1.. SPDX-License-Identifier: BSD-3-Clause 2 Copyright(C) 2022 Intel Corporation. 3 4GVE poll mode driver 5==================== 6 7The GVE PMD (**librte_net_gve**) provides poll mode driver support for 8Google Virtual Ethernet device (also called as gVNIC). 9 10gVNIC is the standard virtual Ethernet interface on Google Cloud Platform (GCP), 11which is one of the multiple virtual interfaces from those leading CSP 12customers in the world. 13 14Please refer to https://cloud.google.com/compute/docs/networking/using-gvnic 15for the device description. 16 17Having a well maintained/optimized gve PMD on DPDK community can help those 18cloud instance consumers with better experience of performance, maintenance 19who wants to run their own VNFs on GCP. 20 21The base code is under MIT license and based on GVE kernel driver v1.3.0. 22GVE base code files are: 23 24- gve_adminq.h 25- gve_adminq.c 26- gve_desc.h 27- gve_desc_dqo.h 28- gve_register.h 29- gve.h 30 31Please refer to https://github.com/GoogleCloudPlatform/compute-virtual-ethernet-linux/tree/v1.3.0/google/gve 32to find the original base code. 33 34GVE has 3 queue formats: 35 36- GQI_QPL - GQI with queue page list 37- GQI_RDA - GQI with raw DMA addressing 38- DQO_RDA - DQO with raw DMA addressing 39 40GQI_QPL queue format is queue page list mode. 41Driver needs to allocate memory and register this memory 42as a Queue Page List (QPL) in hardware (Google Hypervisor/GVE Backend) first. 43Each queue has its own QPL. 44Then Tx needs to copy packets to QPL memory 45and put this packet's offset in the QPL memory into hardware descriptors 46so that hardware can get the packets data. 47And Rx needs to read descriptors of offset in QPL to get QPL address 48and copy packets from the address to get real packets data. 49 50GQI_RDA queue format works like usual NICs 51that driver can put packets' physical address into hardware descriptors. 52 53DQO_RDA queue format has submission and completion queue pair 54for each Tx/Rx queue. 55And similar as GQI_RDA, 56driver can put packets' physical address into hardware descriptors. 57 58Please refer to https://www.kernel.org/doc/html/latest/networking/device_drivers/ethernet/google/gve.html 59to get more information about GVE queue formats. 60 61Features and Limitations 62------------------------ 63 64In this release, the GVE PMD provides the basic functionality 65of packet reception and transmission. 66Supported features of the GVE PMD are: 67 68- Multiple queues for Tx and Rx 69- TSO offload 70- Link state information 71- Tx multi-segments (Scatter Tx) 72- Tx UDP/TCP/SCTP Checksum 73- RSS hash configuration 74- RSS redirection table query and update 75 76Currently, only GQI_QPL and GQI_RDA queue format are supported in PMD. 77Jumbo Frame is not supported in PMD for now. 78It'll be added in a future DPDK release. 79Also, only GQI_QPL queue format is in use on GCP 80since GQI_RDA hasn't been released in production. 81 82RSS 83^^^ 84 85GVE RSS can be enabled and configured using the standard interfaces. 86The driver does not support querying the initial RSS configuration. 87 88The RSS hash key must be exactly 40 bytes. 89Upon RSS hash configuration, a default redirection table will be set 90using a round-robin assignment of hash values to queues. 91The default GVE redirection table has 128 entries. 92 93Note that the initial configuration requires a hash key to be provided 94if one had not been provided before. 95Attempting to set hash types alone without the existence of a set key 96will result in a failed request. 97 98As stated above, the RSS redirection table has exactly 128 entries. 99The RSS hash must be configured before the redirection table can be updated 100using the standard interface. 101Because the initial RSS hash creates a default redirection table, 102the redirection table will be available for querying upon initial hash configuration. 103When performing redirection table updates, 104it is possible to update individual table entries. 105