate_lowest_nonlinear_freq,
&amd_pstate_highest_perf,
+ &amd_pstate_hw_prefcore,
NULL,
};

@@ -1056,6 +1151,7 @@ static struct freq_attr *amd_pstate_epp_attr[] = {
&amd_pstate_max_freq,
&amd_pstate_lowest_nonlinear_freq,
&amd_pstate_highest_perf,
+ &amd_pstate_hw_prefcore,
&energy_performance_preference,
&energy_performance_available_preferences,
NULL,
@@ -1063,6 +1159,7 @@ static struct freq_attr *amd_pstate_epp_attr[] = {

static struct attribute *pstate_global_attributes[] = {
&dev_attr_status.attr,
+ &dev_attr_prefcore.attr,
NULL
};

@@ -1114,6 +1211,8 @@ static int amd_pstate_epp_cpu_init(struct cpufreq_policy *policy)
cpudata->cpu = policy->cpu;
cpudata->epp_policy = 0;

+ amd_pstate_init_prefcore(cpudata);
+
ret = amd_pstate_init_perf(cpudata);
if (ret)
goto free_cpudata1;
@@ -1527,7 +1626,17 @@ static int __init amd_pstate_param(char *str)

return amd_pstate_set_driver(mode_idx);
}
+
+static int __init amd_prefcore_param(char *str)
+{
+ if (!strcmp(str, "disable"))
+ amd_pstate_prefcore = false;
+
+ return 0;
+}
+
early_param("amd_pstate", amd_pstate_param);
+early_param("amd_prefcore", amd_prefcore_param);

MODULE_AUTHOR("Huang Rui <ray.huang@amd.com>");
MODULE_DESCRIPTION("AMD Processor P-state Frequency Driver");
diff --git a/include/linux/amd-pstate.h b/include/linux/amd-pstate.h
index 446394f84606..87e140e9e6db 100644
--- a/include/linux/amd-pstate.h
+++ b/include/linux/amd-pstate.h
@@ -52,6 +52,9 @@ struct amd_aperf_mperf {
* @prev: Last Aperf/Mperf/tsc count value read from register
* @freq: current cpu frequency value
* @boost_supported: check whether the Processor or SBIOS supports boost mode
+ * @hw_prefcore: check whether HW supports preferred core featue.
+ * Only when hw_prefcore and early prefcore param are true,
+ * AMD P-State driver supports preferred core featue.
* @epp_policy: Last saved policy used to set energy-performance preference
* @epp_cached: Cached CPPC energy-performance preference value
* @policy: Cpufreq policy value
@@ -81,6 +84,7 @@ struct amd_cpudata {

u64 freq;
bool boost_supported;
+ bool hw_prefcore;

/* EPP feature related attributes*/
s16 epp_policy;
--
2.34.1