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

   1/*
   2 * QEMU TCG Multi Threaded vCPUs implementation
   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/notify.h"
  32#include "qemu/guest-random.h"
  33#include "exec/exec-all.h"
  34#include "hw/boards.h"
  35
  36#include "tcg-accel-ops.h"
  37#include "tcg-accel-ops-mttcg.h"
  38
  39typedef struct MttcgForceRcuNotifier {
  40    Notifier notifier;
  41    CPUState *cpu;
  42} MttcgForceRcuNotifier;
  43
  44static void do_nothing(CPUState *cpu, run_on_cpu_data d)
  45{
  46}
  47
  48static void mttcg_force_rcu(Notifier *notify, void *data)
  49{
  50    CPUState *cpu = container_of(notify, MttcgForceRcuNotifier, notifier)->cpu;
  51
  52    /*
  53     * Called with rcu_registry_lock held, using async_run_on_cpu() ensures
  54     * that there are no deadlocks.
  55     */
  56    async_run_on_cpu(cpu, do_nothing, RUN_ON_CPU_NULL);
  57}
  58
  59/*
  60 * In the multi-threaded case each vCPU has its own thread. The TLS
  61 * variable current_cpu can be used deep in the code to find the
  62 * current CPUState for a given thread.
  63 */
  64
  65static void *mttcg_cpu_thread_fn(void *arg)
  66{
  67    MttcgForceRcuNotifier force_rcu;
  68    CPUState *cpu = arg;
  69
  70    assert(tcg_enabled());
  71    g_assert(!icount_enabled());
  72
  73    rcu_register_thread();
  74    force_rcu.notifier.notify = mttcg_force_rcu;
  75    force_rcu.cpu = cpu;
  76    rcu_add_force_rcu_notifier(&force_rcu.notifier);
  77    tcg_register_thread();
  78
  79    qemu_mutex_lock_iothread();
  80    qemu_thread_get_self(cpu->thread);
  81
  82    cpu->thread_id = qemu_get_thread_id();
  83    cpu->can_do_io = 1;
  84    current_cpu = cpu;
  85    cpu_thread_signal_created(cpu);
  86    qemu_guest_random_seed_thread_part2(cpu->random_seed);
  87
  88    /* process any pending work */
  89    cpu->exit_request = 1;
  90
  91    do {
  92        if (cpu_can_run(cpu)) {
  93            int r;
  94            qemu_mutex_unlock_iothread();
  95            r = tcg_cpus_exec(cpu);
  96            qemu_mutex_lock_iothread();
  97            switch (r) {
  98            case EXCP_DEBUG:
  99                cpu_handle_guest_debug(cpu);
 100                break;
 101            case EXCP_HALTED:
 102                /*
 103                 * during start-up the vCPU is reset and the thread is
 104                 * kicked several times. If we don't ensure we go back
 105                 * to sleep in the halted state we won't cleanly
 106                 * start-up when the vCPU is enabled.
 107                 *
 108                 * cpu->halted should ensure we sleep in wait_io_event
 109                 */
 110                g_assert(cpu->halted);
 111                break;
 112            case EXCP_ATOMIC:
 113                qemu_mutex_unlock_iothread();
 114                cpu_exec_step_atomic(cpu);
 115                qemu_mutex_lock_iothread();
 116            default:
 117                /* Ignore everything else? */
 118                break;
 119            }
 120        }
 121
 122        qatomic_mb_set(&cpu->exit_request, 0);
 123        qemu_wait_io_event(cpu);
 124    } while (!cpu->unplug || cpu_can_run(cpu));
 125
 126    tcg_cpus_destroy(cpu);
 127    qemu_mutex_unlock_iothread();
 128    rcu_remove_force_rcu_notifier(&force_rcu.notifier);
 129    rcu_unregister_thread();
 130    return NULL;
 131}
 132
 133void mttcg_kick_vcpu_thread(CPUState *cpu)
 134{
 135    cpu_exit(cpu);
 136}
 137
 138void mttcg_start_vcpu_thread(CPUState *cpu)
 139{
 140    char thread_name[VCPU_THREAD_NAME_SIZE];
 141
 142    g_assert(tcg_enabled());
 143    tcg_cpu_init_cflags(cpu, current_machine->smp.max_cpus > 1);
 144
 145    cpu->thread = g_malloc0(sizeof(QemuThread));
 146    cpu->halt_cond = g_malloc0(sizeof(QemuCond));
 147    qemu_cond_init(cpu->halt_cond);
 148
 149    /* create a thread per vCPU with TCG (MTTCG) */
 150    snprintf(thread_name, VCPU_THREAD_NAME_SIZE, "CPU %d/TCG",
 151             cpu->cpu_index);
 152
 153    qemu_thread_create(cpu->thread, thread_name, mttcg_cpu_thread_fn,
 154                       cpu, QEMU_THREAD_JOINABLE);
 155
 156#ifdef _WIN32
 157    cpu->hThread = qemu_thread_get_handle(cpu->thread);
 158#endif
 159}
 160