cachepc-qemu

Fork of AMDESE/qemu with changes for cachepc side-channel attack
git clone https://git.sinitax.com/sinitax/cachepc-qemu
Log | Files | Refs | Submodules | LICENSE | sfeed.txt

cpu-throttle.c (4147B)

      1/*
      2 * QEMU System Emulator
      3 *
      4 * Copyright (c) 2003-2008 Fabrice Bellard
      5 *
      6 * Permission is hereby granted, free of charge, to any person obtaining a copy
      7 * of this software and associated documentation files (the "Software"), to deal
      8 * in the Software without restriction, including without limitation the rights
      9 * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
     10 * copies of the Software, and to permit persons to whom the Software is
     11 * furnished to do so, subject to the following conditions:
     12 *
     13 * The above copyright notice and this permission notice shall be included in
     14 * all copies or substantial portions of the Software.
     15 *
     16 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
     17 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
     18 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
     19 * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
     20 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
     21 * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
     22 * THE SOFTWARE.
     23 */
     24
     25#include "qemu/osdep.h"
     26#include "qemu-common.h"
     27#include "qemu/thread.h"
     28#include "hw/core/cpu.h"
     29#include "qemu/main-loop.h"
     30#include "sysemu/cpus.h"
     31#include "sysemu/cpu-throttle.h"
     32
     33/* vcpu throttling controls */
     34static QEMUTimer *throttle_timer;
     35static unsigned int throttle_percentage;
     36
     37#define CPU_THROTTLE_PCT_MIN 1
     38#define CPU_THROTTLE_PCT_MAX 99
     39#define CPU_THROTTLE_TIMESLICE_NS 10000000
     40
     41static void cpu_throttle_thread(CPUState *cpu, run_on_cpu_data opaque)
     42{
     43    double pct;
     44    double throttle_ratio;
     45    int64_t sleeptime_ns, endtime_ns;
     46
     47    if (!cpu_throttle_get_percentage()) {
     48        return;
     49    }
     50
     51    pct = (double)cpu_throttle_get_percentage() / 100;
     52    throttle_ratio = pct / (1 - pct);
     53    /* Add 1ns to fix double's rounding error (like 0.9999999...) */
     54    sleeptime_ns = (int64_t)(throttle_ratio * CPU_THROTTLE_TIMESLICE_NS + 1);
     55    endtime_ns = qemu_clock_get_ns(QEMU_CLOCK_REALTIME) + sleeptime_ns;
     56    while (sleeptime_ns > 0 && !cpu->stop) {
     57        if (sleeptime_ns > SCALE_MS) {
     58            qemu_cond_timedwait_iothread(cpu->halt_cond,
     59                                         sleeptime_ns / SCALE_MS);
     60        } else {
     61            qemu_mutex_unlock_iothread();
     62            g_usleep(sleeptime_ns / SCALE_US);
     63            qemu_mutex_lock_iothread();
     64        }
     65        sleeptime_ns = endtime_ns - qemu_clock_get_ns(QEMU_CLOCK_REALTIME);
     66    }
     67    qatomic_set(&cpu->throttle_thread_scheduled, 0);
     68}
     69
     70static void cpu_throttle_timer_tick(void *opaque)
     71{
     72    CPUState *cpu;
     73    double pct;
     74
     75    /* Stop the timer if needed */
     76    if (!cpu_throttle_get_percentage()) {
     77        return;
     78    }
     79    CPU_FOREACH(cpu) {
     80        if (!qatomic_xchg(&cpu->throttle_thread_scheduled, 1)) {
     81            async_run_on_cpu(cpu, cpu_throttle_thread,
     82                             RUN_ON_CPU_NULL);
     83        }
     84    }
     85
     86    pct = (double)cpu_throttle_get_percentage() / 100;
     87    timer_mod(throttle_timer, qemu_clock_get_ns(QEMU_CLOCK_VIRTUAL_RT) +
     88                                   CPU_THROTTLE_TIMESLICE_NS / (1 - pct));
     89}
     90
     91void cpu_throttle_set(int new_throttle_pct)
     92{
     93    /*
     94     * boolean to store whether throttle is already active or not,
     95     * before modifying throttle_percentage
     96     */
     97    bool throttle_active = cpu_throttle_active();
     98
     99    /* Ensure throttle percentage is within valid range */
    100    new_throttle_pct = MIN(new_throttle_pct, CPU_THROTTLE_PCT_MAX);
    101    new_throttle_pct = MAX(new_throttle_pct, CPU_THROTTLE_PCT_MIN);
    102
    103    qatomic_set(&throttle_percentage, new_throttle_pct);
    104
    105    if (!throttle_active) {
    106        cpu_throttle_timer_tick(NULL);
    107    }
    108}
    109
    110void cpu_throttle_stop(void)
    111{
    112    qatomic_set(&throttle_percentage, 0);
    113}
    114
    115bool cpu_throttle_active(void)
    116{
    117    return (cpu_throttle_get_percentage() != 0);
    118}
    119
    120int cpu_throttle_get_percentage(void)
    121{
    122    return qatomic_read(&throttle_percentage);
    123}
    124
    125void cpu_throttle_init(void)
    126{
    127    throttle_timer = timer_new_ns(QEMU_CLOCK_VIRTUAL_RT,
    128                                  cpu_throttle_timer_tick, NULL);
    129}