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