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 "sysemu/replay.h" 28 #include "sysemu/cpu-timers.h" 29 #include "qemu/main-loop.h" 30 #include "qemu/guest-random.h" 31 #include "exec/exec-all.h" 32 33 #include "tcg-accel-ops.h" 34 #include "tcg-accel-ops-icount.h" 35 #include "tcg-accel-ops-rr.h" 36 37 static int64_t icount_get_limit(void) 38 { 39 int64_t deadline; 40 41 if (replay_mode != REPLAY_MODE_PLAY) { 42 /* 43 * Include all the timers, because they may need an attention. 44 * Too long CPU execution may create unnecessary delay in UI. 45 */ 46 deadline = qemu_clock_deadline_ns_all(QEMU_CLOCK_VIRTUAL, 47 QEMU_TIMER_ATTR_ALL); 48 /* Check realtime timers, because they help with input processing */ 49 deadline = qemu_soonest_timeout(deadline, 50 qemu_clock_deadline_ns_all(QEMU_CLOCK_REALTIME, 51 QEMU_TIMER_ATTR_ALL)); 52 53 /* 54 * Maintain prior (possibly buggy) behaviour where if no deadline 55 * was set (as there is no QEMU_CLOCK_VIRTUAL timer) or it is more than 56 * INT32_MAX nanoseconds ahead, we still use INT32_MAX 57 * nanoseconds. 58 */ 59 if ((deadline < 0) || (deadline > INT32_MAX)) { 60 deadline = INT32_MAX; 61 } 62 63 return icount_round(deadline); 64 } else { 65 return replay_get_instructions(); 66 } 67 } 68 69 static void icount_notify_aio_contexts(void) 70 { 71 /* Wake up other AioContexts. */ 72 qemu_clock_notify(QEMU_CLOCK_VIRTUAL); 73 qemu_clock_run_timers(QEMU_CLOCK_VIRTUAL); 74 } 75 76 void icount_handle_deadline(void) 77 { 78 assert(qemu_in_vcpu_thread()); 79 int64_t deadline = qemu_clock_deadline_ns_all(QEMU_CLOCK_VIRTUAL, 80 QEMU_TIMER_ATTR_ALL); 81 82 /* 83 * Instructions, interrupts, and exceptions are processed in cpu-exec. 84 * Don't interrupt cpu thread, when these events are waiting 85 * (i.e., there is no checkpoint) 86 */ 87 if (deadline == 0) { 88 icount_notify_aio_contexts(); 89 } 90 } 91 92 /* Distribute the budget evenly across all CPUs */ 93 int64_t icount_percpu_budget(int cpu_count) 94 { 95 int64_t limit = icount_get_limit(); 96 int64_t timeslice = limit / cpu_count; 97 98 if (timeslice == 0) { 99 timeslice = limit; 100 } 101 102 return timeslice; 103 } 104 105 void icount_prepare_for_run(CPUState *cpu, int64_t cpu_budget) 106 { 107 int insns_left; 108 109 /* 110 * These should always be cleared by icount_process_data after 111 * each vCPU execution. However u16.high can be raised 112 * asynchronously by cpu_exit/cpu_interrupt/tcg_handle_interrupt 113 */ 114 g_assert(cpu->neg.icount_decr.u16.low == 0); 115 g_assert(cpu->icount_extra == 0); 116 117 replay_mutex_lock(); 118 119 cpu->icount_budget = MIN(icount_get_limit(), cpu_budget); 120 insns_left = MIN(0xffff, cpu->icount_budget); 121 cpu->neg.icount_decr.u16.low = insns_left; 122 cpu->icount_extra = cpu->icount_budget - insns_left; 123 124 if (cpu->icount_budget == 0) { 125 /* 126 * We're called without the iothread lock, so must take it while 127 * we're calling timer handlers. 128 */ 129 qemu_mutex_lock_iothread(); 130 icount_notify_aio_contexts(); 131 qemu_mutex_unlock_iothread(); 132 } 133 } 134 135 void icount_process_data(CPUState *cpu) 136 { 137 /* Account for executed instructions */ 138 icount_update(cpu); 139 140 /* Reset the counters */ 141 cpu->neg.icount_decr.u16.low = 0; 142 cpu->icount_extra = 0; 143 cpu->icount_budget = 0; 144 145 replay_account_executed_instructions(); 146 147 replay_mutex_unlock(); 148 } 149 150 void icount_handle_interrupt(CPUState *cpu, int mask) 151 { 152 int old_mask = cpu->interrupt_request; 153 154 tcg_handle_interrupt(cpu, mask); 155 if (qemu_cpu_is_self(cpu) && 156 !cpu->neg.can_do_io 157 && (mask & ~old_mask) != 0) { 158 cpu_abort(cpu, "Raised interrupt while not in I/O function"); 159 } 160 } 161