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-rw-r--r--docs/specs/vhost-user.txt32
1 files changed, 30 insertions, 2 deletions
diff --git a/docs/specs/vhost-user.txt b/docs/specs/vhost-user.txt
index 036890feb0..5fa7016cc1 100644
--- a/docs/specs/vhost-user.txt
+++ b/docs/specs/vhost-user.txt
@@ -139,6 +139,7 @@ in the ancillary data:
* VHOST_USER_SET_VRING_KICK
* VHOST_USER_SET_VRING_CALL
* VHOST_USER_SET_VRING_ERR
+ * VHOST_USER_SET_SLAVE_REQ_FD
If Master is unable to send the full message or receives a wrong reply it will
close the connection. An optional reconnection mechanism can be implemented.
@@ -252,6 +253,18 @@ Once the source has finished migration, rings will be stopped by
the source. No further update must be done before rings are
restarted.
+Slave communication
+-------------------
+
+An optional communication channel is provided if the slave declares
+VHOST_USER_PROTOCOL_F_SLAVE_REQ protocol feature, to allow the slave to make
+requests to the master.
+
+The fd is provided via VHOST_USER_SET_SLAVE_REQ_FD ancillary data.
+
+A slave may then send VHOST_USER_SLAVE_* messages to the master
+using this fd communication channel.
+
Protocol features
-----------------
@@ -260,9 +273,10 @@ Protocol features
#define VHOST_USER_PROTOCOL_F_RARP 2
#define VHOST_USER_PROTOCOL_F_REPLY_ACK 3
#define VHOST_USER_PROTOCOL_F_MTU 4
+#define VHOST_USER_PROTOCOL_F_SLAVE_REQ 5
-Message types
--------------
+Master message types
+--------------------
* VHOST_USER_GET_FEATURES
@@ -486,6 +500,20 @@ Message types
If VHOST_USER_PROTOCOL_F_REPLY_ACK is negotiated, slave must respond
with zero in case the specified MTU is valid, or non-zero otherwise.
+ * VHOST_USER_SET_SLAVE_REQ_FD
+
+ Id: 21
+ Equivalent ioctl: N/A
+ Master payload: N/A
+
+ Set the socket file descriptor for slave initiated requests. It is passed
+ in the ancillary data.
+ This request should be sent only when VHOST_USER_F_PROTOCOL_FEATURES
+ has been negotiated, and protocol feature bit VHOST_USER_PROTOCOL_F_SLAVE_REQ
+ bit is present in VHOST_USER_GET_PROTOCOL_FEATURES.
+ If VHOST_USER_PROTOCOL_F_REPLY_ACK is negotiated, slave must respond
+ with zero for success, non-zero otherwise.
+
VHOST_USER_PROTOCOL_F_REPLY_ACK:
-------------------------------
The original vhost-user specification only demands replies for certain