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 "sysemu/cpu-timers.h"
  31 #include "qemu/main-loop.h"
  32 #include "qemu/notify.h"
  33 #include "qemu/guest-random.h"
  34 #include "exec/exec-all.h"
  35 #include "hw/boards.h"
  36
  37 #include "tcg-accel-ops.h"
  38 #include "tcg-accel-ops-mttcg.h"
  39
  40 typedef struct MttcgForceRcuNotifier {
  41     Notifier notifier;
  42     CPUState *cpu;
  43 } MttcgForceRcuNotifier;
  44
  45 static void do_nothing(CPUState *cpu, run_on_cpu_data d)
  46 {
  47 }
  48
  49 static void mttcg_force_rcu(Notifier *notify, void *data)
  50 {
  51     CPUState *cpu = container_of(notify, MttcgForceRcuNotifier, notifier)->cpu;
  52
  53     /*
  54      * Called with rcu_registry_lock held, using async_run_on_cpu() ensures
  55      * that there are no deadlocks.
  56      */
  57     async_run_on_cpu(cpu, do_nothing, RUN_ON_CPU_NULL);
  58 }
  59
  60 /*
  61  * In the multi-threaded case each vCPU has its own thread. The TLS
  62  * variable current_cpu can be used deep in the code to find the
  63  * current CPUState for a given thread.
  64  */
  65
  66 static void *mttcg_cpu_thread_fn(void *arg)
  67 {
  68     MttcgForceRcuNotifier force_rcu;
  69     CPUState *cpu = arg;
  70
  71     assert(tcg_enabled());
  72     g_assert(!icount_enabled());
  73
  74     rcu_register_thread();
  75     force_rcu.notifier.notify = mttcg_force_rcu;
  76     force_rcu.cpu = cpu;
  77     rcu_add_force_rcu_notifier(&force_rcu.notifier);
  78     tcg_register_thread();
  79
  80     qemu_mutex_lock_iothread();
  81     qemu_thread_get_self(cpu->thread);
  82
  83     cpu->thread_id = qemu_get_thread_id();
  84     cpu->can_do_io = 1;
  85     current_cpu = cpu;
  86     cpu_thread_signal_created(cpu);
  87     qemu_guest_random_seed_thread_part2(cpu->random_seed);
  88
  89     /* process any pending work */
  90     cpu->exit_request = 1;
  91
  92     do {
  93         if (cpu_can_run(cpu)) {
  94             int r;
  95             qemu_mutex_unlock_iothread();
  96             r = tcg_cpus_exec(cpu);
  97             qemu_mutex_lock_iothread();
  98             switch (r) {
  99             case EXCP_DEBUG:
 100                 cpu_handle_guest_debug(cpu);
 101                 break;
 102             case EXCP_HALTED:
 103                 /*
 104                  * during start-up the vCPU is reset and the thread is
 105                  * kicked several times. If we don't ensure we go back
 106                  * to sleep in the halted state we won't cleanly
 107                  * start-up when the vCPU is enabled.
 108                  *
 109                  * cpu->halted should ensure we sleep in wait_io_event
 110                  */
 111                 g_assert(cpu->halted);
 112                 break;
 113             case EXCP_ATOMIC:
 114                 qemu_mutex_unlock_iothread();
 115                 cpu_exec_step_atomic(cpu);
 116                 qemu_mutex_lock_iothread();
 117             default:
 118                 /* Ignore everything else? */
 119                 break;
 120             }
 121         }
 122
 123         qatomic_mb_set(&cpu->exit_request, 0);
 124         qemu_wait_io_event(cpu);
 125     } while (!cpu->unplug || cpu_can_run(cpu));
 126
 127     tcg_cpus_destroy(cpu);
 128     qemu_mutex_unlock_iothread();
 129     rcu_remove_force_rcu_notifier(&force_rcu.notifier);
 130     rcu_unregister_thread();
 131     return NULL;
 132 }
 133
 134 void mttcg_kick_vcpu_thread(CPUState *cpu)
 135 {
 136     cpu_exit(cpu);
 137 }
 138
 139 void mttcg_start_vcpu_thread(CPUState *cpu)
 140 {
 141     char thread_name[VCPU_THREAD_NAME_SIZE];
 142
 143     g_assert(tcg_enabled());
 144     tcg_cpu_init_cflags(cpu, current_machine->smp.max_cpus > 1);
 145
 146     cpu->thread = g_new0(QemuThread, 1);
 147     cpu->halt_cond = g_malloc0(sizeof(QemuCond));
 148     qemu_cond_init(cpu->halt_cond);
 149
 150     /* create a thread per vCPU with TCG (MTTCG) */
 151     snprintf(thread_name, VCPU_THREAD_NAME_SIZE, "CPU %d/TCG",
 152              cpu->cpu_index);
 153
 154     qemu_thread_create(cpu->thread, thread_name, mttcg_cpu_thread_fn,
 155                        cpu, QEMU_THREAD_JOINABLE);
 156
 157 #ifdef _WIN32
 158     cpu->hThread = qemu_thread_get_handle(cpu->thread);
 159 #endif
 160 }