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
do_nothing(CPUState * cpu,run_on_cpu_data d)44 static void do_nothing(CPUState *cpu, run_on_cpu_data d)
45 {
46 }
47
mttcg_force_rcu(Notifier * notify,void * data)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
mttcg_cpu_thread_fn(void * arg)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 bql_lock();
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 bql_unlock();
95 r = tcg_cpu_exec(cpu);
96 bql_lock();
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 bql_unlock();
109 cpu_exec_step_atomic(cpu);
110 bql_lock();
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_cpu_destroy(cpu);
122 bql_unlock();
123 rcu_remove_force_rcu_notifier(&force_rcu.notifier);
124 rcu_unregister_thread();
125 return NULL;
126 }
127
mttcg_kick_vcpu_thread(CPUState * cpu)128 void mttcg_kick_vcpu_thread(CPUState *cpu)
129 {
130 cpu_exit(cpu);
131 }
132
mttcg_start_vcpu_thread(CPUState * cpu)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 /* create a thread per vCPU with TCG (MTTCG) */
141 snprintf(thread_name, VCPU_THREAD_NAME_SIZE, "CPU %d/TCG",
142 cpu->cpu_index);
143
144 qemu_thread_create(cpu->thread, thread_name, mttcg_cpu_thread_fn,
145 cpu, QEMU_THREAD_JOINABLE);
146 }
147