On Fri, Oct 12, 2018 at 10:01 PM Pankaj Gupta <pagupta@xxxxxxxxxx> wrote: > > This patch adds virtio-pmem driver for KVM guest. > > Guest reads the persistent memory range information from > Qemu over VIRTIO and registers it on nvdimm_bus. It also > creates a nd_region object with the persistent memory > range information so that existing 'nvdimm/pmem' driver > can reserve this into system memory map. This way > 'virtio-pmem' driver uses existing functionality of pmem > driver to register persistent memory compatible for DAX > capable filesystems. > > This also provides function to perform guest flush over > VIRTIO from 'pmem' driver when userspace performs flush > on DAX memory range. Before we can move forward with this driver we need additional filesystem enabling to detect when the backing device is fronting DAX pmem or a paravirtualized page cache through virtio-pmem. Any interface that requires fsync() and a round trip to the hypervisor to flush host page cache is not DAX.
