[PATCH V7 24/24] xen/ioreq: Make the IOREQ feature selectable on Arm

[Oleksandr Tyshchenko <olekstysh@xxxxxxxxx>]

From: Oleksandr Tyshchenko <oleksandr_tyshchenko@xxxxxxxx>

The purpose of this patch is to add a possibility for user
to be able to select IOREQ support on Arm (which is disabled
by default) with retaining the current behaviour on x86
(is selected by HVM and it's prompt is not visible).

Also make the IOREQ be depended on CONFIG_EXPERT on Arm since
it is considered as Technological Preview feature and
update SUPPORT.md.

Signed-off-by: Oleksandr Tyshchenko <oleksandr_tyshchenko@xxxxxxxx>
Acked-by: Jan Beulich <jbeulich@xxxxxxxx>
Acked-by: Julien Grall <jgrall@xxxxxxxxxx>

---
Please note, this is a split/cleanup/hardening of Julien's PoC:
"Add support for Guest IO forwarding to a device emulator"

Changes V5 -> V6:
   - new patch

Changes V6 -> V7:
   - use "If unsure, say N."
   - add Jan's and Julien's A-b
   - update SUPPORT.md
---
 SUPPORT.md         | 4 ++++
 xen/common/Kconfig | 8 +++++++-
 2 files changed, 11 insertions(+), 1 deletion(-)

diff --git a/SUPPORT.md b/SUPPORT.md
index 5ee3c86..f69edc7 100644
--- a/SUPPORT.md
+++ b/SUPPORT.md
@@ -691,6 +691,10 @@ to be used in addition to QEMU.
 
        Status: Experimental
 
+### ARM/IOREQ servers
+
+       Status: Tech Preview
+
 ### ARM/Non-PCI device passthrough
 
     Status: Supported, not security supported
diff --git a/xen/common/Kconfig b/xen/common/Kconfig
index fa049a6..1ecd4f6 100644
--- a/xen/common/Kconfig
+++ b/xen/common/Kconfig
@@ -137,7 +137,13 @@ config HYPFS_CONFIG
          want to hide the .config contents from dom0.
 
 config IOREQ_SERVER
-       bool
+       bool "IOREQ support (EXPERT)" if EXPERT && !X86
+       default X86
+       depends on HVM
+       ---help---
+         Enables generic mechanism for providing emulated devices to the 
guests.
+
+         If unsure, say N.
 
 config KEXEC
        bool "kexec support"
-- 
2.7.4