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| -rw-r--r-- | Documentation/infiniband/opa_vnic.txt | 153 |
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diff --git a/Documentation/infiniband/opa_vnic.txt b/Documentation/infiniband/opa_vnic.txt new file mode 100644 index 000000000000..282e17be798a --- /dev/null +++ b/Documentation/infiniband/opa_vnic.txt @@ -0,0 +1,153 @@ +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 | + | | + +--------------------------------------------+ |