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