The kernel documentation says:
> The value stored can be of any size, however, all array elements are
> aligned to 8 bytes.
https://www.kernel.org/doc/html/v6.8/bpf/map_array.html
Fixes: 333b3e5fab ("ebpf: Added eBPF map update through mmap.")
Signed-off-by: Akihiko Odaki <akihiko.odaki@daynix.com>
Acked-by: Andrew Melnychenko <andrew@daynix.com>
Signed-off-by: Jason Wang <jasowang@redhat.com>
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>
Signed-off-by: Jason Wang <jasowang@redhat.com>
It allows using file descriptors of eBPF provided
outside of QEMU.
QEMU may be run without capabilities for eBPF and run
RSS program provided by management tool(g.e. libvirt).
Signed-off-by: Andrew Melnychenko <andrew@daynix.com>
Signed-off-by: Jason Wang <jasowang@redhat.com>
Changed eBPF map updates through mmaped array.
Mmaped arrays provide direct access to map data.
It should omit using bpf_map_update_elem() call,
which may require capabilities that are not present.
Signed-off-by: Andrew Melnychenko <andrew@daynix.com>
Signed-off-by: Jason Wang <jasowang@redhat.com>
bpf_program__set_<TYPE> functions have been deprecated since libbpf 0.8.
Replace with the equivalent bpf_program__set_type call to avoid a
deprecation warning.
Signed-off-by: Haochen Tong <i@hexchain.org>
Reviewed-by: Zhang Chen <chen.zhang@intel.com>
Signed-off-by: Jason Wang <jasowang@redhat.com>
Added function that loads RSS eBPF program.
Added stub functions for RSS eBPF loader.
Added meson and configuration options.
By default, eBPF feature enabled if libbpf is present in the build system.
libbpf checked in configuration shell script and meson script.
Signed-off-by: Yuri Benditovich <yuri.benditovich@daynix.com>
Signed-off-by: Andrew Melnychenko <andrew@daynix.com>
Signed-off-by: Jason Wang <jasowang@redhat.com>
