[PULL 61/91] docs: vhost-user: clean up request/reply description

[Michael S. Tsirkin]

From: Paolo Bonzini <pbonzini@redhat.com>

It is not necessary to mention which side is sending/receiving
each payload; it is more interesting to say which is the request
and which is the reply.  This also matches what vhost-user-gpu.rst
already does.

While at it, ensure that all messages list both the request and
the reply payload.

Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Message-Id: <20210226143413.188046-2-pbonzini@redhat.com>
Message-Id: <20220321153037.3622127-5-alex.bennee@linaro.org>
Reviewed-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
Reviewed-by: Philippe Mathieu-Daudé <f4bug@amsat.org>
---
 docs/interop/vhost-user.rst | 163 +++++++++++++++++++++---------------
 1 file changed, 95 insertions(+), 68 deletions(-)

diff --git a/docs/interop/vhost-user.rst b/docs/interop/vhost-user.rst
index f9e721ba5f..1039e7a34e 100644
--- a/docs/interop/vhost-user.rst
+++ b/docs/interop/vhost-user.rst
@@ -866,8 +866,8 @@ Master message types
 ``VHOST_USER_GET_FEATURES``
   :id: 1
   :equivalent ioctl: ``VHOST_GET_FEATURES``
-  :master payload: N/A
-  :slave payload: ``u64``
+  :request payload: N/A
+  :reply payload: ``u64``
 
   Get from the underlying vhost implementation the features bitmask.
   Feature bit ``VHOST_USER_F_PROTOCOL_FEATURES`` signals slave support
@@ -877,7 +877,8 @@ Master message types
 ``VHOST_USER_SET_FEATURES``
   :id: 2
   :equivalent ioctl: ``VHOST_SET_FEATURES``
-  :master payload: ``u64``
+  :request payload: ``u64``
+  :reply payload: N/A
 
   Enable features in the underlying vhost implementation using a
   bitmask.  Feature bit ``VHOST_USER_F_PROTOCOL_FEATURES`` signals
@@ -887,8 +888,8 @@ Master message types
 ``VHOST_USER_GET_PROTOCOL_FEATURES``
   :id: 15
   :equivalent ioctl: ``VHOST_GET_FEATURES``
-  :master payload: N/A
-  :slave payload: ``u64``
+  :request payload: N/A
+  :reply payload: ``u64``
 
   Get the protocol feature bitmask from the underlying vhost
   implementation.  Only legal if feature bit
@@ -903,7 +904,8 @@ Master message types
 ``VHOST_USER_SET_PROTOCOL_FEATURES``
   :id: 16
   :equivalent ioctl: ``VHOST_SET_FEATURES``
-  :master payload: ``u64``
+  :request payload: ``u64``
+  :reply payload: N/A
 
   Enable protocol features in the underlying vhost implementation.
 
@@ -917,7 +919,8 @@ Master message types
 ``VHOST_USER_SET_OWNER``
   :id: 3
   :equivalent ioctl: ``VHOST_SET_OWNER``
-  :master payload: N/A
+  :request payload: N/A
+  :reply payload: N/A
 
   Issued when a new connection is established. It sets the current
   *master* as an owner of the session. This can be used on the *slave*
@@ -925,7 +928,8 @@ Master message types
 
 ``VHOST_USER_RESET_OWNER``
   :id: 4
-  :master payload: N/A
+  :request payload: N/A
+  :reply payload: N/A
 
 .. admonition:: Deprecated
 
@@ -938,8 +942,8 @@ Master message types
 ``VHOST_USER_SET_MEM_TABLE``
   :id: 5
   :equivalent ioctl: ``VHOST_SET_MEM_TABLE``
-  :master payload: memory regions description
-  :slave payload: (postcopy only) memory regions description
+  :request payload: memory regions description
+  :reply payload: (postcopy only) memory regions description
 
   Sets the memory map regions on the slave so it can translate the
   vring addresses. In the ancillary data there is an array of file
@@ -962,8 +966,8 @@ Master message types
 ``VHOST_USER_SET_LOG_BASE``
   :id: 6
   :equivalent ioctl: ``VHOST_SET_LOG_BASE``
-  :master payload: u64
-  :slave payload: N/A
+  :request payload: u64
+  :reply payload: N/A
 
   Sets logging shared memory space.
 
@@ -975,44 +979,48 @@ Master message types
 ``VHOST_USER_SET_LOG_FD``
   :id: 7
   :equivalent ioctl: ``VHOST_SET_LOG_FD``
-  :master payload: N/A
+  :request payload: N/A
+  :reply payload: N/A
 
   Sets the logging file descriptor, which is passed as ancillary data.
 
 ``VHOST_USER_SET_VRING_NUM``
   :id: 8
   :equivalent ioctl: ``VHOST_SET_VRING_NUM``
-  :master payload: vring state description
+  :request payload: vring state description
+  :reply payload: N/A
 
   Set the size of the queue.
 
 ``VHOST_USER_SET_VRING_ADDR``
   :id: 9
   :equivalent ioctl: ``VHOST_SET_VRING_ADDR``
-  :master payload: vring address description
-  :slave payload: N/A
+  :request payload: vring address description
+  :reply payload: N/A
 
   Sets the addresses of the different aspects of the vring.
 
 ``VHOST_USER_SET_VRING_BASE``
   :id: 10
   :equivalent ioctl: ``VHOST_SET_VRING_BASE``
-  :master payload: vring state description
+  :request payload: vring state description
+  :reply payload: N/A
 
   Sets the base offset in the available vring.
 
 ``VHOST_USER_GET_VRING_BASE``
   :id: 11
   :equivalent ioctl: ``VHOST_USER_GET_VRING_BASE``
-  :master payload: vring state description
-  :slave payload: vring state description
+  :request payload: vring state description
+  :reply payload: vring state description
 
   Get the available vring base offset.
 
 ``VHOST_USER_SET_VRING_KICK``
   :id: 12
   :equivalent ioctl: ``VHOST_SET_VRING_KICK``
-  :master payload: ``u64``
+  :request payload: ``u64``
+  :reply payload: N/A
 
   Set the event file descriptor for adding buffers to the vring. It is
   passed in the ancillary data.
@@ -1030,7 +1038,8 @@ Master message types
 ``VHOST_USER_SET_VRING_CALL``
   :id: 13
   :equivalent ioctl: ``VHOST_SET_VRING_CALL``
-  :master payload: ``u64``
+  :request payload: ``u64``
+  :reply payload: N/A
 
   Set the event file descriptor to signal when buffers are used. It is
   passed in the ancillary data.
@@ -1048,7 +1057,8 @@ Master message types
 ``VHOST_USER_SET_VRING_ERR``
   :id: 14
   :equivalent ioctl: ``VHOST_SET_VRING_ERR``
-  :master payload: ``u64``
+  :request payload: ``u64``
+  :reply payload: N/A
 
   Set the event file descriptor to signal when error occurs. It is
   passed in the ancillary data.
@@ -1065,8 +1075,8 @@ Master message types
 ``VHOST_USER_GET_QUEUE_NUM``
   :id: 17
   :equivalent ioctl: N/A
-  :master payload: N/A
-  :slave payload: u64
+  :request payload: N/A
+  :reply payload: u64
 
   Query how many queues the backend supports.
 
@@ -1077,7 +1087,8 @@ Master message types
 ``VHOST_USER_SET_VRING_ENABLE``
   :id: 18
   :equivalent ioctl: N/A
-  :master payload: vring state description
+  :request payload: vring state description
+  :reply payload: N/A
 
   Signal slave to enable or disable corresponding vring.
 
@@ -1087,7 +1098,8 @@ Master message types
 ``VHOST_USER_SEND_RARP``
   :id: 19
   :equivalent ioctl: N/A
-  :master payload: ``u64``
+  :request payload: ``u64``
+  :reply payload: N/A
 
   Ask vhost user backend to broadcast a fake RARP to notify the migration
   is terminated for guest that does not support GUEST_ANNOUNCE.
@@ -1102,7 +1114,8 @@ Master message types
 ``VHOST_USER_NET_SET_MTU``
   :id: 20
   :equivalent ioctl: N/A
-  :master payload: ``u64``
+  :request payload: ``u64``
+  :reply payload: N/A
 
   Set host MTU value exposed to the guest.
 
@@ -1119,7 +1132,8 @@ Master message types
 ``VHOST_USER_SET_SLAVE_REQ_FD``
   :id: 21
   :equivalent ioctl: N/A
-  :master payload: N/A
+  :request payload: N/A
+  :reply payload: N/A
 
   Set the socket file descriptor for slave initiated requests. It is passed
   in the ancillary data.
@@ -1134,8 +1148,8 @@ Master message types
 ``VHOST_USER_IOTLB_MSG``
   :id: 22
   :equivalent ioctl: N/A (equivalent to ``VHOST_IOTLB_MSG`` message type)
-  :master payload: ``struct vhost_iotlb_msg``
-  :slave payload: ``u64``
+  :request payload: ``struct vhost_iotlb_msg``
+  :reply payload: ``u64``
 
   Send IOTLB messages with ``struct vhost_iotlb_msg`` as payload.
 
@@ -1149,7 +1163,8 @@ Master message types
 ``VHOST_USER_SET_VRING_ENDIAN``
   :id: 23
   :equivalent ioctl: ``VHOST_SET_VRING_ENDIAN``
-  :master payload: vring state description
+  :request payload: vring state description
+  :reply payload: N/A
 
   Set the endianness of a VQ for legacy devices. Little-endian is
   indicated with state.num set to 0 and big-endian is indicated with
@@ -1164,8 +1179,8 @@ Master message types
 ``VHOST_USER_GET_CONFIG``
   :id: 24
   :equivalent ioctl: N/A
-  :master payload: virtio device config space
-  :slave payload: virtio device config space
+  :request payload: virtio device config space
+  :reply payload: virtio device config space
 
   When ``VHOST_USER_PROTOCOL_F_CONFIG`` is negotiated, this message is
   submitted by the vhost-user master to fetch the contents of the
@@ -1178,8 +1193,8 @@ Master message types
 ``VHOST_USER_SET_CONFIG``
   :id: 25
   :equivalent ioctl: N/A
-  :master payload: virtio device config space
-  :slave payload: N/A
+  :request payload: virtio device config space
+  :reply payload: N/A
 
   When ``VHOST_USER_PROTOCOL_F_CONFIG`` is negotiated, this message is
   submitted by the vhost-user master when the Guest changes the virtio
@@ -1191,8 +1206,8 @@ Master message types
 ``VHOST_USER_CREATE_CRYPTO_SESSION``
   :id: 26
   :equivalent ioctl: N/A
-  :master payload: crypto session description
-  :slave payload: crypto session description
+  :request payload: crypto session description
+  :reply payload: crypto session description
 
   Create a session for crypto operation. The server side must return
   the session id, 0 or positive for success, negative for failure.
@@ -1204,7 +1219,8 @@ Master message types
 ``VHOST_USER_CLOSE_CRYPTO_SESSION``
   :id: 27
   :equivalent ioctl: N/A
-  :master payload: ``u64``
+  :request payload: ``u64``
+  :reply payload: N/A
 
   Close a session for crypto operation which was previously
   created by ``VHOST_USER_CREATE_CRYPTO_SESSION``.
@@ -1216,8 +1232,8 @@ Master message types
 
 ``VHOST_USER_POSTCOPY_ADVISE``
   :id: 28
-  :master payload: N/A
-  :slave payload: userfault fd
+  :request payload: N/A
+  :reply payload: userfault fd
 
   When ``VHOST_USER_PROTOCOL_F_PAGEFAULT`` is supported, the master
   advises slave that a migration with postcopy enabled is underway,
@@ -1226,7 +1242,8 @@ Master message types
 
 ``VHOST_USER_POSTCOPY_LISTEN``
   :id: 29
-  :master payload: N/A
+  :request payload: N/A
+  :reply payload: N/A
 
   Master advises slave that a transition to postcopy mode has
   happened.  The slave must ensure that shared memory is registered
@@ -1237,10 +1254,11 @@ Master message types
 
 ``VHOST_USER_POSTCOPY_END``
   :id: 30
-  :slave payload: ``u64``
+  :request payload: N/A
+  :reply payload: ``u64``
 
   Master advises that postcopy migration has now completed.  The slave
-  must disable the userfaultfd. The response is an acknowledgement
+  must disable the userfaultfd. The reply is an acknowledgement
   only.
 
   When ``VHOST_USER_PROTOCOL_F_PAGEFAULT`` is supported, this message
@@ -1252,7 +1270,8 @@ Master message types
 ``VHOST_USER_GET_INFLIGHT_FD``
   :id: 31
   :equivalent ioctl: N/A
-  :master payload: inflight description
+  :request payload: inflight description
+  :reply payload: N/A
 
   When ``VHOST_USER_PROTOCOL_F_INFLIGHT_SHMFD`` protocol feature has
   been successfully negotiated, this message is submitted by master to
@@ -1263,7 +1282,8 @@ Master message types
 ``VHOST_USER_SET_INFLIGHT_FD``
   :id: 32
   :equivalent ioctl: N/A
-  :master payload: inflight description
+  :request payload: inflight description
+  :reply payload: N/A
 
   When ``VHOST_USER_PROTOCOL_F_INFLIGHT_SHMFD`` protocol feature has
   been successfully negotiated, this message is submitted by master to
@@ -1273,7 +1293,8 @@ Master message types
 ``VHOST_USER_GPU_SET_SOCKET``
   :id: 33
   :equivalent ioctl: N/A
-  :master payload: N/A
+  :request payload: N/A
+  :reply payload: N/A
 
   Sets the GPU protocol socket file descriptor, which is passed as
   ancillary data. The GPU protocol is used to inform the master of
@@ -1282,8 +1303,8 @@ Master message types
 ``VHOST_USER_RESET_DEVICE``
   :id: 34
   :equivalent ioctl: N/A
-  :master payload: N/A
-  :slave payload: N/A
+  :request payload: N/A
+  :reply payload: N/A
 
   Ask the vhost user backend to disable all rings and reset all
   internal device state to the initial state, ready to be
@@ -1296,8 +1317,8 @@ Master message types
 ``VHOST_USER_VRING_KICK``
   :id: 35
   :equivalent ioctl: N/A
-  :slave payload: vring state description
-  :master payload: N/A
+  :request payload: vring state description
+  :reply payload: N/A
 
   When the ``VHOST_USER_PROTOCOL_F_INBAND_NOTIFICATIONS`` protocol
   feature has been successfully negotiated, this message may be
@@ -1310,7 +1331,8 @@ Master message types
 ``VHOST_USER_GET_MAX_MEM_SLOTS``
   :id: 36
   :equivalent ioctl: N/A
-  :slave payload: u64
+  :request payload: N/A
+  :reply payload: u64
 
   When the ``VHOST_USER_PROTOCOL_F_CONFIGURE_MEM_SLOTS`` protocol
   feature has been successfully negotiated, this message is submitted
@@ -1323,7 +1345,8 @@ Master message types
 ``VHOST_USER_ADD_MEM_REG``
   :id: 37
   :equivalent ioctl: N/A
-  :slave payload: single memory region description
+  :request payload: N/A
+  :reply payload: single memory region description
 
   When the ``VHOST_USER_PROTOCOL_F_CONFIGURE_MEM_SLOTS`` protocol
   feature has been successfully negotiated, this message is submitted
@@ -1346,7 +1369,8 @@ Master message types
 ``VHOST_USER_REM_MEM_REG``
   :id: 38
   :equivalent ioctl: N/A
-  :slave payload: single memory region description
+  :request payload: N/A
+  :reply payload: single memory region description
 
   When the ``VHOST_USER_PROTOCOL_F_CONFIGURE_MEM_SLOTS`` protocol
   feature has been successfully negotiated, this message is submitted
@@ -1369,8 +1393,8 @@ Master message types
 ``VHOST_USER_SET_STATUS``
   :id: 39
   :equivalent ioctl: VHOST_VDPA_SET_STATUS
-  :slave payload: N/A
-  :master payload: ``u64``
+  :request payload: ``u64``
+  :reply payload: N/A
 
   When the ``VHOST_USER_PROTOCOL_F_STATUS`` protocol feature has been
   successfully negotiated, this message is submitted by the master to
@@ -1380,8 +1404,8 @@ Master message types
 ``VHOST_USER_GET_STATUS``
   :id: 40
   :equivalent ioctl: VHOST_VDPA_GET_STATUS
-  :slave payload: ``u64``
-  :master payload: N/A
+  :request payload: N/A
+  :reply payload: ``u64``
 
   When the ``VHOST_USER_PROTOCOL_F_STATUS`` protocol feature has been
   successfully negotiated, this message is submitted by the master to
@@ -1392,11 +1416,14 @@ Master message types
 Slave message types
 -------------------
 
+For this type of message, the request is sent by the slave and the reply
+is sent by the master.
+
 ``VHOST_USER_SLAVE_IOTLB_MSG``
   :id: 1
   :equivalent ioctl: N/A (equivalent to ``VHOST_IOTLB_MSG`` message type)
-  :slave payload: ``struct vhost_iotlb_msg``
-  :master payload: N/A
+  :request payload: ``struct vhost_iotlb_msg``
+  :reply payload: N/A
 
   Send IOTLB messages with ``struct vhost_iotlb_msg`` as payload.
   Slave sends such requests to notify of an IOTLB miss, or an IOTLB
@@ -1410,8 +1437,8 @@ Slave message types
 ``VHOST_USER_SLAVE_CONFIG_CHANGE_MSG``
   :id: 2
   :equivalent ioctl: N/A
-  :slave payload: N/A
-  :master payload: N/A
+  :request payload: N/A
+  :reply payload: N/A
 
   When ``VHOST_USER_PROTOCOL_F_CONFIG`` is negotiated, vhost-user
   slave sends such messages to notify that the virtio device's
@@ -1425,8 +1452,8 @@ Slave message types
 ``VHOST_USER_SLAVE_VRING_HOST_NOTIFIER_MSG``
   :id: 3
   :equivalent ioctl: N/A
-  :slave payload: vring area description
-  :master payload: N/A
+  :request payload: vring area description
+  :reply payload: N/A
 
   Sets host notifier for a specified queue. The queue index is
   contained in the ``u64`` field of the vring area description. The
@@ -1448,8 +1475,8 @@ Slave message types
 ``VHOST_USER_SLAVE_VRING_CALL``
   :id: 4
   :equivalent ioctl: N/A
-  :slave payload: vring state description
-  :master payload: N/A
+  :request payload: vring state description
+  :reply payload: N/A
 
   When the ``VHOST_USER_PROTOCOL_F_INBAND_NOTIFICATIONS`` protocol
   feature has been successfully negotiated, this message may be
@@ -1462,8 +1489,8 @@ Slave message types
 ``VHOST_USER_SLAVE_VRING_ERR``
   :id: 5
   :equivalent ioctl: N/A
-  :slave payload: vring state description
-  :master payload: N/A
+  :request payload: vring state description
+  :reply payload: N/A
 
   When the ``VHOST_USER_PROTOCOL_F_INBAND_NOTIFICATIONS`` protocol
   feature has been successfully negotiated, this message may be
@@ -1489,7 +1516,7 @@ client MUST respond with a Payload ``VhostUserMsg`` 
indicating success
 or failure. The payload should be set to zero on success or non-zero
 on failure, unless the message already has an explicit reply body.
 
-The response payload gives QEMU a deterministic indication of the result
+The reply payload gives QEMU a deterministic indication of the result
 of the command. Today, QEMU is expected to terminate the main vhost-user
 loop upon receiving such errors. In future, qemu could be taught to be more
 resilient for selective requests.
-- 
MST