1 /* 2 * KVM in-kernel PIT (i8254) support 3 * 4 * Copyright (c) 2003-2004 Fabrice Bellard 5 * Copyright (c) 2012 Jan Kiszka, Siemens AG 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 #include "qemu/timer.h" 26 #include "sysemu/sysemu.h" 27 #include "hw/timer/i8254.h" 28 #include "hw/timer/i8254_internal.h" 29 #include "sysemu/kvm.h" 30 31 #define KVM_PIT_REINJECT_BIT 0 32 33 #define CALIBRATION_ROUNDS 3 34 35 #define KVM_PIT(obj) OBJECT_CHECK(KVMPITState, (obj), TYPE_KVM_I8254) 36 37 typedef struct KVMPITState { 38 PITCommonState parent_obj; 39 40 LostTickPolicy lost_tick_policy; 41 bool vm_stopped; 42 int64_t kernel_clock_offset; 43 } KVMPITState; 44 45 static int64_t abs64(int64_t v) 46 { 47 return v < 0 ? -v : v; 48 } 49 50 static void kvm_pit_update_clock_offset(KVMPITState *s) 51 { 52 int64_t offset, clock_offset; 53 struct timespec ts; 54 int i; 55 56 /* 57 * Measure the delta between CLOCK_MONOTONIC, the base used for 58 * kvm_pit_channel_state::count_load_time, and vm_clock. Take the 59 * minimum of several samples to filter out scheduling noise. 60 */ 61 clock_offset = INT64_MAX; 62 for (i = 0; i < CALIBRATION_ROUNDS; i++) { 63 offset = qemu_get_clock_ns(vm_clock); 64 clock_gettime(CLOCK_MONOTONIC, &ts); 65 offset -= ts.tv_nsec; 66 offset -= (int64_t)ts.tv_sec * 1000000000; 67 if (abs64(offset) < abs64(clock_offset)) { 68 clock_offset = offset; 69 } 70 } 71 s->kernel_clock_offset = clock_offset; 72 } 73 74 static void kvm_pit_get(PITCommonState *pit) 75 { 76 KVMPITState *s = KVM_PIT(pit); 77 struct kvm_pit_state2 kpit; 78 struct kvm_pit_channel_state *kchan; 79 struct PITChannelState *sc; 80 int i, ret; 81 82 /* No need to re-read the state if VM is stopped. */ 83 if (s->vm_stopped) { 84 return; 85 } 86 87 if (kvm_has_pit_state2()) { 88 ret = kvm_vm_ioctl(kvm_state, KVM_GET_PIT2, &kpit); 89 if (ret < 0) { 90 fprintf(stderr, "KVM_GET_PIT2 failed: %s\n", strerror(ret)); 91 abort(); 92 } 93 pit->channels[0].irq_disabled = kpit.flags & KVM_PIT_FLAGS_HPET_LEGACY; 94 } else { 95 /* 96 * kvm_pit_state2 is superset of kvm_pit_state struct, 97 * so we can use it for KVM_GET_PIT as well. 98 */ 99 ret = kvm_vm_ioctl(kvm_state, KVM_GET_PIT, &kpit); 100 if (ret < 0) { 101 fprintf(stderr, "KVM_GET_PIT failed: %s\n", strerror(ret)); 102 abort(); 103 } 104 } 105 for (i = 0; i < 3; i++) { 106 kchan = &kpit.channels[i]; 107 sc = &pit->channels[i]; 108 sc->count = kchan->count; 109 sc->latched_count = kchan->latched_count; 110 sc->count_latched = kchan->count_latched; 111 sc->status_latched = kchan->status_latched; 112 sc->status = kchan->status; 113 sc->read_state = kchan->read_state; 114 sc->write_state = kchan->write_state; 115 sc->write_latch = kchan->write_latch; 116 sc->rw_mode = kchan->rw_mode; 117 sc->mode = kchan->mode; 118 sc->bcd = kchan->bcd; 119 sc->gate = kchan->gate; 120 sc->count_load_time = kchan->count_load_time + s->kernel_clock_offset; 121 } 122 123 sc = &pit->channels[0]; 124 sc->next_transition_time = 125 pit_get_next_transition_time(sc, sc->count_load_time); 126 } 127 128 static void kvm_pit_put(PITCommonState *pit) 129 { 130 KVMPITState *s = KVM_PIT(pit); 131 struct kvm_pit_state2 kpit; 132 struct kvm_pit_channel_state *kchan; 133 struct PITChannelState *sc; 134 int i, ret; 135 136 /* The offset keeps changing as long as the VM is stopped. */ 137 if (s->vm_stopped) { 138 kvm_pit_update_clock_offset(s); 139 } 140 141 kpit.flags = pit->channels[0].irq_disabled ? KVM_PIT_FLAGS_HPET_LEGACY : 0; 142 for (i = 0; i < 3; i++) { 143 kchan = &kpit.channels[i]; 144 sc = &pit->channels[i]; 145 kchan->count = sc->count; 146 kchan->latched_count = sc->latched_count; 147 kchan->count_latched = sc->count_latched; 148 kchan->status_latched = sc->status_latched; 149 kchan->status = sc->status; 150 kchan->read_state = sc->read_state; 151 kchan->write_state = sc->write_state; 152 kchan->write_latch = sc->write_latch; 153 kchan->rw_mode = sc->rw_mode; 154 kchan->mode = sc->mode; 155 kchan->bcd = sc->bcd; 156 kchan->gate = sc->gate; 157 kchan->count_load_time = sc->count_load_time - s->kernel_clock_offset; 158 } 159 160 ret = kvm_vm_ioctl(kvm_state, 161 kvm_has_pit_state2() ? KVM_SET_PIT2 : KVM_SET_PIT, 162 &kpit); 163 if (ret < 0) { 164 fprintf(stderr, "%s failed: %s\n", 165 kvm_has_pit_state2() ? "KVM_SET_PIT2" : "KVM_SET_PIT", 166 strerror(ret)); 167 abort(); 168 } 169 } 170 171 static void kvm_pit_set_gate(PITCommonState *s, PITChannelState *sc, int val) 172 { 173 kvm_pit_get(s); 174 175 switch (sc->mode) { 176 default: 177 case 0: 178 case 4: 179 /* XXX: just disable/enable counting */ 180 break; 181 case 1: 182 case 2: 183 case 3: 184 case 5: 185 if (sc->gate < val) { 186 /* restart counting on rising edge */ 187 sc->count_load_time = qemu_get_clock_ns(vm_clock); 188 } 189 break; 190 } 191 sc->gate = val; 192 193 kvm_pit_put(s); 194 } 195 196 static void kvm_pit_get_channel_info(PITCommonState *s, PITChannelState *sc, 197 PITChannelInfo *info) 198 { 199 kvm_pit_get(s); 200 201 pit_get_channel_info_common(s, sc, info); 202 } 203 204 static void kvm_pit_reset(DeviceState *dev) 205 { 206 PITCommonState *s = PIT_COMMON(dev); 207 208 pit_reset_common(s); 209 210 kvm_pit_put(s); 211 } 212 213 static void kvm_pit_irq_control(void *opaque, int n, int enable) 214 { 215 PITCommonState *pit = opaque; 216 PITChannelState *s = &pit->channels[0]; 217 218 kvm_pit_get(pit); 219 220 s->irq_disabled = !enable; 221 222 kvm_pit_put(pit); 223 } 224 225 static void kvm_pit_vm_state_change(void *opaque, int running, 226 RunState state) 227 { 228 KVMPITState *s = opaque; 229 230 if (running) { 231 kvm_pit_update_clock_offset(s); 232 s->vm_stopped = false; 233 } else { 234 kvm_pit_update_clock_offset(s); 235 kvm_pit_get(PIT_COMMON(s)); 236 s->vm_stopped = true; 237 } 238 } 239 240 static int kvm_pit_initfn(PITCommonState *pit) 241 { 242 KVMPITState *s = KVM_PIT(pit); 243 struct kvm_pit_config config = { 244 .flags = 0, 245 }; 246 int ret; 247 248 if (kvm_check_extension(kvm_state, KVM_CAP_PIT2)) { 249 ret = kvm_vm_ioctl(kvm_state, KVM_CREATE_PIT2, &config); 250 } else { 251 ret = kvm_vm_ioctl(kvm_state, KVM_CREATE_PIT); 252 } 253 if (ret < 0) { 254 fprintf(stderr, "Create kernel PIC irqchip failed: %s\n", 255 strerror(ret)); 256 return ret; 257 } 258 switch (s->lost_tick_policy) { 259 case LOST_TICK_DELAY: 260 break; /* enabled by default */ 261 case LOST_TICK_DISCARD: 262 if (kvm_check_extension(kvm_state, KVM_CAP_REINJECT_CONTROL)) { 263 struct kvm_reinject_control control = { .pit_reinject = 0 }; 264 265 ret = kvm_vm_ioctl(kvm_state, KVM_REINJECT_CONTROL, &control); 266 if (ret < 0) { 267 fprintf(stderr, 268 "Can't disable in-kernel PIT reinjection: %s\n", 269 strerror(ret)); 270 return ret; 271 } 272 } 273 break; 274 default: 275 return -EINVAL; 276 } 277 278 memory_region_init_reservation(&pit->ioports, "kvm-pit", 4); 279 280 qdev_init_gpio_in(&pit->dev.qdev, kvm_pit_irq_control, 1); 281 282 qemu_add_vm_change_state_handler(kvm_pit_vm_state_change, s); 283 284 return 0; 285 } 286 287 static Property kvm_pit_properties[] = { 288 DEFINE_PROP_HEX32("iobase", PITCommonState, iobase, -1), 289 DEFINE_PROP_LOSTTICKPOLICY("lost_tick_policy", KVMPITState, 290 lost_tick_policy, LOST_TICK_DELAY), 291 DEFINE_PROP_END_OF_LIST(), 292 }; 293 294 static void kvm_pit_class_init(ObjectClass *klass, void *data) 295 { 296 PITCommonClass *k = PIT_COMMON_CLASS(klass); 297 DeviceClass *dc = DEVICE_CLASS(klass); 298 299 k->init = kvm_pit_initfn; 300 k->set_channel_gate = kvm_pit_set_gate; 301 k->get_channel_info = kvm_pit_get_channel_info; 302 k->pre_save = kvm_pit_get; 303 k->post_load = kvm_pit_put; 304 dc->reset = kvm_pit_reset; 305 dc->props = kvm_pit_properties; 306 } 307 308 static const TypeInfo kvm_pit_info = { 309 .name = TYPE_KVM_I8254, 310 .parent = TYPE_PIT_COMMON, 311 .instance_size = sizeof(KVMPITState), 312 .class_init = kvm_pit_class_init, 313 }; 314 315 static void kvm_pit_register(void) 316 { 317 type_register_static(&kvm_pit_info); 318 } 319 320 type_init(kvm_pit_register) 321