Re: [PATCH v9 4/5] qmp: Added new command to retrieve eBPF blob.

[Andrew Melnichenko]

Hi all,
I've checked - apparently, qapi/ebpf.json should be added to
MAINTAINERS - I'll fix it.

On Fri, Mar 8, 2024 at 10:14 AM Jason Wang <jasowang@redhat.com> wrote:
>
> On Tue, Feb 6, 2024 at 12:55 AM Andrew Melnychenko <andrew@daynix.com> wrote:
> >
> > Now, the binary objects may be retrieved by id.
> > It would require for future qmp commands that may require specific
> > eBPF blob.
> >
> > Added command "request-ebpf". This command returns
> > eBPF program encoded base64. The program taken from the
> > skeleton and essentially is an ELF object that can be
> > loaded in the future with libbpf.
> >
> > The reason to use the command to provide the eBPF object
> > instead of a separate artifact was to avoid issues related
> > to finding the eBPF itself. eBPF object is an ELF binary
> > that contains the eBPF program and eBPF map description(BTF).
> > Overall, eBPF object should contain the program and enough
> > metadata to create/load eBPF with libbpf. As the eBPF
> > maps/program should correspond to QEMU, the eBPF can't
> > be used from different QEMU build.
> >
> > The first solution was a helper that comes with QEMU
> > and loads appropriate eBPF objects. And the issue is
> > to find a proper helper if the system has several
> > different QEMUs installed and/or built from the source,
> > which helpers may not be compatible.
> >
> > Another issue is QEMU updating while there is a running
> > QEMU instance. With an updated helper, it may not be
> > possible to hotplug virtio-net device to the already
> > running QEMU. Overall, requesting the eBPF object from
> > QEMU itself solves possible failures with acceptable effort.
> >
> > Links:
> > [PATCH 3/5] qmp: Added the helper stamp check.
> > https://lore.kernel.org/all/20230219162100.174318-4-andrew@daynix.com/
> >
> > Signed-off-by: Andrew Melnychenko <andrew@daynix.com>
> > ---
> >  ebpf/ebpf.c           | 69 +++++++++++++++++++++++++++++++++++++++++++
>
> Let's add ebpf.c to MAINTAINERS otherwise CI may warn like:
>
> https://gitlab.com/jasowang/qemu/-/jobs/6349138969
>
> Thanks
>