A Linux ECS can be switched from Xen to KVM if xen-pv and VirtIO drivers run on the ECS. Before changing a Xen-based ECS to a KVM-based ECS, ensure that the required drivers have been installed and the UUID has been configured on the ECS.
For details, see Uninstalling the PV Driver from a Linux ECS.
For details, see Changing the Disk Identifier of the GRUB Configuration File to UUID.
For details, see Changing the Disk Identifier of the fstab File to UUID.
For details, see Installing Native Xen and KVM Drivers.