Re: [PATCH 0/2] Enable virtio-fs on s390x

[Michael S. Tsirkin]

On Thu, Jul 30, 2020 at 04:07:29PM +0200, Marc Hartmayer wrote:
> This patch series is about enabling virtio-fs on s390x. For that we need
>  + some shim code (first patch), and we need
>  + libvhost-user to deal with virtio endiannes for non-legacy virtio
>    devices as mandated by the spec.


Please rebase, address Cornelia's minor comments and repost.
Thanks!

> How to use?
> 
> For general instructions how to use virtio-fs (on x86) please have a
> look at https://virtio-fs.gitlab.io/howto-qemu.html. Most of the
> instructions can also be applied on s390x.
> 
> In short:
> 
> 1. Install self-compiled QEMU with this patch series applied
> 2. Prepare host and guest kernel so they support virtio-fs
> 
> Start virtiofsd on the host
> 
>  $ virtiofsd -f --socket-path=/tmp/vhostqemu -o source=/tmp/shared
> 
> Now you can start QEMU in a separate shell on the host:
> 
>  $ qemu-system-s390x -machine 
> type=s390-ccw-virtio,accel=kvm,memory-backend=mem \
>    -object 
> memory-backend-file,id=mem,size=2G,mem-path=/dev/shm/virtiofs,share=on,prealloc=on,prealloc-threads=1
>  \
>    -chardev socket,id=char0,path=/tmp/vhostqemu -device 
> vhost-user-fs-ccw,queue-size=1024,chardev=char0,tag=myfs \
>    -drive if=virtio,file=disk.qcow2 \
>    -m 2G -smp 2 -nographic
> 
> Log into the guest and mount it
> 
>  $ mount -t virtiofs myfs /mnt
> 
> Changelog:
>  RFC v2 -> v1:
>  - patch 1:
>   + Added `force_revision_1 = true` (Conny)
>   + I didn't add the r-b from Stefan Hajnoczi as I've added the
>     changes suggested by Conny
>  - squashed patches 2 and 3:
>   + removed assertion in performance critical code path (Stefan)
>   + dropped all dead code (Stefan)
>   + removed libvhost-access.h
>   
>  RFC v1 -> RFC v2:
>   + rebased
>   + drop patch "libvhost-user: print invalid address on vu_panic" as it's not 
> related to this series
>   + drop patch "[RFC 4/4] HACK: Hard-code the libvhost-user.o-cflags for 
> s390x"
>   + patch "virtio: add vhost-user-fs-ccw device": replace qdev_set_parent_bus 
> and object_property_set_bool by qdev_realize
>   + patch "libvhost-user: handle endianness as mandated by the spec":
>     Drop support for legacy virtio devices
>   + add patch to fence legacy virtio devices
> *** BLURB HERE ***
> 
> Halil Pasic (1):
>   virtio: add vhost-user-fs-ccw device
> 
> Marc Hartmayer (1):
>   libvhost-user: handle endianness as mandated by the spec
> 
>  contrib/libvhost-user/libvhost-user.c | 77 +++++++++++++++------------
>  hw/s390x/Makefile.objs                |  1 +
>  hw/s390x/vhost-user-fs-ccw.c          | 75 ++++++++++++++++++++++++++
>  3 files changed, 119 insertions(+), 34 deletions(-)
>  create mode 100644 hw/s390x/vhost-user-fs-ccw.c
> 
> -- 
> 2.25.4