Merge tag 'for_linus' of git://git.kernel.org/pub/scm/linux/kernel/git/mst/vhost

[cris-mirror.git] / arch / powerpc / platforms / powernv / idle.c

/*
 * PowerNV cpuidle code
 *
 * Copyright 2015 IBM Corp.
 *
 * This program is free software; you can redistribute it and/or
 * modify it under the terms of the GNU General Public License
 * as published by the Free Software Foundation; either version
 * 2 of the License, or (at your option) any later version.
 */

#include <linux/types.h>
#include <linux/mm.h>
#include <linux/slab.h>
#include <linux/of.h>
#include <linux/device.h>
#include <linux/cpu.h>

#include <asm/firmware.h>
#include <asm/machdep.h>
#include <asm/opal.h>
#include <asm/cputhreads.h>
#include <asm/cpuidle.h>
#include <asm/code-patching.h>
#include <asm/smp.h>
#include <asm/runlatch.h>

#include "powernv.h"
#include "subcore.h"

/* Power ISA 3.0 allows for stop states 0x0 - 0xF */
#define MAX_STOP_STATE  0xF

#define P9_STOP_SPR_MSR 2000
#define P9_STOP_SPR_PSSCR      855

static u32 supported_cpuidle_states;

/*
 * The default stop state that will be used by ppc_md.power_save
 * function on platforms that support stop instruction.
 */
static u64 pnv_default_stop_val;
static u64 pnv_default_stop_mask;
static bool default_stop_found;

/*
 * First deep stop state. Used to figure out when to save/restore
 * hypervisor context.
 */
u64 pnv_first_deep_stop_state = MAX_STOP_STATE;

/*
 * psscr value and mask of the deepest stop idle state.
 * Used when a cpu is offlined.
 */
static u64 pnv_deepest_stop_psscr_val;
static u64 pnv_deepest_stop_psscr_mask;
static u64 pnv_deepest_stop_flag;
static bool deepest_stop_found;

static int pnv_save_sprs_for_deep_states(void)
{
        int cpu;
        int rc;

        /*
         * hid0, hid1, hid4, hid5, hmeer and lpcr values are symmetric across
         * all cpus at boot. Get these reg values of current cpu and use the
         * same across all cpus.
         */
        uint64_t lpcr_val = mfspr(SPRN_LPCR);
        uint64_t hid0_val = mfspr(SPRN_HID0);
        uint64_t hid1_val = mfspr(SPRN_HID1);
        uint64_t hid4_val = mfspr(SPRN_HID4);
        uint64_t hid5_val = mfspr(SPRN_HID5);
        uint64_t hmeer_val = mfspr(SPRN_HMEER);
        uint64_t msr_val = MSR_IDLE;
        uint64_t psscr_val = pnv_deepest_stop_psscr_val;

        for_each_possible_cpu(cpu) {
                uint64_t pir = get_hard_smp_processor_id(cpu);
                uint64_t hsprg0_val = (uint64_t)&paca[cpu];

                rc = opal_slw_set_reg(pir, SPRN_HSPRG0, hsprg0_val);
                if (rc != 0)
                        return rc;

                rc = opal_slw_set_reg(pir, SPRN_LPCR, lpcr_val);
                if (rc != 0)
                        return rc;

                if (cpu_has_feature(CPU_FTR_ARCH_300)) {
                        rc = opal_slw_set_reg(pir, P9_STOP_SPR_MSR, msr_val);
                        if (rc)
                                return rc;

                        rc = opal_slw_set_reg(pir,
                                              P9_STOP_SPR_PSSCR, psscr_val);

                        if (rc)
                                return rc;
                }

                /* HIDs are per core registers */
                if (cpu_thread_in_core(cpu) == 0) {

                        rc = opal_slw_set_reg(pir, SPRN_HMEER, hmeer_val);
                        if (rc != 0)
                                return rc;

                        rc = opal_slw_set_reg(pir, SPRN_HID0, hid0_val);
                        if (rc != 0)
                                return rc;

                        /* Only p8 needs to set extra HID regiters */
                        if (!cpu_has_feature(CPU_FTR_ARCH_300)) {

                                rc = opal_slw_set_reg(pir, SPRN_HID1, hid1_val);
                                if (rc != 0)
                                        return rc;

                                rc = opal_slw_set_reg(pir, SPRN_HID4, hid4_val);
                                if (rc != 0)
                                        return rc;

                                rc = opal_slw_set_reg(pir, SPRN_HID5, hid5_val);
                                if (rc != 0)
                                        return rc;
                        }
                }
        }

        return 0;
}

static void pnv_alloc_idle_core_states(void)
{
        int i, j;
        int nr_cores = cpu_nr_cores();
        u32 *core_idle_state;

        /*
         * core_idle_state - The lower 8 bits track the idle state of
         * each thread of the core.
         *
         * The most significant bit is the lock bit.
         *
         * Initially all the bits corresponding to threads_per_core
         * are set. They are cleared when the thread enters deep idle
         * state like sleep and winkle/stop.
         *
         * Initially the lock bit is cleared.  The lock bit has 2
         * purposes:
         *      a. While the first thread in the core waking up from
         *         idle is restoring core state, it prevents other
         *         threads in the core from switching to process
         *         context.
         *      b. While the last thread in the core is saving the
         *         core state, it prevents a different thread from
         *         waking up.
         */
        for (i = 0; i < nr_cores; i++) {
                int first_cpu = i * threads_per_core;
                int node = cpu_to_node(first_cpu);
                size_t paca_ptr_array_size;

                core_idle_state = kmalloc_node(sizeof(u32), GFP_KERNEL, node);
                *core_idle_state = (1 << threads_per_core) - 1;
                paca_ptr_array_size = (threads_per_core *
                                       sizeof(struct paca_struct *));

                for (j = 0; j < threads_per_core; j++) {
                        int cpu = first_cpu + j;

                        paca[cpu].core_idle_state_ptr = core_idle_state;
                        paca[cpu].thread_idle_state = PNV_THREAD_RUNNING;
                        paca[cpu].thread_mask = 1 << j;
                        if (!cpu_has_feature(CPU_FTR_POWER9_DD1))
                                continue;
                        paca[cpu].thread_sibling_pacas =
                                kmalloc_node(paca_ptr_array_size,
                                             GFP_KERNEL, node);
                }
        }

        update_subcore_sibling_mask();

        if (supported_cpuidle_states & OPAL_PM_LOSE_FULL_CONTEXT) {
                int rc = pnv_save_sprs_for_deep_states();

                if (likely(!rc))
                        return;

                /*
                 * The stop-api is unable to restore hypervisor
                 * resources on wakeup from platform idle states which
                 * lose full context. So disable such states.
                 */
                supported_cpuidle_states &= ~OPAL_PM_LOSE_FULL_CONTEXT;
                pr_warn("cpuidle-powernv: Disabling idle states that lose full context\n");
                pr_warn("cpuidle-powernv: Idle power-savings, CPU-Hotplug affected\n");

                if (cpu_has_feature(CPU_FTR_ARCH_300) &&
                    (pnv_deepest_stop_flag & OPAL_PM_LOSE_FULL_CONTEXT)) {
                        /*
                         * Use the default stop state for CPU-Hotplug
                         * if available.
                         */
                        if (default_stop_found) {
                                pnv_deepest_stop_psscr_val =
                                        pnv_default_stop_val;
                                pnv_deepest_stop_psscr_mask =
                                        pnv_default_stop_mask;
                                pr_warn("cpuidle-powernv: Offlined CPUs will stop with psscr = 0x%016llx\n",
                                        pnv_deepest_stop_psscr_val);
                        } else { /* Fallback to snooze loop for CPU-Hotplug */
                                deepest_stop_found = false;
                                pr_warn("cpuidle-powernv: Offlined CPUs will busy wait\n");
                        }
                }
        }
}

u32 pnv_get_supported_cpuidle_states(void)
{
        return supported_cpuidle_states;
}
EXPORT_SYMBOL_GPL(pnv_get_supported_cpuidle_states);

static void pnv_fastsleep_workaround_apply(void *info)

{
        int rc;
        int *err = info;

        rc = opal_config_cpu_idle_state(OPAL_CONFIG_IDLE_FASTSLEEP,
                                        OPAL_CONFIG_IDLE_APPLY);
        if (rc)
                *err = 1;
}

/*
 * Used to store fastsleep workaround state
 * 0 - Workaround applied/undone at fastsleep entry/exit path (Default)
 * 1 - Workaround applied once, never undone.
 */
static u8 fastsleep_workaround_applyonce;

static ssize_t show_fastsleep_workaround_applyonce(struct device *dev,
                struct device_attribute *attr, char *buf)
{
        return sprintf(buf, "%u\n", fastsleep_workaround_applyonce);
}

static ssize_t store_fastsleep_workaround_applyonce(struct device *dev,
                struct device_attribute *attr, const char *buf,
                size_t count)
{
        cpumask_t primary_thread_mask;
        int err;
        u8 val;

        if (kstrtou8(buf, 0, &val) || val != 1)
                return -EINVAL;

        if (fastsleep_workaround_applyonce == 1)
                return count;

        /*
         * fastsleep_workaround_applyonce = 1 implies
         * fastsleep workaround needs to be left in 'applied' state on all
         * the cores. Do this by-
         * 1. Patching out the call to 'undo' workaround in fastsleep exit path
         * 2. Sending ipi to all the cores which have at least one online thread
         * 3. Patching out the call to 'apply' workaround in fastsleep entry
         * path
         * There is no need to send ipi to cores which have all threads
         * offlined, as last thread of the core entering fastsleep or deeper
         * state would have applied workaround.
         */
        err = patch_instruction(
                (unsigned int *)pnv_fastsleep_workaround_at_exit,
                PPC_INST_NOP);
        if (err) {
                pr_err("fastsleep_workaround_applyonce change failed while patching pnv_fastsleep_workaround_at_exit");
                goto fail;
        }

        get_online_cpus();
        primary_thread_mask = cpu_online_cores_map();
        on_each_cpu_mask(&primary_thread_mask,
                                pnv_fastsleep_workaround_apply,
                                &err, 1);
        put_online_cpus();
        if (err) {
                pr_err("fastsleep_workaround_applyonce change failed while running pnv_fastsleep_workaround_apply");
                goto fail;
        }

        err = patch_instruction(
                (unsigned int *)pnv_fastsleep_workaround_at_entry,
                PPC_INST_NOP);
        if (err) {
                pr_err("fastsleep_workaround_applyonce change failed while patching pnv_fastsleep_workaround_at_entry");
                goto fail;
        }

        fastsleep_workaround_applyonce = 1;

        return count;
fail:
        return -EIO;
}

static DEVICE_ATTR(fastsleep_workaround_applyonce, 0600,
                        show_fastsleep_workaround_applyonce,
                        store_fastsleep_workaround_applyonce);

static unsigned long __power7_idle_type(unsigned long type)
{
        unsigned long srr1;

        if (!prep_irq_for_idle_irqsoff())
                return 0;

        __ppc64_runlatch_off();
        srr1 = power7_idle_insn(type);
        __ppc64_runlatch_on();

        fini_irq_for_idle_irqsoff();

        return srr1;
}

void power7_idle_type(unsigned long type)
{
        unsigned long srr1;

        srr1 = __power7_idle_type(type);
        irq_set_pending_from_srr1(srr1);
}

void power7_idle(void)
{
        if (!powersave_nap)
                return;

        power7_idle_type(PNV_THREAD_NAP);
}

static unsigned long __power9_idle_type(unsigned long stop_psscr_val,
                                      unsigned long stop_psscr_mask)
{
        unsigned long psscr;
        unsigned long srr1;

        if (!prep_irq_for_idle_irqsoff())
                return 0;

        psscr = mfspr(SPRN_PSSCR);
        psscr = (psscr & ~stop_psscr_mask) | stop_psscr_val;

        __ppc64_runlatch_off();
        srr1 = power9_idle_stop(psscr);
        __ppc64_runlatch_on();

        fini_irq_for_idle_irqsoff();

        return srr1;
}

void power9_idle_type(unsigned long stop_psscr_val,
                                      unsigned long stop_psscr_mask)
{
        unsigned long srr1;

        srr1 = __power9_idle_type(stop_psscr_val, stop_psscr_mask);
        irq_set_pending_from_srr1(srr1);
}

/*
 * Used for ppc_md.power_save which needs a function with no parameters
 */
void power9_idle(void)
{
        power9_idle_type(pnv_default_stop_val, pnv_default_stop_mask);
}

#ifdef CONFIG_HOTPLUG_CPU
static void pnv_program_cpu_hotplug_lpcr(unsigned int cpu, u64 lpcr_val)
{
        u64 pir = get_hard_smp_processor_id(cpu);

        mtspr(SPRN_LPCR, lpcr_val);

        /*
         * Program the LPCR via stop-api only if the deepest stop state
         * can lose hypervisor context.
         */
        if (supported_cpuidle_states & OPAL_PM_LOSE_FULL_CONTEXT)
                opal_slw_set_reg(pir, SPRN_LPCR, lpcr_val);
}

/*
 * pnv_cpu_offline: A function that puts the CPU into the deepest
 * available platform idle state on a CPU-Offline.
 * interrupts hard disabled and no lazy irq pending.
 */
unsigned long pnv_cpu_offline(unsigned int cpu)
{
        unsigned long srr1;
        u32 idle_states = pnv_get_supported_cpuidle_states();
        u64 lpcr_val;

        /*
         * We don't want to take decrementer interrupts while we are
         * offline, so clear LPCR:PECE1. We keep PECE2 (and
         * LPCR_PECE_HVEE on P9) enabled as to let IPIs in.
         *
         * If the CPU gets woken up by a special wakeup, ensure that
         * the SLW engine sets LPCR with decrementer bit cleared, else
         * the CPU will come back to the kernel due to a spurious
         * wakeup.
         */
        lpcr_val = mfspr(SPRN_LPCR) & ~(u64)LPCR_PECE1;
        pnv_program_cpu_hotplug_lpcr(cpu, lpcr_val);

        __ppc64_runlatch_off();

        if (cpu_has_feature(CPU_FTR_ARCH_300) && deepest_stop_found) {
                unsigned long psscr;

                psscr = mfspr(SPRN_PSSCR);
                psscr = (psscr & ~pnv_deepest_stop_psscr_mask) |
                                                pnv_deepest_stop_psscr_val;
                srr1 = power9_idle_stop(psscr);

        } else if ((idle_states & OPAL_PM_WINKLE_ENABLED) &&
                   (idle_states & OPAL_PM_LOSE_FULL_CONTEXT)) {
                srr1 = power7_idle_insn(PNV_THREAD_WINKLE);
        } else if ((idle_states & OPAL_PM_SLEEP_ENABLED) ||
                   (idle_states & OPAL_PM_SLEEP_ENABLED_ER1)) {
                srr1 = power7_idle_insn(PNV_THREAD_SLEEP);
        } else if (idle_states & OPAL_PM_NAP_ENABLED) {
                srr1 = power7_idle_insn(PNV_THREAD_NAP);
        } else {
                /* This is the fallback method. We emulate snooze */
                while (!generic_check_cpu_restart(cpu)) {
                        HMT_low();
                        HMT_very_low();
                }
                srr1 = 0;
                HMT_medium();
        }

        __ppc64_runlatch_on();

        /*
         * Re-enable decrementer interrupts in LPCR.
         *
         * Further, we want stop states to be woken up by decrementer
         * for non-hotplug cases. So program the LPCR via stop api as
         * well.
         */
        lpcr_val = mfspr(SPRN_LPCR) | (u64)LPCR_PECE1;
        pnv_program_cpu_hotplug_lpcr(cpu, lpcr_val);

        return srr1;
}
#endif

/*
 * Power ISA 3.0 idle initialization.
 *
 * POWER ISA 3.0 defines a new SPR Processor stop Status and Control
 * Register (PSSCR) to control idle behavior.
 *
 * PSSCR layout:
 * ----------------------------------------------------------
 * | PLS | /// | SD | ESL | EC | PSLL | /// | TR | MTL | RL |
 * ----------------------------------------------------------
 * 0      4     41   42    43   44     48    54   56    60
 *
 * PSSCR key fields:
 *      Bits 0:3  - Power-Saving Level Status (PLS). This field indicates the
 *      lowest power-saving state the thread entered since stop instruction was
 *      last executed.
 *
 *      Bit 41 - Status Disable(SD)
 *      0 - Shows PLS entries
 *      1 - PLS entries are all 0
 *
 *      Bit 42 - Enable State Loss
 *      0 - No state is lost irrespective of other fields
 *      1 - Allows state loss
 *
 *      Bit 43 - Exit Criterion
 *      0 - Exit from power-save mode on any interrupt
 *      1 - Exit from power-save mode controlled by LPCR's PECE bits
 *
 *      Bits 44:47 - Power-Saving Level Limit
 *      This limits the power-saving level that can be entered into.
 *
 *      Bits 60:63 - Requested Level
 *      Used to specify which power-saving level must be entered on executing
 *      stop instruction
 */

int validate_psscr_val_mask(u64 *psscr_val, u64 *psscr_mask, u32 flags)
{
        int err = 0;

        /*
         * psscr_mask == 0xf indicates an older firmware.
         * Set remaining fields of psscr to the default values.
         * See NOTE above definition of PSSCR_HV_DEFAULT_VAL
         */
        if (*psscr_mask == 0xf) {
                *psscr_val = *psscr_val | PSSCR_HV_DEFAULT_VAL;
                *psscr_mask = PSSCR_HV_DEFAULT_MASK;
                return err;
        }

        /*
         * New firmware is expected to set the psscr_val bits correctly.
         * Validate that the following invariants are correctly maintained by
         * the new firmware.
         * - ESL bit value matches the EC bit value.
         * - ESL bit is set for all the deep stop states.
         */
        if (GET_PSSCR_ESL(*psscr_val) != GET_PSSCR_EC(*psscr_val)) {
                err = ERR_EC_ESL_MISMATCH;
        } else if ((flags & OPAL_PM_LOSE_FULL_CONTEXT) &&
                GET_PSSCR_ESL(*psscr_val) == 0) {
                err = ERR_DEEP_STATE_ESL_MISMATCH;
        }

        return err;
}

/*
 * pnv_arch300_idle_init: Initializes the default idle state, first
 *                        deep idle state and deepest idle state on
 *                        ISA 3.0 CPUs.
 *
 * @np: /ibm,opal/power-mgt device node
 * @flags: cpu-idle-state-flags array
 * @dt_idle_states: Number of idle state entries
 * Returns 0 on success
 */
static int __init pnv_power9_idle_init(struct device_node *np, u32 *flags,
                                        int dt_idle_states)
{
        u64 *psscr_val = NULL;
        u64 *psscr_mask = NULL;
        u32 *residency_ns = NULL;
        u64 max_residency_ns = 0;
        int rc = 0, i;

        psscr_val = kcalloc(dt_idle_states, sizeof(*psscr_val), GFP_KERNEL);
        psscr_mask = kcalloc(dt_idle_states, sizeof(*psscr_mask), GFP_KERNEL);
        residency_ns = kcalloc(dt_idle_states, sizeof(*residency_ns),
                               GFP_KERNEL);

        if (!psscr_val || !psscr_mask || !residency_ns) {
                rc = -1;
                goto out;
        }

        if (of_property_read_u64_array(np,
                "ibm,cpu-idle-state-psscr",
                psscr_val, dt_idle_states)) {
                pr_warn("cpuidle-powernv: missing ibm,cpu-idle-state-psscr in DT\n");
                rc = -1;
                goto out;
        }

        if (of_property_read_u64_array(np,
                                       "ibm,cpu-idle-state-psscr-mask",
                                       psscr_mask, dt_idle_states)) {
                pr_warn("cpuidle-powernv: missing ibm,cpu-idle-state-psscr-mask in DT\n");
                rc = -1;
                goto out;
        }

        if (of_property_read_u32_array(np,
                                       "ibm,cpu-idle-state-residency-ns",
                                        residency_ns, dt_idle_states)) {
                pr_warn("cpuidle-powernv: missing ibm,cpu-idle-state-residency-ns in DT\n");
                rc = -1;
                goto out;
        }

        /*
         * Set pnv_first_deep_stop_state, pnv_deepest_stop_psscr_{val,mask},
         * and the pnv_default_stop_{val,mask}.
         *
         * pnv_first_deep_stop_state should be set to the first stop
         * level to cause hypervisor state loss.
         *
         * pnv_deepest_stop_{val,mask} should be set to values corresponding to
         * the deepest stop state.
         *
         * pnv_default_stop_{val,mask} should be set to values corresponding to
         * the shallowest (OPAL_PM_STOP_INST_FAST) loss-less stop state.
         */
        pnv_first_deep_stop_state = MAX_STOP_STATE;
        for (i = 0; i < dt_idle_states; i++) {
                int err;
                u64 psscr_rl = psscr_val[i] & PSSCR_RL_MASK;

                if ((flags[i] & OPAL_PM_LOSE_FULL_CONTEXT) &&
                     (pnv_first_deep_stop_state > psscr_rl))
                        pnv_first_deep_stop_state = psscr_rl;

                err = validate_psscr_val_mask(&psscr_val[i], &psscr_mask[i],
                                              flags[i]);
                if (err) {
                        report_invalid_psscr_val(psscr_val[i], err);
                        continue;
                }

                if (max_residency_ns < residency_ns[i]) {
                        max_residency_ns = residency_ns[i];
                        pnv_deepest_stop_psscr_val = psscr_val[i];
                        pnv_deepest_stop_psscr_mask = psscr_mask[i];
                        pnv_deepest_stop_flag = flags[i];
                        deepest_stop_found = true;
                }

                if (!default_stop_found &&
                    (flags[i] & OPAL_PM_STOP_INST_FAST)) {
                        pnv_default_stop_val = psscr_val[i];
                        pnv_default_stop_mask = psscr_mask[i];
                        default_stop_found = true;
                }
        }

        if (unlikely(!default_stop_found)) {
                pr_warn("cpuidle-powernv: No suitable default stop state found. Disabling platform idle.\n");
        } else {
                ppc_md.power_save = power9_idle;
                pr_info("cpuidle-powernv: Default stop: psscr = 0x%016llx,mask=0x%016llx\n",
                        pnv_default_stop_val, pnv_default_stop_mask);
        }

        if (unlikely(!deepest_stop_found)) {
                pr_warn("cpuidle-powernv: No suitable stop state for CPU-Hotplug. Offlined CPUs will busy wait");
        } else {
                pr_info("cpuidle-powernv: Deepest stop: psscr = 0x%016llx,mask=0x%016llx\n",
                        pnv_deepest_stop_psscr_val,
                        pnv_deepest_stop_psscr_mask);
        }

        pr_info("cpuidle-powernv: Requested Level (RL) value of first deep stop = 0x%llx\n",
                pnv_first_deep_stop_state);
out:
        kfree(psscr_val);
        kfree(psscr_mask);
        kfree(residency_ns);
        return rc;
}

/*
 * Probe device tree for supported idle states
 */
static void __init pnv_probe_idle_states(void)
{
        struct device_node *np;
        int dt_idle_states;
        u32 *flags = NULL;
        int i;

        np = of_find_node_by_path("/ibm,opal/power-mgt");
        if (!np) {
                pr_warn("opal: PowerMgmt Node not found\n");
                goto out;
        }
        dt_idle_states = of_property_count_u32_elems(np,
                        "ibm,cpu-idle-state-flags");
        if (dt_idle_states < 0) {
                pr_warn("cpuidle-powernv: no idle states found in the DT\n");
                goto out;
        }

        flags = kcalloc(dt_idle_states, sizeof(*flags),  GFP_KERNEL);

        if (of_property_read_u32_array(np,
                        "ibm,cpu-idle-state-flags", flags, dt_idle_states)) {
                pr_warn("cpuidle-powernv: missing ibm,cpu-idle-state-flags in DT\n");
                goto out;
        }

        if (cpu_has_feature(CPU_FTR_ARCH_300)) {
                if (pnv_power9_idle_init(np, flags, dt_idle_states))
                        goto out;
        }

        for (i = 0; i < dt_idle_states; i++)
                supported_cpuidle_states |= flags[i];

out:
        kfree(flags);
}
static int __init pnv_init_idle_states(void)
{

        supported_cpuidle_states = 0;

        if (cpuidle_disable != IDLE_NO_OVERRIDE)
                goto out;

        pnv_probe_idle_states();

        if (!(supported_cpuidle_states & OPAL_PM_SLEEP_ENABLED_ER1)) {
                patch_instruction(
                        (unsigned int *)pnv_fastsleep_workaround_at_entry,
                        PPC_INST_NOP);
                patch_instruction(
                        (unsigned int *)pnv_fastsleep_workaround_at_exit,
                        PPC_INST_NOP);
        } else {
                /*
                 * OPAL_PM_SLEEP_ENABLED_ER1 is set. It indicates that
                 * workaround is needed to use fastsleep. Provide sysfs
                 * control to choose how this workaround has to be applied.
                 */
                device_create_file(cpu_subsys.dev_root,
                                &dev_attr_fastsleep_workaround_applyonce);
        }

        pnv_alloc_idle_core_states();

        /*
         * For each CPU, record its PACA address in each of it's
         * sibling thread's PACA at the slot corresponding to this
         * CPU's index in the core.
         */
        if (cpu_has_feature(CPU_FTR_POWER9_DD1)) {
                int cpu;

                pr_info("powernv: idle: Saving PACA pointers of all CPUs in their thread sibling PACA\n");
                for_each_possible_cpu(cpu) {
                        int base_cpu = cpu_first_thread_sibling(cpu);
                        int idx = cpu_thread_in_core(cpu);
                        int i;

                        for (i = 0; i < threads_per_core; i++) {
                                int j = base_cpu + i;

                                paca[j].thread_sibling_pacas[idx] = &paca[cpu];
                        }
                }
        }

        if (supported_cpuidle_states & OPAL_PM_NAP_ENABLED)
                ppc_md.power_save = power7_idle;

out:
        return 0;
}
machine_subsys_initcall(powernv, pnv_init_idle_states);