static int emulator_set_cr(int cr, unsigned long val, struct kvm_vcpu *vcpu)
{
	int res = 0;

	switch (cr) {
	case 0:
		res = kvm_set_cr0(vcpu, mk_cr_64(kvm_read_cr0(vcpu), val));
		break;
	case 2:
		vcpu->arch.cr2 = val;
		break;
	case 3:
		res = kvm_set_cr3(vcpu, val);
		break;
	case 4:
		res = kvm_set_cr4(vcpu, mk_cr_64(kvm_read_cr4(vcpu), val));
		break;
	case 8:
		res = __kvm_set_cr8(vcpu, val & 0xfUL);
		break;
	default:
		vcpu_printf(vcpu, "%s: unexpected cr %u\n", __func__, cr);
		res = -1;
	}

	return res;
}

The product contains a concurrent code sequence that requires temporary, exclusive access to a shared resource, but a timing window exists in which the shared resource can be modified by another code sequence operating concurrently.