[Date Prev] | [Thread Prev] | [Thread Next] | [Date Next] -- [Date Index] | [Thread Index] | [List Home]
Subject: [PATCH v3 1/3] spec/vhost-user: extend vhost-user to support the vhost-pci based inter-vm communiaction
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
[Date Prev] | [Thread Prev] | [Thread Next] | [Date Next] -- [Date Index] | [Thread Index] | [List Home]