[SPDK] Registering other than NVMe device as a PCI memory buffer

It looks like in SPDK we can register only handful of devices (nvme, ioat, idxd, virtio, vmd).
Is there any way to register Pure PCI Memory device (say 1 to 8 GB of DDR behind the PCIe)?
My intention is to register the PCI memory and use it as a data buffer which will be passed to either spdk_nvme_ctrlr_cmd_io_raw() command or spdk_nvme_ns_cmd_read() or spdk_nvme_ns_cmd_write(). Basically instead of using Host DDR memory, I wish to use memory on PCIe. While doing so, I do not intend to use CMB as my SSDs do not have CMB.
Please let me know if there is any possibility in SPDK. If yes, what would be the procedure?
Thank you!