hw/i386/kvm/i8254.c

   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/osdep.h"
  26 #include "qapi/error.h"
  27 #include "qemu/timer.h"
  28 #include "sysemu/sysemu.h"
  29 #include "hw/timer/i8254.h"
  30 #include "hw/timer/i8254_internal.h"
  31 #include "sysemu/kvm.h"
  32 #include "linux/kvm.h"
  33
  34 #define KVM_PIT_REINJECT_BIT 0
  35
  36 #define CALIBRATION_ROUNDS   3
  37
  38 #define KVM_PIT(obj) OBJECT_CHECK(KVMPITState, (obj), TYPE_KVM_I8254)
  39 #define KVM_PIT_CLASS(class) \
  40     OBJECT_CLASS_CHECK(KVMPITClass, (class), TYPE_KVM_I8254)
  41 #define KVM_PIT_GET_CLASS(obj) \
  42     OBJECT_GET_CLASS(KVMPITClass, (obj), TYPE_KVM_I8254)
  43
  44 typedef struct KVMPITState {
  45     PITCommonState parent_obj;
  46
  47     LostTickPolicy lost_tick_policy;
  48     bool vm_stopped;
  49     int64_t kernel_clock_offset;
  50 } KVMPITState;
  51
  52 typedef struct KVMPITClass {
  53     PITCommonClass parent_class;
  54
  55     DeviceRealize parent_realize;
  56 } KVMPITClass;
  57
  58 static int64_t abs64(int64_t v)
  59 {
  60     return v < 0 ? -v : v;
  61 }
  62
  63 static void kvm_pit_update_clock_offset(KVMPITState *s)
  64 {
  65     int64_t offset, clock_offset;
  66     struct timespec ts;
  67     int i;
  68
  69     /*
  70      * Measure the delta between CLOCK_MONOTONIC, the base used for
  71      * kvm_pit_channel_state::count_load_time, and QEMU_CLOCK_VIRTUAL. Take the
  72      * minimum of several samples to filter out scheduling noise.
  73      */
  74     clock_offset = INT64_MAX;
  75     for (i = 0; i < CALIBRATION_ROUNDS; i++) {
  76         offset = qemu_clock_get_ns(QEMU_CLOCK_VIRTUAL);
  77         clock_gettime(CLOCK_MONOTONIC, &ts);
  78         offset -= ts.tv_nsec;
  79         offset -= (int64_t)ts.tv_sec * 1000000000;
  80         if (abs64(offset) < abs64(clock_offset)) {
  81             clock_offset = offset;
  82         }
  83     }
  84     s->kernel_clock_offset = clock_offset;
  85 }
  86
  87 static void kvm_pit_get(PITCommonState *pit)
  88 {
  89     KVMPITState *s = KVM_PIT(pit);
  90     struct kvm_pit_state2 kpit;
  91     struct kvm_pit_channel_state *kchan;
  92     struct PITChannelState *sc;
  93     int i, ret;
  94
  95     /* No need to re-read the state if VM is stopped. */
  96     if (s->vm_stopped) {
  97         return;
  98     }
  99
 100     if (kvm_has_pit_state2()) {
 101         ret = kvm_vm_ioctl(kvm_state, KVM_GET_PIT2, &kpit);
 102         if (ret < 0) {
 103             fprintf(stderr, "KVM_GET_PIT2 failed: %s\n", strerror(ret));
 104             abort();
 105         }
 106         pit->channels[0].irq_disabled = kpit.flags & KVM_PIT_FLAGS_HPET_LEGACY;
 107     } else {
 108         /*
 109          * kvm_pit_state2 is superset of kvm_pit_state struct,
 110          * so we can use it for KVM_GET_PIT as well.
 111          */
 112         ret = kvm_vm_ioctl(kvm_state, KVM_GET_PIT, &kpit);
 113         if (ret < 0) {
 114             fprintf(stderr, "KVM_GET_PIT failed: %s\n", strerror(ret));
 115             abort();
 116         }
 117     }
 118     for (i = 0; i < 3; i++) {
 119         kchan = &kpit.channels[i];
 120         sc = &pit->channels[i];
 121         sc->count = kchan->count;
 122         sc->latched_count = kchan->latched_count;
 123         sc->count_latched = kchan->count_latched;
 124         sc->status_latched = kchan->status_latched;
 125         sc->status = kchan->status;
 126         sc->read_state = kchan->read_state;
 127         sc->write_state = kchan->write_state;
 128         sc->write_latch = kchan->write_latch;
 129         sc->rw_mode = kchan->rw_mode;
 130         sc->mode = kchan->mode;
 131         sc->bcd = kchan->bcd;
 132         sc->gate = kchan->gate;
 133         sc->count_load_time = kchan->count_load_time + s->kernel_clock_offset;
 134     }
 135
 136     sc = &pit->channels[0];
 137     sc->next_transition_time =
 138         pit_get_next_transition_time(sc, sc->count_load_time);
 139 }
 140
 141 static void kvm_pit_put(PITCommonState *pit)
 142 {
 143     KVMPITState *s = KVM_PIT(pit);
 144     struct kvm_pit_state2 kpit = {};
 145     struct kvm_pit_channel_state *kchan;
 146     struct PITChannelState *sc;
 147     int i, ret;
 148
 149     /* The offset keeps changing as long as the VM is stopped. */
 150     if (s->vm_stopped) {
 151         kvm_pit_update_clock_offset(s);
 152     }
 153
 154     kpit.flags = pit->channels[0].irq_disabled ? KVM_PIT_FLAGS_HPET_LEGACY : 0;
 155     for (i = 0; i < 3; i++) {
 156         kchan = &kpit.channels[i];
 157         sc = &pit->channels[i];
 158         kchan->count = sc->count;
 159         kchan->latched_count = sc->latched_count;
 160         kchan->count_latched = sc->count_latched;
 161         kchan->status_latched = sc->status_latched;
 162         kchan->status = sc->status;
 163         kchan->read_state = sc->read_state;
 164         kchan->write_state = sc->write_state;
 165         kchan->write_latch = sc->write_latch;
 166         kchan->rw_mode = sc->rw_mode;
 167         kchan->mode = sc->mode;
 168         kchan->bcd = sc->bcd;
 169         kchan->gate = sc->gate;
 170         kchan->count_load_time = sc->count_load_time - s->kernel_clock_offset;
 171     }
 172
 173     ret = kvm_vm_ioctl(kvm_state,
 174                        kvm_has_pit_state2() ? KVM_SET_PIT2 : KVM_SET_PIT,
 175                        &kpit);
 176     if (ret < 0) {
 177         fprintf(stderr, "%s failed: %s\n",
 178                 kvm_has_pit_state2() ? "KVM_SET_PIT2" : "KVM_SET_PIT",
 179                 strerror(ret));
 180         abort();
 181     }
 182 }
 183
 184 static void kvm_pit_set_gate(PITCommonState *s, PITChannelState *sc, int val)
 185 {
 186     kvm_pit_get(s);
 187
 188     switch (sc->mode) {
 189     default:
 190     case 0:
 191     case 4:
 192         /* XXX: just disable/enable counting */
 193         break;
 194     case 1:
 195     case 2:
 196     case 3:
 197     case 5:
 198         if (sc->gate < val) {
 199             /* restart counting on rising edge */
 200             sc->count_load_time = qemu_clock_get_ns(QEMU_CLOCK_VIRTUAL);
 201         }
 202         break;
 203     }
 204     sc->gate = val;
 205
 206     kvm_pit_put(s);
 207 }
 208
 209 static void kvm_pit_get_channel_info(PITCommonState *s, PITChannelState *sc,
 210                                      PITChannelInfo *info)
 211 {
 212     kvm_pit_get(s);
 213
 214     pit_get_channel_info_common(s, sc, info);
 215 }
 216
 217 static void kvm_pit_reset(DeviceState *dev)
 218 {
 219     PITCommonState *s = PIT_COMMON(dev);
 220
 221     pit_reset_common(s);
 222
 223     kvm_pit_put(s);
 224 }
 225
 226 static void kvm_pit_irq_control(void *opaque, int n, int enable)
 227 {
 228     PITCommonState *pit = opaque;
 229     PITChannelState *s = &pit->channels[0];
 230
 231     kvm_pit_get(pit);
 232
 233     s->irq_disabled = !enable;
 234
 235     kvm_pit_put(pit);
 236 }
 237
 238 static void kvm_pit_vm_state_change(void *opaque, int running,
 239                                     RunState state)
 240 {
 241     KVMPITState *s = opaque;
 242
 243     if (running) {
 244         kvm_pit_update_clock_offset(s);
 245         kvm_pit_put(PIT_COMMON(s));
 246         s->vm_stopped = false;
 247     } else {
 248         kvm_pit_update_clock_offset(s);
 249         kvm_pit_get(PIT_COMMON(s));
 250         s->vm_stopped = true;
 251     }
 252 }
 253
 254 static void kvm_pit_realizefn(DeviceState *dev, Error **errp)
 255 {
 256     PITCommonState *pit = PIT_COMMON(dev);
 257     KVMPITClass *kpc = KVM_PIT_GET_CLASS(dev);
 258     KVMPITState *s = KVM_PIT(pit);
 259     struct kvm_pit_config config = {
 260         .flags = 0,
 261     };
 262     int ret;
 263
 264     if (kvm_check_extension(kvm_state, KVM_CAP_PIT2)) {
 265         ret = kvm_vm_ioctl(kvm_state, KVM_CREATE_PIT2, &config);
 266     } else {
 267         ret = kvm_vm_ioctl(kvm_state, KVM_CREATE_PIT);
 268     }
 269     if (ret < 0) {
 270         error_setg(errp, "Create kernel PIC irqchip failed: %s",
 271                    strerror(ret));
 272         return;
 273     }
 274     switch (s->lost_tick_policy) {
 275     case LOST_TICK_POLICY_DELAY:
 276         break; /* enabled by default */
 277     case LOST_TICK_POLICY_DISCARD:
 278         if (kvm_check_extension(kvm_state, KVM_CAP_REINJECT_CONTROL)) {
 279             struct kvm_reinject_control control = { .pit_reinject = 0 };
 280
 281             ret = kvm_vm_ioctl(kvm_state, KVM_REINJECT_CONTROL, &control);
 282             if (ret < 0) {
 283                 error_setg(errp,
 284                            "Can't disable in-kernel PIT reinjection: %s",
 285                            strerror(ret));
 286                 return;
 287             }
 288         }
 289         break;
 290     default:
 291         error_setg(errp, "Lost tick policy not supported.");
 292         return;
 293     }
 294
 295     memory_region_init_reservation(&pit->ioports, NULL, "kvm-pit", 4);
 296
 297     qdev_init_gpio_in(dev, kvm_pit_irq_control, 1);
 298
 299     qemu_add_vm_change_state_handler(kvm_pit_vm_state_change, s);
 300
 301     kpc->parent_realize(dev, errp);
 302 }
 303
 304 static Property kvm_pit_properties[] = {
 305     DEFINE_PROP_UINT32("iobase", PITCommonState, iobase,  -1),
 306     DEFINE_PROP_LOSTTICKPOLICY("lost_tick_policy", KVMPITState,
 307                                lost_tick_policy, LOST_TICK_POLICY_DELAY),
 308     DEFINE_PROP_END_OF_LIST(),
 309 };
 310
 311 static void kvm_pit_class_init(ObjectClass *klass, void *data)
 312 {
 313     KVMPITClass *kpc = KVM_PIT_CLASS(klass);
 314     PITCommonClass *k = PIT_COMMON_CLASS(klass);
 315     DeviceClass *dc = DEVICE_CLASS(klass);
 316
 317     kpc->parent_realize = dc->realize;
 318     dc->realize = kvm_pit_realizefn;
 319     k->set_channel_gate = kvm_pit_set_gate;
 320     k->get_channel_info = kvm_pit_get_channel_info;
 321     dc->reset = kvm_pit_reset;
 322     dc->props = kvm_pit_properties;
 323 }
 324
 325 static const TypeInfo kvm_pit_info = {
 326     .name          = TYPE_KVM_I8254,
 327     .parent        = TYPE_PIT_COMMON,
 328     .instance_size = sizeof(KVMPITState),
 329     .class_init = kvm_pit_class_init,
 330     .class_size = sizeof(KVMPITClass),
 331 };
 332
 333 static void kvm_pit_register(void)
 334 {
 335     type_register_static(&kvm_pit_info);
 336 }
 337
 338 type_init(kvm_pit_register)