@@ -17,31 +17,39 @@ The protocol defines 2 sides of the communication, master and slave. Master is
the application that shares its virtqueues, in our case QEMU. Slave is the
consumer of the virtqueues.
-In the current implementation QEMU is the Master, and the Slave is intended to
+In the traditional implementation QEMU is the Master, and the Slave is intended to
be a software Ethernet switch running in user space, such as Snabbswitch.
Master and slave can be either a client (i.e. connecting) or server (listening)
in the socket communication.
+The current vhost-user protocol is extended to support the vhost-pci based inter-VM
+communication. In this case, Slave is a QEMU which runs a vhost-pci server, and
+Master is another QEMU which runs a vhost-pci client.
+
Message Specification
---------------------
Note that all numbers are in the machine native byte order. A vhost-user message
-consists of 3 header fields and a payload:
+consists of 4 header fields and a payload:
-------------------------------------
-| request | flags | size | payload |
-------------------------------------
+----------------------------------------------
+| request | flags | conn_id | size | payload |
+----------------------------------------------
* Request: 32-bit type of the request
* Flags: 32-bit bit field:
- - Lower 2 bits are the version (currently 0x01)
- - Bit 2 is the reply flag - needs to be sent on each reply from the slave
+ - Lower 2 bits are the version (currently 0x02)
+ - Bit 2 is the reply flag - needs to be sent on each reply
- Bit 3 is the need_reply flag - see VHOST_USER_PROTOCOL_F_REPLY_ACK for
details.
+ * Conn_id: 64-bit connection id to indentify a client socket connection. It is
+ introduced in version 0x02 to support the "1-server-N-client" model
+ and an asynchronous client read implementation. The connection id,
+ 0xFFFFFFFFFFFFFFFF, is used by an anonymous client (e.g. a client who
+ has not got its connection id from the server in the initial talk)
* Size - 32-bit size of the payload
-
Depending on the request type, payload can be:
* A single 64-bit integer
@@ -72,10 +80,12 @@ Depending on the request type, payload can be:
Log: a 64-bit guest address for logging
* Memory regions description
- ---------------------------------------------------
- | num regions | padding | region0 | ... | region7 |
- ---------------------------------------------------
+ ----------------------------------------------------------
+ | uuid | num regions | padding | region0 | ... | region7 |
+ ----------------------------------------------------------
+ UUID: a 128-bit identification of the QEMU that the memory region
+ belongs to
Num regions: a 32-bit number of regions
Padding: 32-bit
@@ -97,6 +107,19 @@ Depending on the request type, payload can be:
log offset: offset from start of supplied file descriptor
where logging starts (i.e. where guest address 0 would be logged)
+* UUID description
+ --------
+ | uuid |
+ --------
+ uuid: 128 bit uuid
+
+* Rx queue gsi description
+ --------------------------------------
+ | num rx queues | gsi[num rx queues] |
+ --------------------------------------
+ num rx queues: 16 bit.
+ gsi[]: stores the GSI of each rx queue.
+
In QEMU the vhost-user message is implemented with the following struct:
typedef struct VhostUserMsg {
@@ -109,6 +132,8 @@ typedef struct VhostUserMsg {
struct vhost_vring_addr addr;
VhostUserMemory memory;
VhostUserLog log;
+ uuit_t uuid;
+ RxQueueGSI rx_gsi;
};
} QEMU_PACKED VhostUserMsg;
@@ -119,17 +144,27 @@ The protocol for vhost-user is based on the existing implementation of vhost
for the Linux Kernel. Most messages that can be sent via the Unix domain socket
implementing vhost-user have an equivalent ioctl to the kernel implementation.
-The communication consists of master sending message requests and slave sending
-message replies. Most of the requests don't require replies. Here is a list of
-the ones that do:
+Traditionally, the communication consists of master sending message requests
+and slave sending message replies. Most of the requests don't require replies.
+Here is a list of the ones that do:
- * VHOST_GET_FEATURES
- * VHOST_GET_PROTOCOL_FEATURES
- * VHOST_GET_VRING_BASE
- * VHOST_SET_LOG_BASE (if VHOST_USER_PROTOCOL_F_LOG_SHMFD)
+ * VHOST_USER_GET_FEATURES
+ * VHOST_USER_GET_PROTOCOL_FEATURES
+ * VHOST_USER_GET_VRING_BASE
+ * VHOST_USER_SET_LOG_BASE (if VHOST_USER_PROTOCOL_F_LOG_SHMFD)
+ * VHOST_USER_GET_CONN_ID
+ * VHOST_USER_SET_PVI_SENDER_UUID
+ * VHOST_USER_SET_PEER_CONNECTION
[ Also see the section on REPLY_ACK protocol extension. ]
+Currently, the communiaction also supports the Slave (server) sending messages or
+asynchronously replying to the Master (client). Here is a list of them:
+ * VHOST_USER_SET_RX_QUEUE_GSI
+ * VHOST_USER_SET_PVI_SENDER_UUID
+ * VHOST_USER_SET_PEER_CONNECTION (the serve may actively request to disconnect
+ with the client)
+
There are several messages that the master sends with file descriptors passed
in the ancillary data:
@@ -259,6 +294,7 @@ Protocol features
#define VHOST_USER_PROTOCOL_F_LOG_SHMFD 1
#define VHOST_USER_PROTOCOL_F_RARP 2
#define VHOST_USER_PROTOCOL_F_REPLY_ACK 3
+#define VHOST_USER_PROTOCOL_F_VHOST_PCI 4
Message types
-------------
@@ -470,6 +506,61 @@ Message types
The first 6 bytes of the payload contain the mac address of the guest to
allow the vhost user backend to construct and broadcast the fake RARP.
+ * VHOST_USER_GET_CONN_ID
+ Id: 20
+ Equivalent ioctl: N/A
+ Master payload: u64
+
+ The client sends this message to the server to ask for its connection id.
+ The connection id is then put into the message header (the conn_id field),
+ so that the server can always know who it is talking with.
+
+ * VHOST_USER_SET_DEV_TYPE
+ Id: 21
+ Equivalent ioctl: N/A
+ Master payload: u64
+
+ The client sends the necessary info about the producer virtio device to
+ the server.
+ This request should be sent only when VHOST_USER_PROTOCOL_F_VHOST_PCI has
+ been negotiated.
+ #define VHOST_USER_DEV_TYPE_NET 1
+
+ * VHOST_USER_SET_PVI_SENDER_UUID
+ Id: 22
+ Equivalent ioctl: N/A
+ Master payload: uuid description
+
+ The producer sends its QEMU uuid to the consumer, the vhost-pci device, to
+ enable sending PV interrupts to the consumer, and vice versa.
+
+ * VHOST_USER_SET_RX_QUEUE_GSI
+ Id: 23
+ Equivalent ioctl: N/A
+ Master payload: rx queue gsi description
+
+ The producer device sends its rx queues' GSIs to its consumer device.
+ The consumer device also sends one of its rx queues' GSI to the producer
+ device after the queue's GSI is assigned.
+ This request should be sent only when VHOST_USER_PROTOCOL_F_VHOST_PCI has
+ been negotiated.
+
+ * VHOST_USER_SET_PEER_CONNECTION
+ Id: 24
+ Equivalent ioctl: N/A
+ Master payload: u64
+
+ The producer device requests to connect or disconnect with the consumer device.
+ The consumer device may request to disconnect with the producer device. This
+ request should be sent only when VHOST_USER_PROTOCOL_F_VHOST_PCI has been
+ negotiated.
+ Connection request: If the reply message indicates "success", the vhost-pci based
+ inter-VM communication channel has been established.
+ Disconnection request: If the reply message indicates "success", the vhost-pci based
+ inter-VM communication channel has been destroyed.
+ #define VHOST_USER_SET_PEER_CONNECTION_F_DISCONNECT 0
+ #define VHOST_USER_SET_PEER_CONNECTION_F_CONNECT 1
+
VHOST_USER_PROTOCOL_F_REPLY_ACK:
-------------------------------
The original vhost-user specification only demands replies for certain
Signed-off-by: Wei Wang <wei.w.wang@intel.com> --- docs/specs/vhost-user.txt | 127 +++++++++++++++++++++++++++++++++++++++------- 1 file changed, 109 insertions(+), 18 deletions(-)