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



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



 


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