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Re: [Qemu-devel] [PATCH v2 0/7] Qemu virtio pmem device
From: |
Pankaj Gupta |
Subject: |
Re: [Qemu-devel] [PATCH v2 0/7] Qemu virtio pmem device |
Date: |
Tue, 2 Jul 2019 21:31:43 -0400 (EDT) |
> >
> >>
> >> On Wed, Jun 19, 2019 at 03:19:00PM +0530, Pankaj Gupta wrote:
> >> > 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
> >> >
> >>
> >> Hi, Pankaj
> >
> >Hi Wei,
> >
> >>
> >> I tried this series with v14 kernel driver, while getting some error on
> >> using
> >> this. Not sure this is my error configuration.
> >>
> >> The qemu command line is:
> >>
> >> -object
> >>
> >> memory-backend-file,id=mem1,share=on,mem-path=/dev/dax0.0,size=1G,align=2M
> >> -device virtio-pmem-pci,memdev=mem1,id=nv1
> >
> >Are you using host backing on real NVDIMM? Currently, we only support
> >backing image
> >file on regular SSD. We have plans to support backing file on real NVDIMM
> >device
> >as well but this is part of future work.
> >
> >Can you please try by allocating a raw image file on regular SSD. It is
> >working fine
> >for me.
> >
>
> I created a file with 2G on my disk.
>
> #ll -h 2G-file
> -rw-r--r-- 1 richard richard 2.0G 6月 26 09:26 2G-file
>
> The command line is changed to:
>
> -object
>
> memory-backend-file,id=mem1,share,mem-path=/home/richard/guest/2G-file,size=2G
> -device virtio-pmem-pci,memdev=mem1,id=nv1
>
> The behavior in guest is the same.
Are you still facing an error with this? or its working fine for you?
>
> I took a look into the directory /sys/bus/nd/device. These files are listed.
> Compared with normal system, one device file is missed.
virtio pmem does not support namespace/region mappings which ACPI NFIT supports.
>
> btt0.0 dax0.0 namespace0.0 ndbus0 pfn0.0 region0
>
> But the sysfs shows pmem0 block device is created.
>
> /sys/devices/pci0000:00/0000:00:04.0/virtio0/ndbus0/region0/namespace0.0/block/pmem0
>
> Then I took a look into the pci device:
>
> # lspci -vs 00:04.0
> 00:04.0 Unclassified device [00ff]: Red Hat, Inc. Device 1013
> Subsystem: Red Hat, Inc. Device 001b
> Physical Slot: 4
> Flags: bus master, fast devsel, latency 0, IRQ 11
> I/O ports at c040 [size=64]
> Memory at fe000000 (64-bit, prefetchable) [size=16K]
> Capabilities: [84] Vendor Specific Information: VirtIO:
> Capabilities: [70] Vendor Specific Information: VirtIO: Notify
> Capabilities: [60] Vendor Specific Information: VirtIO: DeviceCfg
> Capabilities: [50] Vendor Specific Information: VirtIO: ISR
> Capabilities: [40] Vendor Specific Information: VirtIO: CommonCfg
> Kernel driver in use: virtio-pci
>
> This looks good.
Good to know.
>
> >>
> >> The guest boots up and I can see /dev/pmem0 device. But when I want to
> >> partition this device, I got the error:
> >>
> >> # parted /dev/pmem0 mklabel gpt
> >> Warning: Error fsyncing/closing /dev/pmem0: Input/output error
> >>
> >> Also I see an error when running "ndctl list":
> >>
> >> libndctl: __sysfs_device_parse: ndctl0: add_dev() failed
> >
> >Will look at this if it is related.
>
> This log still there.
It looks to me libndctl needs to be taught about about virtio pmem
data parsing. But this is unrelated to kernel and qemu patch series.
>
> >
> >Thanks,
> >Pankaj
> >>
> >> Would you mind letting me know which part I am wrong?
> >>
> >> > (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(-)
> >> >----
> >>
> >> --
> >> Wei Yang
> >> Help you, Help me
> >>
> >>
>
> --
> Wei Yang
> Help you, Help me
>
>