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 "qemu-common.h"
  28#include "sysemu/tcg.h"
  29#include "sysemu/replay.h"
  30#include "qemu/main-loop.h"
  31#include "qemu/guest-random.h"
  32#include "exec/exec-all.h"
  33
  34#include "tcg-accel-ops.h"
  35#include "tcg-accel-ops-icount.h"
  36#include "tcg-accel-ops-rr.h"
  37
  38static int64_t icount_get_limit(void)
  39{
  40    int64_t deadline;
  41
  42    if (replay_mode != REPLAY_MODE_PLAY) {
  43        /*
  44         * Include all the timers, because they may need an attention.
  45         * Too long CPU execution may create unnecessary delay in UI.
  46         */
  47        deadline = qemu_clock_deadline_ns_all(QEMU_CLOCK_VIRTUAL,
  48                                              QEMU_TIMER_ATTR_ALL);
  49        /* Check realtime timers, because they help with input processing */
  50        deadline = qemu_soonest_timeout(deadline,
  51                qemu_clock_deadline_ns_all(QEMU_CLOCK_REALTIME,
  52                                           QEMU_TIMER_ATTR_ALL));
  53
  54        /*
  55         * Maintain prior (possibly buggy) behaviour where if no deadline
  56         * was set (as there is no QEMU_CLOCK_VIRTUAL timer) or it is more than
  57         * INT32_MAX nanoseconds ahead, we still use INT32_MAX
  58         * nanoseconds.
  59         */
  60        if ((deadline < 0) || (deadline > INT32_MAX)) {
  61            deadline = INT32_MAX;
  62        }
  63
  64        return icount_round(deadline);
  65    } else {
  66        return replay_get_instructions();
  67    }
  68}
  69
  70static void icount_notify_aio_contexts(void)
  71{
  72    /* Wake up other AioContexts.  */
  73    qemu_clock_notify(QEMU_CLOCK_VIRTUAL);
  74    qemu_clock_run_timers(QEMU_CLOCK_VIRTUAL);
  75}
  76
  77void icount_handle_deadline(void)
  78{
  79    assert(qemu_in_vcpu_thread());
  80    int64_t deadline = qemu_clock_deadline_ns_all(QEMU_CLOCK_VIRTUAL,
  81                                                  QEMU_TIMER_ATTR_ALL);
  82
  83    /*
  84     * Instructions, interrupts, and exceptions are processed in cpu-exec.
  85     * Don't interrupt cpu thread, when these events are waiting
  86     * (i.e., there is no checkpoint)
  87     */
  88    if (deadline == 0
  89        && (replay_mode != REPLAY_MODE_PLAY || replay_has_checkpoint())) {
  90        icount_notify_aio_contexts();
  91    }
  92}
  93
  94void icount_prepare_for_run(CPUState *cpu)
  95{
  96    int insns_left;
  97
  98    /*
  99     * These should always be cleared by icount_process_data after
 100     * each vCPU execution. However u16.high can be raised
 101     * asynchronously by cpu_exit/cpu_interrupt/tcg_handle_interrupt
 102     */
 103    g_assert(cpu_neg(cpu)->icount_decr.u16.low == 0);
 104    g_assert(cpu->icount_extra == 0);
 105
 106    cpu->icount_budget = icount_get_limit();
 107    insns_left = MIN(0xffff, cpu->icount_budget);
 108    cpu_neg(cpu)->icount_decr.u16.low = insns_left;
 109    cpu->icount_extra = cpu->icount_budget - insns_left;
 110
 111    replay_mutex_lock();
 112
 113    if (cpu->icount_budget == 0 && replay_has_checkpoint()) {
 114        icount_notify_aio_contexts();
 115    }
 116}
 117
 118void icount_process_data(CPUState *cpu)
 119{
 120    /* Account for executed instructions */
 121    icount_update(cpu);
 122
 123    /* Reset the counters */
 124    cpu_neg(cpu)->icount_decr.u16.low = 0;
 125    cpu->icount_extra = 0;
 126    cpu->icount_budget = 0;
 127
 128    replay_account_executed_instructions();
 129
 130    replay_mutex_unlock();
 131}
 132
 133void icount_handle_interrupt(CPUState *cpu, int mask)
 134{
 135    int old_mask = cpu->interrupt_request;
 136
 137    tcg_handle_interrupt(cpu, mask);
 138    if (qemu_cpu_is_self(cpu) &&
 139        !cpu->can_do_io
 140        && (mask & ~old_mask) != 0) {
 141        cpu_abort(cpu, "Raised interrupt while not in I/O function");
 142    }
 143}
 144