hw/kvmclock.c

   1 /*
   2  * QEMU KVM support, paravirtual clock device
   3  *
   4  * Copyright (C) 2011 Siemens AG
   5  *
   6  * Authors:
   7  *  Jan Kiszka        <jan.kiszka@siemens.com>
   8  *
   9  * This work is licensed under the terms of the GNU GPL version 2.
  10  * See the COPYING file in the top-level directory.
  11  *
  12  * Contributions after 2012-01-13 are licensed under the terms of the
  13  * GNU GPL, version 2 or (at your option) any later version.
  14  */
  15
  16 #include "qemu-common.h"
  17 #include "sysemu.h"
  18 #include "sysbus.h"
  19 #include "kvm.h"
  20 #include "kvmclock.h"
  21
  22 #include <linux/kvm.h>
  23 #include <linux/kvm_para.h>
  24
  25 typedef struct KVMClockState {
  26     SysBusDevice busdev;
  27     uint64_t clock;
  28     bool clock_valid;
  29 } KVMClockState;
  30
  31 static void kvmclock_pre_save(void *opaque)
  32 {
  33     KVMClockState *s = opaque;
  34     struct kvm_clock_data data;
  35     int ret;
  36
  37     if (s->clock_valid) {
  38         return;
  39     }
  40     ret = kvm_vm_ioctl(kvm_state, KVM_GET_CLOCK, &data);
  41     if (ret < 0) {
  42         fprintf(stderr, "KVM_GET_CLOCK failed: %s\n", strerror(ret));
  43         data.clock = 0;
  44     }
  45     s->clock = data.clock;
  46     /*
  47      * If the VM is stopped, declare the clock state valid to avoid re-reading
  48      * it on next vmsave (which would return a different value). Will be reset
  49      * when the VM is continued.
  50      */
  51     s->clock_valid = !runstate_is_running();
  52 }
  53
  54 static int kvmclock_post_load(void *opaque, int version_id)
  55 {
  56     KVMClockState *s = opaque;
  57     struct kvm_clock_data data;
  58
  59     data.clock = s->clock;
  60     data.flags = 0;
  61     return kvm_vm_ioctl(kvm_state, KVM_SET_CLOCK, &data);
  62 }
  63
  64 static void kvmclock_vm_state_change(void *opaque, int running,
  65                                      RunState state)
  66 {
  67     KVMClockState *s = opaque;
  68
  69     if (running) {
  70         s->clock_valid = false;
  71     }
  72 }
  73
  74 static int kvmclock_init(SysBusDevice *dev)
  75 {
  76     KVMClockState *s = FROM_SYSBUS(KVMClockState, dev);
  77
  78     qemu_add_vm_change_state_handler(kvmclock_vm_state_change, s);
  79     return 0;
  80 }
  81
  82 static const VMStateDescription kvmclock_vmsd = {
  83     .name = "kvmclock",
  84     .version_id = 1,
  85     .minimum_version_id = 1,
  86     .minimum_version_id_old = 1,
  87     .pre_save = kvmclock_pre_save,
  88     .post_load = kvmclock_post_load,
  89     .fields = (VMStateField[]) {
  90         VMSTATE_UINT64(clock, KVMClockState),
  91         VMSTATE_END_OF_LIST()
  92     }
  93 };
  94
  95 static SysBusDeviceInfo kvmclock_info = {
  96     .qdev.name = "kvmclock",
  97     .qdev.size = sizeof(KVMClockState),
  98     .qdev.vmsd = &kvmclock_vmsd,
  99     .qdev.no_user = 1,
 100     .init = kvmclock_init,
 101 };
 102
 103 /* Note: Must be called after VCPU initialization. */
 104 void kvmclock_create(void)
 105 {
 106     if (kvm_enabled() &&
 107         first_cpu->cpuid_kvm_features & ((1ULL << KVM_FEATURE_CLOCKSOURCE) |
 108                                          (1ULL << KVM_FEATURE_CLOCKSOURCE2))) {
 109         sysbus_create_simple("kvmclock", -1, NULL);
 110     }
 111 }
 112
 113 static void kvmclock_register_device(void)
 114 {
 115     if (kvm_enabled()) {
 116         sysbus_register_withprop(&kvmclock_info);
 117     }
 118 }
 119
 120 device_init(kvmclock_register_device);