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
do_nothing(CPUState * cpu,run_on_cpu_data d)43 static void do_nothing(CPUState *cpu, run_on_cpu_data d)
44 {
45 }
46
mttcg_force_rcu(Notifier * notify,void * data)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
mttcg_cpu_thread_fn(void * arg)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
mttcg_kick_vcpu_thread(CPUState * cpu)127 void mttcg_kick_vcpu_thread(CPUState *cpu)
128 {
129 cpu_exit(cpu);
130 }
131
mttcg_start_vcpu_thread(CPUState * cpu)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