Revert "cpufreq: intel_pstate: Use ACPI perf configuration"

Revert commit 37afb000 (cpufreq: intel_pstate: Use ACPI perf
configuration) that is reported to cause a regression to happen
on a system where invalid data are returned by the ACPI _PSS object.

Since that commit makes assumptions regarding the _PSS output
correctness that may turn out to be overly optimistic in general,
there is a concern that it may introduce regression on more
systems, so it's better to revert it now and we'll revisit the
underlying issue in the next cycle with a more robust solution.

Conflicts:
        drivers/cpufreq/intel_pstate.c

Fixes: 37afb000 (cpufreq: intel_pstate: Use ACPI perf configuration)
Reported-by: Borislav Petkov <bp@alien8.de>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>

drivers/cpufreq/Kconfig.x86

@@ -5,7 +5,6 @@
 config X86_INTEL_PSTATE
        bool "Intel P state control"
        depends on X86
-       select ACPI_PROCESSOR if ACPI
        help
           This driver provides a P state for Intel core processors.
 	  The driver implements an internal governor and will become

drivers/cpufreq/intel_pstate.c

@@ -34,10 +34,6 @@
 #include <asm/cpu_device_id.h>
 #include <asm/cpufeature.h>
 
-#if IS_ENABLED(CONFIG_ACPI)
-#include <acpi/processor.h>
-#endif
-
 #define BYT_RATIOS		0x66a
 #define BYT_VIDS		0x66b
 #define BYT_TURBO_RATIOS	0x66c
@@ -117,9 +113,6 @@ struct cpudata {
 	u64	prev_mperf;
 	u64	prev_tsc;
 	struct sample sample;
-#if IS_ENABLED(CONFIG_ACPI)
-	struct acpi_processor_performance acpi_perf_data;
-#endif
 };
 
 static struct cpudata **all_cpu_data;
@@ -150,7 +143,6 @@ struct cpu_defaults {
 static struct pstate_adjust_policy pid_params;
 static struct pstate_funcs pstate_funcs;
 static int hwp_active;
-static int no_acpi_perf;
 
 struct perf_limits {
 	int no_turbo;
@@ -197,153 +189,6 @@ static struct perf_limits *limits = &performance_limits;
 static struct perf_limits *limits = &powersave_limits;
 #endif
 
-#if IS_ENABLED(CONFIG_ACPI)
-/*
- * The max target pstate ratio is a 8 bit value in both PLATFORM_INFO MSR and
- * in TURBO_RATIO_LIMIT MSR, which pstate driver stores in max_pstate and
- * max_turbo_pstate fields. The PERF_CTL MSR contains 16 bit value for P state
- * ratio, out of it only high 8 bits are used. For example 0x1700 is setting
- * target ratio 0x17. The _PSS control value stores in a format which can be
- * directly written to PERF_CTL MSR. But in intel_pstate driver this shift
- * occurs during write to PERF_CTL (E.g. for cores core_set_pstate()).
- * This function converts the _PSS control value to intel pstate driver format
- * for comparison and assignment.
- */
-static int convert_to_native_pstate_format(struct cpudata *cpu, int index)
-{
-	return cpu->acpi_perf_data.states[index].control >> 8;
-}
-
-static int intel_pstate_init_perf_limits(struct cpufreq_policy *policy)
-{
-	struct cpudata *cpu;
-	int ret;
-	bool turbo_absent = false;
-	int max_pstate_index;
-	int min_pss_ctl, max_pss_ctl, turbo_pss_ctl;
-	int i;
-
-	cpu = all_cpu_data[policy->cpu];
-
-	pr_debug("intel_pstate: default limits 0x%x 0x%x 0x%x\n",
-		 cpu->pstate.min_pstate, cpu->pstate.max_pstate,
-		 cpu->pstate.turbo_pstate);
-
-	if (!cpu->acpi_perf_data.shared_cpu_map &&
-	    zalloc_cpumask_var_node(&cpu->acpi_perf_data.shared_cpu_map,
-				    GFP_KERNEL, cpu_to_node(policy->cpu))) {
-		return -ENOMEM;
-	}
-
-	ret = acpi_processor_register_performance(&cpu->acpi_perf_data,
-						  policy->cpu);
-	if (ret)
-		return ret;
-
-	/*
-	 * Check if the control value in _PSS is for PERF_CTL MSR, which should
-	 * guarantee that the states returned by it map to the states in our
-	 * list directly.
-	 */
-	if (cpu->acpi_perf_data.control_register.space_id !=
-						ACPI_ADR_SPACE_FIXED_HARDWARE)
-		return -EIO;
-
-	pr_debug("intel_pstate: CPU%u - ACPI _PSS perf data\n", policy->cpu);
-	for (i = 0; i < cpu->acpi_perf_data.state_count; i++)
-		pr_debug("     %cP%d: %u MHz, %u mW, 0x%x\n",
-			 (i == cpu->acpi_perf_data.state ? '*' : ' '), i,
-			 (u32) cpu->acpi_perf_data.states[i].core_frequency,
-			 (u32) cpu->acpi_perf_data.states[i].power,
-			 (u32) cpu->acpi_perf_data.states[i].control);
-
-	/*
-	 * If there is only one entry _PSS, simply ignore _PSS and continue as
-	 * usual without taking _PSS into account
-	 */
-	if (cpu->acpi_perf_data.state_count < 2)
-		return 0;
-
-	turbo_pss_ctl = convert_to_native_pstate_format(cpu, 0);
-	min_pss_ctl = convert_to_native_pstate_format(cpu,
-					cpu->acpi_perf_data.state_count - 1);
-	/* Check if there is a turbo freq in _PSS */
-	if (turbo_pss_ctl <= cpu->pstate.max_pstate &&
-	    turbo_pss_ctl > cpu->pstate.min_pstate) {
-		pr_debug("intel_pstate: no turbo range exists in _PSS\n");
-		limits->no_turbo = limits->turbo_disabled = 1;
-		cpu->pstate.turbo_pstate = cpu->pstate.max_pstate;
-		turbo_absent = true;
-	}
-
-	/* Check if the max non turbo p state < Intel P state max */
-	max_pstate_index = turbo_absent ? 0 : 1;
-	max_pss_ctl = convert_to_native_pstate_format(cpu, max_pstate_index);
-	if (max_pss_ctl < cpu->pstate.max_pstate &&
-	    max_pss_ctl > cpu->pstate.min_pstate)
-		cpu->pstate.max_pstate = max_pss_ctl;
-
-	/* check If min perf > Intel P State min */
-	if (min_pss_ctl > cpu->pstate.min_pstate &&
-	    min_pss_ctl < cpu->pstate.max_pstate) {
-		cpu->pstate.min_pstate = min_pss_ctl;
-		policy->cpuinfo.min_freq = min_pss_ctl * cpu->pstate.scaling;
-	}
-
-	if (turbo_absent)
-		policy->cpuinfo.max_freq = cpu->pstate.max_pstate *
-						cpu->pstate.scaling;
-	else {
-		policy->cpuinfo.max_freq = cpu->pstate.turbo_pstate *
-						cpu->pstate.scaling;
-		/*
-		 * The _PSS table doesn't contain whole turbo frequency range.
-		 * This just contains +1 MHZ above the max non turbo frequency,
-		 * with control value corresponding to max turbo ratio. But
-		 * when cpufreq set policy is called, it will call with this
-		 * max frequency, which will cause a reduced performance as
-		 * this driver uses real max turbo frequency as the max
-		 * frequeny. So correct this frequency in _PSS table to
-		 * correct max turbo frequency based on the turbo ratio.
-		 * Also need to convert to MHz as _PSS freq is in MHz.
-		 */
-		cpu->acpi_perf_data.states[0].core_frequency =
-						turbo_pss_ctl * 100;
-	}
-
-	pr_debug("intel_pstate: Updated limits using _PSS 0x%x 0x%x 0x%x\n",
-		 cpu->pstate.min_pstate, cpu->pstate.max_pstate,
-		 cpu->pstate.turbo_pstate);
-	pr_debug("intel_pstate: policy max_freq=%d Khz min_freq = %d KHz\n",
-		 policy->cpuinfo.max_freq, policy->cpuinfo.min_freq);
-
-	return 0;
-}
-
-static int intel_pstate_exit_perf_limits(struct cpufreq_policy *policy)
-{
-	struct cpudata *cpu;
-
-	if (!no_acpi_perf)
-		return 0;
-
-	cpu = all_cpu_data[policy->cpu];
-	acpi_processor_unregister_performance(policy->cpu);
-	return 0;
-}
-
-#else
-static int intel_pstate_init_perf_limits(struct cpufreq_policy *policy)
-{
-	return 0;
-}
-
-static int intel_pstate_exit_perf_limits(struct cpufreq_policy *policy)
-{
-	return 0;
-}
-#endif
-
 static inline void pid_reset(struct _pid *pid, int setpoint, int busy,
 			     int deadband, int integral) {
 	pid->setpoint = setpoint;
@@ -1303,30 +1148,18 @@ static int intel_pstate_cpu_init(struct cpufreq_policy *policy)
 	policy->cpuinfo.min_freq = cpu->pstate.min_pstate * cpu->pstate.scaling;
 	policy->cpuinfo.max_freq =
 		cpu->pstate.turbo_pstate * cpu->pstate.scaling;
-	if (!no_acpi_perf)
-		intel_pstate_init_perf_limits(policy);
-	/*
-	 * If there is no acpi perf data or error, we ignore and use Intel P
-	 * state calculated limits, So this is not fatal error.
-	 */
 	policy->cpuinfo.transition_latency = CPUFREQ_ETERNAL;
 	cpumask_set_cpu(policy->cpu, policy->cpus);
 
 	return 0;
 }
 
-static int intel_pstate_cpu_exit(struct cpufreq_policy *policy)
-{
-	return intel_pstate_exit_perf_limits(policy);
-}
-
 static struct cpufreq_driver intel_pstate_driver = {
 	.flags		= CPUFREQ_CONST_LOOPS,
 	.verify		= intel_pstate_verify_policy,
 	.setpolicy	= intel_pstate_set_policy,
 	.get		= intel_pstate_get,
 	.init		= intel_pstate_cpu_init,
-	.exit		= intel_pstate_cpu_exit,
 	.stop_cpu	= intel_pstate_stop_cpu,
 	.name		= "intel_pstate",
 };
@@ -1368,6 +1201,7 @@ static void copy_cpu_funcs(struct pstate_funcs *funcs)
 }
 
 #if IS_ENABLED(CONFIG_ACPI)
+#include <acpi/processor.h>
 
 static bool intel_pstate_no_acpi_pss(void)
 {
@@ -1563,9 +1397,6 @@ static int __init intel_pstate_setup(char *str)
 		force_load = 1;
 	if (!strcmp(str, "hwp_only"))
 		hwp_only = 1;
-	if (!strcmp(str, "no_acpi"))
-		no_acpi_perf = 1;
-
 	return 0;
 }
 early_param("intel_pstate", intel_pstate_setup);