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 "qemu/main-loop.h"
31 #include "qemu/guest-random.h"
32 #include "exec/exec-all.h"
33 #include "hw/boards.h"
34 
35 #include "tcg-accel-ops.h"
36 #include "tcg-accel-ops-mttcg.h"
37 
38 /*
39  * In the multi-threaded case each vCPU has its own thread. The TLS
40  * variable current_cpu can be used deep in the code to find the
41  * current CPUState for a given thread.
42  */
43 
44 static void *mttcg_cpu_thread_fn(void *arg)
45 {
46     CPUState *cpu = arg;
47 
48     assert(tcg_enabled());
49     g_assert(!icount_enabled());
50 
51     rcu_register_thread();
52     tcg_register_thread();
53 
54     qemu_mutex_lock_iothread();
55     qemu_thread_get_self(cpu->thread);
56 
57     cpu->thread_id = qemu_get_thread_id();
58     cpu->can_do_io = 1;
59     current_cpu = cpu;
60     cpu_thread_signal_created(cpu);
61     qemu_guest_random_seed_thread_part2(cpu->random_seed);
62 
63     /* process any pending work */
64     cpu->exit_request = 1;
65 
66     do {
67         if (cpu_can_run(cpu)) {
68             int r;
69             qemu_mutex_unlock_iothread();
70             r = tcg_cpus_exec(cpu);
71             qemu_mutex_lock_iothread();
72             switch (r) {
73             case EXCP_DEBUG:
74                 cpu_handle_guest_debug(cpu);
75                 break;
76             case EXCP_HALTED:
77                 /*
78                  * during start-up the vCPU is reset and the thread is
79                  * kicked several times. If we don't ensure we go back
80                  * to sleep in the halted state we won't cleanly
81                  * start-up when the vCPU is enabled.
82                  *
83                  * cpu->halted should ensure we sleep in wait_io_event
84                  */
85                 g_assert(cpu->halted);
86                 break;
87             case EXCP_ATOMIC:
88                 qemu_mutex_unlock_iothread();
89                 cpu_exec_step_atomic(cpu);
90                 qemu_mutex_lock_iothread();
91             default:
92                 /* Ignore everything else? */
93                 break;
94             }
95         }
96 
97         qatomic_mb_set(&cpu->exit_request, 0);
98         qemu_wait_io_event(cpu);
99     } while (!cpu->unplug || cpu_can_run(cpu));
100 
101     tcg_cpus_destroy(cpu);
102     qemu_mutex_unlock_iothread();
103     rcu_unregister_thread();
104     return NULL;
105 }
106 
107 void mttcg_kick_vcpu_thread(CPUState *cpu)
108 {
109     cpu_exit(cpu);
110 }
111 
112 void mttcg_start_vcpu_thread(CPUState *cpu)
113 {
114     char thread_name[VCPU_THREAD_NAME_SIZE];
115 
116     g_assert(tcg_enabled());
117 
118     parallel_cpus = (current_machine->smp.max_cpus > 1);
119 
120     cpu->thread = g_malloc0(sizeof(QemuThread));
121     cpu->halt_cond = g_malloc0(sizeof(QemuCond));
122     qemu_cond_init(cpu->halt_cond);
123 
124     /* create a thread per vCPU with TCG (MTTCG) */
125     snprintf(thread_name, VCPU_THREAD_NAME_SIZE, "CPU %d/TCG",
126              cpu->cpu_index);
127 
128     qemu_thread_create(cpu->thread, thread_name, mttcg_cpu_thread_fn,
129                        cpu, QEMU_THREAD_JOINABLE);
130 
131 #ifdef _WIN32
132     cpu->hThread = qemu_thread_get_handle(cpu->thread);
133 #endif
134 }
135