qemu

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tcg-accel-ops-icount.c (4805B)

      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 
     37 static 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 
     69 static 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 
     76 void 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 
     92 void 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 
    122 void 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 
    137 void 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 }