This RFC serie is a first proposal to enable VM to VM communications
through FF-A on Arm.
It is sent as an RFC because some aspects of this serie will need to be
discussed:
- How to control/configure which VM can communicate with which VM
- How to enable this without conflicting with Optee support
- Would a system communicating with Optee without FF-A but using FF-A to
  communicate between VM make any sense

One main feature missing from this serie is the support for memory
sharing or lending through FF-A. Implementing such a feature is raising
the question of how to cleanly have FF-A mem sharing living on the side
of Xen grantables.

This serie must be applied on top of [1] which introduces
some rework of FF-A support required by this patch serie.

!! This patch serie must no be merged !!

[1] https://lore.kernel.org/xen-devel/cover.1729066788.git.bertrand.marquis@arm.com/

Bertrand Marquis (4):
  xen/arm: ffa: Introduce VM to VM support
  xen/arm: ffa: Add buffer full notification support
  xen/arm: ffa: Add indirect message between VM
  xen/arm: ffa: Enable VM to VM without firmware

 xen/arch/arm/tee/Kconfig        |  11 +++
 xen/arch/arm/tee/ffa.c          |  11 +++
 xen/arch/arm/tee/ffa_msg.c      |  96 +++++++++++++++++++--
 xen/arch/arm/tee/ffa_notif.c    | 142 ++++++++++++++++++--------------
 xen/arch/arm/tee/ffa_partinfo.c | 137 ++++++++++++++++++++++++------
 xen/arch/arm/tee/ffa_private.h  |  25 ++++++
 6 files changed, 329 insertions(+), 93 deletions(-)

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2.47.0