From mboxrd@z Thu Jan 1 00:00:00 1970 From: Pankaj Gupta Subject: [RFC v3 0/2] kvm "fake DAX" device flushing Date: Fri, 13 Jul 2018 13:22:29 +0530 Message-ID: <20180713075232.9575-1-pagupta@redhat.com> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Return-path: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: linux-nvdimm-bounces-hn68Rpc1hR1g9hUCZPvPmw@public.gmane.org Sender: "Linux-nvdimm" To: linux-kernel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, kvm-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, qemu-devel-qX2TKyscuCcdnm+yROfE0A@public.gmane.org, linux-nvdimm-y27Ovi1pjclAfugRpC6u6w@public.gmane.org Cc: kwolf-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org, jack-AlSwsSmVLrQ@public.gmane.org, xiaoguangrong.eric-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org, riel-ebMLmSuQjDVBDgjK7y7TUQ@public.gmane.org, niteshnarayanlal-PkbjNfxxIARBDgjK7y7TUQ@public.gmane.org, david-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org, ross.zwisler-ral2JQCrhuEAvxtiuMwx3w@public.gmane.org, lcapitulino-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org, hch-wEGCiKHe2LqWVfeAwA7xHQ@public.gmane.org, mst-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org, stefanha-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org, imammedo-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org, pbonzini-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org, nilal-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org, eblake-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org List-Id: linux-nvdimm@lists.01.org This is RFC V3 for 'fake DAX' flushing interface sharing 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 [2] & [3]. Pankaj Gupta (2): Add virtio-pmem guest driver pmem: device flush over VIRTIO [1] https://marc.info/?l=linux-mm&m=150782346802290&w=2 [2] https://www.spinics.net/lists/kvm/msg149761.html [3] 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(-)