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 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 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 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 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 } 117 118 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 } 132 133 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