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"
25 #include "disas/disas.h"
26 #include "exec/exec-all.h"
28 #include "qemu/atomic.h"
29 #include "qemu/compiler.h"
30 #include "sysemu/qtest.h"
31 #include "qemu/timer.h"
33 #include "exec/tb-hash.h"
34 #include "exec/tb-lookup.h"
36 #include "qemu/main-loop.h"
37 #if defined(TARGET_I386) && !defined(CONFIG_USER_ONLY)
38 #include "hw/i386/apic.h"
40 #include "sysemu/cpus.h"
41 #include "exec/cpu-all.h"
42 #include "sysemu/cpu-timers.h"
43 #include "sysemu/replay.h"
45 /* -icount align implementation. */
47 typedef struct SyncClocks
{
49 int64_t last_cpu_icount
;
50 int64_t realtime_clock
;
53 #if !defined(CONFIG_USER_ONLY)
54 /* Allow the guest to have a max 3ms advance.
55 * The difference between the 2 clocks could therefore
58 #define VM_CLOCK_ADVANCE 3000000
59 #define THRESHOLD_REDUCE 1.5
60 #define MAX_DELAY_PRINT_RATE 2000000000LL
61 #define MAX_NB_PRINTS 100
63 static int64_t max_delay
;
64 static int64_t max_advance
;
66 static void align_clocks(SyncClocks
*sc
, CPUState
*cpu
)
70 if (!icount_align_option
) {
74 cpu_icount
= cpu
->icount_extra
+ cpu_neg(cpu
)->icount_decr
.u16
.low
;
75 sc
->diff_clk
+= icount_to_ns(sc
->last_cpu_icount
- cpu_icount
);
76 sc
->last_cpu_icount
= cpu_icount
;
78 if (sc
->diff_clk
> VM_CLOCK_ADVANCE
) {
80 struct timespec sleep_delay
, rem_delay
;
81 sleep_delay
.tv_sec
= sc
->diff_clk
/ 1000000000LL;
82 sleep_delay
.tv_nsec
= sc
->diff_clk
% 1000000000LL;
83 if (nanosleep(&sleep_delay
, &rem_delay
) < 0) {
84 sc
->diff_clk
= rem_delay
.tv_sec
* 1000000000LL + rem_delay
.tv_nsec
;
89 Sleep(sc
->diff_clk
/ SCALE_MS
);
95 static void print_delay(const SyncClocks
*sc
)
97 static float threshold_delay
;
98 static int64_t last_realtime_clock
;
101 if (icount_align_option
&&
102 sc
->realtime_clock
- last_realtime_clock
>= MAX_DELAY_PRINT_RATE
&&
103 nb_prints
< MAX_NB_PRINTS
) {
104 if ((-sc
->diff_clk
/ (float)1000000000LL > threshold_delay
) ||
105 (-sc
->diff_clk
/ (float)1000000000LL <
106 (threshold_delay
- THRESHOLD_REDUCE
))) {
107 threshold_delay
= (-sc
->diff_clk
/ 1000000000LL) + 1;
108 qemu_printf("Warning: The guest is now late by %.1f to %.1f seconds\n",
112 last_realtime_clock
= sc
->realtime_clock
;
117 static void init_delay_params(SyncClocks
*sc
, CPUState
*cpu
)
119 if (!icount_align_option
) {
122 sc
->realtime_clock
= qemu_clock_get_ns(QEMU_CLOCK_VIRTUAL_RT
);
123 sc
->diff_clk
= qemu_clock_get_ns(QEMU_CLOCK_VIRTUAL
) - sc
->realtime_clock
;
125 = cpu
->icount_extra
+ cpu_neg(cpu
)->icount_decr
.u16
.low
;
126 if (sc
->diff_clk
< max_delay
) {
127 max_delay
= sc
->diff_clk
;
129 if (sc
->diff_clk
> max_advance
) {
130 max_advance
= sc
->diff_clk
;
133 /* Print every 2s max if the guest is late. We limit the number
134 of printed messages to NB_PRINT_MAX(currently 100) */
138 static void align_clocks(SyncClocks
*sc
, const CPUState
*cpu
)
142 static void init_delay_params(SyncClocks
*sc
, const CPUState
*cpu
)
145 #endif /* CONFIG USER ONLY */
147 /* Execute a TB, and fix up the CPU state afterwards if necessary */
149 * Disable CFI checks.
150 * TCG creates binary blobs at runtime, with the transformed code.
151 * A TB is a blob of binary code, created at runtime and called with an
152 * indirect function call. Since such function did not exist at compile time,
153 * the CFI runtime has no way to verify its signature and would fail.
154 * TCG is not considered a security-sensitive part of QEMU so this does not
155 * affect the impact of CFI in environment with high security requirements
157 static inline TranslationBlock
* QEMU_DISABLE_CFI
158 cpu_tb_exec(CPUState
*cpu
, TranslationBlock
*itb
, int *tb_exit
)
160 CPUArchState
*env
= cpu
->env_ptr
;
162 TranslationBlock
*last_tb
;
163 const void *tb_ptr
= itb
->tc
.ptr
;
165 qemu_log_mask_and_addr(CPU_LOG_EXEC
, itb
->pc
,
167 TARGET_FMT_lx
"/" TARGET_FMT_lx
"/%#x] %s\n",
168 cpu
->cpu_index
, itb
->tc
.ptr
,
169 itb
->cs_base
, itb
->pc
, itb
->flags
,
170 lookup_symbol(itb
->pc
));
172 #if defined(DEBUG_DISAS)
173 if (qemu_loglevel_mask(CPU_LOG_TB_CPU
)
174 && qemu_log_in_addr_range(itb
->pc
)) {
175 FILE *logfile
= qemu_log_lock();
177 if (qemu_loglevel_mask(CPU_LOG_TB_FPU
)) {
178 flags
|= CPU_DUMP_FPU
;
180 #if defined(TARGET_I386)
181 flags
|= CPU_DUMP_CCOP
;
183 log_cpu_state(cpu
, flags
);
184 qemu_log_unlock(logfile
);
186 #endif /* DEBUG_DISAS */
188 ret
= tcg_qemu_tb_exec(env
, tb_ptr
);
191 * TODO: Delay swapping back to the read-write region of the TB
192 * until we actually need to modify the TB. The read-only copy,
193 * coming from the rx region, shares the same host TLB entry as
194 * the code that executed the exit_tb opcode that arrived here.
195 * If we insist on touching both the RX and the RW pages, we
196 * double the host TLB pressure.
198 last_tb
= tcg_splitwx_to_rw((void *)(ret
& ~TB_EXIT_MASK
));
199 *tb_exit
= ret
& TB_EXIT_MASK
;
201 trace_exec_tb_exit(last_tb
, *tb_exit
);
203 if (*tb_exit
> TB_EXIT_IDX1
) {
204 /* We didn't start executing this TB (eg because the instruction
205 * counter hit zero); we must restore the guest PC to the address
206 * of the start of the TB.
208 CPUClass
*cc
= CPU_GET_CLASS(cpu
);
209 qemu_log_mask_and_addr(CPU_LOG_EXEC
, last_tb
->pc
,
210 "Stopped execution of TB chain before %p ["
211 TARGET_FMT_lx
"] %s\n",
212 last_tb
->tc
.ptr
, last_tb
->pc
,
213 lookup_symbol(last_tb
->pc
));
214 if (cc
->synchronize_from_tb
) {
215 cc
->synchronize_from_tb(cpu
, last_tb
);
218 cc
->set_pc(cpu
, last_tb
->pc
);
224 #ifndef CONFIG_USER_ONLY
225 /* Execute the code without caching the generated code. An interpreter
226 could be used if available. */
227 static void cpu_exec_nocache(CPUState
*cpu
, int max_cycles
,
228 TranslationBlock
*orig_tb
, bool ignore_icount
)
230 TranslationBlock
*tb
;
231 uint32_t cflags
= curr_cflags() | CF_NOCACHE
;
235 cflags
&= ~CF_USE_ICOUNT
;
238 /* Should never happen.
239 We only end up here when an existing TB is too long. */
240 cflags
|= MIN(max_cycles
, CF_COUNT_MASK
);
243 tb
= tb_gen_code(cpu
, orig_tb
->pc
, orig_tb
->cs_base
,
244 orig_tb
->flags
, cflags
);
245 tb
->orig_tb
= orig_tb
;
248 /* execute the generated code */
249 trace_exec_tb_nocache(tb
, tb
->pc
);
250 cpu_tb_exec(cpu
, tb
, &tb_exit
);
253 tb_phys_invalidate(tb
, -1);
259 static void cpu_exec_enter(CPUState
*cpu
)
261 CPUClass
*cc
= CPU_GET_CLASS(cpu
);
263 if (cc
->cpu_exec_enter
) {
264 cc
->cpu_exec_enter(cpu
);
268 static void cpu_exec_exit(CPUState
*cpu
)
270 CPUClass
*cc
= CPU_GET_CLASS(cpu
);
272 if (cc
->cpu_exec_exit
) {
273 cc
->cpu_exec_exit(cpu
);
277 void cpu_exec_step_atomic(CPUState
*cpu
)
279 TranslationBlock
*tb
;
280 target_ulong cs_base
, pc
;
283 uint32_t cf_mask
= cflags
& CF_HASH_MASK
;
286 if (sigsetjmp(cpu
->jmp_env
, 0) == 0) {
289 tb
= tb_lookup__cpu_state(cpu
, &pc
, &cs_base
, &flags
, cf_mask
);
292 tb
= tb_gen_code(cpu
, pc
, cs_base
, flags
, cflags
);
296 /* Since we got here, we know that parallel_cpus must be true. */
297 parallel_cpus
= false;
299 /* execute the generated code */
300 trace_exec_tb(tb
, pc
);
301 cpu_tb_exec(cpu
, tb
, &tb_exit
);
305 * The mmap_lock is dropped by tb_gen_code if it runs out of
308 #ifndef CONFIG_SOFTMMU
309 tcg_debug_assert(!have_mmap_lock());
311 if (qemu_mutex_iothread_locked()) {
312 qemu_mutex_unlock_iothread();
314 assert_no_pages_locked();
315 qemu_plugin_disable_mem_helpers(cpu
);
320 * As we start the exclusive region before codegen we must still
321 * be in the region if we longjump out of either the codegen or
324 g_assert(cpu_in_exclusive_context(cpu
));
325 parallel_cpus
= true;
331 target_ulong cs_base
;
333 tb_page_addr_t phys_page1
;
336 uint32_t trace_vcpu_dstate
;
339 static bool tb_lookup_cmp(const void *p
, const void *d
)
341 const TranslationBlock
*tb
= p
;
342 const struct tb_desc
*desc
= d
;
344 if (tb
->pc
== desc
->pc
&&
345 tb
->page_addr
[0] == desc
->phys_page1
&&
346 tb
->cs_base
== desc
->cs_base
&&
347 tb
->flags
== desc
->flags
&&
348 tb
->trace_vcpu_dstate
== desc
->trace_vcpu_dstate
&&
349 (tb_cflags(tb
) & (CF_HASH_MASK
| CF_INVALID
)) == desc
->cf_mask
) {
350 /* check next page if needed */
351 if (tb
->page_addr
[1] == -1) {
354 tb_page_addr_t phys_page2
;
355 target_ulong virt_page2
;
357 virt_page2
= (desc
->pc
& TARGET_PAGE_MASK
) + TARGET_PAGE_SIZE
;
358 phys_page2
= get_page_addr_code(desc
->env
, virt_page2
);
359 if (tb
->page_addr
[1] == phys_page2
) {
367 TranslationBlock
*tb_htable_lookup(CPUState
*cpu
, target_ulong pc
,
368 target_ulong cs_base
, uint32_t flags
,
371 tb_page_addr_t phys_pc
;
375 desc
.env
= (CPUArchState
*)cpu
->env_ptr
;
376 desc
.cs_base
= cs_base
;
378 desc
.cf_mask
= cf_mask
;
379 desc
.trace_vcpu_dstate
= *cpu
->trace_dstate
;
381 phys_pc
= get_page_addr_code(desc
.env
, pc
);
385 desc
.phys_page1
= phys_pc
& TARGET_PAGE_MASK
;
386 h
= tb_hash_func(phys_pc
, pc
, flags
, cf_mask
, *cpu
->trace_dstate
);
387 return qht_lookup_custom(&tb_ctx
.htable
, &desc
, h
, tb_lookup_cmp
);
390 void tb_set_jmp_target(TranslationBlock
*tb
, int n
, uintptr_t addr
)
392 if (TCG_TARGET_HAS_direct_jump
) {
393 uintptr_t offset
= tb
->jmp_target_arg
[n
];
394 uintptr_t tc_ptr
= (uintptr_t)tb
->tc
.ptr
;
395 uintptr_t jmp_rx
= tc_ptr
+ offset
;
396 uintptr_t jmp_rw
= jmp_rx
- tcg_splitwx_diff
;
397 tb_target_set_jmp_target(tc_ptr
, jmp_rx
, jmp_rw
, addr
);
399 tb
->jmp_target_arg
[n
] = addr
;
403 static inline void tb_add_jump(TranslationBlock
*tb
, int n
,
404 TranslationBlock
*tb_next
)
408 assert(n
< ARRAY_SIZE(tb
->jmp_list_next
));
409 qemu_spin_lock(&tb_next
->jmp_lock
);
411 /* make sure the destination TB is valid */
412 if (tb_next
->cflags
& CF_INVALID
) {
413 goto out_unlock_next
;
415 /* Atomically claim the jump destination slot only if it was NULL */
416 old
= qatomic_cmpxchg(&tb
->jmp_dest
[n
], (uintptr_t)NULL
,
419 goto out_unlock_next
;
422 /* patch the native jump address */
423 tb_set_jmp_target(tb
, n
, (uintptr_t)tb_next
->tc
.ptr
);
425 /* add in TB jmp list */
426 tb
->jmp_list_next
[n
] = tb_next
->jmp_list_head
;
427 tb_next
->jmp_list_head
= (uintptr_t)tb
| n
;
429 qemu_spin_unlock(&tb_next
->jmp_lock
);
431 qemu_log_mask_and_addr(CPU_LOG_EXEC
, tb
->pc
,
432 "Linking TBs %p [" TARGET_FMT_lx
433 "] index %d -> %p [" TARGET_FMT_lx
"]\n",
434 tb
->tc
.ptr
, tb
->pc
, n
,
435 tb_next
->tc
.ptr
, tb_next
->pc
);
439 qemu_spin_unlock(&tb_next
->jmp_lock
);
443 static inline TranslationBlock
*tb_find(CPUState
*cpu
,
444 TranslationBlock
*last_tb
,
445 int tb_exit
, uint32_t cf_mask
)
447 TranslationBlock
*tb
;
448 target_ulong cs_base
, pc
;
451 tb
= tb_lookup__cpu_state(cpu
, &pc
, &cs_base
, &flags
, cf_mask
);
454 tb
= tb_gen_code(cpu
, pc
, cs_base
, flags
, cf_mask
);
456 /* We add the TB in the virtual pc hash table for the fast lookup */
457 qatomic_set(&cpu
->tb_jmp_cache
[tb_jmp_cache_hash_func(pc
)], tb
);
459 #ifndef CONFIG_USER_ONLY
460 /* We don't take care of direct jumps when address mapping changes in
461 * system emulation. So it's not safe to make a direct jump to a TB
462 * spanning two pages because the mapping for the second page can change.
464 if (tb
->page_addr
[1] != -1) {
468 /* See if we can patch the calling TB. */
470 tb_add_jump(last_tb
, tb_exit
, tb
);
475 static inline bool cpu_handle_halt(CPUState
*cpu
)
478 #if defined(TARGET_I386) && !defined(CONFIG_USER_ONLY)
479 if (cpu
->interrupt_request
& CPU_INTERRUPT_POLL
) {
480 X86CPU
*x86_cpu
= X86_CPU(cpu
);
481 qemu_mutex_lock_iothread();
482 apic_poll_irq(x86_cpu
->apic_state
);
483 cpu_reset_interrupt(cpu
, CPU_INTERRUPT_POLL
);
484 qemu_mutex_unlock_iothread();
487 if (!cpu_has_work(cpu
)) {
497 static inline void cpu_handle_debug_exception(CPUState
*cpu
)
499 CPUClass
*cc
= CPU_GET_CLASS(cpu
);
502 if (!cpu
->watchpoint_hit
) {
503 QTAILQ_FOREACH(wp
, &cpu
->watchpoints
, entry
) {
504 wp
->flags
&= ~BP_WATCHPOINT_HIT
;
508 if (cc
->debug_excp_handler
) {
509 cc
->debug_excp_handler(cpu
);
513 static inline bool cpu_handle_exception(CPUState
*cpu
, int *ret
)
515 if (cpu
->exception_index
< 0) {
516 #ifndef CONFIG_USER_ONLY
517 if (replay_has_exception()
518 && cpu_neg(cpu
)->icount_decr
.u16
.low
+ cpu
->icount_extra
== 0) {
519 /* try to cause an exception pending in the log */
520 cpu_exec_nocache(cpu
, 1, tb_find(cpu
, NULL
, 0, curr_cflags()), true);
523 if (cpu
->exception_index
< 0) {
528 if (cpu
->exception_index
>= EXCP_INTERRUPT
) {
529 /* exit request from the cpu execution loop */
530 *ret
= cpu
->exception_index
;
531 if (*ret
== EXCP_DEBUG
) {
532 cpu_handle_debug_exception(cpu
);
534 cpu
->exception_index
= -1;
537 #if defined(CONFIG_USER_ONLY)
538 /* if user mode only, we simulate a fake exception
539 which will be handled outside the cpu execution
541 #if defined(TARGET_I386)
542 CPUClass
*cc
= CPU_GET_CLASS(cpu
);
543 cc
->do_interrupt(cpu
);
545 *ret
= cpu
->exception_index
;
546 cpu
->exception_index
= -1;
549 if (replay_exception()) {
550 CPUClass
*cc
= CPU_GET_CLASS(cpu
);
551 qemu_mutex_lock_iothread();
552 cc
->do_interrupt(cpu
);
553 qemu_mutex_unlock_iothread();
554 cpu
->exception_index
= -1;
556 if (unlikely(cpu
->singlestep_enabled
)) {
558 * After processing the exception, ensure an EXCP_DEBUG is
559 * raised when single-stepping so that GDB doesn't miss the
563 cpu_handle_debug_exception(cpu
);
566 } else if (!replay_has_interrupt()) {
567 /* give a chance to iothread in replay mode */
568 *ret
= EXCP_INTERRUPT
;
578 * CPU_INTERRUPT_POLL is a virtual event which gets converted into a
579 * "real" interrupt event later. It does not need to be recorded for
582 static inline bool need_replay_interrupt(int interrupt_request
)
584 #if defined(TARGET_I386)
585 return !(interrupt_request
& CPU_INTERRUPT_POLL
);
591 static inline bool cpu_handle_interrupt(CPUState
*cpu
,
592 TranslationBlock
**last_tb
)
594 CPUClass
*cc
= CPU_GET_CLASS(cpu
);
596 /* Clear the interrupt flag now since we're processing
597 * cpu->interrupt_request and cpu->exit_request.
598 * Ensure zeroing happens before reading cpu->exit_request or
599 * cpu->interrupt_request (see also smp_wmb in cpu_exit())
601 qatomic_mb_set(&cpu_neg(cpu
)->icount_decr
.u16
.high
, 0);
603 if (unlikely(qatomic_read(&cpu
->interrupt_request
))) {
604 int interrupt_request
;
605 qemu_mutex_lock_iothread();
606 interrupt_request
= cpu
->interrupt_request
;
607 if (unlikely(cpu
->singlestep_enabled
& SSTEP_NOIRQ
)) {
608 /* Mask out external interrupts for this step. */
609 interrupt_request
&= ~CPU_INTERRUPT_SSTEP_MASK
;
611 if (interrupt_request
& CPU_INTERRUPT_DEBUG
) {
612 cpu
->interrupt_request
&= ~CPU_INTERRUPT_DEBUG
;
613 cpu
->exception_index
= EXCP_DEBUG
;
614 qemu_mutex_unlock_iothread();
617 if (replay_mode
== REPLAY_MODE_PLAY
&& !replay_has_interrupt()) {
619 } else if (interrupt_request
& CPU_INTERRUPT_HALT
) {
621 cpu
->interrupt_request
&= ~CPU_INTERRUPT_HALT
;
623 cpu
->exception_index
= EXCP_HLT
;
624 qemu_mutex_unlock_iothread();
627 #if defined(TARGET_I386)
628 else if (interrupt_request
& CPU_INTERRUPT_INIT
) {
629 X86CPU
*x86_cpu
= X86_CPU(cpu
);
630 CPUArchState
*env
= &x86_cpu
->env
;
632 cpu_svm_check_intercept_param(env
, SVM_EXIT_INIT
, 0, 0);
633 do_cpu_init(x86_cpu
);
634 cpu
->exception_index
= EXCP_HALTED
;
635 qemu_mutex_unlock_iothread();
639 else if (interrupt_request
& CPU_INTERRUPT_RESET
) {
642 qemu_mutex_unlock_iothread();
646 /* The target hook has 3 exit conditions:
647 False when the interrupt isn't processed,
648 True when it is, and we should restart on a new TB,
649 and via longjmp via cpu_loop_exit. */
651 if (cc
->cpu_exec_interrupt
&&
652 cc
->cpu_exec_interrupt(cpu
, interrupt_request
)) {
653 if (need_replay_interrupt(interrupt_request
)) {
657 * After processing the interrupt, ensure an EXCP_DEBUG is
658 * raised when single-stepping so that GDB doesn't miss the
661 cpu
->exception_index
=
662 (cpu
->singlestep_enabled
? EXCP_DEBUG
: -1);
665 /* The target hook may have updated the 'cpu->interrupt_request';
666 * reload the 'interrupt_request' value */
667 interrupt_request
= cpu
->interrupt_request
;
669 if (interrupt_request
& CPU_INTERRUPT_EXITTB
) {
670 cpu
->interrupt_request
&= ~CPU_INTERRUPT_EXITTB
;
671 /* ensure that no TB jump will be modified as
672 the program flow was changed */
676 /* If we exit via cpu_loop_exit/longjmp it is reset in cpu_exec */
677 qemu_mutex_unlock_iothread();
680 /* Finally, check if we need to exit to the main loop. */
681 if (unlikely(qatomic_read(&cpu
->exit_request
))
683 && cpu_neg(cpu
)->icount_decr
.u16
.low
+ cpu
->icount_extra
== 0)) {
684 qatomic_set(&cpu
->exit_request
, 0);
685 if (cpu
->exception_index
== -1) {
686 cpu
->exception_index
= EXCP_INTERRUPT
;
694 static inline void cpu_loop_exec_tb(CPUState
*cpu
, TranslationBlock
*tb
,
695 TranslationBlock
**last_tb
, int *tb_exit
)
699 trace_exec_tb(tb
, tb
->pc
);
700 tb
= cpu_tb_exec(cpu
, tb
, tb_exit
);
701 if (*tb_exit
!= TB_EXIT_REQUESTED
) {
707 insns_left
= qatomic_read(&cpu_neg(cpu
)->icount_decr
.u32
);
708 if (insns_left
< 0) {
709 /* Something asked us to stop executing chained TBs; just
710 * continue round the main loop. Whatever requested the exit
711 * will also have set something else (eg exit_request or
712 * interrupt_request) which will be handled by
713 * cpu_handle_interrupt. cpu_handle_interrupt will also
714 * clear cpu->icount_decr.u16.high.
719 /* Instruction counter expired. */
720 assert(icount_enabled());
721 #ifndef CONFIG_USER_ONLY
722 /* Ensure global icount has gone forward */
724 /* Refill decrementer and continue execution. */
725 insns_left
= MIN(0xffff, cpu
->icount_budget
);
726 cpu_neg(cpu
)->icount_decr
.u16
.low
= insns_left
;
727 cpu
->icount_extra
= cpu
->icount_budget
- insns_left
;
728 if (!cpu
->icount_extra
&& insns_left
< tb
->icount
) {
729 /* Execute any remaining instructions, then let the main loop
730 * handle the next event.
732 if (insns_left
> 0) {
733 cpu_exec_nocache(cpu
, insns_left
, tb
, false);
739 /* main execution loop */
741 int cpu_exec(CPUState
*cpu
)
743 CPUClass
*cc
= CPU_GET_CLASS(cpu
);
745 SyncClocks sc
= { 0 };
747 /* replay_interrupt may need current_cpu */
750 if (cpu_handle_halt(cpu
)) {
758 /* Calculate difference between guest clock and host clock.
759 * This delay includes the delay of the last cycle, so
760 * what we have to do is sleep until it is 0. As for the
761 * advance/delay we gain here, we try to fix it next time.
763 init_delay_params(&sc
, cpu
);
765 /* prepare setjmp context for exception handling */
766 if (sigsetjmp(cpu
->jmp_env
, 0) != 0) {
767 #if defined(__clang__)
768 /* Some compilers wrongly smash all local variables after
769 * siglongjmp. There were bug reports for gcc 4.5.0 and clang.
770 * Reload essential local variables here for those compilers.
771 * Newer versions of gcc would complain about this code (-Wclobbered). */
773 cc
= CPU_GET_CLASS(cpu
);
774 #else /* buggy compiler */
775 /* Assert that the compiler does not smash local variables. */
776 g_assert(cpu
== current_cpu
);
777 g_assert(cc
== CPU_GET_CLASS(cpu
));
778 #endif /* buggy compiler */
779 #ifndef CONFIG_SOFTMMU
780 tcg_debug_assert(!have_mmap_lock());
782 if (qemu_mutex_iothread_locked()) {
783 qemu_mutex_unlock_iothread();
785 qemu_plugin_disable_mem_helpers(cpu
);
787 assert_no_pages_locked();
790 /* if an exception is pending, we execute it here */
791 while (!cpu_handle_exception(cpu
, &ret
)) {
792 TranslationBlock
*last_tb
= NULL
;
795 while (!cpu_handle_interrupt(cpu
, &last_tb
)) {
796 uint32_t cflags
= cpu
->cflags_next_tb
;
797 TranslationBlock
*tb
;
799 /* When requested, use an exact setting for cflags for the next
800 execution. This is used for icount, precise smc, and stop-
801 after-access watchpoints. Since this request should never
802 have CF_INVALID set, -1 is a convenient invalid value that
803 does not require tcg headers for cpu_common_reset. */
805 cflags
= curr_cflags();
807 cpu
->cflags_next_tb
= -1;
810 tb
= tb_find(cpu
, last_tb
, tb_exit
, cflags
);
811 cpu_loop_exec_tb(cpu
, tb
, &last_tb
, &tb_exit
);
812 /* Try to align the host and virtual clocks
813 if the guest is in advance */
814 align_clocks(&sc
, cpu
);
824 #ifndef CONFIG_USER_ONLY
826 void dump_drift_info(void)
828 if (!icount_enabled()) {
832 qemu_printf("Host - Guest clock %"PRIi64
" ms\n",
833 (cpu_get_clock() - icount_get()) / SCALE_MS
);
834 if (icount_align_option
) {
835 qemu_printf("Max guest delay %"PRIi64
" ms\n",
836 -max_delay
/ SCALE_MS
);
837 qemu_printf("Max guest advance %"PRIi64
" ms\n",
838 max_advance
/ SCALE_MS
);
840 qemu_printf("Max guest delay NA\n");
841 qemu_printf("Max guest advance NA\n");
845 #endif /* !CONFIG_USER_ONLY */