cachepc-linux

Fork of AMDESE/linux with modifications for CachePC side-channel attack
git clone https://git.sinitax.com/sinitax/cachepc-linux
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amd_freq_sensitivity.c (4094B)

      1// SPDX-License-Identifier: GPL-2.0-only
      2/*
      3 * amd_freq_sensitivity.c: AMD frequency sensitivity feedback powersave bias
      4 *                         for the ondemand governor.
      5 *
      6 * Copyright (C) 2013 Advanced Micro Devices, Inc.
      7 *
      8 * Author: Jacob Shin <jacob.shin@amd.com>
      9 */
     10
     11#include <linux/kernel.h>
     12#include <linux/module.h>
     13#include <linux/types.h>
     14#include <linux/pci.h>
     15#include <linux/percpu-defs.h>
     16#include <linux/init.h>
     17#include <linux/mod_devicetable.h>
     18
     19#include <asm/msr.h>
     20#include <asm/cpufeature.h>
     21#include <asm/cpu_device_id.h>
     22
     23#include "cpufreq_ondemand.h"
     24
     25#define MSR_AMD64_FREQ_SENSITIVITY_ACTUAL	0xc0010080
     26#define MSR_AMD64_FREQ_SENSITIVITY_REFERENCE	0xc0010081
     27#define CLASS_CODE_SHIFT			56
     28#define POWERSAVE_BIAS_MAX			1000
     29#define POWERSAVE_BIAS_DEF			400
     30
     31struct cpu_data_t {
     32	u64 actual;
     33	u64 reference;
     34	unsigned int freq_prev;
     35};
     36
     37static DEFINE_PER_CPU(struct cpu_data_t, cpu_data);
     38
     39static unsigned int amd_powersave_bias_target(struct cpufreq_policy *policy,
     40					      unsigned int freq_next,
     41					      unsigned int relation)
     42{
     43	int sensitivity;
     44	long d_actual, d_reference;
     45	struct msr actual, reference;
     46	struct cpu_data_t *data = &per_cpu(cpu_data, policy->cpu);
     47	struct policy_dbs_info *policy_dbs = policy->governor_data;
     48	struct dbs_data *od_data = policy_dbs->dbs_data;
     49	struct od_dbs_tuners *od_tuners = od_data->tuners;
     50
     51	if (!policy->freq_table)
     52		return freq_next;
     53
     54	rdmsr_on_cpu(policy->cpu, MSR_AMD64_FREQ_SENSITIVITY_ACTUAL,
     55		&actual.l, &actual.h);
     56	rdmsr_on_cpu(policy->cpu, MSR_AMD64_FREQ_SENSITIVITY_REFERENCE,
     57		&reference.l, &reference.h);
     58	actual.h &= 0x00ffffff;
     59	reference.h &= 0x00ffffff;
     60
     61	/* counter wrapped around, so stay on current frequency */
     62	if (actual.q < data->actual || reference.q < data->reference) {
     63		freq_next = policy->cur;
     64		goto out;
     65	}
     66
     67	d_actual = actual.q - data->actual;
     68	d_reference = reference.q - data->reference;
     69
     70	/* divide by 0, so stay on current frequency as well */
     71	if (d_reference == 0) {
     72		freq_next = policy->cur;
     73		goto out;
     74	}
     75
     76	sensitivity = POWERSAVE_BIAS_MAX -
     77		(POWERSAVE_BIAS_MAX * (d_reference - d_actual) / d_reference);
     78
     79	clamp(sensitivity, 0, POWERSAVE_BIAS_MAX);
     80
     81	/* this workload is not CPU bound, so choose a lower freq */
     82	if (sensitivity < od_tuners->powersave_bias) {
     83		if (data->freq_prev == policy->cur)
     84			freq_next = policy->cur;
     85
     86		if (freq_next > policy->cur)
     87			freq_next = policy->cur;
     88		else if (freq_next < policy->cur)
     89			freq_next = policy->min;
     90		else {
     91			unsigned int index;
     92
     93			index = cpufreq_table_find_index_h(policy,
     94							   policy->cur - 1,
     95							   relation & CPUFREQ_RELATION_E);
     96			freq_next = policy->freq_table[index].frequency;
     97		}
     98
     99		data->freq_prev = freq_next;
    100	} else
    101		data->freq_prev = 0;
    102
    103out:
    104	data->actual = actual.q;
    105	data->reference = reference.q;
    106	return freq_next;
    107}
    108
    109static int __init amd_freq_sensitivity_init(void)
    110{
    111	u64 val;
    112	struct pci_dev *pcidev;
    113	unsigned int pci_vendor;
    114
    115	if (boot_cpu_data.x86_vendor == X86_VENDOR_AMD)
    116		pci_vendor = PCI_VENDOR_ID_AMD;
    117	else if (boot_cpu_data.x86_vendor == X86_VENDOR_HYGON)
    118		pci_vendor = PCI_VENDOR_ID_HYGON;
    119	else
    120		return -ENODEV;
    121
    122	pcidev = pci_get_device(pci_vendor,
    123			PCI_DEVICE_ID_AMD_KERNCZ_SMBUS, NULL);
    124
    125	if (!pcidev) {
    126		if (!boot_cpu_has(X86_FEATURE_PROC_FEEDBACK))
    127			return -ENODEV;
    128	}
    129
    130	if (rdmsrl_safe(MSR_AMD64_FREQ_SENSITIVITY_ACTUAL, &val))
    131		return -ENODEV;
    132
    133	if (!(val >> CLASS_CODE_SHIFT))
    134		return -ENODEV;
    135
    136	od_register_powersave_bias_handler(amd_powersave_bias_target,
    137			POWERSAVE_BIAS_DEF);
    138	return 0;
    139}
    140late_initcall(amd_freq_sensitivity_init);
    141
    142static void __exit amd_freq_sensitivity_exit(void)
    143{
    144	od_unregister_powersave_bias_handler();
    145}
    146module_exit(amd_freq_sensitivity_exit);
    147
    148static const struct x86_cpu_id __maybe_unused amd_freq_sensitivity_ids[] = {
    149	X86_MATCH_FEATURE(X86_FEATURE_PROC_FEEDBACK, NULL),
    150	{}
    151};
    152MODULE_DEVICE_TABLE(x86cpu, amd_freq_sensitivity_ids);
    153
    154MODULE_AUTHOR("Jacob Shin <jacob.shin@amd.com>");
    155MODULE_DESCRIPTION("AMD frequency sensitivity feedback powersave bias for "
    156		"the ondemand governor.");
    157MODULE_LICENSE("GPL");