static int kvm_pv_clock_pairing(struct kvm_vcpu *vcpu, gpa_t paddr,
			        unsigned long clock_type)
{
	struct kvm_clock_pairing clock_pairing;
	struct timespec64 ts;
	u64 cycle;
	int ret;

	if (clock_type != KVM_CLOCK_PAIRING_WALLCLOCK)
		return -KVM_EOPNOTSUPP;

	/*
	 * When tsc is in permanent catchup mode guests won't be able to use
	 * pvclock_read_retry loop to get consistent view of pvclock
	 */
	if (vcpu->arch.tsc_always_catchup)
		return -KVM_EOPNOTSUPP;

	if (!kvm_get_walltime_and_clockread(&ts, &cycle))
		return -KVM_EOPNOTSUPP;

	clock_pairing.sec = ts.tv_sec;
	clock_pairing.nsec = ts.tv_nsec;
	clock_pairing.tsc = kvm_read_l1_tsc(vcpu, cycle);
	clock_pairing.flags = 0;
	memset(&clock_pairing.pad, 0, sizeof(clock_pairing.pad));

	ret = 0;
	if (kvm_write_guest(vcpu->kvm, paddr, &clock_pairing,
			    sizeof(struct kvm_clock_pairing)))
		ret = -KVM_EFAULT;

	return ret;
}
static int kvm_pv_clock_pairing(struct kvm_vcpu *vcpu, gpa_t paddr,
			        unsigned long clock_type)
{
	struct kvm_clock_pairing clock_pairing;
	struct timespec64 ts;
	u64 cycle;
	int ret;

	if (clock_type != KVM_CLOCK_PAIRING_WALLCLOCK)
		return -KVM_EOPNOTSUPP;

	 
	if (vcpu->arch.tsc_always_catchup)
		return -KVM_EOPNOTSUPP;

	if (!kvm_get_walltime_and_clockread(&ts, &cycle))
		return -KVM_EOPNOTSUPP;

	clock_pairing.sec = ts.tv_sec;
	clock_pairing.nsec = ts.tv_nsec;
	clock_pairing.tsc = kvm_read_l1_tsc(vcpu, cycle);
	clock_pairing.flags = 0;
	memset(&clock_pairing.pad, 0, sizeof(clock_pairing.pad));

	ret = 0;
	if (kvm_write_guest(vcpu->kvm, paddr, &clock_pairing,
			    sizeof(struct kvm_clock_pairing)))
		ret = -KVM_EFAULT;

	return ret;
}