Merge tag 'pm-6.1-rc7' of git://git.kernel.org/pub/scm/linux/kernel/git/rafael/linux-pm

Pull power management fixes from Rafael Wysocki:
 "These revert a recent change in the schedutil cpufreq governor that
  had not been expected to make any functional difference, but turned
  out to introduce a performance regression, fix an initialization issue
  in the amd-pstate driver and make it actually replace the venerable
  ACPI cpufreq driver on the supported systems by default.

  Specifics:

   - Revert a recent schedutil cpufreq governor change that introduced a
     performace regression on Pixel 6 (Sam Wu)

   - Fix amd-pstate driver initialization after running the kernel via
     kexec (Wyes Karny)

   - Turn amd-pstate into a built-in driver which allows it to take
     precedence over acpi-cpufreq by default on supported systems and
     amend it with a mechanism to disable this behavior (Perry Yuan)

   - Update amd-pstate documentation in accordance with the other
     changes made to it (Perry Yuan)"

* tag 'pm-6.1-rc7' of git://git.kernel.org/pub/scm/linux/kernel/git/rafael/linux-pm:
  Documentation: add amd-pstate kernel command line options
  Documentation: amd-pstate: add driver working mode introduction
  cpufreq: amd-pstate: add amd-pstate driver parameter for mode selection
  cpufreq: amd-pstate: change amd-pstate driver to be built-in type
  cpufreq: amd-pstate: cpufreq: amd-pstate: reset MSR_AMD_PERF_CTL register at init
  Revert "cpufreq: schedutil: Move max CPU capacity to sugov_policy"

Author: torvalds

Documentation/admin-guide/kernel-parameters.txt

@@ -6959,3 +6959,14 @@
 				memory, and other data can't be written using
 				xmon commands.
 			off	xmon is disabled.
+
+	amd_pstate=	[X86]
+			disable
+			  Do not enable amd_pstate as the default
+			  scaling driver for the supported processors
+			passive
+			  Use amd_pstate as a scaling driver, driver requests a
+			  desired performance on this abstract scale and the power
+			  management firmware translates the requests into actual
+			  hardware states (core frequency, data fabric and memory
+			  clocks etc.)

Documentation/admin-guide/pm/amd-pstate.rst

@@ -283,23 +283,19 @@ efficiency frequency management method on AMD processors.
 Kernel Module Options for ``amd-pstate``
 =========================================
 
-.. _shared_mem:
-
-``shared_mem``
-Use a module param (shared_mem) to enable related processors manually with
-**amd_pstate.shared_mem=1**.
-Due to the performance issue on the processors with `Shared Memory Support
-<perf_cap_>`_, we disable it presently and will re-enable this by default
-once we address performance issue with this solution.
-
-To check whether the current processor is using `Full MSR Support <perf_cap_>`_
-or `Shared Memory Support <perf_cap_>`_ : ::
-
-  ray@hr-test1:~$ lscpu | grep cppc
-  Flags:                           fpu vme de pse tsc msr pae mce cx8 apic sep mtrr pge mca cmov pat pse36 clflush mmx fxsr sse sse2 ht syscall nx mmxext fxsr_opt pdpe1gb rdtscp lm constant_tsc rep_good nopl nonstop_tsc cpuid extd_apicid aperfmperf rapl pni pclmulqdq monitor ssse3 fma cx16 sse4_1 sse4_2 x2apic movbe popcnt aes xsave avx f16c rdrand lahf_lm cmp_legacy svm extapic cr8_legacy abm sse4a misalignsse 3dnowprefetch osvw ibs skinit wdt tce topoext perfctr_core perfctr_nb bpext perfctr_llc mwaitx cpb cat_l3 cdp_l3 hw_pstate ssbd mba ibrs ibpb stibp vmmcall fsgsbase bmi1 avx2 smep bmi2 erms invpcid cqm rdt_a rdseed adx smap clflushopt clwb sha_ni xsaveopt xsavec xgetbv1 xsaves cqm_llc cqm_occup_llc cqm_mbm_total cqm_mbm_local clzero irperf xsaveerptr rdpru wbnoinvd cppc arat npt lbrv svm_lock nrip_save tsc_scale vmcb_clean flushbyasid decodeassists pausefilter pfthreshold avic v_vmsave_vmload vgif v_spec_ctrl umip pku ospke vaes vpclmulqdq rdpid overflow_recov succor smca fsrm
-
-If the CPU flags have ``cppc``, then this processor supports `Full MSR Support
-<perf_cap_>`_. Otherwise, it supports `Shared Memory Support <perf_cap_>`_.
+Passive Mode
+------------
+
+``amd_pstate=passive``
+
+It will be enabled if the ``amd_pstate=passive`` is passed to the kernel in the command line.
+In this mode, ``amd_pstate`` driver software specifies a desired QoS target in the CPPC
+performance scale as a relative number. This can be expressed as percentage of nominal
+performance (infrastructure max). Below the nominal sustained performance level,
+desired performance expresses the average performance level of the processor subject
+to the Performance Reduction Tolerance register. Above the nominal performance level,
+processor must provide at least nominal performance requested and go higher if current
+operating conditions allow.
 
 
 ``cpupower`` tool support for ``amd-pstate``

drivers/cpufreq/Kconfig.x86

@@ -35,7 +35,7 @@ config X86_PCC_CPUFREQ
 	  If in doubt, say N.
 
 config X86_AMD_PSTATE
-	tristate "AMD Processor P-State driver"
+	bool "AMD Processor P-State driver"
 	depends on X86 && ACPI
 	select ACPI_PROCESSOR
 	select ACPI_CPPC_LIB if X86_64

drivers/cpufreq/amd-pstate.c

@@ -59,12 +59,8 @@
  * we disable it by default to go acpi-cpufreq on these processors and add a
  * module parameter to be able to enable it manually for debugging.
  */
-static bool shared_mem = false;
-module_param(shared_mem, bool, 0444);
-MODULE_PARM_DESC(shared_mem,
-		 "enable amd-pstate on processors with shared memory solution (false = disabled (default), true = enabled)");
-
 static struct cpufreq_driver amd_pstate_driver;
+static int cppc_load __initdata;
 
 static inline int pstate_enable(bool enable)
 {
@@ -424,12 +420,22 @@ static void amd_pstate_boost_init(struct amd_cpudata *cpudata)
 	amd_pstate_driver.boost_enabled = true;
 }
 
+static void amd_perf_ctl_reset(unsigned int cpu)
+{
+	wrmsrl_on_cpu(cpu, MSR_AMD_PERF_CTL, 0);
+}
+
 static int amd_pstate_cpu_init(struct cpufreq_policy *policy)
 {
 	int min_freq, max_freq, nominal_freq, lowest_nonlinear_freq, ret;
 	struct device *dev;
 	struct amd_cpudata *cpudata;
 
+	/*
+	 * Resetting PERF_CTL_MSR will put the CPU in P0 frequency,
+	 * which is ideal for initialization process.
+	 */
+	amd_perf_ctl_reset(policy->cpu);
 	dev = get_cpu_device(policy->cpu);
 	if (!dev)
 		return -ENODEV;
@@ -616,6 +622,15 @@ 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 in kernel command line
+	 */
+	if (!cppc_load) {
+		pr_debug("driver load is disabled, boot with amd_pstate=passive 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");
@@ -630,13 +645,11 @@ static int __init amd_pstate_init(void)
 	if (boot_cpu_has(X86_FEATURE_CPPC)) {
 		pr_debug("AMD CPPC MSR based functionality is supported\n");
 		amd_pstate_driver.adjust_perf = amd_pstate_adjust_perf;
-	} else if (shared_mem) {
+	} else {
+		pr_debug("AMD CPPC shared memory based functionality is supported\n");
 		static_call_update(amd_pstate_enable, cppc_enable);
 		static_call_update(amd_pstate_init_perf, cppc_init_perf);
 		static_call_update(amd_pstate_update_perf, cppc_update_perf);
-	} else {
-		pr_info("This processor supports shared memory solution, you can enable it with amd_pstate.shared_mem=1\n");
-		return -ENODEV;
 	}
 
 	/* enable amd pstate feature */
@@ -653,16 +666,22 @@ static int __init amd_pstate_init(void)
 
 	return ret;
 }
+device_initcall(amd_pstate_init);
 
-static void __exit amd_pstate_exit(void)
+static int __init amd_pstate_param(char *str)
 {
-	cpufreq_unregister_driver(&amd_pstate_driver);
+	if (!str)
+		return -EINVAL;
 
-	amd_pstate_enable(false);
-}
+	if (!strcmp(str, "disable")) {
+		cppc_load = 0;
+		pr_info("driver is explicitly disabled\n");
+	} else if (!strcmp(str, "passive"))
+		cppc_load = 1;
 
-module_init(amd_pstate_init);
-module_exit(amd_pstate_exit);
+	return 0;
+}
+early_param("amd_pstate", amd_pstate_param);
 
 MODULE_AUTHOR("Huang Rui <[email protected]>");
 MODULE_DESCRIPTION("AMD Processor P-state Frequency Driver");

kernel/sched/cpufreq_schedutil.c

@@ -25,9 +25,6 @@ struct sugov_policy {
 	unsigned int		next_freq;
 	unsigned int		cached_raw_freq;
 
-	/* max CPU capacity, which is equal for all CPUs in freq. domain */
-	unsigned long		max;
-
 	/* The next fields are only needed if fast switch cannot be used: */
 	struct			irq_work irq_work;
 	struct			kthread_work work;
@@ -51,6 +48,7 @@ struct sugov_cpu {
 
 	unsigned long		util;
 	unsigned long		bw_dl;
+	unsigned long		max;
 
 	/* The field below is for single-CPU policies only: */
 #ifdef CONFIG_NO_HZ_COMMON
@@ -160,6 +158,7 @@ static void sugov_get_util(struct sugov_cpu *sg_cpu)
 {
 	struct rq *rq = cpu_rq(sg_cpu->cpu);
 
+	sg_cpu->max = arch_scale_cpu_capacity(sg_cpu->cpu);
 	sg_cpu->bw_dl = cpu_bw_dl(rq);
 	sg_cpu->util = effective_cpu_util(sg_cpu->cpu, cpu_util_cfs(sg_cpu->cpu),
 					  FREQUENCY_UTIL, NULL);
@@ -254,7 +253,6 @@ static void sugov_iowait_boost(struct sugov_cpu *sg_cpu, u64 time,
  */
 static void sugov_iowait_apply(struct sugov_cpu *sg_cpu, u64 time)
 {
-	struct sugov_policy *sg_policy = sg_cpu->sg_policy;
 	unsigned long boost;
 
 	/* No boost currently required */
@@ -282,8 +280,7 @@ static void sugov_iowait_apply(struct sugov_cpu *sg_cpu, u64 time)
 	 * sg_cpu->util is already in capacity scale; convert iowait_boost
 	 * into the same scale so we can compare.
 	 */
-	boost = sg_cpu->iowait_boost * sg_policy->max;
-	boost >>= SCHED_CAPACITY_SHIFT;
+	boost = (sg_cpu->iowait_boost * sg_cpu->max) >> SCHED_CAPACITY_SHIFT;
 	boost = uclamp_rq_util_with(cpu_rq(sg_cpu->cpu), boost, NULL);
 	if (sg_cpu->util < boost)
 		sg_cpu->util = boost;
@@ -340,7 +337,7 @@ static void sugov_update_single_freq(struct update_util_data *hook, u64 time,
 	if (!sugov_update_single_common(sg_cpu, time, flags))
 		return;
 
-	next_f = get_next_freq(sg_policy, sg_cpu->util, sg_policy->max);
+	next_f = get_next_freq(sg_policy, sg_cpu->util, sg_cpu->max);
 	/*
 	 * Do not reduce the frequency if the CPU has not been idle
 	 * recently, as the reduction is likely to be premature then.
@@ -376,7 +373,6 @@ static void sugov_update_single_perf(struct update_util_data *hook, u64 time,
 				     unsigned int flags)
 {
 	struct sugov_cpu *sg_cpu = container_of(hook, struct sugov_cpu, update_util);
-	struct sugov_policy *sg_policy = sg_cpu->sg_policy;
 	unsigned long prev_util = sg_cpu->util;
 
 	/*
@@ -403,8 +399,7 @@ static void sugov_update_single_perf(struct update_util_data *hook, u64 time,
 		sg_cpu->util = prev_util;
 
 	cpufreq_driver_adjust_perf(sg_cpu->cpu, map_util_perf(sg_cpu->bw_dl),
-				   map_util_perf(sg_cpu->util),
-				   sg_policy->max);
+				   map_util_perf(sg_cpu->util), sg_cpu->max);
 
 	sg_cpu->sg_policy->last_freq_update_time = time;
 }
@@ -413,19 +408,25 @@ static unsigned int sugov_next_freq_shared(struct sugov_cpu *sg_cpu, u64 time)
 {
 	struct sugov_policy *sg_policy = sg_cpu->sg_policy;
 	struct cpufreq_policy *policy = sg_policy->policy;
-	unsigned long util = 0;
+	unsigned long util = 0, max = 1;
 	unsigned int j;
 
 	for_each_cpu(j, policy->cpus) {
 		struct sugov_cpu *j_sg_cpu = &per_cpu(sugov_cpu, j);
+		unsigned long j_util, j_max;
 
 		sugov_get_util(j_sg_cpu);
 		sugov_iowait_apply(j_sg_cpu, time);
+		j_util = j_sg_cpu->util;
+		j_max = j_sg_cpu->max;
 
-		util = max(j_sg_cpu->util, util);
+		if (j_util * max > j_max * util) {
+			util = j_util;
+			max = j_max;
+		}
 	}
 
-	return get_next_freq(sg_policy, util, sg_policy->max);
+	return get_next_freq(sg_policy, util, max);
 }
 
 static void
@@ -751,15 +752,14 @@ static int sugov_start(struct cpufreq_policy *policy)
 {
 	struct sugov_policy *sg_policy = policy->governor_data;
 	void (*uu)(struct update_util_data *data, u64 time, unsigned int flags);
-	unsigned int cpu = cpumask_first(policy->cpus);
+	unsigned int cpu;
 
 	sg_policy->freq_update_delay_ns	= sg_policy->tunables->rate_limit_us * NSEC_PER_USEC;
 	sg_policy->last_freq_update_time	= 0;
 	sg_policy->next_freq			= 0;
 	sg_policy->work_in_progress		= false;
 	sg_policy->limits_changed		= false;
 	sg_policy->cached_raw_freq		= 0;
-	sg_policy->max				= arch_scale_cpu_capacity(cpu);
 
 	sg_policy->need_freq_update = cpufreq_driver_test_flags(CPUFREQ_NEED_UPDATE_LIMITS);