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

[Julien Grall <julien@xxxxxxx>]

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?
Cheers,

--
Julien Grall