[RFC PATCH V5 00/15] Implement 3-level event channel ABI in Xen

[Wei Liu <wei.liu2@citrix.com>]

This is the 5th RFC series (in fact 6th because I dropped RFC in one of the
series I posted) for the 3-level event channel design.

Changes since V4:
* Rework internal event channel object store to optimize memory usage.
* Switch back to function pointers, because it has the same (or less)
  performance degradation compared to 'switch' statement, while at the same
  time it allows for clearer code structure.
* Separate internal event channel inteface and ABI implementation.
* Only enable 3-level event channel for Dom0, this should be a good starting
  point for testing. The toolstack integration is left open.
* A compat shim is missing, but should be trivial to add.

Changes since V3:
* Dedicated EVTCHNOP for extended ABI query
* Dedicated EVTCHNOP for 3-level ABI registration
* 3-level ABI is registered in two phases:
  * register the bitmaps
  * register per-cpu L2 selector
* libxl: evtchn_extended -> evtchn_extended_allowed

Changes since V2:
* new interface to register extended event channel ABI
* use vmap to simplify mapping
* replace MAX_EVTCHNS macro with inline function
* libxl: evtchn_l3 -> evtchn_extended

The most notable bit of this series is the interface change. In order to cope
with future ABIs, the interface is renamed to EVTCHNOP_register_extended. It
also provides supported ABI query, so that we can remove unused ABI in the
future.

The semantic meaning of EVTCHNOP_register_extended changes a bit. The `level'
in parameter now changes to `cmd', which means we should go down to specific
ABI routines. ABI-specific structures are still embedded in the union.

Changes since V1:
* move all evtchn related macros / struct definitions to event.h
* only allow 3-level evtchn for Dom0 and driver domains
* add evtchn_l3 flag in libxl


Diffstat:
 xen/arch/arm/domain.c              |    1 +
 xen/arch/x86/domain.c              |    1 +
 xen/arch/x86/irq.c                 |    7 +-
 xen/common/Makefile                |    1 +
 xen/common/event_channel.c         |  404 +++++++++++++++++++++++++-----------
 xen/common/evtchn_bitmap_abi.c     |  323 ++++++++++++++++++++++++++++
 xen/common/keyhandler.c            |    6 +-
 xen/common/schedule.c              |    4 +-
 xen/include/asm-arm/config.h       |    1 +
 xen/include/asm-x86/config.h       |    5 +-
 xen/include/public/event_channel.h |   48 +++++
 xen/include/public/xen.h           |   35 ++--
 xen/include/xen/event.h            |   70 ++++++-
 xen/include/xen/sched.h            |   31 ++-
 14 files changed, 779 insertions(+), 158 deletions(-)