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45e077d7 CF |
1 | /* |
2 | * QEMU TCG Single 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" | |
45e077d7 CF |
27 | #include "sysemu/tcg.h" |
28 | #include "sysemu/replay.h" | |
03ff4f8d | 29 | #include "sysemu/cpu-timers.h" |
45e077d7 | 30 | #include "qemu/main-loop.h" |
dd47a8f6 | 31 | #include "qemu/notify.h" |
45e077d7 CF |
32 | #include "qemu/guest-random.h" |
33 | #include "exec/exec-all.h" | |
45e077d7 | 34 | |
b86f59c7 CF |
35 | #include "tcg-accel-ops.h" |
36 | #include "tcg-accel-ops-rr.h" | |
37 | #include "tcg-accel-ops-icount.h" | |
45e077d7 CF |
38 | |
39 | /* Kick all RR vCPUs */ | |
9e2658d6 | 40 | void rr_kick_vcpu_thread(CPUState *unused) |
45e077d7 CF |
41 | { |
42 | CPUState *cpu; | |
43 | ||
44 | CPU_FOREACH(cpu) { | |
45 | cpu_exit(cpu); | |
46 | }; | |
47 | } | |
48 | ||
49 | /* | |
50 | * TCG vCPU kick timer | |
51 | * | |
52 | * The kick timer is responsible for moving single threaded vCPU | |
53 | * emulation on to the next vCPU. If more than one vCPU is running a | |
54 | * timer event with force a cpu->exit so the next vCPU can get | |
55 | * scheduled. | |
56 | * | |
57 | * The timer is removed if all vCPUs are idle and restarted again once | |
58 | * idleness is complete. | |
59 | */ | |
60 | ||
9e2658d6 CF |
61 | static QEMUTimer *rr_kick_vcpu_timer; |
62 | static CPUState *rr_current_cpu; | |
45e077d7 | 63 | |
9e2658d6 | 64 | static inline int64_t rr_next_kick_time(void) |
45e077d7 CF |
65 | { |
66 | return qemu_clock_get_ns(QEMU_CLOCK_VIRTUAL) + TCG_KICK_PERIOD; | |
67 | } | |
68 | ||
69 | /* Kick the currently round-robin scheduled vCPU to next */ | |
9e2658d6 | 70 | static void rr_kick_next_cpu(void) |
45e077d7 CF |
71 | { |
72 | CPUState *cpu; | |
73 | do { | |
9e2658d6 | 74 | cpu = qatomic_mb_read(&rr_current_cpu); |
45e077d7 CF |
75 | if (cpu) { |
76 | cpu_exit(cpu); | |
77 | } | |
9e2658d6 | 78 | } while (cpu != qatomic_mb_read(&rr_current_cpu)); |
45e077d7 CF |
79 | } |
80 | ||
9e2658d6 | 81 | static void rr_kick_thread(void *opaque) |
45e077d7 | 82 | { |
9e2658d6 CF |
83 | timer_mod(rr_kick_vcpu_timer, rr_next_kick_time()); |
84 | rr_kick_next_cpu(); | |
45e077d7 CF |
85 | } |
86 | ||
9e2658d6 | 87 | static void rr_start_kick_timer(void) |
45e077d7 | 88 | { |
9e2658d6 CF |
89 | if (!rr_kick_vcpu_timer && CPU_NEXT(first_cpu)) { |
90 | rr_kick_vcpu_timer = timer_new_ns(QEMU_CLOCK_VIRTUAL, | |
91 | rr_kick_thread, NULL); | |
45e077d7 | 92 | } |
9e2658d6 CF |
93 | if (rr_kick_vcpu_timer && !timer_pending(rr_kick_vcpu_timer)) { |
94 | timer_mod(rr_kick_vcpu_timer, rr_next_kick_time()); | |
45e077d7 CF |
95 | } |
96 | } | |
97 | ||
9e2658d6 | 98 | static void rr_stop_kick_timer(void) |
45e077d7 | 99 | { |
9e2658d6 CF |
100 | if (rr_kick_vcpu_timer && timer_pending(rr_kick_vcpu_timer)) { |
101 | timer_del(rr_kick_vcpu_timer); | |
45e077d7 CF |
102 | } |
103 | } | |
104 | ||
9e2658d6 | 105 | static void rr_wait_io_event(void) |
45e077d7 CF |
106 | { |
107 | CPUState *cpu; | |
108 | ||
109 | while (all_cpu_threads_idle()) { | |
9e2658d6 | 110 | rr_stop_kick_timer(); |
45e077d7 CF |
111 | qemu_cond_wait_iothread(first_cpu->halt_cond); |
112 | } | |
113 | ||
9e2658d6 | 114 | rr_start_kick_timer(); |
45e077d7 CF |
115 | |
116 | CPU_FOREACH(cpu) { | |
117 | qemu_wait_io_event_common(cpu); | |
118 | } | |
119 | } | |
120 | ||
121 | /* | |
122 | * Destroy any remaining vCPUs which have been unplugged and have | |
123 | * finished running | |
124 | */ | |
9e2658d6 | 125 | static void rr_deal_with_unplugged_cpus(void) |
45e077d7 CF |
126 | { |
127 | CPUState *cpu; | |
128 | ||
129 | CPU_FOREACH(cpu) { | |
130 | if (cpu->unplug && !cpu_can_run(cpu)) { | |
9e2658d6 | 131 | tcg_cpus_destroy(cpu); |
45e077d7 CF |
132 | break; |
133 | } | |
134 | } | |
135 | } | |
136 | ||
dd47a8f6 GK |
137 | static void rr_force_rcu(Notifier *notify, void *data) |
138 | { | |
139 | rr_kick_next_cpu(); | |
140 | } | |
141 | ||
45e077d7 CF |
142 | /* |
143 | * In the single-threaded case each vCPU is simulated in turn. If | |
144 | * there is more than a single vCPU we create a simple timer to kick | |
145 | * the vCPU and ensure we don't get stuck in a tight loop in one vCPU. | |
146 | * This is done explicitly rather than relying on side-effects | |
147 | * elsewhere. | |
148 | */ | |
149 | ||
9e2658d6 | 150 | static void *rr_cpu_thread_fn(void *arg) |
45e077d7 | 151 | { |
dd47a8f6 | 152 | Notifier force_rcu; |
45e077d7 CF |
153 | CPUState *cpu = arg; |
154 | ||
155 | assert(tcg_enabled()); | |
156 | rcu_register_thread(); | |
dd47a8f6 GK |
157 | force_rcu.notify = rr_force_rcu; |
158 | rcu_add_force_rcu_notifier(&force_rcu); | |
45e077d7 CF |
159 | tcg_register_thread(); |
160 | ||
161 | qemu_mutex_lock_iothread(); | |
162 | qemu_thread_get_self(cpu->thread); | |
163 | ||
164 | cpu->thread_id = qemu_get_thread_id(); | |
165 | cpu->can_do_io = 1; | |
166 | cpu_thread_signal_created(cpu); | |
167 | qemu_guest_random_seed_thread_part2(cpu->random_seed); | |
168 | ||
169 | /* wait for initial kick-off after machine start */ | |
170 | while (first_cpu->stopped) { | |
171 | qemu_cond_wait_iothread(first_cpu->halt_cond); | |
172 | ||
173 | /* process any pending work */ | |
174 | CPU_FOREACH(cpu) { | |
175 | current_cpu = cpu; | |
176 | qemu_wait_io_event_common(cpu); | |
177 | } | |
178 | } | |
179 | ||
9e2658d6 | 180 | rr_start_kick_timer(); |
45e077d7 CF |
181 | |
182 | cpu = first_cpu; | |
183 | ||
184 | /* process any pending work */ | |
185 | cpu->exit_request = 1; | |
186 | ||
187 | while (1) { | |
188 | qemu_mutex_unlock_iothread(); | |
189 | replay_mutex_lock(); | |
190 | qemu_mutex_lock_iothread(); | |
191 | ||
192 | if (icount_enabled()) { | |
193 | /* Account partial waits to QEMU_CLOCK_VIRTUAL. */ | |
194 | icount_account_warp_timer(); | |
195 | /* | |
196 | * Run the timers here. This is much more efficient than | |
197 | * waking up the I/O thread and waiting for completion. | |
198 | */ | |
9e2658d6 | 199 | icount_handle_deadline(); |
45e077d7 CF |
200 | } |
201 | ||
202 | replay_mutex_unlock(); | |
203 | ||
204 | if (!cpu) { | |
205 | cpu = first_cpu; | |
206 | } | |
207 | ||
208 | while (cpu && cpu_work_list_empty(cpu) && !cpu->exit_request) { | |
209 | ||
9e2658d6 | 210 | qatomic_mb_set(&rr_current_cpu, cpu); |
45e077d7 CF |
211 | current_cpu = cpu; |
212 | ||
213 | qemu_clock_enable(QEMU_CLOCK_VIRTUAL, | |
214 | (cpu->singlestep_enabled & SSTEP_NOTIMER) == 0); | |
215 | ||
216 | if (cpu_can_run(cpu)) { | |
217 | int r; | |
218 | ||
219 | qemu_mutex_unlock_iothread(); | |
220 | if (icount_enabled()) { | |
9e2658d6 | 221 | icount_prepare_for_run(cpu); |
45e077d7 | 222 | } |
9e2658d6 | 223 | r = tcg_cpus_exec(cpu); |
45e077d7 | 224 | if (icount_enabled()) { |
9e2658d6 | 225 | icount_process_data(cpu); |
45e077d7 CF |
226 | } |
227 | qemu_mutex_lock_iothread(); | |
228 | ||
229 | if (r == EXCP_DEBUG) { | |
230 | cpu_handle_guest_debug(cpu); | |
231 | break; | |
232 | } else if (r == EXCP_ATOMIC) { | |
233 | qemu_mutex_unlock_iothread(); | |
234 | cpu_exec_step_atomic(cpu); | |
235 | qemu_mutex_lock_iothread(); | |
236 | break; | |
237 | } | |
238 | } else if (cpu->stop) { | |
239 | if (cpu->unplug) { | |
240 | cpu = CPU_NEXT(cpu); | |
241 | } | |
242 | break; | |
243 | } | |
244 | ||
245 | cpu = CPU_NEXT(cpu); | |
246 | } /* while (cpu && !cpu->exit_request).. */ | |
247 | ||
248 | /* Does not need qatomic_mb_set because a spurious wakeup is okay. */ | |
9e2658d6 | 249 | qatomic_set(&rr_current_cpu, NULL); |
45e077d7 CF |
250 | |
251 | if (cpu && cpu->exit_request) { | |
252 | qatomic_mb_set(&cpu->exit_request, 0); | |
253 | } | |
254 | ||
255 | if (icount_enabled() && all_cpu_threads_idle()) { | |
256 | /* | |
257 | * When all cpus are sleeping (e.g in WFI), to avoid a deadlock | |
258 | * in the main_loop, wake it up in order to start the warp timer. | |
259 | */ | |
260 | qemu_notify_event(); | |
261 | } | |
262 | ||
9e2658d6 CF |
263 | rr_wait_io_event(); |
264 | rr_deal_with_unplugged_cpus(); | |
45e077d7 CF |
265 | } |
266 | ||
dd47a8f6 | 267 | rcu_remove_force_rcu_notifier(&force_rcu); |
45e077d7 CF |
268 | rcu_unregister_thread(); |
269 | return NULL; | |
270 | } | |
271 | ||
37c2f9a7 CF |
272 | void rr_start_vcpu_thread(CPUState *cpu) |
273 | { | |
274 | char thread_name[VCPU_THREAD_NAME_SIZE]; | |
275 | static QemuCond *single_tcg_halt_cond; | |
276 | static QemuThread *single_tcg_cpu_thread; | |
277 | ||
278 | g_assert(tcg_enabled()); | |
6cc9d67c | 279 | tcg_cpu_init_cflags(cpu, false); |
37c2f9a7 CF |
280 | |
281 | if (!single_tcg_cpu_thread) { | |
b21e2380 MA |
282 | cpu->thread = g_new0(QemuThread, 1); |
283 | cpu->halt_cond = g_new0(QemuCond, 1); | |
37c2f9a7 CF |
284 | qemu_cond_init(cpu->halt_cond); |
285 | ||
286 | /* share a single thread for all cpus with TCG */ | |
287 | snprintf(thread_name, VCPU_THREAD_NAME_SIZE, "ALL CPUs/TCG"); | |
288 | qemu_thread_create(cpu->thread, thread_name, | |
9e2658d6 | 289 | rr_cpu_thread_fn, |
37c2f9a7 CF |
290 | cpu, QEMU_THREAD_JOINABLE); |
291 | ||
292 | single_tcg_halt_cond = cpu->halt_cond; | |
293 | single_tcg_cpu_thread = cpu->thread; | |
294 | #ifdef _WIN32 | |
295 | cpu->hThread = qemu_thread_get_handle(cpu->thread); | |
296 | #endif | |
297 | } else { | |
298 | /* we share the thread */ | |
299 | cpu->thread = single_tcg_cpu_thread; | |
300 | cpu->halt_cond = single_tcg_halt_cond; | |
301 | cpu->thread_id = first_cpu->thread_id; | |
302 | cpu->can_do_io = 1; | |
303 | cpu->created = true; | |
304 | } | |
305 | } |