qapi2texi: Fix up output around #optional
[qemu.git] / cpu-exec-common.c
1 /*
2 * emulator main execution loop
3 *
4 * Copyright (c) 2003-2005 Fabrice Bellard
5 *
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 of the License, or (at your option) any later version.
10 *
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.
15 *
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/>.
18 */
19
20 #include "qemu/osdep.h"
21 #include "cpu.h"
22 #include "sysemu/cpus.h"
23 #include "exec/exec-all.h"
24 #include "exec/memory-internal.h"
25
26 /* exit the current TB, but without causing any exception to be raised */
27 void cpu_loop_exit_noexc(CPUState *cpu)
28 {
29 /* XXX: restore cpu registers saved in host registers */
30
31 cpu->exception_index = -1;
32 siglongjmp(cpu->jmp_env, 1);
33 }
34
35 #if defined(CONFIG_SOFTMMU)
36 void cpu_reloading_memory_map(void)
37 {
38 if (qemu_in_vcpu_thread()) {
39 /* The guest can in theory prolong the RCU critical section as long
40 * as it feels like. The major problem with this is that because it
41 * can do multiple reconfigurations of the memory map within the
42 * critical section, we could potentially accumulate an unbounded
43 * collection of memory data structures awaiting reclamation.
44 *
45 * Because the only thing we're currently protecting with RCU is the
46 * memory data structures, it's sufficient to break the critical section
47 * in this callback, which we know will get called every time the
48 * memory map is rearranged.
49 *
50 * (If we add anything else in the system that uses RCU to protect
51 * its data structures, we will need to implement some other mechanism
52 * to force TCG CPUs to exit the critical section, at which point this
53 * part of this callback might become unnecessary.)
54 *
55 * This pair matches cpu_exec's rcu_read_lock()/rcu_read_unlock(), which
56 * only protects cpu->as->dispatch. Since we know our caller is about
57 * to reload it, it's safe to split the critical section.
58 */
59 rcu_read_unlock();
60 rcu_read_lock();
61 }
62 }
63 #endif
64
65 void cpu_loop_exit(CPUState *cpu)
66 {
67 siglongjmp(cpu->jmp_env, 1);
68 }
69
70 void cpu_loop_exit_restore(CPUState *cpu, uintptr_t pc)
71 {
72 if (pc) {
73 cpu_restore_state(cpu, pc);
74 }
75 siglongjmp(cpu->jmp_env, 1);
76 }
77
78 void cpu_loop_exit_atomic(CPUState *cpu, uintptr_t pc)
79 {
80 cpu->exception_index = EXCP_ATOMIC;
81 cpu_loop_exit_restore(cpu, pc);
82 }