[RFC PATCH 00/10] VirtioNet RSS support

[Andrew Melnichenko]

Ping

On Wed, Jul 28, 2021 at 11:17 AM Andrew Melnychenko <andrew at daynix.com>
wrote:

> This series of patches add RSS property support for virtio-net-pci.
>
> Virtio RSS effectively works with TAP devices, it requires additional
> vectors for VirtioNet, queues for TAP device, and vCPU cores.
> Example of device configuration:
> ```
> <interface type="network">
>   <mac address="52:54:00:c4:90:25"/>
>   <source network="default"/>
>   <model type="virtio"/>
>   <driver name="qemu" queues="9" rss="on" rss_hash_report="off"/>
>   <address type="pci" domain="0x0000" bus="0x01" slot="0x00"
> function="0x0"/>
> </interface>
> ```
>
> Capability "rss" enables RSS, "rss_hash_report" - enables hashes in
> vheader.
> Qemu uses eBPF program as RSS driver.
> For loading RSS eBPF program, the helper is used.
> Path to the helper is provided by Qemu through "query-helper-paths" qmp
> command.
> The helper "qemu-ebpf-rss-helper" is built with Qemu and may differ from
> build to build.
> So it's required that the Qemu should provide a proper helper path.
> Libvirt would call the helper and receive the program and map fd through
> unix socket.
> Fds would be passed to Qemu in "ebpf_rss_fds" property by passing to child
> process or unix socket.
> If libvirt would fail at helper call or Qemu didn't provide the path,
> the Qemu would be launched without "ebpf_rss_fds" property.
> Without "ebpf_rss_fds" property, Qemu would try to load eBPF program by
> itself - usually, it would require additional system permissions.
> Qemu may use "in-qemu" RSS as a fallback option, which will not require
> system
> permissions, but doesn't work with vhost TAP.
>
> Qemu patches:
> https://lists.nongnu.org/archive/html/qemu-devel/2021-07/msg03535.html
>
> Andrew Melnychenko (10):
>   domain_conf: Added configs for RSS and Hash report.
>   qemu_capabilities: Added capabilites for qemu's "rss" and "hash".
>   qemu_command: Added "rss" and "hash" properties.
>   virsocket: Added receive for multiple fds.
>   qemu_capabilities: Added capability for qemu's "ebpf_rss_fds".
>   qemu_capabilities: Added capability for ebpf helper path.
>   qemu_interface: Added ebpf helper call.
>   qemu_command: Added ebpf RSS helper call for NIC creation.
>   qemu_hotplug: Added helper call for hotplug NIC.
>   docs: Added descriptions for "rss" and "rss_hash_report"
>     configurations.
>
>  docs/formatdomain.rst        | 16 +++++++
>  src/conf/domain_conf.c       | 31 +++++++++++++-
>  src/conf/domain_conf.h       |  2 +
>  src/libvirt_private.syms     |  1 +
>  src/qemu/qemu_capabilities.c | 48 +++++++++++++++++++++
>  src/qemu/qemu_capabilities.h |  5 +++
>  src/qemu/qemu_command.c      | 46 +++++++++++++++++++-
>  src/qemu/qemu_command.h      |  2 +
>  src/qemu/qemu_hotplug.c      | 30 ++++++++++++-
>  src/qemu/qemu_interface.c    | 54 +++++++++++++++++++++++
>  src/qemu/qemu_interface.h    |  2 +
>  src/qemu/qemu_monitor.c      |  9 ++++
>  src/qemu/qemu_monitor.h      |  3 ++
>  src/qemu/qemu_monitor_json.c | 50 ++++++++++++++++++++++
>  src/qemu/qemu_monitor_json.h |  3 ++
>  src/qemu/qemu_validate.c     | 16 +++++++
>  src/util/virsocket.c         | 83 ++++++++++++++++++++++++++++++++++++
>  src/util/virsocket.h         |  2 +
>  18 files changed, 399 insertions(+), 4 deletions(-)
>
> --
> 2.31.1
>
>
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