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2a606a18cd
Add an optional callback needed by some PMU features, e.g., AMD BRS, to give a chance to the perf_events code to change its state before a CPU goes to low power and after it comes back. The callback is void when the PERF_NEEDS_LOPWR_CB flag is not set. This flag must be set in arch specific perf_event.h header whenever needed. When not set, there is no impact on the ACPI code. Signed-off-by: Stephane Eranian <eranian@google.com> [peterz: build fix] Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Link: https://lore.kernel.org/r/20220322221517.2510440-9-eranian@google.com
503 lines
12 KiB
C
503 lines
12 KiB
C
// SPDX-License-Identifier: GPL-2.0-only
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/*
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* acpi_pad.c ACPI Processor Aggregator Driver
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*
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* Copyright (c) 2009, Intel Corporation.
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*/
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#include <linux/kernel.h>
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#include <linux/cpumask.h>
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#include <linux/module.h>
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#include <linux/init.h>
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#include <linux/types.h>
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#include <linux/kthread.h>
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#include <uapi/linux/sched/types.h>
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#include <linux/freezer.h>
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#include <linux/cpu.h>
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#include <linux/tick.h>
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#include <linux/slab.h>
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#include <linux/acpi.h>
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#include <linux/perf_event.h>
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#include <asm/mwait.h>
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#include <xen/xen.h>
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#define ACPI_PROCESSOR_AGGREGATOR_CLASS "acpi_pad"
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#define ACPI_PROCESSOR_AGGREGATOR_DEVICE_NAME "Processor Aggregator"
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#define ACPI_PROCESSOR_AGGREGATOR_NOTIFY 0x80
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static DEFINE_MUTEX(isolated_cpus_lock);
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static DEFINE_MUTEX(round_robin_lock);
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static unsigned long power_saving_mwait_eax;
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static unsigned char tsc_detected_unstable;
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static unsigned char tsc_marked_unstable;
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static void power_saving_mwait_init(void)
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{
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unsigned int eax, ebx, ecx, edx;
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unsigned int highest_cstate = 0;
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unsigned int highest_subcstate = 0;
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int i;
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if (!boot_cpu_has(X86_FEATURE_MWAIT))
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return;
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if (boot_cpu_data.cpuid_level < CPUID_MWAIT_LEAF)
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return;
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cpuid(CPUID_MWAIT_LEAF, &eax, &ebx, &ecx, &edx);
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if (!(ecx & CPUID5_ECX_EXTENSIONS_SUPPORTED) ||
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!(ecx & CPUID5_ECX_INTERRUPT_BREAK))
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return;
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edx >>= MWAIT_SUBSTATE_SIZE;
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for (i = 0; i < 7 && edx; i++, edx >>= MWAIT_SUBSTATE_SIZE) {
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if (edx & MWAIT_SUBSTATE_MASK) {
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highest_cstate = i;
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highest_subcstate = edx & MWAIT_SUBSTATE_MASK;
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}
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}
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power_saving_mwait_eax = (highest_cstate << MWAIT_SUBSTATE_SIZE) |
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(highest_subcstate - 1);
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#if defined(CONFIG_X86)
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switch (boot_cpu_data.x86_vendor) {
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case X86_VENDOR_HYGON:
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case X86_VENDOR_AMD:
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case X86_VENDOR_INTEL:
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case X86_VENDOR_ZHAOXIN:
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/*
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* AMD Fam10h TSC will tick in all
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* C/P/S0/S1 states when this bit is set.
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*/
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if (!boot_cpu_has(X86_FEATURE_NONSTOP_TSC))
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tsc_detected_unstable = 1;
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break;
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default:
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/* TSC could halt in idle */
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tsc_detected_unstable = 1;
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}
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#endif
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}
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static unsigned long cpu_weight[NR_CPUS];
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static int tsk_in_cpu[NR_CPUS] = {[0 ... NR_CPUS-1] = -1};
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static DECLARE_BITMAP(pad_busy_cpus_bits, NR_CPUS);
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static void round_robin_cpu(unsigned int tsk_index)
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{
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struct cpumask *pad_busy_cpus = to_cpumask(pad_busy_cpus_bits);
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cpumask_var_t tmp;
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int cpu;
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unsigned long min_weight = -1;
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unsigned long preferred_cpu;
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if (!alloc_cpumask_var(&tmp, GFP_KERNEL))
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return;
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mutex_lock(&round_robin_lock);
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cpumask_clear(tmp);
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for_each_cpu(cpu, pad_busy_cpus)
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cpumask_or(tmp, tmp, topology_sibling_cpumask(cpu));
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cpumask_andnot(tmp, cpu_online_mask, tmp);
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/* avoid HT sibilings if possible */
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if (cpumask_empty(tmp))
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cpumask_andnot(tmp, cpu_online_mask, pad_busy_cpus);
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if (cpumask_empty(tmp)) {
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mutex_unlock(&round_robin_lock);
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free_cpumask_var(tmp);
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return;
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}
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for_each_cpu(cpu, tmp) {
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if (cpu_weight[cpu] < min_weight) {
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min_weight = cpu_weight[cpu];
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preferred_cpu = cpu;
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}
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}
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if (tsk_in_cpu[tsk_index] != -1)
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cpumask_clear_cpu(tsk_in_cpu[tsk_index], pad_busy_cpus);
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tsk_in_cpu[tsk_index] = preferred_cpu;
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cpumask_set_cpu(preferred_cpu, pad_busy_cpus);
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cpu_weight[preferred_cpu]++;
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mutex_unlock(&round_robin_lock);
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set_cpus_allowed_ptr(current, cpumask_of(preferred_cpu));
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free_cpumask_var(tmp);
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}
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static void exit_round_robin(unsigned int tsk_index)
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{
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struct cpumask *pad_busy_cpus = to_cpumask(pad_busy_cpus_bits);
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cpumask_clear_cpu(tsk_in_cpu[tsk_index], pad_busy_cpus);
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tsk_in_cpu[tsk_index] = -1;
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}
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static unsigned int idle_pct = 5; /* percentage */
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static unsigned int round_robin_time = 1; /* second */
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static int power_saving_thread(void *data)
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{
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int do_sleep;
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unsigned int tsk_index = (unsigned long)data;
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u64 last_jiffies = 0;
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sched_set_fifo_low(current);
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while (!kthread_should_stop()) {
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unsigned long expire_time;
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/* round robin to cpus */
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expire_time = last_jiffies + round_robin_time * HZ;
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if (time_before(expire_time, jiffies)) {
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last_jiffies = jiffies;
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round_robin_cpu(tsk_index);
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}
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do_sleep = 0;
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expire_time = jiffies + HZ * (100 - idle_pct) / 100;
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while (!need_resched()) {
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if (tsc_detected_unstable && !tsc_marked_unstable) {
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/* TSC could halt in idle, so notify users */
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mark_tsc_unstable("TSC halts in idle");
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tsc_marked_unstable = 1;
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}
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local_irq_disable();
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perf_lopwr_cb(true);
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tick_broadcast_enable();
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tick_broadcast_enter();
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stop_critical_timings();
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mwait_idle_with_hints(power_saving_mwait_eax, 1);
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start_critical_timings();
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tick_broadcast_exit();
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perf_lopwr_cb(false);
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local_irq_enable();
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if (time_before(expire_time, jiffies)) {
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do_sleep = 1;
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break;
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}
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}
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/*
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* current sched_rt has threshold for rt task running time.
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* When a rt task uses 95% CPU time, the rt thread will be
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* scheduled out for 5% CPU time to not starve other tasks. But
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* the mechanism only works when all CPUs have RT task running,
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* as if one CPU hasn't RT task, RT task from other CPUs will
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* borrow CPU time from this CPU and cause RT task use > 95%
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* CPU time. To make 'avoid starvation' work, takes a nap here.
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*/
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if (unlikely(do_sleep))
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schedule_timeout_killable(HZ * idle_pct / 100);
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/* If an external event has set the need_resched flag, then
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* we need to deal with it, or this loop will continue to
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* spin without calling __mwait().
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*/
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if (unlikely(need_resched()))
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schedule();
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}
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exit_round_robin(tsk_index);
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return 0;
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}
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static struct task_struct *ps_tsks[NR_CPUS];
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static unsigned int ps_tsk_num;
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static int create_power_saving_task(void)
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{
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int rc;
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ps_tsks[ps_tsk_num] = kthread_run(power_saving_thread,
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(void *)(unsigned long)ps_tsk_num,
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"acpi_pad/%d", ps_tsk_num);
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if (IS_ERR(ps_tsks[ps_tsk_num])) {
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rc = PTR_ERR(ps_tsks[ps_tsk_num]);
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ps_tsks[ps_tsk_num] = NULL;
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} else {
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rc = 0;
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ps_tsk_num++;
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}
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return rc;
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}
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static void destroy_power_saving_task(void)
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{
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if (ps_tsk_num > 0) {
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ps_tsk_num--;
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kthread_stop(ps_tsks[ps_tsk_num]);
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ps_tsks[ps_tsk_num] = NULL;
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}
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}
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static void set_power_saving_task_num(unsigned int num)
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{
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if (num > ps_tsk_num) {
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while (ps_tsk_num < num) {
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if (create_power_saving_task())
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return;
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}
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} else if (num < ps_tsk_num) {
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while (ps_tsk_num > num)
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destroy_power_saving_task();
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}
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}
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static void acpi_pad_idle_cpus(unsigned int num_cpus)
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{
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cpus_read_lock();
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num_cpus = min_t(unsigned int, num_cpus, num_online_cpus());
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set_power_saving_task_num(num_cpus);
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cpus_read_unlock();
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}
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static uint32_t acpi_pad_idle_cpus_num(void)
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{
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return ps_tsk_num;
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}
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static ssize_t rrtime_store(struct device *dev,
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struct device_attribute *attr, const char *buf, size_t count)
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{
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unsigned long num;
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if (kstrtoul(buf, 0, &num))
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return -EINVAL;
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if (num < 1 || num >= 100)
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return -EINVAL;
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mutex_lock(&isolated_cpus_lock);
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round_robin_time = num;
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mutex_unlock(&isolated_cpus_lock);
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return count;
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}
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static ssize_t rrtime_show(struct device *dev,
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struct device_attribute *attr, char *buf)
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{
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return scnprintf(buf, PAGE_SIZE, "%d\n", round_robin_time);
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}
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static DEVICE_ATTR_RW(rrtime);
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static ssize_t idlepct_store(struct device *dev,
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struct device_attribute *attr, const char *buf, size_t count)
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{
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unsigned long num;
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if (kstrtoul(buf, 0, &num))
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return -EINVAL;
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if (num < 1 || num >= 100)
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return -EINVAL;
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mutex_lock(&isolated_cpus_lock);
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idle_pct = num;
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mutex_unlock(&isolated_cpus_lock);
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return count;
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}
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static ssize_t idlepct_show(struct device *dev,
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struct device_attribute *attr, char *buf)
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{
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return scnprintf(buf, PAGE_SIZE, "%d\n", idle_pct);
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}
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static DEVICE_ATTR_RW(idlepct);
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static ssize_t idlecpus_store(struct device *dev,
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struct device_attribute *attr, const char *buf, size_t count)
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{
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unsigned long num;
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if (kstrtoul(buf, 0, &num))
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return -EINVAL;
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mutex_lock(&isolated_cpus_lock);
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acpi_pad_idle_cpus(num);
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mutex_unlock(&isolated_cpus_lock);
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return count;
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}
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static ssize_t idlecpus_show(struct device *dev,
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struct device_attribute *attr, char *buf)
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{
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return cpumap_print_to_pagebuf(false, buf,
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to_cpumask(pad_busy_cpus_bits));
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}
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static DEVICE_ATTR_RW(idlecpus);
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static int acpi_pad_add_sysfs(struct acpi_device *device)
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{
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int result;
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result = device_create_file(&device->dev, &dev_attr_idlecpus);
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if (result)
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return -ENODEV;
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result = device_create_file(&device->dev, &dev_attr_idlepct);
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if (result) {
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device_remove_file(&device->dev, &dev_attr_idlecpus);
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return -ENODEV;
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}
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result = device_create_file(&device->dev, &dev_attr_rrtime);
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if (result) {
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device_remove_file(&device->dev, &dev_attr_idlecpus);
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device_remove_file(&device->dev, &dev_attr_idlepct);
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return -ENODEV;
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}
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return 0;
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}
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static void acpi_pad_remove_sysfs(struct acpi_device *device)
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{
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device_remove_file(&device->dev, &dev_attr_idlecpus);
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device_remove_file(&device->dev, &dev_attr_idlepct);
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device_remove_file(&device->dev, &dev_attr_rrtime);
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}
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/*
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* Query firmware how many CPUs should be idle
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* return -1 on failure
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*/
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static int acpi_pad_pur(acpi_handle handle)
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{
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struct acpi_buffer buffer = {ACPI_ALLOCATE_BUFFER, NULL};
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union acpi_object *package;
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int num = -1;
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if (ACPI_FAILURE(acpi_evaluate_object(handle, "_PUR", NULL, &buffer)))
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return num;
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if (!buffer.length || !buffer.pointer)
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return num;
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package = buffer.pointer;
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if (package->type == ACPI_TYPE_PACKAGE &&
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package->package.count == 2 &&
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package->package.elements[0].integer.value == 1) /* rev 1 */
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num = package->package.elements[1].integer.value;
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kfree(buffer.pointer);
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return num;
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}
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static void acpi_pad_handle_notify(acpi_handle handle)
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{
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int num_cpus;
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uint32_t idle_cpus;
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struct acpi_buffer param = {
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.length = 4,
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.pointer = (void *)&idle_cpus,
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};
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mutex_lock(&isolated_cpus_lock);
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num_cpus = acpi_pad_pur(handle);
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if (num_cpus < 0) {
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mutex_unlock(&isolated_cpus_lock);
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return;
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}
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acpi_pad_idle_cpus(num_cpus);
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idle_cpus = acpi_pad_idle_cpus_num();
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acpi_evaluate_ost(handle, ACPI_PROCESSOR_AGGREGATOR_NOTIFY, 0, ¶m);
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mutex_unlock(&isolated_cpus_lock);
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}
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static void acpi_pad_notify(acpi_handle handle, u32 event,
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void *data)
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{
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struct acpi_device *device = data;
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switch (event) {
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case ACPI_PROCESSOR_AGGREGATOR_NOTIFY:
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acpi_pad_handle_notify(handle);
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acpi_bus_generate_netlink_event(device->pnp.device_class,
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dev_name(&device->dev), event, 0);
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break;
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default:
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pr_warn("Unsupported event [0x%x]\n", event);
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break;
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}
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}
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static int acpi_pad_add(struct acpi_device *device)
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{
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acpi_status status;
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strcpy(acpi_device_name(device), ACPI_PROCESSOR_AGGREGATOR_DEVICE_NAME);
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strcpy(acpi_device_class(device), ACPI_PROCESSOR_AGGREGATOR_CLASS);
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if (acpi_pad_add_sysfs(device))
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return -ENODEV;
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status = acpi_install_notify_handler(device->handle,
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ACPI_DEVICE_NOTIFY, acpi_pad_notify, device);
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if (ACPI_FAILURE(status)) {
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acpi_pad_remove_sysfs(device);
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return -ENODEV;
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}
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return 0;
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}
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static int acpi_pad_remove(struct acpi_device *device)
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{
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mutex_lock(&isolated_cpus_lock);
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acpi_pad_idle_cpus(0);
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mutex_unlock(&isolated_cpus_lock);
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acpi_remove_notify_handler(device->handle,
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ACPI_DEVICE_NOTIFY, acpi_pad_notify);
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acpi_pad_remove_sysfs(device);
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return 0;
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}
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static const struct acpi_device_id pad_device_ids[] = {
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{"ACPI000C", 0},
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{"", 0},
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};
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MODULE_DEVICE_TABLE(acpi, pad_device_ids);
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static struct acpi_driver acpi_pad_driver = {
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.name = "processor_aggregator",
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.class = ACPI_PROCESSOR_AGGREGATOR_CLASS,
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.ids = pad_device_ids,
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.ops = {
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.add = acpi_pad_add,
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.remove = acpi_pad_remove,
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},
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};
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static int __init acpi_pad_init(void)
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{
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/* Xen ACPI PAD is used when running as Xen Dom0. */
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if (xen_initial_domain())
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return -ENODEV;
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power_saving_mwait_init();
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if (power_saving_mwait_eax == 0)
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return -EINVAL;
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return acpi_bus_register_driver(&acpi_pad_driver);
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}
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static void __exit acpi_pad_exit(void)
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{
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acpi_bus_unregister_driver(&acpi_pad_driver);
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}
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module_init(acpi_pad_init);
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module_exit(acpi_pad_exit);
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MODULE_AUTHOR("Shaohua Li<shaohua.li@intel.com>");
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MODULE_DESCRIPTION("ACPI Processor Aggregator Driver");
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MODULE_LICENSE("GPL");
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