Re: [PATCH v4 00/32] tools: enable xenstore-stubdom to use 9pfs

[Jürgen Groß <jgross@xxxxxxxx>]

On 05.02.24 11:55, Julien Grall wrote:
> Hi Juergen,
>
> On 05/02/2024 10:49, Juergen Gross wrote:
> > This series is adding 9pfs support to Xenstore-stubdom, enabling it
> > to do logging to a dom0 directory.
> >
> > This is a prerequisite for the final goal to add live update support
> > to Xenstore-stubdom, as it enables the stubdom to store its state in
> > a dom0 file.
> >
> > The 9pfs backend is a new daemon written from scratch. Using a
> > dedicated 9pfs daemon has several advantages:
> >
> > - it is using much less resources than a full blown qemu process
> > - it can serve multiple guests (the idea is to use it for other
> >    infrastructure domains, like qemu-stubdom or driver domains, too)
> > - it is designed to support several security enhancements, like
> >    limiting the number of files for a guest, or limiting the allocated
> >    file system space
> > - it doesn't support file links (neither hard nor soft links) or
> >    referencing parent directories via "..", minimizing the risk that
> >    a guest can "escape" from its home directory
> >
> > Note that for now the daemon only contains the minimal needed
> > functionality to do logging from Xenstore-stubdom. I didn't want to
> > add all the 9pfs commands and security add-ons in the beginning, in
> > order to avoid needless efforts in case the idea of the daemon is
> > being rejected.
> >
> > Changes in V4:
> > - patch 2 of V3 was applied
> > - added support of reading directories
> > - addressed review comments
> >
> > Changes in V3:
> > - new patches 1, 23-25
> > - addressed review comments
> >
> > Changes in V2:
> > - support of multiple rings per device
> > - xenlogd->xen-9pfsd rename
> > - addressed review comments
> > - fixed some bugs
> >
> > Juergen Gross (32):
> >    tools: add access macros for unaligned data
> >    tools: add a new xen logging daemon
> >    tools/xen-9pfsd: connect to frontend
> >    tools/xen-9pfsd: add transport layer
> >    tools/xen-9pfsd: add 9pfs response generation support
> >    tools/xen-9pfsd: add 9pfs version request support
> >    tools/xen-9pfsd: add 9pfs attach request support
> >    tools/xen-9pfsd: add 9pfs walk request support
> >    tools/xen-9pfsd: add 9pfs open request support
> >    tools/xen-9pfsd: add 9pfs clunk request support
> >    tools/xen-9pfsd: add 9pfs create request support
> >    tools/xen-9pfsd: add 9pfs stat request support
> >    tools/xen-9pfsd: add 9pfs write request support
> >    tools/xen-9pfsd: add 9pfs read request support
> >    tools/libs/light: add backend type for 9pfs PV devices
> >    tools/xl: support new 9pfs backend xen_9pfsd
> >    tools/helpers: allocate xenstore event channel for xenstore stubdom
> >    tools/xenstored: rename xenbus_evtchn()
> >    stubdom: extend xenstore stubdom configs
> >    tools: add 9pfs device to xenstore-stubdom
> >    tools/xenstored: add early_init() function
> >    tools/xenstored: move systemd handling to posix.c
> >    tools/xenstored: move all log-pipe handling into posix.c
> >    tools/xenstored: move all socket handling into posix.c
> >    tools/xenstored: get own domid in stubdom case
> >    tools/xenstored: rework ring page (un)map functions
> >    tools/xenstored: split domain_init()
> >    tools/xenstored: map stubdom interface
> >    tools/xenstored: mount 9pfs device in stubdom
> >    tools/xenstored: add helpers for filename handling
> >    tools/xenstored: support complete log capabilities in stubdom
> >    tools/xenstored: have a single do_control_memreport()
> I haven't checked what's the state of the 9PFS patches. Can part of the 
> xenstored changes be committed without the 9PFS changes?
The following patches can go in without the 9pfs daemon:

tools/helpers: allocate xenstore event channel for xenstore stubdom
tools/xenstored: rename xenbus_evtchn()
stubdom: extend xenstore stubdom configs
tools/xenstored: add early_init() function
tools/xenstored: move systemd handling to posix.c
tools/xenstored: move all log-pipe handling into posix.c
tools/xenstored: move all socket handling into posix.c
tools/xenstored: get own domid in stubdom case
tools/xenstored: rework ring page (un)map functions
tools/xenstored: split domain_init()
tools/xenstored: map stubdom interface


Juergen