accel/tcg/tcg-cpus-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 #include "hw/boards.h"
  34
  35 #include "tcg-cpus.h"
  36 #include "tcg-cpus-icount.h"
  37 #include "tcg-cpus-rr.h"
  38
  39 static int64_t icount_get_limit(void)
  40 {
  41     int64_t deadline;
  42
  43     if (replay_mode != REPLAY_MODE_PLAY) {
  44         /*
  45          * Include all the timers, because they may need an attention.
  46          * Too long CPU execution may create unnecessary delay in UI.
  47          */
  48         deadline = qemu_clock_deadline_ns_all(QEMU_CLOCK_VIRTUAL,
  49                                               QEMU_TIMER_ATTR_ALL);
  50         /* Check realtime timers, because they help with input processing */
  51         deadline = qemu_soonest_timeout(deadline,
  52                 qemu_clock_deadline_ns_all(QEMU_CLOCK_REALTIME,
  53                                            QEMU_TIMER_ATTR_ALL));
  54
  55         /*
  56          * Maintain prior (possibly buggy) behaviour where if no deadline
  57          * was set (as there is no QEMU_CLOCK_VIRTUAL timer) or it is more than
  58          * INT32_MAX nanoseconds ahead, we still use INT32_MAX
  59          * nanoseconds.
  60          */
  61         if ((deadline < 0) || (deadline > INT32_MAX)) {
  62             deadline = INT32_MAX;
  63         }
  64
  65         return icount_round(deadline);
  66     } else {
  67         return replay_get_instructions();
  68     }
  69 }
  70
  71 static void icount_notify_aio_contexts(void)
  72 {
  73     /* Wake up other AioContexts.  */
  74     qemu_clock_notify(QEMU_CLOCK_VIRTUAL);
  75     qemu_clock_run_timers(QEMU_CLOCK_VIRTUAL);
  76 }
  77
  78 void icount_handle_deadline(void)
  79 {
  80     assert(qemu_in_vcpu_thread());
  81     int64_t deadline = qemu_clock_deadline_ns_all(QEMU_CLOCK_VIRTUAL,
  82                                                   QEMU_TIMER_ATTR_ALL);
  83
  84     if (deadline == 0) {
  85         icount_notify_aio_contexts();
  86     }
  87 }
  88
  89 void icount_prepare_for_run(CPUState *cpu)
  90 {
  91     int insns_left;
  92
  93     /*
  94      * These should always be cleared by icount_process_data after
  95      * each vCPU execution. However u16.high can be raised
  96      * asynchronously by cpu_exit/cpu_interrupt/tcg_cpus_handle_interrupt
  97      */
  98     g_assert(cpu_neg(cpu)->icount_decr.u16.low == 0);
  99     g_assert(cpu->icount_extra == 0);
 100
 101     cpu->icount_budget = icount_get_limit();
 102     insns_left = MIN(0xffff, cpu->icount_budget);
 103     cpu_neg(cpu)->icount_decr.u16.low = insns_left;
 104     cpu->icount_extra = cpu->icount_budget - insns_left;
 105
 106     replay_mutex_lock();
 107
 108     if (cpu->icount_budget == 0 && replay_has_checkpoint()) {
 109         icount_notify_aio_contexts();
 110     }
 111 }
 112
 113 void icount_process_data(CPUState *cpu)
 114 {
 115     /* Account for executed instructions */
 116     icount_update(cpu);
 117
 118     /* Reset the counters */
 119     cpu_neg(cpu)->icount_decr.u16.low = 0;
 120     cpu->icount_extra = 0;
 121     cpu->icount_budget = 0;
 122
 123     replay_account_executed_instructions();
 124
 125     replay_mutex_unlock();
 126 }
 127
 128 static void icount_handle_interrupt(CPUState *cpu, int mask)
 129 {
 130     int old_mask = cpu->interrupt_request;
 131
 132     tcg_cpus_handle_interrupt(cpu, mask);
 133     if (qemu_cpu_is_self(cpu) &&
 134         !cpu->can_do_io
 135         && (mask & ~old_mask) != 0) {
 136         cpu_abort(cpu, "Raised interrupt while not in I/O function");
 137     }
 138 }
 139
 140 const CpusAccel tcg_cpus_icount = {
 141     .create_vcpu_thread = rr_start_vcpu_thread,
 142     .kick_vcpu_thread = rr_kick_vcpu_thread,
 143
 144     .handle_interrupt = icount_handle_interrupt,
 145     .get_virtual_clock = icount_get,
 146     .get_elapsed_ticks = icount_get,
 147 };