160 lines
7.4 KiB
ReStructuredText
160 lines
7.4 KiB
ReStructuredText
|
=================================================================
|
||
|
|
Intel Omni-Path (OPA) Virtual Network Interface Controller (VNIC)
|
||
|
|
=================================================================
|
||
|
|
|
||
|
|
Intel Omni-Path (OPA) Virtual Network Interface Controller (VNIC) feature
|
||
|
|
supports Ethernet functionality over Omni-Path fabric by encapsulating
|
||
|
|
the Ethernet packets between HFI nodes.
|
||
|
|
|
||
|
|
Architecture
|
||
|
|
=============
|
||
|
|
The patterns of exchanges of Omni-Path encapsulated Ethernet packets
|
||
|
|
involves one or more virtual Ethernet switches overlaid on the Omni-Path
|
||
|
|
fabric topology. A subset of HFI nodes on the Omni-Path fabric are
|
||
|
|
permitted to exchange encapsulated Ethernet packets across a particular
|
||
|
|
virtual Ethernet switch. The virtual Ethernet switches are logical
|
||
|
|
abstractions achieved by configuring the HFI nodes on the fabric for
|
||
|
|
header generation and processing. In the simplest configuration all HFI
|
||
|
|
nodes across the fabric exchange encapsulated Ethernet packets over a
|
||
|
|
single virtual Ethernet switch. A virtual Ethernet switch, is effectively
|
||
|
|
an independent Ethernet network. The configuration is performed by an
|
||
|
|
Ethernet Manager (EM) which is part of the trusted Fabric Manager (FM)
|
||
|
|
application. HFI nodes can have multiple VNICs each connected to a
|
||
|
|
different virtual Ethernet switch. The below diagram presents a case
|
||
|
|
of two virtual Ethernet switches with two HFI nodes::
|
||
|
|
|
||
|
|
+-------------------+
|
||
|
|
| Subnet/ |
|
||
|
|
| Ethernet |
|
||
|
|
| Manager |
|
||
|
|
+-------------------+
|
||
|
|
/ /
|
||
|
|
/ /
|
||
|
|
/ /
|
||
|
|
/ /
|
||
|
|
+-----------------------------+ +------------------------------+
|
||
|
|
| Virtual Ethernet Switch | | Virtual Ethernet Switch |
|
||
|
|
| +---------+ +---------+ | | +---------+ +---------+ |
|
||
|
|
| | VPORT | | VPORT | | | | VPORT | | VPORT | |
|
||
|
|
+--+---------+----+---------+-+ +-+---------+----+---------+---+
|
||
|
|
| \ / |
|
||
|
|
| \ / |
|
||
|
|
| \/ |
|
||
|
|
| / \ |
|
||
|
|
| / \ |
|
||
|
|
+-----------+------------+ +-----------+------------+
|
||
|
|
| VNIC | VNIC | | VNIC | VNIC |
|
||
|
|
+-----------+------------+ +-----------+------------+
|
||
|
|
| HFI | | HFI |
|
||
|
|
+------------------------+ +------------------------+
|
||
|
|
|
||
|
|
|
||
|
|
The Omni-Path encapsulated Ethernet packet format is as described below.
|
||
|
|
|
||
|
|
==================== ================================
|
||
|
|
Bits Field
|
||
|
|
==================== ================================
|
||
|
|
Quad Word 0:
|
||
|
|
0-19 SLID (lower 20 bits)
|
||
|
|
20-30 Length (in Quad Words)
|
||
|
|
31 BECN bit
|
||
|
|
32-51 DLID (lower 20 bits)
|
||
|
|
52-56 SC (Service Class)
|
||
|
|
57-59 RC (Routing Control)
|
||
|
|
60 FECN bit
|
||
|
|
61-62 L2 (=10, 16B format)
|
||
|
|
63 LT (=1, Link Transfer Head Flit)
|
||
|
|
|
||
|
|
Quad Word 1:
|
||
|
|
0-7 L4 type (=0x78 ETHERNET)
|
||
|
|
8-11 SLID[23:20]
|
||
|
|
12-15 DLID[23:20]
|
||
|
|
16-31 PKEY
|
||
|
|
32-47 Entropy
|
||
|
|
48-63 Reserved
|
||
|
|
|
||
|
|
Quad Word 2:
|
||
|
|
0-15 Reserved
|
||
|
|
16-31 L4 header
|
||
|
|
32-63 Ethernet Packet
|
||
|
|
|
||
|
|
Quad Words 3 to N-1:
|
||
|
|
0-63 Ethernet packet (pad extended)
|
||
|
|
|
||
|
|
Quad Word N (last):
|
||
|
|
0-23 Ethernet packet (pad extended)
|
||
|
|
24-55 ICRC
|
||
|
|
56-61 Tail
|
||
|
|
62-63 LT (=01, Link Transfer Tail Flit)
|
||
|
|
==================== ================================
|
||
|
|
|
||
|
|
Ethernet packet is padded on the transmit side to ensure that the VNIC OPA
|
||
|
|
packet is quad word aligned. The 'Tail' field contains the number of bytes
|
||
|
|
padded. On the receive side the 'Tail' field is read and the padding is
|
||
|
|
removed (along with ICRC, Tail and OPA header) before passing packet up
|
||
|
|
the network stack.
|
||
|
|
|
||
|
|
The L4 header field contains the virtual Ethernet switch id the VNIC port
|
||
|
|
belongs to. On the receive side, this field is used to de-multiplex the
|
||
|
|
received VNIC packets to different VNIC ports.
|
||
|
|
|
||
|
|
Driver Design
|
||
|
|
==============
|
||
|
|
Intel OPA VNIC software design is presented in the below diagram.
|
||
|
|
OPA VNIC functionality has a HW dependent component and a HW
|
||
|
|
independent component.
|
||
|
|
|
||
|
|
The support has been added for IB device to allocate and free the RDMA
|
||
|
|
netdev devices. The RDMA netdev supports interfacing with the network
|
||
|
|
stack thus creating standard network interfaces. OPA_VNIC is an RDMA
|
||
|
|
netdev device type.
|
||
|
|
|
||
|
|
The HW dependent VNIC functionality is part of the HFI1 driver. It
|
||
|
|
implements the verbs to allocate and free the OPA_VNIC RDMA netdev.
|
||
|
|
It involves HW resource allocation/management for VNIC functionality.
|
||
|
|
It interfaces with the network stack and implements the required
|
||
|
|
net_device_ops functions. It expects Omni-Path encapsulated Ethernet
|
||
|
|
packets in the transmit path and provides HW access to them. It strips
|
||
|
|
the Omni-Path header from the received packets before passing them up
|
||
|
|
the network stack. It also implements the RDMA netdev control operations.
|
||
|
|
|
||
|
|
The OPA VNIC module implements the HW independent VNIC functionality.
|
||
|
|
It consists of two parts. The VNIC Ethernet Management Agent (VEMA)
|
||
|
|
registers itself with IB core as an IB client and interfaces with the
|
||
|
|
IB MAD stack. It exchanges the management information with the Ethernet
|
||
|
|
Manager (EM) and the VNIC netdev. The VNIC netdev part allocates and frees
|
||
|
|
the OPA_VNIC RDMA netdev devices. It overrides the net_device_ops functions
|
||
|
|
set by HW dependent VNIC driver where required to accommodate any control
|
||
|
|
operation. It also handles the encapsulation of Ethernet packets with an
|
||
|
|
Omni-Path header in the transmit path. For each VNIC interface, the
|
||
|
|
information required for encapsulation is configured by the EM via VEMA MAD
|
||
|
|
interface. It also passes any control information to the HW dependent driver
|
||
|
|
by invoking the RDMA netdev control operations::
|
||
|
|
|
||
|
|
+-------------------+ +----------------------+
|
||
|
|
| | | Linux |
|
||
|
|
| IB MAD | | Network |
|
||
|
|
| | | Stack |
|
||
|
|
+-------------------+ +----------------------+
|
||
|
|
| | |
|
||
|
|
| | |
|
||
|
|
+----------------------------+ |
|
||
|
|
| | |
|
||
|
|
| OPA VNIC Module | |
|
||
|
|
| (OPA VNIC RDMA Netdev | |
|
||
|
|
| & EMA functions) | |
|
||
|
|
| | |
|
||
|
|
+----------------------------+ |
|
||
|
|
| |
|
||
|
|
| |
|
||
|
|
+------------------+ |
|
||
|
|
| IB core | |
|
||
|
|
+------------------+ |
|
||
|
|
| |
|
||
|
|
| |
|
||
|
|
+--------------------------------------------+
|
||
|
|
| |
|
||
|
|
| HFI1 Driver with VNIC support |
|
||
|
|
| |
|
||
|
|
+--------------------------------------------+
|