Re: [PATCH 0/5] ebpf: Added ebpf helper for libvirtd.

[Jason Wang]

On Mon, Aug 16, 2021 at 7:58 PM Yuri Benditovich
<yuri.benditovich@daynix.com> wrote:
>
> Jason,
> Can you please review the series?

WIll do it this week.

Thanks

>
> Thanks,
> Yuri
>
> On Thu, Jul 22, 2021 at 11:38 AM Andrew Melnichenko <andrew@daynix.com> wrote:
> >
> > ping
> >
> > On Tue, Jul 13, 2021 at 6:38 PM Andrew Melnychenko <andrew@daynix.com> 
> > wrote:
> >>
> >> Libvirt usually launches qemu with strict permissions.
> >> To enable eBPF RSS steering, qemu-ebpf-rss-helper was added.
> >>
> >> Added property "ebpf_rss_fds" for "virtio-net" that allows to
> >> initialize eBPF RSS context with passed program & maps fds.
> >>
> >> Added qemu-ebpf-rss-helper - simple helper that loads eBPF
> >> context and passes fds through unix socket.
> >> Libvirt should call the helper and pass fds to qemu through
> >> "ebpf_rss_fds" property.
> >>
> >> Added explicit target OS check for libbpf dependency in meson.
> >> eBPF RSS works only with Linux TAP, so there is no reason to
> >> build eBPF loader/helper for non-Linux.
> >>
> >> Changed Qemu updates eBPF maps to array mmaping. Mmaping allows
> >> bypassing unprivileged BPF map update. Also, instead of 3 maps
> >> (config, key and indirection table) there is one map that
> >> combines everything.
> >>
> >> Added helper stamp. To check that helper was build with qemu,
> >> qemu would check helper symbols that should contain the stamp.
> >> It was done similar to qemu modules, but checking was performed
> >> by the helper's ELF parsing.
> >>
> >> Overall, libvirt process should not be aware of the "interface"
> >> of eBPF RSS, it will not be aware of eBPF maps/program "type" and
> >> their quantity. That's why qemu and the helper should be from
> >> the same build and be "synchronized". Technically each qemu may
> >> have its own helper. That's why "query-helper-paths" qmp command
> >> was added. Qemu should return the path to the helper that suits
> >> and libvirt should use "that" helper for "that" emulator.
> >>
> >> qmp sample:
> >> C: { "execute": "query-helper-paths" }
> >> S: { "return": [
> >>      {
> >>        "name": "qemu-ebpf-rss-helper",
> >>        "path": "/usr/local/libexec/qemu-ebpf-rss-helper"
> >>      }
> >>     ]
> >>    }
> >>
> >> Changes since v1:
> >> * Mmap() used instead if bpf_map_update_elem().
> >> * Added helper stamp.
> >>
> >> Andrew Melnychenko (5):
> >>   ebpf: Added eBPF initialization by fds and map update.
> >>   virtio-net: Added property to load eBPF RSS with fds.
> >>   qmp: Added the helper stamp check.
> >>   ebpf_rss_helper: Added helper for eBPF RSS.
> >>   qmp: Added qemu-ebpf-rss-path command.
> >>
> >>  ebpf/ebpf_rss-stub.c              |   6 +
> >>  ebpf/ebpf_rss.c                   | 120 ++++---
> >>  ebpf/ebpf_rss.h                   |   8 +-
> >>  ebpf/qemu-ebpf-rss-helper.c       | 130 +++++++
> >>  ebpf/rss.bpf.skeleton.h           | 557 +++++++++++++++---------------
> >>  hw/net/virtio-net.c               |  77 ++++-
> >>  include/hw/virtio/virtio-net.h    |   1 +
> >>  meson.build                       |  47 ++-
> >>  monitor/meson.build               |   1 +
> >>  monitor/qemu-helper-stamp-utils.c | 297 ++++++++++++++++
> >>  monitor/qemu-helper-stamp-utils.h |  24 ++
> >>  monitor/qmp-cmds.c                |  32 ++
> >>  qapi/misc.json                    |  33 ++
> >>  tools/ebpf/rss.bpf.c              |  67 ++--
> >>  14 files changed, 990 insertions(+), 410 deletions(-)
> >>  create mode 100644 ebpf/qemu-ebpf-rss-helper.c
> >>  create mode 100644 monitor/qemu-helper-stamp-utils.c
> >>  create mode 100644 monitor/qemu-helper-stamp-utils.h
> >>
> >> --
> >> 2.31.1
> >>
>