1 /*
2 * QEMU TCG Single Threaded vCPUs implementation using instruction counting
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"
27 #include "qemu-common.h"
28 #include "sysemu/tcg.h"
29 #include "sysemu/replay.h"
30 #include "qemu/main-loop.h"
31 #include "qemu/guest-random.h"
32 #include "exec/exec-all.h"
33
34 #include "tcg-accel-ops.h"
35 #include "tcg-accel-ops-icount.h"
36 #include "tcg-accel-ops-rr.h"
37
icount_get_limit(void)38 static int64_t icount_get_limit(void)
39 {
40 int64_t deadline;
41
42 if (replay_mode != REPLAY_MODE_PLAY) {
43 /*
44 * Include all the timers, because they may need an attention.
45 * Too long CPU execution may create unnecessary delay in UI.
46 */
47 deadline = qemu_clock_deadline_ns_all(QEMU_CLOCK_VIRTUAL,
48 QEMU_TIMER_ATTR_ALL);
49 /* Check realtime timers, because they help with input processing */
50 deadline = qemu_soonest_timeout(deadline,
51 qemu_clock_deadline_ns_all(QEMU_CLOCK_REALTIME,
52 QEMU_TIMER_ATTR_ALL));
53
54 /*
55 * Maintain prior (possibly buggy) behaviour where if no deadline
56 * was set (as there is no QEMU_CLOCK_VIRTUAL timer) or it is more than
57 * INT32_MAX nanoseconds ahead, we still use INT32_MAX
58 * nanoseconds.
59 */
60 if ((deadline < 0) || (deadline > INT32_MAX)) {
61 deadline = INT32_MAX;
62 }
63
64 return icount_round(deadline);
65 } else {
66 return replay_get_instructions();
67 }
68 }
69
icount_notify_aio_contexts(void)70 static void icount_notify_aio_contexts(void)
71 {
72 /* Wake up other AioContexts. */
73 qemu_clock_notify(QEMU_CLOCK_VIRTUAL);
74 qemu_clock_run_timers(QEMU_CLOCK_VIRTUAL);
75 }
76
icount_handle_deadline(void)77 void icount_handle_deadline(void)
78 {
79 assert(qemu_in_vcpu_thread());
80 int64_t deadline = qemu_clock_deadline_ns_all(QEMU_CLOCK_VIRTUAL,
81 QEMU_TIMER_ATTR_ALL);
82
83 /*
84 * Instructions, interrupts, and exceptions are processed in cpu-exec.
85 * Don't interrupt cpu thread, when these events are waiting
86 * (i.e., there is no checkpoint)
87 */
88 if (deadline == 0
89 && (replay_mode != REPLAY_MODE_PLAY || replay_has_checkpoint())) {
90 icount_notify_aio_contexts();
91 }
92 }
93
icount_prepare_for_run(CPUState * cpu)94 void icount_prepare_for_run(CPUState *cpu)
95 {
96 int insns_left;
97
98 /*
99 * These should always be cleared by icount_process_data after
100 * each vCPU execution. However u16.high can be raised
101 * asynchronously by cpu_exit/cpu_interrupt/tcg_handle_interrupt
102 */
103 g_assert(cpu_neg(cpu)->icount_decr.u16.low == 0);
104 g_assert(cpu->icount_extra == 0);
105
106 cpu->icount_budget = icount_get_limit();
107 insns_left = MIN(0xffff, cpu->icount_budget);
108 cpu_neg(cpu)->icount_decr.u16.low = insns_left;
109 cpu->icount_extra = cpu->icount_budget - insns_left;
110
111 replay_mutex_lock();
112
113 if (cpu->icount_budget == 0 && replay_has_checkpoint()) {
114 icount_notify_aio_contexts();
115 }
116 }
117
icount_process_data(CPUState * cpu)118 void icount_process_data(CPUState *cpu)
119 {
120 /* Account for executed instructions */
121 icount_update(cpu);
122
123 /* Reset the counters */
124 cpu_neg(cpu)->icount_decr.u16.low = 0;
125 cpu->icount_extra = 0;
126 cpu->icount_budget = 0;
127
128 replay_account_executed_instructions();
129
130 replay_mutex_unlock();
131 }
132
icount_handle_interrupt(CPUState * cpu,int mask)133 void icount_handle_interrupt(CPUState *cpu, int mask)
134 {
135 int old_mask = cpu->interrupt_request;
136
137 tcg_handle_interrupt(cpu, mask);
138 if (qemu_cpu_is_self(cpu) &&
139 !cpu->can_do_io
140 && (mask & ~old_mask) != 0) {
141 cpu_abort(cpu, "Raised interrupt while not in I/O function");
142 }
143 }
144