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 "system/tcg.h" 28 #include "system/replay.h" 29 #include "exec/icount.h" 30 #include "qemu/main-loop.h" 31 #include "qemu/notify.h" 32 #include "qemu/guest-random.h" 33 #include "hw/boards.h" 34 #include "tcg/startup.h" 35 #include "tcg-accel-ops.h" 36 #include "tcg-accel-ops-mttcg.h" 37 38 typedef struct MttcgForceRcuNotifier { 39 Notifier notifier; 40 CPUState *cpu; 41 } MttcgForceRcuNotifier; 42 43 static void do_nothing(CPUState *cpu, run_on_cpu_data d) 44 { 45 } 46 47 static void mttcg_force_rcu(Notifier *notify, void *data) 48 { 49 CPUState *cpu = container_of(notify, MttcgForceRcuNotifier, notifier)->cpu; 50 51 /* 52 * Called with rcu_registry_lock held, using async_run_on_cpu() ensures 53 * that there are no deadlocks. 54 */ 55 async_run_on_cpu(cpu, do_nothing, RUN_ON_CPU_NULL); 56 } 57 58 /* 59 * In the multi-threaded case each vCPU has its own thread. The TLS 60 * variable current_cpu can be used deep in the code to find the 61 * current CPUState for a given thread. 62 */ 63 64 static void *mttcg_cpu_thread_fn(void *arg) 65 { 66 MttcgForceRcuNotifier force_rcu; 67 CPUState *cpu = arg; 68 69 assert(tcg_enabled()); 70 g_assert(!icount_enabled()); 71 72 rcu_register_thread(); 73 force_rcu.notifier.notify = mttcg_force_rcu; 74 force_rcu.cpu = cpu; 75 rcu_add_force_rcu_notifier(&force_rcu.notifier); 76 tcg_register_thread(); 77 78 bql_lock(); 79 qemu_thread_get_self(cpu->thread); 80 81 cpu->thread_id = qemu_get_thread_id(); 82 cpu->neg.can_do_io = true; 83 current_cpu = cpu; 84 cpu_thread_signal_created(cpu); 85 qemu_guest_random_seed_thread_part2(cpu->random_seed); 86 87 /* process any pending work */ 88 cpu->exit_request = 1; 89 90 do { 91 if (cpu_can_run(cpu)) { 92 int r; 93 bql_unlock(); 94 r = tcg_cpu_exec(cpu); 95 bql_lock(); 96 switch (r) { 97 case EXCP_DEBUG: 98 cpu_handle_guest_debug(cpu); 99 break; 100 case EXCP_HALTED: 101 /* 102 * Usually cpu->halted is set, but may have already been 103 * reset by another thread by the time we arrive here. 104 */ 105 break; 106 case EXCP_ATOMIC: 107 bql_unlock(); 108 cpu_exec_step_atomic(cpu); 109 bql_lock(); 110 default: 111 /* Ignore everything else? */ 112 break; 113 } 114 } 115 116 qatomic_set_mb(&cpu->exit_request, 0); 117 qemu_wait_io_event(cpu); 118 } while (!cpu->unplug || cpu_can_run(cpu)); 119 120 tcg_cpu_destroy(cpu); 121 bql_unlock(); 122 rcu_remove_force_rcu_notifier(&force_rcu.notifier); 123 rcu_unregister_thread(); 124 return NULL; 125 } 126 127 void mttcg_kick_vcpu_thread(CPUState *cpu) 128 { 129 cpu_exit(cpu); 130 } 131 132 void mttcg_start_vcpu_thread(CPUState *cpu) 133 { 134 char thread_name[VCPU_THREAD_NAME_SIZE]; 135 136 g_assert(tcg_enabled()); 137 tcg_cpu_init_cflags(cpu, current_machine->smp.max_cpus > 1); 138 139 /* create a thread per vCPU with TCG (MTTCG) */ 140 snprintf(thread_name, VCPU_THREAD_NAME_SIZE, "CPU %d/TCG", 141 cpu->cpu_index); 142 143 qemu_thread_create(cpu->thread, thread_name, mttcg_cpu_thread_fn, 144 cpu, QEMU_THREAD_JOINABLE); 145 } 146