LXR qemu/accel/tcg/tcg-accel-ops-icount.c

   1/*
   2 * QEMU TCG Single Threaded vCPUs implementation using instruction counting
   3 *
   4 * Copyright (c) 2003-2008 Fabrice Bellard
   5 * Copyright (c) 2014 Red Hat Inc.
   6 *
   7 * Permission is hereby granted, free of charge, to any person obtaining a copy
   8 * of this software and associated documentation files (the "Software"), to deal
   9 * in the Software without restriction, including without limitation the rights
  10 * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
  11 * copies of the Software, and to permit persons to whom the Software is
  12 * furnished to do so, subject to the following conditions:
  13 *
  14 * The above copyright notice and this permission notice shall be included in
  15 * all copies or substantial portions of the Software.
  16 *
  17 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
  18 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
  19 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
  20 * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
  21 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
  22 * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
  23 * THE SOFTWARE.
  24 */
  25
  26#include "qemu/osdep.h"
  27#include "sysemu/replay.h"
  28#include "sysemu/cpu-timers.h"
  29#include "qemu/main-loop.h"
  30#include "qemu/guest-random.h"
  31#include "exec/exec-all.h"
  32
  33#include "tcg-accel-ops.h"
  34#include "tcg-accel-ops-icount.h"
  35#include "tcg-accel-ops-rr.h"
  36
  37static int64_t icount_get_limit(void)
  38{
  39    int64_t deadline;
  40
  41    if (replay_mode != REPLAY_MODE_PLAY) {
  42        /*
  43         * Include all the timers, because they may need an attention.
  44         * Too long CPU execution may create unnecessary delay in UI.
  45         */
  46        deadline = qemu_clock_deadline_ns_all(QEMU_CLOCK_VIRTUAL,
  47                                              QEMU_TIMER_ATTR_ALL);
  48        /* Check realtime timers, because they help with input processing */
  49        deadline = qemu_soonest_timeout(deadline,
  50                qemu_clock_deadline_ns_all(QEMU_CLOCK_REALTIME,
  51                                           QEMU_TIMER_ATTR_ALL));
  52
  53        /*
  54         * Maintain prior (possibly buggy) behaviour where if no deadline
  55         * was set (as there is no QEMU_CLOCK_VIRTUAL timer) or it is more than
  56         * INT32_MAX nanoseconds ahead, we still use INT32_MAX
  57         * nanoseconds.
  58         */
  59        if ((deadline < 0) || (deadline > INT32_MAX)) {
  60            deadline = INT32_MAX;
  61        }
  62
  63        return icount_round(deadline);
  64    } else {
  65        return replay_get_instructions();
  66    }
  67}
  68
  69static void icount_notify_aio_contexts(void)
  70{
  71    /* Wake up other AioContexts.  */
  72    qemu_clock_notify(QEMU_CLOCK_VIRTUAL);
  73    qemu_clock_run_timers(QEMU_CLOCK_VIRTUAL);
  74}
  75
  76void icount_handle_deadline(void)
  77{
  78    assert(qemu_in_vcpu_thread());
  79    int64_t deadline = qemu_clock_deadline_ns_all(QEMU_CLOCK_VIRTUAL,
  80                                                  QEMU_TIMER_ATTR_ALL);
  81
  82    /*
  83     * Instructions, interrupts, and exceptions are processed in cpu-exec.
  84     * Don't interrupt cpu thread, when these events are waiting
  85     * (i.e., there is no checkpoint)
  86     */
  87    if (deadline == 0) {
  88        icount_notify_aio_contexts();
  89    }
  90}
  91
  92void icount_prepare_for_run(CPUState *cpu)
  93{
  94    int insns_left;
  95
  96    /*
  97     * These should always be cleared by icount_process_data after
  98     * each vCPU execution. However u16.high can be raised
  99     * asynchronously by cpu_exit/cpu_interrupt/tcg_handle_interrupt
 100     */
 101    g_assert(cpu_neg(cpu)->icount_decr.u16.low == 0);
 102    g_assert(cpu->icount_extra == 0);
 103
 104    cpu->icount_budget = icount_get_limit();
 105    insns_left = MIN(0xffff, cpu->icount_budget);
 106    cpu_neg(cpu)->icount_decr.u16.low = insns_left;
 107    cpu->icount_extra = cpu->icount_budget - insns_left;
 108
 109    replay_mutex_lock();
 110
 111    if (cpu->icount_budget == 0) {
 112        /*
 113         * We're called without the iothread lock, so must take it while
 114         * we're calling timer handlers.
 115         */
 116        qemu_mutex_lock_iothread();
 117        icount_notify_aio_contexts();
 118        qemu_mutex_unlock_iothread();
 119    }
 120}
 121
 122void icount_process_data(CPUState *cpu)
 123{
 124    /* Account for executed instructions */
 125    icount_update(cpu);
 126
 127    /* Reset the counters */
 128    cpu_neg(cpu)->icount_decr.u16.low = 0;
 129    cpu->icount_extra = 0;
 130    cpu->icount_budget = 0;
 131
 132    replay_account_executed_instructions();
 133
 134    replay_mutex_unlock();
 135}
 136
 137void icount_handle_interrupt(CPUState *cpu, int mask)
 138{
 139    int old_mask = cpu->interrupt_request;
 140
 141    tcg_handle_interrupt(cpu, mask);
 142    if (qemu_cpu_is_self(cpu) &&
 143        !cpu->can_do_io
 144        && (mask & ~old_mask) != 0) {
 145        cpu_abort(cpu, "Raised interrupt while not in I/O function");
 146    }
 147}
 148