[RFC PATCH 19/19] docs: add a man page for vhost-user-rpmb

["Alex Bennée" <alex.bennee@linaro.org>]

Basic usage and example invocation.

Signed-off-by: Alex Bennée <alex.bennee@linaro.org>
---
 docs/tools/index.rst           |   1 +
 docs/tools/vhost-user-rpmb.rst | 102 +++++++++++++++++++++++++++++++++
 2 files changed, 103 insertions(+)
 create mode 100644 docs/tools/vhost-user-rpmb.rst

diff --git a/docs/tools/index.rst b/docs/tools/index.rst
index 232ce9f3e463..488784b3bf1f 100644
--- a/docs/tools/index.rst
+++ b/docs/tools/index.rst
@@ -15,3 +15,4 @@ Contents:
    qemu-trace-stap
    virtfs-proxy-helper
    virtiofsd
+   vhost-user-rpmb
diff --git a/docs/tools/vhost-user-rpmb.rst b/docs/tools/vhost-user-rpmb.rst
new file mode 100644
index 000000000000..40d5d3bceb7c
--- /dev/null
+++ b/docs/tools/vhost-user-rpmb.rst
@@ -0,0 +1,102 @@
+QEMU vhost-user-rpmb - rpmb emulation backend
+=============================================
+
+Synopsis
+--------
+
+**vhost-user-rpmb** [*OPTIONS*]
+
+Description
+-----------
+
+This program is a vhost-user backed that emulates a VirtIO Replay
+Protected Memory Block device. These are usually special partitions
+that are part of a flash device that offer protection against reply
+attacks. They are used to store secure information in a way that is
+hard to tamper with.
+
+This program is designed to work with QEMU's ``--device
+vhost-user-rpmb-pci`` but should work with any virtual machine
+monitor (VMM) that supports vhost-user. See the Examples section
+below.
+
+This program requires a backing store to persist any data programmed
+into the device. The spec supports devices up 32Mb in size. For the
+daemon this is simply a raw file of the appropriate size. To program
+the device it needs to have a key. This can either be programmed by
+the guest at the start or come from a key file supplied to the daemon.
+
+Options
+-------
+
+.. program:: vhost-user-rpmb
+
+.. option:: -h, --help
+
+  Print help.
+
+.. option:: -V, --version
+
+  Print version.
+
+.. option:: -v, --verbose
+
+   Increase verbosity of output
+            
+.. option:: --debug
+
+  Enable debug output.
+
+.. option:: --socket-path=PATH
+
+  Listen on vhost-user UNIX domain socket at PATH. Incompatible with --fd.
+
+.. option:: --fd=FDNUM
+
+  Accept connections from vhost-user UNIX domain socket file descriptor FDNUM.
+  The file descriptor must already be listening for connections.
+  Incompatible with --socket-path.
+
+.. option:: --flash-path=PATH
+
+  Path to the backing store for the flash image, can be up to 32Mb in size.
+
+.. option:: --key-path=PATH
+
+  Path to the backing store for the key of 32 bytes.
+            
+.. option:: --key-set
+
+  Treat the value of key-path as set meaning the key cannot be
+  reprogrammed by the guest.
+
+.. option:: --initial-counter=N
+
+  Set the initial value of the devices write count. It is
+  incremented by each write operation. 
+
+Examples
+--------
+
+The daemon should be started first:
+
+::
+
+  host# vhost-user-rpmb --socket-path=vrpmb.sock \
+   --flash-path=flash.img \
+   --key-path=key --key-set \
+   --initial-counter=1234
+
+The QEMU invocation needs to create a chardev socket the device can
+use to communicate as well as share the guests memory over a memfd.
+
+::
+
+  host# qemu-system \
+      -chardev socket,path=vrpmb.sock,id=vrpmb \
+      -device vhost-user-rpmb-pci,chardev=vrpmb,id=rpmb \
+      -m 4096 \
+      -object memory-backend-file,id=mem,size=4G,mem-path=/dev/shm,share=on \
+      -numa node,memdev=mem \
+      ...
+
-- 
2.20.1