[PATCH v5 00/13] introduce the Xen PV Calls frontend:wq

[Stefano Stabellini]

Hi all,

this series introduces the frontend for the newly introduced PV Calls
procotol.

PV Calls is a paravirtualized protocol that allows the implementation of
a set of POSIX functions in a different domain. The PV Calls frontend
sends POSIX function calls to the backend, which implements them and
returns a value to the frontend and acts on the function call.

For more information about PV Calls, please read:

https://xenbits.xen.org/docs/unstable/misc/pvcalls.html

This patch series only implements the frontend driver. It doesn't
attempt to redirect POSIX calls to it. The functions exported in
pvcalls-front.h are meant to be used for that. A separate patch series
will be sent to use them and hook them into the system.


Changes in v5:
- add a comment about single frontend-backend connection
- remove atomic_inc/dec in pvcalls_enter/exit
- add reviewed-by
- redefine pvcalls_enter/exit as pvcalls_enter/exit()
- move initial error checks in functions as early as possible (before
  locks, refcounts, etc)
- remove WRITE_ONCE when used after a barrier
- fix code style
- move init_waitqueue_head(&map->passive.inflight_accept_req) to patch #8
- clear PVCALLS_FLAG_ACCEPT_INFLIGHT on errors in accept
- clear INFLIGHT then set RET in pvcalls_front_event_handler, see
  alpine.DEB.2.10.1710061515060.3073@sstabellini-ThinkPad-X260
- add smp_rmb() after reading req_id before reading ret in all functions
- remove smp_mb() after reading ret and before clearing req_id
- create an empty pvcalls_front_free_map in patch #2


Stefano Stabellini (13):
      xen/pvcalls: introduce the pvcalls xenbus frontend
      xen/pvcalls: implement frontend disconnect
      xen/pvcalls: connect to the backend
      xen/pvcalls: implement socket command and handle events
      xen/pvcalls: implement connect command
      xen/pvcalls: implement bind command
      xen/pvcalls: implement listen command
      xen/pvcalls: implement accept command
      xen/pvcalls: implement sendmsg
      xen/pvcalls: implement recvmsg
      xen/pvcalls: implement poll command
      xen/pvcalls: implement release command
      xen: introduce a Kconfig option to enable the pvcalls frontend

 drivers/xen/Kconfig         |    9 +
 drivers/xen/Makefile        |    1 +
 drivers/xen/pvcalls-front.c | 1275 +++++++++++++++++++++++++++++++++++++++++++
 drivers/xen/pvcalls-front.h |   28 +
 4 files changed, 1313 insertions(+)
 create mode 100644 drivers/xen/pvcalls-front.c
 create mode 100644 drivers/xen/pvcalls-front.h