qemu/target/riscv/pmu.c

/*
 * RISC-V PMU file.
 *
 * Copyright (c) 2021 Western Digital Corporation or its affiliates.
 *
 * This program is free software; you can redistribute it and/or modify it
 * under the terms and conditions of the GNU General Public License,
 * version 2 or later, as published by the Free Software Foundation.
 *
 * This program is distributed in the hope it will be useful, but WITHOUT
 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
 * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License for
 * more details.
 *
 * You should have received a copy of the GNU General Public License along with
 * this program.  If not, see <http://www.gnu.org/licenses/>.
 */

#include "qemu/osdep.h"
#include "cpu.h"
#include "pmu.h"
#include "sysemu/cpu-timers.h"

#define RISCV_TIMEBASE_FREQ 1000000000 /* 1Ghz */
#define MAKE_32BIT_MASK(shift, length) \
        (((uint32_t)(~0UL) >> (32 - (length))) << (shift))

static bool riscv_pmu_counter_valid(RISCVCPU *cpu, uint32_t ctr_idx)
{
    if (ctr_idx < 3 || ctr_idx >= RV_MAX_MHPMCOUNTERS ||
        !(cpu->pmu_avail_ctrs & BIT(ctr_idx))) {
        return false;
    } else {
        return true;
    }
}

static bool riscv_pmu_counter_enabled(RISCVCPU *cpu, uint32_t ctr_idx)
{
    CPURISCVState *env = &cpu->env;

    if (riscv_pmu_counter_valid(cpu, ctr_idx) &&
        !get_field(env->mcountinhibit, BIT(ctr_idx))) {
        return true;
    } else {
        return false;
    }
}

static int riscv_pmu_incr_ctr_rv32(RISCVCPU *cpu, uint32_t ctr_idx)
{
    CPURISCVState *env = &cpu->env;
    target_ulong max_val = UINT32_MAX;
    PMUCTRState *counter = &env->pmu_ctrs[ctr_idx];
    bool virt_on = riscv_cpu_virt_enabled(env);

    /* Privilege mode filtering */
    if ((env->priv == PRV_M &&
        (env->mhpmeventh_val[ctr_idx] & MHPMEVENTH_BIT_MINH)) ||
        (env->priv == PRV_S && virt_on &&
        (env->mhpmeventh_val[ctr_idx] & MHPMEVENTH_BIT_VSINH)) ||
        (env->priv == PRV_U && virt_on &&
        (env->mhpmeventh_val[ctr_idx] & MHPMEVENTH_BIT_VUINH)) ||
        (env->priv == PRV_S && !virt_on &&
        (env->mhpmeventh_val[ctr_idx] & MHPMEVENTH_BIT_SINH)) ||
        (env->priv == PRV_U && !virt_on &&
        (env->mhpmeventh_val[ctr_idx] & MHPMEVENTH_BIT_UINH))) {
        return 0;
    }

    /* Handle the overflow scenario */
    if (counter->mhpmcounter_val == max_val) {
        if (counter->mhpmcounterh_val == max_val) {
            counter->mhpmcounter_val = 0;
            counter->mhpmcounterh_val = 0;
            /* Generate interrupt only if OF bit is clear */
            if (!(env->mhpmeventh_val[ctr_idx] & MHPMEVENTH_BIT_OF)) {
                env->mhpmeventh_val[ctr_idx] |= MHPMEVENTH_BIT_OF;
                riscv_cpu_update_mip(cpu, MIP_LCOFIP, BOOL_TO_MASK(1));
            }
        } else {
            counter->mhpmcounterh_val++;
        }
    } else {
        counter->mhpmcounter_val++;
    }

    return 0;
}

static int riscv_pmu_incr_ctr_rv64(RISCVCPU *cpu, uint32_t ctr_idx)
{
    CPURISCVState *env = &cpu->env;
    PMUCTRState *counter = &env->pmu_ctrs[ctr_idx];
    uint64_t max_val = UINT64_MAX;
    bool virt_on = riscv_cpu_virt_enabled(env);

    /* Privilege mode filtering */
    if ((env->priv == PRV_M &&
        (env->mhpmevent_val[ctr_idx] & MHPMEVENT_BIT_MINH)) ||
        (env->priv == PRV_S && virt_on &&
        (env->mhpmevent_val[ctr_idx] & MHPMEVENT_BIT_VSINH)) ||
        (env->priv == PRV_U && virt_on &&
        (env->mhpmevent_val[ctr_idx] & MHPMEVENT_BIT_VUINH)) ||
        (env->priv == PRV_S && !virt_on &&
        (env->mhpmevent_val[ctr_idx] & MHPMEVENT_BIT_SINH)) ||
        (env->priv == PRV_U && !virt_on &&
        (env->mhpmevent_val[ctr_idx] & MHPMEVENT_BIT_UINH))) {
        return 0;
    }

    /* Handle the overflow scenario */
    if (counter->mhpmcounter_val == max_val) {
        counter->mhpmcounter_val = 0;
        /* Generate interrupt only if OF bit is clear */
        if (!(env->mhpmevent_val[ctr_idx] & MHPMEVENT_BIT_OF)) {
            env->mhpmevent_val[ctr_idx] |= MHPMEVENT_BIT_OF;
            riscv_cpu_update_mip(cpu, MIP_LCOFIP, BOOL_TO_MASK(1));
        }
    } else {
        counter->mhpmcounter_val++;
    }
    return 0;
}

int riscv_pmu_incr_ctr(RISCVCPU *cpu, enum riscv_pmu_event_idx event_idx)
{
    uint32_t ctr_idx;
    int ret;
    CPURISCVState *env = &cpu->env;
    gpointer value;

    if (!cpu->cfg.pmu_num) {
        return 0;
    }
    value = g_hash_table_lookup(cpu->pmu_event_ctr_map,
                                GUINT_TO_POINTER(event_idx));
    if (!value) {
        return -1;
    }

    ctr_idx = GPOINTER_TO_UINT(value);
    if (!riscv_pmu_counter_enabled(cpu, ctr_idx) ||
        get_field(env->mcountinhibit, BIT(ctr_idx))) {
        return -1;
    }

    if (riscv_cpu_mxl(env) == MXL_RV32) {
        ret = riscv_pmu_incr_ctr_rv32(cpu, ctr_idx);
    } else {
        ret = riscv_pmu_incr_ctr_rv64(cpu, ctr_idx);
    }

    return ret;
}

bool riscv_pmu_ctr_monitor_instructions(CPURISCVState *env,
                                        uint32_t target_ctr)
{
    RISCVCPU *cpu;
    uint32_t event_idx;
    uint32_t ctr_idx;

    /* Fixed instret counter */
    if (target_ctr == 2) {
        return true;
    }

    cpu = RISCV_CPU(env_cpu(env));
    if (!cpu->pmu_event_ctr_map) {
        return false;
    }

    event_idx = RISCV_PMU_EVENT_HW_INSTRUCTIONS;
    ctr_idx = GPOINTER_TO_UINT(g_hash_table_lookup(cpu->pmu_event_ctr_map,
                               GUINT_TO_POINTER(event_idx)));
    if (!ctr_idx) {
        return false;
    }

    return target_ctr == ctr_idx ? true : false;
}

bool riscv_pmu_ctr_monitor_cycles(CPURISCVState *env, uint32_t target_ctr)
{
    RISCVCPU *cpu;
    uint32_t event_idx;
    uint32_t ctr_idx;

    /* Fixed mcycle counter */
    if (target_ctr == 0) {
        return true;
    }

    cpu = RISCV_CPU(env_cpu(env));
    if (!cpu->pmu_event_ctr_map) {
        return false;
    }

    event_idx = RISCV_PMU_EVENT_HW_CPU_CYCLES;
    ctr_idx = GPOINTER_TO_UINT(g_hash_table_lookup(cpu->pmu_event_ctr_map,
                               GUINT_TO_POINTER(event_idx)));

    /* Counter zero is not used for event_ctr_map */
    if (!ctr_idx) {
        return false;
    }

    return (target_ctr == ctr_idx) ? true : false;
}

static gboolean pmu_remove_event_map(gpointer key, gpointer value,
                                     gpointer udata)
{
    return (GPOINTER_TO_UINT(value) == GPOINTER_TO_UINT(udata)) ? true : false;
}

static int64_t pmu_icount_ticks_to_ns(int64_t value)
{
    int64_t ret = 0;

    if (icount_enabled()) {
        ret = icount_to_ns(value);
    } else {
        ret = (NANOSECONDS_PER_SECOND / RISCV_TIMEBASE_FREQ) * value;
    }

    return ret;
}

int riscv_pmu_update_event_map(CPURISCVState *env, uint64_t value,
                               uint32_t ctr_idx)
{
    uint32_t event_idx;
    RISCVCPU *cpu = RISCV_CPU(env_cpu(env));

    if (!riscv_pmu_counter_valid(cpu, ctr_idx) || !cpu->pmu_event_ctr_map) {
        return -1;
    }

    /*
     * Expected mhpmevent value is zero for reset case. Remove the current
     * mapping.
     */
    if (!value) {
        g_hash_table_foreach_remove(cpu->pmu_event_ctr_map,
                                    pmu_remove_event_map,
                                    GUINT_TO_POINTER(ctr_idx));
        return 0;
    }

    event_idx = value & MHPMEVENT_IDX_MASK;
    if (g_hash_table_lookup(cpu->pmu_event_ctr_map,
                            GUINT_TO_POINTER(event_idx))) {
        return 0;
    }

    switch (event_idx) {
    case RISCV_PMU_EVENT_HW_CPU_CYCLES:
    case RISCV_PMU_EVENT_HW_INSTRUCTIONS:
    case RISCV_PMU_EVENT_CACHE_DTLB_READ_MISS:
    case RISCV_PMU_EVENT_CACHE_DTLB_WRITE_MISS:
    case RISCV_PMU_EVENT_CACHE_ITLB_PREFETCH_MISS:
        break;
    default:
        /* We don't support any raw events right now */
        return -1;
    }
    g_hash_table_insert(cpu->pmu_event_ctr_map, GUINT_TO_POINTER(event_idx),
                        GUINT_TO_POINTER(ctr_idx));

    return 0;
}

static void pmu_timer_trigger_irq(RISCVCPU *cpu,
                                  enum riscv_pmu_event_idx evt_idx)
{
    uint32_t ctr_idx;
    CPURISCVState *env = &cpu->env;
    PMUCTRState *counter;
    target_ulong *mhpmevent_val;
    uint64_t of_bit_mask;
    int64_t irq_trigger_at;

    if (evt_idx != RISCV_PMU_EVENT_HW_CPU_CYCLES &&
        evt_idx != RISCV_PMU_EVENT_HW_INSTRUCTIONS) {
        return;
    }

    ctr_idx = GPOINTER_TO_UINT(g_hash_table_lookup(cpu->pmu_event_ctr_map,
                               GUINT_TO_POINTER(evt_idx)));
    if (!riscv_pmu_counter_enabled(cpu, ctr_idx)) {
        return;
    }

    if (riscv_cpu_mxl(env) == MXL_RV32) {
        mhpmevent_val = &env->mhpmeventh_val[ctr_idx];
        of_bit_mask = MHPMEVENTH_BIT_OF;
     } else {
        mhpmevent_val = &env->mhpmevent_val[ctr_idx];
        of_bit_mask = MHPMEVENT_BIT_OF;
    }

    counter = &env->pmu_ctrs[ctr_idx];
    if (counter->irq_overflow_left > 0) {
        irq_trigger_at = qemu_clock_get_ns(QEMU_CLOCK_VIRTUAL) +
                        counter->irq_overflow_left;
        timer_mod_anticipate_ns(cpu->pmu_timer, irq_trigger_at);
        counter->irq_overflow_left = 0;
        return;
    }

    if (cpu->pmu_avail_ctrs & BIT(ctr_idx)) {
        /* Generate interrupt only if OF bit is clear */
        if (!(*mhpmevent_val & of_bit_mask)) {
            *mhpmevent_val |= of_bit_mask;
            riscv_cpu_update_mip(cpu, MIP_LCOFIP, BOOL_TO_MASK(1));
        }
    }
}

/* Timer callback for instret and cycle counter overflow */
void riscv_pmu_timer_cb(void *priv)
{
    RISCVCPU *cpu = priv;

    /* Timer event was triggered only for these events */
    pmu_timer_trigger_irq(cpu, RISCV_PMU_EVENT_HW_CPU_CYCLES);
    pmu_timer_trigger_irq(cpu, RISCV_PMU_EVENT_HW_INSTRUCTIONS);
}

int riscv_pmu_setup_timer(CPURISCVState *env, uint64_t value, uint32_t ctr_idx)
{
    uint64_t overflow_delta, overflow_at;
    int64_t overflow_ns, overflow_left = 0;
    RISCVCPU *cpu = RISCV_CPU(env_cpu(env));
    PMUCTRState *counter = &env->pmu_ctrs[ctr_idx];

    if (!riscv_pmu_counter_valid(cpu, ctr_idx) || !cpu->cfg.ext_sscofpmf) {
        return -1;
    }

    if (value) {
        overflow_delta = UINT64_MAX - value + 1;
    } else {
        overflow_delta = UINT64_MAX;
    }

    /*
     * QEMU supports only int64_t timers while RISC-V counters are uint64_t.
     * Compute the leftover and save it so that it can be reprogrammed again
     * when timer expires.
     */
    if (overflow_delta > INT64_MAX) {
        overflow_left = overflow_delta - INT64_MAX;
    }

    if (riscv_pmu_ctr_monitor_cycles(env, ctr_idx) ||
        riscv_pmu_ctr_monitor_instructions(env, ctr_idx)) {
        overflow_ns = pmu_icount_ticks_to_ns((int64_t)overflow_delta);
        overflow_left = pmu_icount_ticks_to_ns(overflow_left) ;
    } else {
        return -1;
    }
    overflow_at = (uint64_t)qemu_clock_get_ns(QEMU_CLOCK_VIRTUAL) + overflow_ns;

    if (overflow_at > INT64_MAX) {
        overflow_left += overflow_at - INT64_MAX;
        counter->irq_overflow_left = overflow_left;
        overflow_at = INT64_MAX;
    }
    timer_mod_anticipate_ns(cpu->pmu_timer, overflow_at);

    return 0;
}


int riscv_pmu_init(RISCVCPU *cpu, int num_counters)
{
    if (num_counters > (RV_MAX_MHPMCOUNTERS - 3)) {
        return -1;
    }

    cpu->pmu_event_ctr_map = g_hash_table_new(g_direct_hash, g_direct_equal);
    if (!cpu->pmu_event_ctr_map) {
        /* PMU support can not be enabled */
        qemu_log_mask(LOG_UNIMP, "PMU events can't be supported\n");
        cpu->cfg.pmu_num = 0;
        return -1;
    }

    /* Create a bitmask of available programmable counters */
    cpu->pmu_avail_ctrs = MAKE_32BIT_MASK(3, num_counters);

    return 0;
}