qapi: Restrict Xen migration commands to migration.json
[qemu/armbru.git] / accel / tcg / cpu-exec.c
blob58aea605d805e1da6dc43d327dbda309f2ba3f2e
1 /*
2 * emulator main execution loop
4 * Copyright (c) 2003-2005 Fabrice Bellard
6 * This library is free software; you can redistribute it and/or
7 * modify it under the terms of the GNU Lesser General Public
8 * License as published by the Free Software Foundation; either
9 * version 2.1 of the License, or (at your option) any later version.
11 * This library is distributed in the hope that it will be useful,
12 * but WITHOUT ANY WARRANTY; without even the implied warranty of
13 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
14 * Lesser General Public License for more details.
16 * You should have received a copy of the GNU Lesser General Public
17 * License along with this library; if not, see <http://www.gnu.org/licenses/>.
20 #include "qemu/osdep.h"
21 #include "qemu-common.h"
22 #include "qemu/qemu-print.h"
23 #include "cpu.h"
24 #include "trace.h"
25 #include "disas/disas.h"
26 #include "exec/exec-all.h"
27 #include "tcg/tcg.h"
28 #include "qemu/atomic.h"
29 #include "sysemu/qtest.h"
30 #include "qemu/timer.h"
31 #include "qemu/rcu.h"
32 #include "exec/tb-hash.h"
33 #include "exec/tb-lookup.h"
34 #include "exec/log.h"
35 #include "qemu/main-loop.h"
36 #if defined(TARGET_I386) && !defined(CONFIG_USER_ONLY)
37 #include "hw/i386/apic.h"
38 #endif
39 #include "sysemu/cpus.h"
40 #include "exec/cpu-all.h"
41 #include "sysemu/cpu-timers.h"
42 #include "sysemu/replay.h"
44 /* -icount align implementation. */
46 typedef struct SyncClocks {
47 int64_t diff_clk;
48 int64_t last_cpu_icount;
49 int64_t realtime_clock;
50 } SyncClocks;
52 #if !defined(CONFIG_USER_ONLY)
53 /* Allow the guest to have a max 3ms advance.
54 * The difference between the 2 clocks could therefore
55 * oscillate around 0.
57 #define VM_CLOCK_ADVANCE 3000000
58 #define THRESHOLD_REDUCE 1.5
59 #define MAX_DELAY_PRINT_RATE 2000000000LL
60 #define MAX_NB_PRINTS 100
62 static int64_t max_delay;
63 static int64_t max_advance;
65 static void align_clocks(SyncClocks *sc, CPUState *cpu)
67 int64_t cpu_icount;
69 if (!icount_align_option) {
70 return;
73 cpu_icount = cpu->icount_extra + cpu_neg(cpu)->icount_decr.u16.low;
74 sc->diff_clk += icount_to_ns(sc->last_cpu_icount - cpu_icount);
75 sc->last_cpu_icount = cpu_icount;
77 if (sc->diff_clk > VM_CLOCK_ADVANCE) {
78 #ifndef _WIN32
79 struct timespec sleep_delay, rem_delay;
80 sleep_delay.tv_sec = sc->diff_clk / 1000000000LL;
81 sleep_delay.tv_nsec = sc->diff_clk % 1000000000LL;
82 if (nanosleep(&sleep_delay, &rem_delay) < 0) {
83 sc->diff_clk = rem_delay.tv_sec * 1000000000LL + rem_delay.tv_nsec;
84 } else {
85 sc->diff_clk = 0;
87 #else
88 Sleep(sc->diff_clk / SCALE_MS);
89 sc->diff_clk = 0;
90 #endif
94 static void print_delay(const SyncClocks *sc)
96 static float threshold_delay;
97 static int64_t last_realtime_clock;
98 static int nb_prints;
100 if (icount_align_option &&
101 sc->realtime_clock - last_realtime_clock >= MAX_DELAY_PRINT_RATE &&
102 nb_prints < MAX_NB_PRINTS) {
103 if ((-sc->diff_clk / (float)1000000000LL > threshold_delay) ||
104 (-sc->diff_clk / (float)1000000000LL <
105 (threshold_delay - THRESHOLD_REDUCE))) {
106 threshold_delay = (-sc->diff_clk / 1000000000LL) + 1;
107 qemu_printf("Warning: The guest is now late by %.1f to %.1f seconds\n",
108 threshold_delay - 1,
109 threshold_delay);
110 nb_prints++;
111 last_realtime_clock = sc->realtime_clock;
116 static void init_delay_params(SyncClocks *sc, CPUState *cpu)
118 if (!icount_align_option) {
119 return;
121 sc->realtime_clock = qemu_clock_get_ns(QEMU_CLOCK_VIRTUAL_RT);
122 sc->diff_clk = qemu_clock_get_ns(QEMU_CLOCK_VIRTUAL) - sc->realtime_clock;
123 sc->last_cpu_icount
124 = cpu->icount_extra + cpu_neg(cpu)->icount_decr.u16.low;
125 if (sc->diff_clk < max_delay) {
126 max_delay = sc->diff_clk;
128 if (sc->diff_clk > max_advance) {
129 max_advance = sc->diff_clk;
132 /* Print every 2s max if the guest is late. We limit the number
133 of printed messages to NB_PRINT_MAX(currently 100) */
134 print_delay(sc);
136 #else
137 static void align_clocks(SyncClocks *sc, const CPUState *cpu)
141 static void init_delay_params(SyncClocks *sc, const CPUState *cpu)
144 #endif /* CONFIG USER ONLY */
146 /* Execute a TB, and fix up the CPU state afterwards if necessary */
147 static inline tcg_target_ulong cpu_tb_exec(CPUState *cpu, TranslationBlock *itb)
149 CPUArchState *env = cpu->env_ptr;
150 uintptr_t ret;
151 TranslationBlock *last_tb;
152 int tb_exit;
153 uint8_t *tb_ptr = itb->tc.ptr;
155 qemu_log_mask_and_addr(CPU_LOG_EXEC, itb->pc,
156 "Trace %d: %p ["
157 TARGET_FMT_lx "/" TARGET_FMT_lx "/%#x] %s\n",
158 cpu->cpu_index, itb->tc.ptr,
159 itb->cs_base, itb->pc, itb->flags,
160 lookup_symbol(itb->pc));
162 #if defined(DEBUG_DISAS)
163 if (qemu_loglevel_mask(CPU_LOG_TB_CPU)
164 && qemu_log_in_addr_range(itb->pc)) {
165 FILE *logfile = qemu_log_lock();
166 int flags = 0;
167 if (qemu_loglevel_mask(CPU_LOG_TB_FPU)) {
168 flags |= CPU_DUMP_FPU;
170 #if defined(TARGET_I386)
171 flags |= CPU_DUMP_CCOP;
172 #endif
173 log_cpu_state(cpu, flags);
174 qemu_log_unlock(logfile);
176 #endif /* DEBUG_DISAS */
178 ret = tcg_qemu_tb_exec(env, tb_ptr);
179 cpu->can_do_io = 1;
180 last_tb = (TranslationBlock *)(ret & ~TB_EXIT_MASK);
181 tb_exit = ret & TB_EXIT_MASK;
182 trace_exec_tb_exit(last_tb, tb_exit);
184 if (tb_exit > TB_EXIT_IDX1) {
185 /* We didn't start executing this TB (eg because the instruction
186 * counter hit zero); we must restore the guest PC to the address
187 * of the start of the TB.
189 CPUClass *cc = CPU_GET_CLASS(cpu);
190 qemu_log_mask_and_addr(CPU_LOG_EXEC, last_tb->pc,
191 "Stopped execution of TB chain before %p ["
192 TARGET_FMT_lx "] %s\n",
193 last_tb->tc.ptr, last_tb->pc,
194 lookup_symbol(last_tb->pc));
195 if (cc->synchronize_from_tb) {
196 cc->synchronize_from_tb(cpu, last_tb);
197 } else {
198 assert(cc->set_pc);
199 cc->set_pc(cpu, last_tb->pc);
202 return ret;
205 #ifndef CONFIG_USER_ONLY
206 /* Execute the code without caching the generated code. An interpreter
207 could be used if available. */
208 static void cpu_exec_nocache(CPUState *cpu, int max_cycles,
209 TranslationBlock *orig_tb, bool ignore_icount)
211 TranslationBlock *tb;
212 uint32_t cflags = curr_cflags() | CF_NOCACHE;
214 if (ignore_icount) {
215 cflags &= ~CF_USE_ICOUNT;
218 /* Should never happen.
219 We only end up here when an existing TB is too long. */
220 cflags |= MIN(max_cycles, CF_COUNT_MASK);
222 mmap_lock();
223 tb = tb_gen_code(cpu, orig_tb->pc, orig_tb->cs_base,
224 orig_tb->flags, cflags);
225 tb->orig_tb = orig_tb;
226 mmap_unlock();
228 /* execute the generated code */
229 trace_exec_tb_nocache(tb, tb->pc);
230 cpu_tb_exec(cpu, tb);
232 mmap_lock();
233 tb_phys_invalidate(tb, -1);
234 mmap_unlock();
235 tcg_tb_remove(tb);
237 #endif
239 void cpu_exec_step_atomic(CPUState *cpu)
241 CPUClass *cc = CPU_GET_CLASS(cpu);
242 TranslationBlock *tb;
243 target_ulong cs_base, pc;
244 uint32_t flags;
245 uint32_t cflags = 1;
246 uint32_t cf_mask = cflags & CF_HASH_MASK;
248 if (sigsetjmp(cpu->jmp_env, 0) == 0) {
249 start_exclusive();
251 tb = tb_lookup__cpu_state(cpu, &pc, &cs_base, &flags, cf_mask);
252 if (tb == NULL) {
253 mmap_lock();
254 tb = tb_gen_code(cpu, pc, cs_base, flags, cflags);
255 mmap_unlock();
258 /* Since we got here, we know that parallel_cpus must be true. */
259 parallel_cpus = false;
260 cc->cpu_exec_enter(cpu);
261 /* execute the generated code */
262 trace_exec_tb(tb, pc);
263 cpu_tb_exec(cpu, tb);
264 cc->cpu_exec_exit(cpu);
265 } else {
267 * The mmap_lock is dropped by tb_gen_code if it runs out of
268 * memory.
270 #ifndef CONFIG_SOFTMMU
271 tcg_debug_assert(!have_mmap_lock());
272 #endif
273 if (qemu_mutex_iothread_locked()) {
274 qemu_mutex_unlock_iothread();
276 assert_no_pages_locked();
277 qemu_plugin_disable_mem_helpers(cpu);
282 * As we start the exclusive region before codegen we must still
283 * be in the region if we longjump out of either the codegen or
284 * the execution.
286 g_assert(cpu_in_exclusive_context(cpu));
287 parallel_cpus = true;
288 end_exclusive();
291 struct tb_desc {
292 target_ulong pc;
293 target_ulong cs_base;
294 CPUArchState *env;
295 tb_page_addr_t phys_page1;
296 uint32_t flags;
297 uint32_t cf_mask;
298 uint32_t trace_vcpu_dstate;
301 static bool tb_lookup_cmp(const void *p, const void *d)
303 const TranslationBlock *tb = p;
304 const struct tb_desc *desc = d;
306 if (tb->pc == desc->pc &&
307 tb->page_addr[0] == desc->phys_page1 &&
308 tb->cs_base == desc->cs_base &&
309 tb->flags == desc->flags &&
310 tb->trace_vcpu_dstate == desc->trace_vcpu_dstate &&
311 (tb_cflags(tb) & (CF_HASH_MASK | CF_INVALID)) == desc->cf_mask) {
312 /* check next page if needed */
313 if (tb->page_addr[1] == -1) {
314 return true;
315 } else {
316 tb_page_addr_t phys_page2;
317 target_ulong virt_page2;
319 virt_page2 = (desc->pc & TARGET_PAGE_MASK) + TARGET_PAGE_SIZE;
320 phys_page2 = get_page_addr_code(desc->env, virt_page2);
321 if (tb->page_addr[1] == phys_page2) {
322 return true;
326 return false;
329 TranslationBlock *tb_htable_lookup(CPUState *cpu, target_ulong pc,
330 target_ulong cs_base, uint32_t flags,
331 uint32_t cf_mask)
333 tb_page_addr_t phys_pc;
334 struct tb_desc desc;
335 uint32_t h;
337 desc.env = (CPUArchState *)cpu->env_ptr;
338 desc.cs_base = cs_base;
339 desc.flags = flags;
340 desc.cf_mask = cf_mask;
341 desc.trace_vcpu_dstate = *cpu->trace_dstate;
342 desc.pc = pc;
343 phys_pc = get_page_addr_code(desc.env, pc);
344 if (phys_pc == -1) {
345 return NULL;
347 desc.phys_page1 = phys_pc & TARGET_PAGE_MASK;
348 h = tb_hash_func(phys_pc, pc, flags, cf_mask, *cpu->trace_dstate);
349 return qht_lookup_custom(&tb_ctx.htable, &desc, h, tb_lookup_cmp);
352 void tb_set_jmp_target(TranslationBlock *tb, int n, uintptr_t addr)
354 if (TCG_TARGET_HAS_direct_jump) {
355 uintptr_t offset = tb->jmp_target_arg[n];
356 uintptr_t tc_ptr = (uintptr_t)tb->tc.ptr;
357 tb_target_set_jmp_target(tc_ptr, tc_ptr + offset, addr);
358 } else {
359 tb->jmp_target_arg[n] = addr;
363 static inline void tb_add_jump(TranslationBlock *tb, int n,
364 TranslationBlock *tb_next)
366 uintptr_t old;
368 assert(n < ARRAY_SIZE(tb->jmp_list_next));
369 qemu_spin_lock(&tb_next->jmp_lock);
371 /* make sure the destination TB is valid */
372 if (tb_next->cflags & CF_INVALID) {
373 goto out_unlock_next;
375 /* Atomically claim the jump destination slot only if it was NULL */
376 old = qatomic_cmpxchg(&tb->jmp_dest[n], (uintptr_t)NULL,
377 (uintptr_t)tb_next);
378 if (old) {
379 goto out_unlock_next;
382 /* patch the native jump address */
383 tb_set_jmp_target(tb, n, (uintptr_t)tb_next->tc.ptr);
385 /* add in TB jmp list */
386 tb->jmp_list_next[n] = tb_next->jmp_list_head;
387 tb_next->jmp_list_head = (uintptr_t)tb | n;
389 qemu_spin_unlock(&tb_next->jmp_lock);
391 qemu_log_mask_and_addr(CPU_LOG_EXEC, tb->pc,
392 "Linking TBs %p [" TARGET_FMT_lx
393 "] index %d -> %p [" TARGET_FMT_lx "]\n",
394 tb->tc.ptr, tb->pc, n,
395 tb_next->tc.ptr, tb_next->pc);
396 return;
398 out_unlock_next:
399 qemu_spin_unlock(&tb_next->jmp_lock);
400 return;
403 static inline TranslationBlock *tb_find(CPUState *cpu,
404 TranslationBlock *last_tb,
405 int tb_exit, uint32_t cf_mask)
407 TranslationBlock *tb;
408 target_ulong cs_base, pc;
409 uint32_t flags;
411 tb = tb_lookup__cpu_state(cpu, &pc, &cs_base, &flags, cf_mask);
412 if (tb == NULL) {
413 mmap_lock();
414 tb = tb_gen_code(cpu, pc, cs_base, flags, cf_mask);
415 mmap_unlock();
416 /* We add the TB in the virtual pc hash table for the fast lookup */
417 qatomic_set(&cpu->tb_jmp_cache[tb_jmp_cache_hash_func(pc)], tb);
419 #ifndef CONFIG_USER_ONLY
420 /* We don't take care of direct jumps when address mapping changes in
421 * system emulation. So it's not safe to make a direct jump to a TB
422 * spanning two pages because the mapping for the second page can change.
424 if (tb->page_addr[1] != -1) {
425 last_tb = NULL;
427 #endif
428 /* See if we can patch the calling TB. */
429 if (last_tb) {
430 tb_add_jump(last_tb, tb_exit, tb);
432 return tb;
435 static inline bool cpu_handle_halt(CPUState *cpu)
437 if (cpu->halted) {
438 #if defined(TARGET_I386) && !defined(CONFIG_USER_ONLY)
439 if (cpu->interrupt_request & CPU_INTERRUPT_POLL) {
440 X86CPU *x86_cpu = X86_CPU(cpu);
441 qemu_mutex_lock_iothread();
442 apic_poll_irq(x86_cpu->apic_state);
443 cpu_reset_interrupt(cpu, CPU_INTERRUPT_POLL);
444 qemu_mutex_unlock_iothread();
446 #endif
447 if (!cpu_has_work(cpu)) {
448 return true;
451 cpu->halted = 0;
454 return false;
457 static inline void cpu_handle_debug_exception(CPUState *cpu)
459 CPUClass *cc = CPU_GET_CLASS(cpu);
460 CPUWatchpoint *wp;
462 if (!cpu->watchpoint_hit) {
463 QTAILQ_FOREACH(wp, &cpu->watchpoints, entry) {
464 wp->flags &= ~BP_WATCHPOINT_HIT;
468 cc->debug_excp_handler(cpu);
471 static inline bool cpu_handle_exception(CPUState *cpu, int *ret)
473 if (cpu->exception_index < 0) {
474 #ifndef CONFIG_USER_ONLY
475 if (replay_has_exception()
476 && cpu_neg(cpu)->icount_decr.u16.low + cpu->icount_extra == 0) {
477 /* try to cause an exception pending in the log */
478 cpu_exec_nocache(cpu, 1, tb_find(cpu, NULL, 0, curr_cflags()), true);
480 #endif
481 if (cpu->exception_index < 0) {
482 return false;
486 if (cpu->exception_index >= EXCP_INTERRUPT) {
487 /* exit request from the cpu execution loop */
488 *ret = cpu->exception_index;
489 if (*ret == EXCP_DEBUG) {
490 cpu_handle_debug_exception(cpu);
492 cpu->exception_index = -1;
493 return true;
494 } else {
495 #if defined(CONFIG_USER_ONLY)
496 /* if user mode only, we simulate a fake exception
497 which will be handled outside the cpu execution
498 loop */
499 #if defined(TARGET_I386)
500 CPUClass *cc = CPU_GET_CLASS(cpu);
501 cc->do_interrupt(cpu);
502 #endif
503 *ret = cpu->exception_index;
504 cpu->exception_index = -1;
505 return true;
506 #else
507 if (replay_exception()) {
508 CPUClass *cc = CPU_GET_CLASS(cpu);
509 qemu_mutex_lock_iothread();
510 cc->do_interrupt(cpu);
511 qemu_mutex_unlock_iothread();
512 cpu->exception_index = -1;
514 if (unlikely(cpu->singlestep_enabled)) {
516 * After processing the exception, ensure an EXCP_DEBUG is
517 * raised when single-stepping so that GDB doesn't miss the
518 * next instruction.
520 *ret = EXCP_DEBUG;
521 cpu_handle_debug_exception(cpu);
522 return true;
524 } else if (!replay_has_interrupt()) {
525 /* give a chance to iothread in replay mode */
526 *ret = EXCP_INTERRUPT;
527 return true;
529 #endif
532 return false;
536 * CPU_INTERRUPT_POLL is a virtual event which gets converted into a
537 * "real" interrupt event later. It does not need to be recorded for
538 * replay purposes.
540 static inline bool need_replay_interrupt(int interrupt_request)
542 #if defined(TARGET_I386)
543 return !(interrupt_request & CPU_INTERRUPT_POLL);
544 #else
545 return true;
546 #endif
549 static inline bool cpu_handle_interrupt(CPUState *cpu,
550 TranslationBlock **last_tb)
552 CPUClass *cc = CPU_GET_CLASS(cpu);
554 /* Clear the interrupt flag now since we're processing
555 * cpu->interrupt_request and cpu->exit_request.
556 * Ensure zeroing happens before reading cpu->exit_request or
557 * cpu->interrupt_request (see also smp_wmb in cpu_exit())
559 qatomic_mb_set(&cpu_neg(cpu)->icount_decr.u16.high, 0);
561 if (unlikely(qatomic_read(&cpu->interrupt_request))) {
562 int interrupt_request;
563 qemu_mutex_lock_iothread();
564 interrupt_request = cpu->interrupt_request;
565 if (unlikely(cpu->singlestep_enabled & SSTEP_NOIRQ)) {
566 /* Mask out external interrupts for this step. */
567 interrupt_request &= ~CPU_INTERRUPT_SSTEP_MASK;
569 if (interrupt_request & CPU_INTERRUPT_DEBUG) {
570 cpu->interrupt_request &= ~CPU_INTERRUPT_DEBUG;
571 cpu->exception_index = EXCP_DEBUG;
572 qemu_mutex_unlock_iothread();
573 return true;
575 if (replay_mode == REPLAY_MODE_PLAY && !replay_has_interrupt()) {
576 /* Do nothing */
577 } else if (interrupt_request & CPU_INTERRUPT_HALT) {
578 replay_interrupt();
579 cpu->interrupt_request &= ~CPU_INTERRUPT_HALT;
580 cpu->halted = 1;
581 cpu->exception_index = EXCP_HLT;
582 qemu_mutex_unlock_iothread();
583 return true;
585 #if defined(TARGET_I386)
586 else if (interrupt_request & CPU_INTERRUPT_INIT) {
587 X86CPU *x86_cpu = X86_CPU(cpu);
588 CPUArchState *env = &x86_cpu->env;
589 replay_interrupt();
590 cpu_svm_check_intercept_param(env, SVM_EXIT_INIT, 0, 0);
591 do_cpu_init(x86_cpu);
592 cpu->exception_index = EXCP_HALTED;
593 qemu_mutex_unlock_iothread();
594 return true;
596 #else
597 else if (interrupt_request & CPU_INTERRUPT_RESET) {
598 replay_interrupt();
599 cpu_reset(cpu);
600 qemu_mutex_unlock_iothread();
601 return true;
603 #endif
604 /* The target hook has 3 exit conditions:
605 False when the interrupt isn't processed,
606 True when it is, and we should restart on a new TB,
607 and via longjmp via cpu_loop_exit. */
608 else {
609 if (cc->cpu_exec_interrupt(cpu, interrupt_request)) {
610 if (need_replay_interrupt(interrupt_request)) {
611 replay_interrupt();
614 * After processing the interrupt, ensure an EXCP_DEBUG is
615 * raised when single-stepping so that GDB doesn't miss the
616 * next instruction.
618 cpu->exception_index =
619 (cpu->singlestep_enabled ? EXCP_DEBUG : -1);
620 *last_tb = NULL;
622 /* The target hook may have updated the 'cpu->interrupt_request';
623 * reload the 'interrupt_request' value */
624 interrupt_request = cpu->interrupt_request;
626 if (interrupt_request & CPU_INTERRUPT_EXITTB) {
627 cpu->interrupt_request &= ~CPU_INTERRUPT_EXITTB;
628 /* ensure that no TB jump will be modified as
629 the program flow was changed */
630 *last_tb = NULL;
633 /* If we exit via cpu_loop_exit/longjmp it is reset in cpu_exec */
634 qemu_mutex_unlock_iothread();
637 /* Finally, check if we need to exit to the main loop. */
638 if (unlikely(qatomic_read(&cpu->exit_request))
639 || (icount_enabled()
640 && cpu_neg(cpu)->icount_decr.u16.low + cpu->icount_extra == 0)) {
641 qatomic_set(&cpu->exit_request, 0);
642 if (cpu->exception_index == -1) {
643 cpu->exception_index = EXCP_INTERRUPT;
645 return true;
648 return false;
651 static inline void cpu_loop_exec_tb(CPUState *cpu, TranslationBlock *tb,
652 TranslationBlock **last_tb, int *tb_exit)
654 uintptr_t ret;
655 int32_t insns_left;
657 trace_exec_tb(tb, tb->pc);
658 ret = cpu_tb_exec(cpu, tb);
659 tb = (TranslationBlock *)(ret & ~TB_EXIT_MASK);
660 *tb_exit = ret & TB_EXIT_MASK;
661 if (*tb_exit != TB_EXIT_REQUESTED) {
662 *last_tb = tb;
663 return;
666 *last_tb = NULL;
667 insns_left = qatomic_read(&cpu_neg(cpu)->icount_decr.u32);
668 if (insns_left < 0) {
669 /* Something asked us to stop executing chained TBs; just
670 * continue round the main loop. Whatever requested the exit
671 * will also have set something else (eg exit_request or
672 * interrupt_request) which will be handled by
673 * cpu_handle_interrupt. cpu_handle_interrupt will also
674 * clear cpu->icount_decr.u16.high.
676 return;
679 /* Instruction counter expired. */
680 assert(icount_enabled());
681 #ifndef CONFIG_USER_ONLY
682 /* Ensure global icount has gone forward */
683 icount_update(cpu);
684 /* Refill decrementer and continue execution. */
685 insns_left = MIN(0xffff, cpu->icount_budget);
686 cpu_neg(cpu)->icount_decr.u16.low = insns_left;
687 cpu->icount_extra = cpu->icount_budget - insns_left;
688 if (!cpu->icount_extra) {
689 /* Execute any remaining instructions, then let the main loop
690 * handle the next event.
692 if (insns_left > 0) {
693 cpu_exec_nocache(cpu, insns_left, tb, false);
696 #endif
699 /* main execution loop */
701 int cpu_exec(CPUState *cpu)
703 CPUClass *cc = CPU_GET_CLASS(cpu);
704 int ret;
705 SyncClocks sc = { 0 };
707 /* replay_interrupt may need current_cpu */
708 current_cpu = cpu;
710 if (cpu_handle_halt(cpu)) {
711 return EXCP_HALTED;
714 rcu_read_lock();
716 cc->cpu_exec_enter(cpu);
718 /* Calculate difference between guest clock and host clock.
719 * This delay includes the delay of the last cycle, so
720 * what we have to do is sleep until it is 0. As for the
721 * advance/delay we gain here, we try to fix it next time.
723 init_delay_params(&sc, cpu);
725 /* prepare setjmp context for exception handling */
726 if (sigsetjmp(cpu->jmp_env, 0) != 0) {
727 #if defined(__clang__) || !QEMU_GNUC_PREREQ(4, 6)
728 /* Some compilers wrongly smash all local variables after
729 * siglongjmp. There were bug reports for gcc 4.5.0 and clang.
730 * Reload essential local variables here for those compilers.
731 * Newer versions of gcc would complain about this code (-Wclobbered). */
732 cpu = current_cpu;
733 cc = CPU_GET_CLASS(cpu);
734 #else /* buggy compiler */
735 /* Assert that the compiler does not smash local variables. */
736 g_assert(cpu == current_cpu);
737 g_assert(cc == CPU_GET_CLASS(cpu));
738 #endif /* buggy compiler */
739 #ifndef CONFIG_SOFTMMU
740 tcg_debug_assert(!have_mmap_lock());
741 #endif
742 if (qemu_mutex_iothread_locked()) {
743 qemu_mutex_unlock_iothread();
745 qemu_plugin_disable_mem_helpers(cpu);
747 assert_no_pages_locked();
750 /* if an exception is pending, we execute it here */
751 while (!cpu_handle_exception(cpu, &ret)) {
752 TranslationBlock *last_tb = NULL;
753 int tb_exit = 0;
755 while (!cpu_handle_interrupt(cpu, &last_tb)) {
756 uint32_t cflags = cpu->cflags_next_tb;
757 TranslationBlock *tb;
759 /* When requested, use an exact setting for cflags for the next
760 execution. This is used for icount, precise smc, and stop-
761 after-access watchpoints. Since this request should never
762 have CF_INVALID set, -1 is a convenient invalid value that
763 does not require tcg headers for cpu_common_reset. */
764 if (cflags == -1) {
765 cflags = curr_cflags();
766 } else {
767 cpu->cflags_next_tb = -1;
770 tb = tb_find(cpu, last_tb, tb_exit, cflags);
771 cpu_loop_exec_tb(cpu, tb, &last_tb, &tb_exit);
772 /* Try to align the host and virtual clocks
773 if the guest is in advance */
774 align_clocks(&sc, cpu);
778 cc->cpu_exec_exit(cpu);
779 rcu_read_unlock();
781 return ret;
784 #ifndef CONFIG_USER_ONLY
786 void dump_drift_info(void)
788 if (!icount_enabled()) {
789 return;
792 qemu_printf("Host - Guest clock %"PRIi64" ms\n",
793 (cpu_get_clock() - icount_get()) / SCALE_MS);
794 if (icount_align_option) {
795 qemu_printf("Max guest delay %"PRIi64" ms\n",
796 -max_delay / SCALE_MS);
797 qemu_printf("Max guest advance %"PRIi64" ms\n",
798 max_advance / SCALE_MS);
799 } else {
800 qemu_printf("Max guest delay NA\n");
801 qemu_printf("Max guest advance NA\n");
805 #endif /* !CONFIG_USER_ONLY */