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/*

 * QEMU KVM support, paravirtual clock device

 *

 * Copyright (C) 2011 Siemens AG

 *

 * Authors:

 *  Jan Kiszka        <jan.kiszka@siemens.com>

 *

 * This work is licensed under the terms of the GNU GPL version 2.

 * See the COPYING file in the top-level directory.

 *

 */

#include "qemu-common.h"

#include "sysemu.h"

#include "sysbus.h"

#include "kvm.h"

#include "kvmclock.h"

#include <linux/kvm.h>

#include <linux/kvm_para.h>

typedef struct KVMClockState {

    SysBusDevice busdev;

    uint64_t clock;

    bool clock_valid;

} KVMClockState;

static void kvmclock_pre_save(void *opaque)

{

    KVMClockState *s = opaque;

    struct kvm_clock_data data;

    int ret;

    if (s->clock_valid) {

        return;

    }

    ret = kvm_vm_ioctl(kvm_state, KVM_GET_CLOCK, &data);

    if (ret < 0) {

        fprintf(stderr, "KVM_GET_CLOCK failed: %s\n", strerror(ret));

        data.clock = 0;

    }

    s->clock = data.clock;

    /*

     * If the VM is stopped, declare the clock state valid to avoid re-reading

     * it on next vmsave (which would return a different value). Will be reset

     * when the VM is continued.

     */

    s->clock_valid = !vm_running;

}

static int kvmclock_post_load(void *opaque, int version_id)

{

    KVMClockState *s = opaque;

    struct kvm_clock_data data;

    data.clock = s->clock;

    data.flags = 0;

    return kvm_vm_ioctl(kvm_state, KVM_SET_CLOCK, &data);

}

static void kvmclock_vm_state_change(void *opaque, int running, int reason)

{

    KVMClockState *s = opaque;

    if (running) {

        s->clock_valid = false;

    }

}

static int kvmclock_init(SysBusDevice *dev)

{

    KVMClockState *s = FROM_SYSBUS(KVMClockState, dev);

    qemu_add_vm_change_state_handler(kvmclock_vm_state_change, s);

    return 0;

}

static const VMStateDescription kvmclock_vmsd = {

    .name = "kvmclock",

    .version_id = 1,

    .minimum_version_id = 1,

    .minimum_version_id_old = 1,

    .pre_save = kvmclock_pre_save,

    .post_load = kvmclock_post_load,

    .fields = (VMStateField[]) {

        VMSTATE_UINT64(clock, KVMClockState),

        VMSTATE_END_OF_LIST()

    }

};

static SysBusDeviceInfo kvmclock_info = {

    .qdev.name = "kvmclock",

    .qdev.size = sizeof(KVMClockState),

    .qdev.vmsd = &kvmclock_vmsd,

    .qdev.no_user = 1,

    .init = kvmclock_init,

};

/* Note: Must be called after VCPU initialization. */

void kvmclock_create(void)

{

    if (kvm_enabled() &&

        first_cpu->cpuid_kvm_features & ((1ULL << KVM_FEATURE_CLOCKSOURCE)

#ifdef KVM_FEATURE_CLOCKSOURCE2

        || (1ULL << KVM_FEATURE_CLOCKSOURCE2)

#endif

    )) {

        sysbus_create_simple("kvmclock", -1, NULL);

    }

}

static void kvmclock_register_device(void)

{

    if (kvm_enabled()) {

        sysbus_register_withprop(&kvmclock_info);

    }

}

device_init(kvmclock_register_device);