2  * QEMU TCG Single Threaded vCPUs implementation
4  * Copyright (c) 2003-2008 Fabrice Bellard
30 #include "sysemu/cpu-timers.h"
31 #include "qemu/main-loop.h"
33 #include "qemu/guest-random.h"
34 #include "exec/exec-all.h"
36 #include "tcg-accel-ops.h"
37 #include "tcg-accel-ops-rr.h"
38 #include "tcg-accel-ops-icount.h"
43     CPUState *cpu;  in rr_kick_vcpu_thread()  local
45     CPU_FOREACH(cpu) {  in rr_kick_vcpu_thread()
46         cpu_exit(cpu);  in rr_kick_vcpu_thread()
53  * The kick timer is responsible for moving single threaded vCPU
55  * timer event we force a cpu->exit so the next vCPU can get
70 /* Kick the currently round-robin scheduled vCPU to next */
73     CPUState *cpu;  in rr_kick_next_cpu()  local
75         cpu = qatomic_read(&rr_current_cpu);  in rr_kick_next_cpu()
76         if (cpu) {  in rr_kick_next_cpu()
77             cpu_exit(cpu);  in rr_kick_next_cpu()
79         /* Finish kicking this cpu before reading again.  */  in rr_kick_next_cpu()
81     } while (cpu != qatomic_read(&rr_current_cpu));  in rr_kick_next_cpu()
110     CPUState *cpu;  in rr_wait_io_event()  local
114         qemu_cond_wait_bql(first_cpu->halt_cond);  in rr_wait_io_event()
119     CPU_FOREACH(cpu) {  in rr_wait_io_event()
120         qemu_wait_io_event_common(cpu);  in rr_wait_io_event()
130     CPUState *cpu;  in rr_deal_with_unplugged_cpus()  local
132     CPU_FOREACH(cpu) {  in rr_deal_with_unplugged_cpus()
133         if (cpu->unplug && !cpu_can_run(cpu)) {  in rr_deal_with_unplugged_cpus()
134             tcg_cpu_destroy(cpu);  in rr_deal_with_unplugged_cpus()
146  * Calculate the number of CPUs that we will process in a single iteration of
147  * the main CPU thread loop so that we can fairly distribute the instruction
150  * The CPU count is cached based on the CPU list generation ID to avoid
157     CPUState *cpu;  in rr_cpu_count()  local
163         CPU_FOREACH(cpu) {  in rr_cpu_count()
173  * In the single-threaded case each vCPU is simulated in turn. If
174  * there is more than a single vCPU we create a simple timer to kick
176  * This is done explicitly rather than relying on side-effects
183     CPUState *cpu = arg;  in rr_cpu_thread_fn()  local
192     qemu_thread_get_self(cpu->thread);  in rr_cpu_thread_fn()
194     cpu->thread_id = qemu_get_thread_id();  in rr_cpu_thread_fn()
195     cpu->neg.can_do_io = true;  in rr_cpu_thread_fn()
196     cpu_thread_signal_created(cpu);  in rr_cpu_thread_fn()
197     qemu_guest_random_seed_thread_part2(cpu->random_seed);  in rr_cpu_thread_fn()
199     /* wait for initial kick-off after machine start */  in rr_cpu_thread_fn()
200     while (first_cpu->stopped) {  in rr_cpu_thread_fn()
201         qemu_cond_wait_bql(first_cpu->halt_cond);  in rr_cpu_thread_fn()
204         CPU_FOREACH(cpu) {  in rr_cpu_thread_fn()
205             current_cpu = cpu;  in rr_cpu_thread_fn()
206             qemu_wait_io_event_common(cpu);  in rr_cpu_thread_fn()
212     cpu = first_cpu;  in rr_cpu_thread_fn()
215     cpu->exit_request = 1;  in rr_cpu_thread_fn()
241         if (!cpu) {  in rr_cpu_thread_fn()
242             cpu = first_cpu;  in rr_cpu_thread_fn()
245         while (cpu && cpu_work_list_empty(cpu) && !cpu->exit_request) {  in rr_cpu_thread_fn()
247             qatomic_set_mb(&rr_current_cpu, cpu);  in rr_cpu_thread_fn()
249             current_cpu = cpu;  in rr_cpu_thread_fn()
252                               (cpu->singlestep_enabled & SSTEP_NOTIMER) == 0);  in rr_cpu_thread_fn()
254             if (cpu_can_run(cpu)) {  in rr_cpu_thread_fn()
259                     icount_prepare_for_run(cpu, cpu_budget);  in rr_cpu_thread_fn()
261                 r = tcg_cpu_exec(cpu);  in rr_cpu_thread_fn()
263                     icount_process_data(cpu);  in rr_cpu_thread_fn()
268                     cpu_handle_guest_debug(cpu);  in rr_cpu_thread_fn()
272                     cpu_exec_step_atomic(cpu);  in rr_cpu_thread_fn()
276             } else if (cpu->stop) {  in rr_cpu_thread_fn()
277                 if (cpu->unplug) {  in rr_cpu_thread_fn()
278                     cpu = CPU_NEXT(cpu);  in rr_cpu_thread_fn()
283             cpu = CPU_NEXT(cpu);  in rr_cpu_thread_fn()
284         } /* while (cpu && !cpu->exit_request).. */  in rr_cpu_thread_fn()
289         if (cpu && cpu->exit_request) {  in rr_cpu_thread_fn()
290             qatomic_set_mb(&cpu->exit_request, 0);  in rr_cpu_thread_fn()
308 void rr_start_vcpu_thread(CPUState *cpu)  in rr_start_vcpu_thread()  argument
315     tcg_cpu_init_cflags(cpu, false);  in rr_start_vcpu_thread()
318         single_tcg_halt_cond = cpu->halt_cond;  in rr_start_vcpu_thread()
319         single_tcg_cpu_thread = cpu->thread;  in rr_start_vcpu_thread()
321         /* share a single thread for all cpus with TCG */  in rr_start_vcpu_thread()
323         qemu_thread_create(cpu->thread, thread_name,  in rr_start_vcpu_thread()
325                            cpu, QEMU_THREAD_JOINABLE);  in rr_start_vcpu_thread()
328         g_free(cpu->thread);  in rr_start_vcpu_thread()
329         qemu_cond_destroy(cpu->halt_cond);  in rr_start_vcpu_thread()
330         g_free(cpu->halt_cond);  in rr_start_vcpu_thread()
331         cpu->thread = single_tcg_cpu_thread;  in rr_start_vcpu_thread()
332         cpu->halt_cond = single_tcg_halt_cond;  in rr_start_vcpu_thread()
335         cpu->thread_id = first_cpu->thread_id;  in rr_start_vcpu_thread()
336         cpu->neg.can_do_io = 1;  in rr_start_vcpu_thread()
337         cpu->created = true;  in rr_start_vcpu_thread()