softmmu/cpu-timers.c

   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/cutils.h"
  28 #include "migration/vmstate.h"
  29 #include "qapi/error.h"
  30 #include "qemu/error-report.h"
  31 #include "sysemu/cpus.h"
  32 #include "qemu/main-loop.h"
  33 #include "qemu/option.h"
  34 #include "qemu/seqlock.h"
  35 #include "sysemu/replay.h"
  36 #include "sysemu/runstate.h"
  37 #include "hw/core/cpu.h"
  38 #include "sysemu/cpu-timers.h"
  39 #include "sysemu/cpu-throttle.h"
  40 #include "timers-state.h"
  41
  42 /* clock and ticks */
  43
  44 static int64_t cpu_get_ticks_locked(void)
  45 {
  46     int64_t ticks = timers_state.cpu_ticks_offset;
  47     if (timers_state.cpu_ticks_enabled) {
  48         ticks += cpu_get_host_ticks();
  49     }
  50
  51     if (timers_state.cpu_ticks_prev > ticks) {
  52         /* Non increasing ticks may happen if the host uses software suspend. */
  53         timers_state.cpu_ticks_offset += timers_state.cpu_ticks_prev - ticks;
  54         ticks = timers_state.cpu_ticks_prev;
  55     }
  56
  57     timers_state.cpu_ticks_prev = ticks;
  58     return ticks;
  59 }
  60
  61 /*
  62  * return the time elapsed in VM between vm_start and vm_stop.
  63  * cpu_get_ticks() uses units of the host CPU cycle counter.
  64  */
  65 int64_t cpu_get_ticks(void)
  66 {
  67     int64_t ticks;
  68
  69     qemu_spin_lock(&timers_state.vm_clock_lock);
  70     ticks = cpu_get_ticks_locked();
  71     qemu_spin_unlock(&timers_state.vm_clock_lock);
  72     return ticks;
  73 }
  74
  75 int64_t cpu_get_clock_locked(void)
  76 {
  77     int64_t time;
  78
  79     time = timers_state.cpu_clock_offset;
  80     if (timers_state.cpu_ticks_enabled) {
  81         time += get_clock();
  82     }
  83
  84     return time;
  85 }
  86
  87 /*
  88  * Return the monotonic time elapsed in VM, i.e.,
  89  * the time between vm_start and vm_stop
  90  */
  91 int64_t cpu_get_clock(void)
  92 {
  93     int64_t ti;
  94     unsigned start;
  95
  96     do {
  97         start = seqlock_read_begin(&timers_state.vm_clock_seqlock);
  98         ti = cpu_get_clock_locked();
  99     } while (seqlock_read_retry(&timers_state.vm_clock_seqlock, start));
 100
 101     return ti;
 102 }
 103
 104 /*
 105  * enable cpu_get_ticks()
 106  * Caller must hold BQL which serves as mutex for vm_clock_seqlock.
 107  */
 108 void cpu_enable_ticks(void)
 109 {
 110     seqlock_write_lock(&timers_state.vm_clock_seqlock,
 111                        &timers_state.vm_clock_lock);
 112     if (!timers_state.cpu_ticks_enabled) {
 113         timers_state.cpu_ticks_offset -= cpu_get_host_ticks();
 114         timers_state.cpu_clock_offset -= get_clock();
 115         timers_state.cpu_ticks_enabled = 1;
 116     }
 117     seqlock_write_unlock(&timers_state.vm_clock_seqlock,
 118                        &timers_state.vm_clock_lock);
 119 }
 120
 121 /*
 122  * disable cpu_get_ticks() : the clock is stopped. You must not call
 123  * cpu_get_ticks() after that.
 124  * Caller must hold BQL which serves as mutex for vm_clock_seqlock.
 125  */
 126 void cpu_disable_ticks(void)
 127 {
 128     seqlock_write_lock(&timers_state.vm_clock_seqlock,
 129                        &timers_state.vm_clock_lock);
 130     if (timers_state.cpu_ticks_enabled) {
 131         timers_state.cpu_ticks_offset += cpu_get_host_ticks();
 132         timers_state.cpu_clock_offset = cpu_get_clock_locked();
 133         timers_state.cpu_ticks_enabled = 0;
 134     }
 135     seqlock_write_unlock(&timers_state.vm_clock_seqlock,
 136                          &timers_state.vm_clock_lock);
 137 }
 138
 139 static bool icount_state_needed(void *opaque)
 140 {
 141     return icount_enabled();
 142 }
 143
 144 static bool warp_timer_state_needed(void *opaque)
 145 {
 146     TimersState *s = opaque;
 147     return s->icount_warp_timer != NULL;
 148 }
 149
 150 static bool adjust_timers_state_needed(void *opaque)
 151 {
 152     TimersState *s = opaque;
 153     return s->icount_rt_timer != NULL;
 154 }
 155
 156 static bool icount_shift_state_needed(void *opaque)
 157 {
 158     return icount_enabled() == 2;
 159 }
 160
 161 /*
 162  * Subsection for warp timer migration is optional, because may not be created
 163  */
 164 static const VMStateDescription icount_vmstate_warp_timer = {
 165     .name = "timer/icount/warp_timer",
 166     .version_id = 1,
 167     .minimum_version_id = 1,
 168     .needed = warp_timer_state_needed,
 169     .fields = (VMStateField[]) {
 170         VMSTATE_INT64(vm_clock_warp_start, TimersState),
 171         VMSTATE_TIMER_PTR(icount_warp_timer, TimersState),
 172         VMSTATE_END_OF_LIST()
 173     }
 174 };
 175
 176 static const VMStateDescription icount_vmstate_adjust_timers = {
 177     .name = "timer/icount/timers",
 178     .version_id = 1,
 179     .minimum_version_id = 1,
 180     .needed = adjust_timers_state_needed,
 181     .fields = (VMStateField[]) {
 182         VMSTATE_TIMER_PTR(icount_rt_timer, TimersState),
 183         VMSTATE_TIMER_PTR(icount_vm_timer, TimersState),
 184         VMSTATE_END_OF_LIST()
 185     }
 186 };
 187
 188 static const VMStateDescription icount_vmstate_shift = {
 189     .name = "timer/icount/shift",
 190     .version_id = 2,
 191     .minimum_version_id = 2,
 192     .needed = icount_shift_state_needed,
 193     .fields = (VMStateField[]) {
 194         VMSTATE_INT16(icount_time_shift, TimersState),
 195         VMSTATE_INT64(last_delta, TimersState),
 196         VMSTATE_END_OF_LIST()
 197     }
 198 };
 199
 200 /*
 201  * This is a subsection for icount migration.
 202  */
 203 static const VMStateDescription icount_vmstate_timers = {
 204     .name = "timer/icount",
 205     .version_id = 1,
 206     .minimum_version_id = 1,
 207     .needed = icount_state_needed,
 208     .fields = (VMStateField[]) {
 209         VMSTATE_INT64(qemu_icount_bias, TimersState),
 210         VMSTATE_INT64(qemu_icount, TimersState),
 211         VMSTATE_END_OF_LIST()
 212     },
 213     .subsections = (const VMStateDescription * []) {
 214         &icount_vmstate_warp_timer,
 215         &icount_vmstate_adjust_timers,
 216         &icount_vmstate_shift,
 217         NULL
 218     }
 219 };
 220
 221 static const VMStateDescription vmstate_timers = {
 222     .name = "timer",
 223     .version_id = 2,
 224     .minimum_version_id = 1,
 225     .fields = (VMStateField[]) {
 226         VMSTATE_INT64(cpu_ticks_offset, TimersState),
 227         VMSTATE_UNUSED(8),
 228         VMSTATE_INT64_V(cpu_clock_offset, TimersState, 2),
 229         VMSTATE_END_OF_LIST()
 230     },
 231     .subsections = (const VMStateDescription * []) {
 232         &icount_vmstate_timers,
 233         NULL
 234     }
 235 };
 236
 237 static void do_nothing(CPUState *cpu, run_on_cpu_data unused)
 238 {
 239 }
 240
 241 void qemu_timer_notify_cb(void *opaque, QEMUClockType type)
 242 {
 243     if (!icount_enabled() || type != QEMU_CLOCK_VIRTUAL) {
 244         qemu_notify_event();
 245         return;
 246     }
 247
 248     if (qemu_in_vcpu_thread()) {
 249         /*
 250          * A CPU is currently running; kick it back out to the
 251          * tcg_cpu_exec() loop so it will recalculate its
 252          * icount deadline immediately.
 253          */
 254         qemu_cpu_kick(current_cpu);
 255     } else if (first_cpu) {
 256         /*
 257          * qemu_cpu_kick is not enough to kick a halted CPU out of
 258          * qemu_tcg_wait_io_event.  async_run_on_cpu, instead,
 259          * causes cpu_thread_is_idle to return false.  This way,
 260          * handle_icount_deadline can run.
 261          * If we have no CPUs at all for some reason, we don't
 262          * need to do anything.
 263          */
 264         async_run_on_cpu(first_cpu, do_nothing, RUN_ON_CPU_NULL);
 265     }
 266 }
 267
 268 TimersState timers_state;
 269
 270 /* initialize timers state and the cpu throttle for convenience */
 271 void cpu_timers_init(void)
 272 {
 273     seqlock_init(&timers_state.vm_clock_seqlock);
 274     qemu_spin_init(&timers_state.vm_clock_lock);
 275     vmstate_register(NULL, 0, &vmstate_timers, &timers_state);
 276
 277     cpu_throttle_init();
 278 }