[PATCH v7 0/7] Xen transport for 9pfs frontend driver

[Stefano Stabellini]

Hi all,

This patch series implements a new transport for 9pfs, aimed at Xen
systems.

The transport is based on a traditional Xen frontend and backend drivers
pair. This patch series implements the frontend, which typically runs in
a regular unprivileged guest.

I also sent a series that implements the backend in userspace in QEMU,
which typically runs in Dom0 (but could also run in a another guest).

The frontend complies to the Xen transport for 9pfs specification
version 1, available here:

https://xenbits.xen.org/docs/unstable/misc/9pfs.html


The new Xen ring macros pulled in Linux in the first patch of the series
have been committed upstream in Xen, so there is nothing holding back
this series any longer. It could be considered for 4.12 or 4.13. It
should probably go via the Xen tree.


Changes in v7:
- merging the final version of the macros (Xen upstream commit
  f000908276382e1c0a3de359f9bbc7ba83999119)
- fixup argument ordering of the ring/write_packet macros callers

Changes in v6:
- add reviewd-bys
- fix error paths
- make p9_xen_write_todo return bool

Changes in v5:
- test priv->tag instead of ret
- run checkpatch.pl against the whole series, fix all issues
- set intf->ring_order appropriately
- use shorter link to 9pfs spec

Changes in v4:
- code style improvements
- use xenbus_read_unsigned when possible
- do not leak "versions"
- introduce BUILD_BUG_ON
- introduce rwlock to protect the xen_9pfs_devs list
- add review-by

Changes in v3:
- add full copyright header to trans_xen.c
- rename ring->ring to ring->data
- handle gnttab_grant_foreign_access errors
- remove ring->bytes
- wrap long lines
- add reviewed-by

Changes in v2:
- use XEN_PAGE_SHIFT instead of PAGE_SHIFT
- remove unnecessary initializations
- fix error paths
- fix memory allocations for 64K kernels
- simplify p9_xen_create and p9_xen_close
- use virt_XXX barriers
- set status = REQ_STATUS_ERROR inside the p9_xen_response loop
- add in-code comments


Stefano Stabellini (7):
      xen: import new ring macros in ring.h
      xen: introduce the header file for the Xen 9pfs transport protocol
      xen/9pfs: introduce Xen 9pfs transport driver
      xen/9pfs: connect to the backend
      xen/9pfs: send requests to the backend
      xen/9pfs: receive responses
      xen/9pfs: build 9pfs Xen transport driver

 include/xen/interface/io/9pfs.h |  36 +++
 include/xen/interface/io/ring.h | 143 +++++++++++
 net/9p/Kconfig                  |   8 +
 net/9p/Makefile                 |   4 +
 net/9p/trans_xen.c              | 545 ++++++++++++++++++++++++++++++++++++++++
 5 files changed, 736 insertions(+)
 create mode 100644 include/xen/interface/io/9pfs.h
 create mode 100644 net/9p/trans_xen.c

Cheers,

Stefano