qemu/include/system/cpu-timers.h

/*
 * CPU timers state API
 *
 * Copyright 2020 SUSE LLC
 *
 * This work is licensed under the terms of the GNU GPL, version 2 or later.
 * See the COPYING file in the top-level directory.
 *
 */
#ifndef SYSTEM_CPU_TIMERS_H
#define SYSTEM_CPU_TIMERS_H

#include "qemu/timer.h"

/* init the whole cpu timers API, including icount, ticks, and cpu_throttle */
void cpu_timers_init(void);

/* icount - Instruction Counter API */

/**
 * ICountMode: icount enablement state:
 *
 * @ICOUNT_DISABLED: Disabled - Do not count executed instructions.
 * @ICOUNT_PRECISE: Enabled - Fixed conversion of insn to ns via "shift" option
 * @ICOUNT_ADAPTATIVE: Enabled - Runtime adaptive algorithm to compute shift
 */
typedef enum {
    ICOUNT_DISABLED = 0,
    ICOUNT_PRECISE,
    ICOUNT_ADAPTATIVE,
} ICountMode;

#if defined(CONFIG_TCG) && !defined(CONFIG_USER_ONLY)
extern ICountMode use_icount;
#define icount_enabled() (use_icount)
#else
#define icount_enabled() ICOUNT_DISABLED
#endif

/*
 * Update the icount with the executed instructions. Called by
 * cpus-tcg vCPU thread so the main-loop can see time has moved forward.
 */
void icount_update(CPUState *cpu);

/* get raw icount value */
int64_t icount_get_raw(void);

/* return the virtual CPU time in ns, based on the instruction counter. */
int64_t icount_get(void);
/*
 * convert an instruction counter value to ns, based on the icount shift.
 * This shift is set as a fixed value with the icount "shift" option
 * (precise mode), or it is constantly approximated and corrected at
 * runtime in adaptive mode.
 */
int64_t icount_to_ns(int64_t icount);

/**
 * icount_configure: configure the icount options, including "shift"
 * @opts: Options to parse
 * @errp: pointer to a NULL-initialized error object
 *
 * Return: true on success, else false setting @errp with error
 */
bool icount_configure(QemuOpts *opts, Error **errp);

/* used by tcg vcpu thread to calc icount budget */
int64_t icount_round(int64_t count);

/* if the CPUs are idle, start accounting real time to virtual clock. */
void icount_start_warp_timer(void);
void icount_account_warp_timer(void);
void icount_notify_exit(void);

/*
 * CPU Ticks and Clock
 */

/* Caller must hold BQL */
void cpu_enable_ticks(void);
/* Caller must hold BQL */
void cpu_disable_ticks(void);

/*
 * return the time elapsed in VM between vm_start and vm_stop.
 * cpu_get_ticks() uses units of the host CPU cycle counter.
 */
int64_t cpu_get_ticks(void);

/*
 * Returns the monotonic time elapsed in VM, i.e.,
 * the time between vm_start and vm_stop
 */
int64_t cpu_get_clock(void);

void qemu_timer_notify_cb(void *opaque, QEMUClockType type);

/* get/set VIRTUAL clock and VM elapsed ticks via the cpus accel interface */
int64_t cpus_get_virtual_clock(void);
void cpus_set_virtual_clock(int64_t new_time);
int64_t cpus_get_elapsed_ticks(void);

#endif /* SYSTEM_CPU_TIMERS_H */