Ping.
>
> This patch series has implementation for "virtio pmem"
> device. "virtio pmem" is persistent memory(nvdimm) device in
> guest which allows to bypass the guest page cache. This
> also implements a VIRTIO based asynchronous flush mechanism.
> Details of project idea for 'virtio pmem' flushing interface
> is shared [2] & [3].
>
> Sharing Qemu device emulation in this patchset. Tested with
> guest kernel driver [1]. This series is based on David's
> memory device refactoring [5] work with modified version of
> my initial virtio pmem [4] series.
>
> Usage:
> ./qemu -name test -machine pc -m 8G,slots=240,maxmem=20G
> -object memory-backend-file,id=mem1,share,mem-path=test.img,
> size=4G,share
> -device virtio-pmem-pci,memdev=mem1,id=nv1
>
> (qemu) info memory-devices
> Memory device [virtio-pmem]: "nv1"
> memaddr: 0x240000000
> size: 4294967296
> memdev: /objects/mem1
>
> Implementation is divided into two parts:
> New virtio pmem guest driver and qemu code changes for new
> virtio pmem paravirtualized device. In this series we are
> sharing Qemu device emulation.
>
> 1. Guest virtio-pmem kernel driver
> ---------------------------------
> - Reads persistent memory range from paravirt device and
> registers with 'nvdimm_bus'.
> - 'nvdimm/pmem' driver uses this information to allocate
> persistent memory region and setup filesystem operations
> to the allocated memory.
> - virtio pmem driver implements asynchronous flushing
> interface to flush from guest to host.
>
> 2. Qemu virtio-pmem device
> ---------------------------------
> - Creates virtio pmem device and exposes a memory range to
> KVM guest.
> - At host side this is file backed memory which acts as
> persistent memory.
> - Qemu side flush uses aio thread pool API's and virtio
> for asynchronous guest multi request handling.
>
> Virtio-pmem security implications and suggested countermeasures:
> ---------------------------------------------------------------
>
> In previous posting of kernel driver, there was discussion [7]
> on possible implications of page cache side channel attacks with
> virtio pmem. After thorough analysis of details of known side
> channel attacks, below are the suggestions:
>
> - Depends entirely on how host backing image file is mapped
> into guest address space.
>
> - virtio-pmem device emulation, by default shared mapping is used
> to map host backing file. It is recommended to use separate
> backing file at host side for every guest. This will prevent
> any possibility of executing common code from multiple guests
> and any chance of inferring guest local data based based on
> execution time.
>
> - If backing file is required to be shared among multiple guests
> it is recommended to don't support host page cache eviction
> commands from the guest driver. This will avoid any possibility
> of inferring guest local data or host data from another guest.
>
> - Proposed device specification [6] for virtio-pmem device with
> details of possible security implications and suggested
> countermeasures for device emulation.
>
> Changes from PATCH v1:
> - Change proposed version from qemu 4.0 to 4.1 - Eric
> - Remove virtio queue_add from unrealize function - Cornelia
>
> [1] https://lkml.org/lkml/2019/6/12/624
> [2] https://www.spinics.net/lists/kvm/msg149761.html
> [3] https://www.spinics.net/lists/kvm/msg153095.html
> [4] https://marc.info/?l=linux-kernel&m=153572228719237&w=2
> [5] https://marc.info/?l=qemu-devel&m=153555721901824&w=2
> [6] https://lists.oasis-open.org/archives/virtio-dev/201903/msg00083.html
> [7] https://lkml.org/lkml/2019/1/9/1191
>
> Pankaj Gupta (3):
> virtio-pmem: add virtio device
> virtio-pmem: sync linux headers
> virtio-pci: proxy for virtio-pmem
>
> David Hildenbrand (4):
> virtio-pci: Allow to specify additional interfaces for the base type
> hmp: Handle virtio-pmem when printing memory device infos
> numa: Handle virtio-pmem in NUMA stats
> pc: Support for virtio-pmem-pci
>
> hmp.c | 27 ++-
> hw/i386/Kconfig | 1
> hw/i386/pc.c | 72 ++++++++++
> hw/virtio/Kconfig | 10 +
> hw/virtio/Makefile.objs | 2
> hw/virtio/virtio-pci.c | 1
> hw/virtio/virtio-pci.h | 1
> hw/virtio/virtio-pmem-pci.c | 131 ++++++++++++++++++
> hw/virtio/virtio-pmem-pci.h | 34 ++++
> hw/virtio/virtio-pmem.c | 189
> +++++++++++++++++++++++++++
> include/hw/pci/pci.h | 1
> include/hw/virtio/virtio-pmem.h | 49 +++++++
> include/standard-headers/linux/virtio_ids.h | 1
> include/standard-headers/linux/virtio_pmem.h | 35 +++++
> numa.c | 24 +--
> qapi/misc.json | 28 +++-
> 16 files changed, 580 insertions(+), 26 deletions(-)
> ----
>
>
