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
  38 static 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
  70 static 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
  77 void 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
  94 void 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
 118 void 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
 133 void 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 }