[XEN PATCH v9 24/24] docs: add Arm FF-A mediator

[Jens Wiklander <jens.wiklander@xxxxxxxxxx>]

Describes a FF-A version 1.1 [1] mediator to communicate with a Secure
Partition in secure world.

[1] https://developer.arm.com/documentation/den0077/latest
Signed-off-by: Jens Wiklander <jens.wiklander@xxxxxxxxxx>
Reviewed-by: Henry Wang <Henry.Wang@xxxxxxx>
---
 SUPPORT.md               |  9 +++++++++
 docs/man/xl.cfg.5.pod.in | 15 +++++++++++++++
 2 files changed, 24 insertions(+)

diff --git a/SUPPORT.md b/SUPPORT.md
index 35a6249e03b2..fe512762cee7 100644
--- a/SUPPORT.md
+++ b/SUPPORT.md
@@ -840,6 +840,15 @@ that covers the DMA of the device to be passed through.
 
 No support for QEMU backends in a 16K or 64K domain.
 
+### ARM: Firmware Framework for Arm A-profile (FF-A) Mediator
+
+    Status, Arm64: Tech Preview
+
+There are still some code paths where a vCPU may hog a pCPU longer than
+necessary. The FF-A mediator is not yet implemented for Arm32. Part of the
+FF-A specification is not supported, see the top comment in
+xen/arch/arm/tee/ffa.c for limitations.
+
 ### ARM: Guest Device Tree support
 
     Status: Supported
diff --git a/docs/man/xl.cfg.5.pod.in b/docs/man/xl.cfg.5.pod.in
index 3979be2a590a..911c3619ce32 100644
--- a/docs/man/xl.cfg.5.pod.in
+++ b/docs/man/xl.cfg.5.pod.in
@@ -1648,6 +1648,21 @@ in OP-TEE.
 
 This feature is a B<technology preview>.
 
+=item B<ffa>
+
+B<Arm only.> Allow a guest to communicate via FF-A with Secure Partitions
+(SP), default false.
+
+Currently only a small subset of the FF-A specification is supported. Just
+enough to communicate with OP-TEE. In general only direct messaging and
+sharing memory with one SP. More advanced use cases where memory might be
+shared or donated to multiple SPs are not supported.
+
+See L<https://developer.arm.com/documentation/den0077/latest> for more
+information about FF-A.
+
+This feature is a B<technology preview>.
+
 =back
 
 =back
-- 
2.34.1