[Qemu-devel] [PATCH v3 0/3] Vhost-user Spec: extension for vhost-pci

[Qemu-devel] [PATCH v3 0/3] Vhost-user Spec: extension for vhost-pci

[Wei Wang]

This spec patch series extends the vhost-user protocol to support the vhost-pci
based inter-VM communiaction.

v2->v3 changes:
1) replace VHOST_USER_SET_DEV_INFO with VHOST_USER_SET_DEVICE_ID 
2) replace VHOST_USER_SET_PEER_CONNECTION with VHOST_USER_SET_VHOST_PCI

v1->v2 changes:
1) start from the simpler case - change "1-slave-N-master" to "1-slave-1-master"
configuration plane. Accordingly, the previous "uuid", "conn_id" are removed;
2) add the _CREATE_ and _DESTROY_ comands to the VHOST_USER_SET_PEER_CONNECTION
message; and
3) fix the VHOST_USER prefix.

Wei Wang (3):
  spec/vhost-user: extend vhost-user to support the vhost-pci based
    inter-vm communiaction
  spec/vhost-user: add VHOST_USER_PROTOCOL_F_SET_DEVICE_ID
  spec/vhost-user: add the VHOST_USER_SET_VHOST_PCI message

 docs/specs/vhost-user.txt | 44 ++++++++++++++++++++++++++++++++++++++------
 1 file changed, 38 insertions(+), 6 deletions(-)

-- 
2.7.4

[Qemu-devel] [PATCH v3 1/3] spec/vhost-user: extend vhost-user to support the vhost-pci based inter-vm communiaction

[Wei Wang]

The protocol feature, VHOST_USER_PROTOCOL_F_VHOST_PCI, indicates the
support of vhost-pci. The vhost-pci extension requires the master side
implementation to support an asynchronous socket read method. This is
used when the slave side vhost-pci device and driver finishes the
feature bits negotiation. The negotiated feature bits are sent to the
master. If the feature bits sent by the slave are a subset of the ones
that were sent by the master, the master should perform a reset of the
master device (e.g. virtio_net), to re-negotiate the feature bits using
the ones sent by the slave.

Signed-off-by: Wei Wang <wei.w.wang@intel.com>
---
 docs/specs/vhost-user.txt | 21 +++++++++++++++------
 1 file changed, 15 insertions(+), 6 deletions(-)

diff --git a/docs/specs/vhost-user.txt b/docs/specs/vhost-user.txt
index d70bd83..18e49d0 100644
--- a/docs/specs/vhost-user.txt
+++ b/docs/specs/vhost-user.txt
@@ -17,12 +17,15 @@ 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, both the slave and master are QEMU instances.
+
 Message Specification
 ---------------------
 
@@ -36,7 +39,7 @@ consists of 3 header fields and a 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
+   - 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.
  * Size - 32-bit size of the payload
@@ -119,9 +122,9 @@ 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_USER_GET_FEATURES
  * VHOST_USER_GET_PROTOCOL_FEATURES
@@ -130,6 +133,10 @@ the ones that do:
 
 [ Also see the section on REPLY_ACK protocol extension. ]
 
+Currently, the communication also supports the slave actively sending messages
+to the master. Here is a list of them:
+ * VHOST_USER_SET_FEATURES
+
 There are several messages that the master sends with file descriptors passed
 in the ancillary data:
 
@@ -259,6 +266,7 @@ 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
 -------------
@@ -279,8 +287,9 @@ Message types
       Id: 2
       Ioctl: VHOST_SET_FEATURES
       Master payload: u64
+      Slave payload: u64
 
-      Enable features in the underlying vhost implementation using a bitmask.
+      Feature bits negotiation between the master and slave using a bitmask.
       Feature bit VHOST_USER_F_PROTOCOL_FEATURES signals slave support for
       VHOST_USER_GET_PROTOCOL_FEATURES and VHOST_USER_SET_PROTOCOL_FEATURES.
 
-- 
2.7.4

[Qemu-devel] [PATCH v3 2/3] spec/vhost-user: add VHOST_USER_PROTOCOL_F_SET_DEVICE_ID

[Wei Wang]

The VHOST_USER_PROTOCOL_F_SET_DEVICE_ID protocol feature indicates
that the slave side implementation supports different types of devices.
The master tells the slave what type of device to create by sending
a VHOST_USER_SET_DEVICE_ID message.

Signed-off-by: Wei Wang <wei.w.wang@intel.com>
---
 docs/specs/vhost-user.txt | 11 +++++++++++
 1 file changed, 11 insertions(+)

diff --git a/docs/specs/vhost-user.txt b/docs/specs/vhost-user.txt
index 18e49d0..80dcfc1 100644
--- a/docs/specs/vhost-user.txt
+++ b/docs/specs/vhost-user.txt
@@ -267,6 +267,7 @@ Protocol features
 #define VHOST_USER_PROTOCOL_F_RARP           2
 #define VHOST_USER_PROTOCOL_F_REPLY_ACK      3
 #define VHOST_USER_PROTOCOL_F_VHOST_PCI      4
+#define VHOST_USER_PROTOCOL_F_SET_DEVICE_ID  5
 
 Message types
 -------------
@@ -479,6 +480,16 @@ 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_SET_DEVICE_ID
+      Id: 20
+      Equivalent ioctl: N/A
+      Master payload: u64
+
+      The master sends the virtio device id to the slave. The virtio device id
+      indicates the device type of the master device.
+      This request should be sent only when VHOST_USER_PROTOCOL_F_SET_DEVICE_ID
+      has been negotiated.
+
 VHOST_USER_PROTOCOL_F_REPLY_ACK:
 -------------------------------
 The original vhost-user specification only demands replies for certain
-- 
2.7.4

[Qemu-devel] [PATCH v3 3/3] spec/vhost-user: add the VHOST_USER_SET_VHOST_PCI message

[Wei Wang]

The VHOST_USER_SET_VHOST_PCI message is introduced to start/stop
the vhost-pci based inter-VM communiaction by the master.

Signed-off-by: Wei Wang <wei.w.wang@intel.com>
---
 docs/specs/vhost-user.txt | 12 ++++++++++++
 1 file changed, 12 insertions(+)

diff --git a/docs/specs/vhost-user.txt b/docs/specs/vhost-user.txt
index 80dcfc1..4e2ce60 100644
--- a/docs/specs/vhost-user.txt
+++ b/docs/specs/vhost-user.txt
@@ -490,6 +490,18 @@ Message types
       This request should be sent only when VHOST_USER_PROTOCOL_F_SET_DEVICE_ID
       has been negotiated.
 
+ * VHOST_USER_SET_VHOST_PCI
+
+      Id: 21
+      Equivalent ioctl: N/A
+      Master payload: u64
+
+      The master requests the slave to start or stop the vhost-pci device for
+      the inter-VM communication.
+      This request should be sent only when VHOST_USER_PROTOCOL_F_VHOST_PCI has
+      been negotiated.
+
+
 VHOST_USER_PROTOCOL_F_REPLY_ACK:
 -------------------------------
 The original vhost-user specification only demands replies for certain
-- 
2.7.4