Re: [Qemu-devel] [RFC v3 0/2] kvm "fake DAX" device flushing
From: Pankaj Gupta
Date: Tue Aug 28 2018 - 08:39:57 EST
> > for review. This patchset has two parts:
> > - Guest virtio-pmem driver
> > Guest driver reads persistent memory range from paravirt device
> > and registers with 'nvdimm_bus'. 'nvdimm/pmem' driver uses this
> > information to allocate persistent memory range. Also, we have
> > implemented guest side of VIRTIO flushing interface.
> > - Qemu virtio-pmem device
> > It exposes a persistent memory range to KVM guest which at host
> > side is file backed memory and works as persistent memory device.
> > In addition to this it provides virtio device handling of flushing
> > interface. KVM guest performs Qemu side asynchronous sync using
> > this interface.
> > Changes from RFC v2:
> > - Add flush function in the nd_region in place of switching
> > on a flag - Dan & Stefan
> > - Add flush completion function with proper locking and wait
> > for host side flush completion - Stefan & Dan
> > - Keep userspace API in uapi header file - Stefan, MST
> > - Use LE fields & New device id - MST
> > - Indentation & spacing suggestions - MST & Eric
> > - Remove extra header files & add licensing - Stefan
> > Changes from RFC v1:
> > - Reuse existing 'pmem' code for registering persistent
> > memory and other operations instead of creating an entirely
> > new block driver.
> > - Use VIRTIO driver to register memory information with
> > nvdimm_bus and create region_type accordingly.
> > - Call VIRTIO flush from existing pmem driver.
> > Details of project idea for 'fake DAX' flushing interface is
> > shared  & .
> > Pankaj Gupta (2):
> > Add virtio-pmem guest driver
> > pmem: device flush over VIRTIO
> >  https://marc.info/?l=linux-mm&m=150782346802290&w=2
> >  https://www.spinics.net/lists/kvm/msg149761.html
> >  https://www.spinics.net/lists/kvm/msg153095.html
> > drivers/nvdimm/nd.h | 1
> > drivers/nvdimm/pmem.c | 4
> > drivers/nvdimm/region_devs.c | 24 +++-
> > drivers/virtio/Kconfig | 9 +
> > drivers/virtio/Makefile | 1
> > drivers/virtio/virtio_pmem.c | 190
> > +++++++++++++++++++++++++++++++++++++++
> > include/linux/libnvdimm.h | 5 -
> > include/linux/virtio_pmem.h | 44 +++++++++
> > include/uapi/linux/virtio_ids.h | 1
> > include/uapi/linux/virtio_pmem.h | 40 ++++++++
> > 10 files changed, 310 insertions(+), 9 deletions(-)
> Hi Pankaj,
> do you have a branch for the QEMU part somewhere available? I want to
> see how this works with MemoryDevice changes.
o.k I will update the guest virtio-pmem and Qemu current changes
and share with you. BTW previous version is here:
> David / dhildenb