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 "sysemu/tcg.h"
  28 #include "sysemu/replay.h"
  29 #include "sysemu/cpu-timers.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 #include "tcg/startup.h"
  36 #include "tcg-accel-ops.h"
  37 #include "tcg-accel-ops-mttcg.h"
  38
  39 typedef struct MttcgForceRcuNotifier {
  40     Notifier notifier;
  41     CPUState *cpu;
  42 } MttcgForceRcuNotifier;
  43
  44 static void do_nothing(CPUState *cpu, run_on_cpu_data d)
  45 {
  46 }
  47
  48 static 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
  65 static 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->neg.can_do_io = true;
  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                  * Usually cpu->halted is set, but may have already been
 104                  * reset by another thread by the time we arrive here.
 105                  */
 106                 break;
 107             case EXCP_ATOMIC:
 108                 qemu_mutex_unlock_iothread();
 109                 cpu_exec_step_atomic(cpu);
 110                 qemu_mutex_lock_iothread();
 111             default:
 112                 /* Ignore everything else? */
 113                 break;
 114             }
 115         }
 116
 117         qatomic_set_mb(&cpu->exit_request, 0);
 118         qemu_wait_io_event(cpu);
 119     } while (!cpu->unplug || cpu_can_run(cpu));
 120
 121     tcg_cpus_destroy(cpu);
 122     qemu_mutex_unlock_iothread();
 123     rcu_remove_force_rcu_notifier(&force_rcu.notifier);
 124     rcu_unregister_thread();
 125     return NULL;
 126 }
 127
 128 void mttcg_kick_vcpu_thread(CPUState *cpu)
 129 {
 130     cpu_exit(cpu);
 131 }
 132
 133 void mttcg_start_vcpu_thread(CPUState *cpu)
 134 {
 135     char thread_name[VCPU_THREAD_NAME_SIZE];
 136
 137     g_assert(tcg_enabled());
 138     tcg_cpu_init_cflags(cpu, current_machine->smp.max_cpus > 1);
 139
 140     cpu->thread = g_new0(QemuThread, 1);
 141     cpu->halt_cond = g_malloc0(sizeof(QemuCond));
 142     qemu_cond_init(cpu->halt_cond);
 143
 144     /* create a thread per vCPU with TCG (MTTCG) */
 145     snprintf(thread_name, VCPU_THREAD_NAME_SIZE, "CPU %d/TCG",
 146              cpu->cpu_index);
 147
 148     qemu_thread_create(cpu->thread, thread_name, mttcg_cpu_thread_fn,
 149                        cpu, QEMU_THREAD_JOINABLE);
 150 }