Re: [PATCH v6 4/5] qmp: Added new command to retrieve eBPF blob.

["Daniel P. Berrangé" <berrange@redhat.com>]

On Wed, Aug 09, 2023 at 02:30:14AM +0300, Andrew Melnychenko 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           | 70 +++++++++++++++++++++++++++++++++++++++++++
>  ebpf/ebpf.h           | 31 +++++++++++++++++++
>  ebpf/ebpf_rss.c       |  6 ++++
>  ebpf/meson.build      |  2 +-
>  qapi/ebpf.json        | 56 ++++++++++++++++++++++++++++++++++
>  qapi/meson.build      |  1 +
>  qapi/qapi-schema.json |  1 +
>  7 files changed, 166 insertions(+), 1 deletion(-)
>  create mode 100644 ebpf/ebpf.c
>  create mode 100644 ebpf/ebpf.h
>  create mode 100644 qapi/ebpf.json

Reviewed-by: Daniel P. Berrangé <berrange@redhat.com>


With regards,
Daniel
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