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-and...@daynix.com/ Signed-off-by: Andrew Melnychenko <and...@daynix.com> --- ebpf/ebpf.c | 70 +++++++++++++++++++++++++++++++++++++++++++ ebpf/ebpf.h | 31 +++++++++++++++++++ ebpf/ebpf_rss.c | 6 ++++ ebpf/meson.build | 2 +- qapi/ebpf.json | 57 +++++++++++++++++++++++++++++++++++ qapi/meson.build | 1 + qapi/qapi-schema.json | 1 + 7 files changed, 167 insertions(+), 1 deletion(-) create mode 100644 ebpf/ebpf.c create mode 100644 ebpf/ebpf.h create mode 100644 qapi/ebpf.json diff --git a/ebpf/ebpf.c b/ebpf/ebpf.c new file mode 100644 index 00000000000..ea97c0403ee --- /dev/null +++ b/ebpf/ebpf.c @@ -0,0 +1,70 @@ +/* + * QEMU eBPF binary declaration routine. + * + * Developed by Daynix Computing LTD (http://www.daynix.com) + * + * Authors: + * Andrew Melnychenko <and...@daynix.com> + * + * This work is licensed under the terms of the GNU GPL, version 2 or + * later. See the COPYING file in the top-level directory. + */ + +#include "qemu/osdep.h" +#include "qemu/queue.h" +#include "qapi/error.h" +#include "qapi/qapi-commands-ebpf.h" +#include "ebpf/ebpf.h" + +struct ElfBinaryDataEntry { + int id; + const void *data; + size_t datalen; + + QSLIST_ENTRY(ElfBinaryDataEntry) node; +}; + +static QSLIST_HEAD(, ElfBinaryDataEntry) ebpf_elf_obj_list = + QSLIST_HEAD_INITIALIZER(); + +void ebpf_register_binary_data(int id, const void *data, size_t datalen) +{ + struct ElfBinaryDataEntry *dataentry = NULL; + + dataentry = g_new0(struct ElfBinaryDataEntry, 1); + dataentry->data = data; + dataentry->datalen = datalen; + dataentry->id = id; + + QSLIST_INSERT_HEAD(&ebpf_elf_obj_list, dataentry, node); +} + +const void *ebpf_find_binary_by_id(int id, size_t *sz, Error **errp) +{ + struct ElfBinaryDataEntry *it = NULL; + QSLIST_FOREACH(it, &ebpf_elf_obj_list, node) { + if (id == it->id) { + *sz = it->datalen; + return it->data; + } + } + + error_setg(errp, "can't find eBPF object with id: %d", id); + + return NULL; +} + +EbpfObject *qmp_request_ebpf(EbpfProgramID id, Error **errp) +{ + EbpfObject *ret = NULL; + size_t size = 0; + const void *data = ebpf_find_binary_by_id(id, &size, errp); + if (!data) { + return NULL; + } + + ret = g_new0(EbpfObject, 1); + ret->object = g_base64_encode(data, size); + + return ret; +} diff --git a/ebpf/ebpf.h b/ebpf/ebpf.h new file mode 100644 index 00000000000..b6266b28b8c --- /dev/null +++ b/ebpf/ebpf.h @@ -0,0 +1,31 @@ +/* + * QEMU eBPF binary declaration routine. + * + * Developed by Daynix Computing LTD (http://www.daynix.com) + * + * Authors: + * Andrew Melnychenko <and...@daynix.com> + * + * This work is licensed under the terms of the GNU GPL, version 2 or + * later. See the COPYING file in the top-level directory. + */ + +#ifndef EBPF_H +#define EBPF_H + +struct Error; + +void ebpf_register_binary_data(int id, const void *data, + size_t datalen); +const void *ebpf_find_binary_by_id(int id, size_t *sz, + struct Error **errp); + +#define ebpf_binary_init(id, fn) \ +static void __attribute__((constructor)) ebpf_binary_init_ ## fn(void) \ +{ \ + size_t datalen = 0; \ + const void *data = fn(&datalen); \ + ebpf_register_binary_data(id, data, datalen); \ +} + +#endif /* EBPF_H */ diff --git a/ebpf/ebpf_rss.c b/ebpf/ebpf_rss.c index 24bc6cc409e..8679dc452df 100644 --- a/ebpf/ebpf_rss.c +++ b/ebpf/ebpf_rss.c @@ -13,6 +13,8 @@ #include "qemu/osdep.h" #include "qemu/error-report.h" +#include "qapi/qapi-types-misc.h" +#include "qapi/qapi-commands-ebpf.h" #include <bpf/libbpf.h> #include <bpf/bpf.h> @@ -21,6 +23,8 @@ #include "ebpf/ebpf_rss.h" #include "ebpf/rss.bpf.skeleton.h" +#include "ebpf/ebpf.h" + #include "trace.h" void ebpf_rss_init(struct EBPFRSSContext *ctx) @@ -261,3 +265,5 @@ void ebpf_rss_unload(struct EBPFRSSContext *ctx) ctx->map_toeplitz_key = -1; ctx->map_indirections_table = -1; } + +ebpf_binary_init(EBPF_PROGRAMID_RSS, rss_bpf__elf_bytes) diff --git a/ebpf/meson.build b/ebpf/meson.build index 2f627d6c7d0..c5bf9295a20 100644 --- a/ebpf/meson.build +++ b/ebpf/meson.build @@ -1 +1 @@ -system_ss.add(when: libbpf, if_true: files('ebpf_rss.c'), if_false: files('ebpf_rss-stub.c')) +common_ss.add(when: libbpf, if_true: files('ebpf.c', 'ebpf_rss.c'), if_false: files('ebpf_rss-stub.c')) diff --git a/qapi/ebpf.json b/qapi/ebpf.json new file mode 100644 index 00000000000..40851f8c177 --- /dev/null +++ b/qapi/ebpf.json @@ -0,0 +1,57 @@ +# -*- Mode: Python -*- +# vim: filetype=python +# +# This work is licensed under the terms of the GNU GPL, version 2 or later. +# See the COPYING file in the top-level directory. + +## +# = eBPF Objects +## + +{ 'include': 'common.json' } + +## +# @EbpfObject: +# +# Structure that holds eBPF ELF object encoded in base64. +# +# Since: 8.3 +# +## +{ 'struct': 'EbpfObject', + 'data': {'object': 'str'}, + 'if': 'CONFIG_EBPF' } + +## +# @EbpfProgramID: +# +# The eBPF programs that can be gotten with request-ebpf. +# +# @rss: Receive side scaling, technology that allows steering traffic +# between queues by calculation hash. Users may set up indirection table +# and hash/packet types configurations. Used with virtio-net. +# +# Since: 8.3 +## +{ 'enum': 'EbpfProgramID', + 'if': 'CONFIG_EBPF', + 'data': [ { 'name': 'rss' } ] } + +## +# @request-ebpf: +# +# Returns eBPF object that can be loaded with libbpf. +# Management applications (g.e. libvirt) may load it and pass file +# descriptors to QEMU. Which allows running QEMU without BPF capabilities. +# It's crucial that eBPF program/map is compatible with QEMU, so it's +# provided through QMP. +# +# Returns: RSS eBPF object encoded in base64. +# +# Since: 8.3 +# +## +{ 'command': 'request-ebpf', + 'data': { 'id': 'EbpfProgramID' }, + 'returns': 'EbpfObject', + 'if': 'CONFIG_EBPF' } diff --git a/qapi/meson.build b/qapi/meson.build index 60a668b3432..90047dae1c8 100644 --- a/qapi/meson.build +++ b/qapi/meson.build @@ -33,6 +33,7 @@ qapi_all_modules = [ 'crypto', 'cxl', 'dump', + 'ebpf', 'error', 'introspect', 'job', diff --git a/qapi/qapi-schema.json b/qapi/qapi-schema.json index 6594afba312..2c82a49baec 100644 --- a/qapi/qapi-schema.json +++ b/qapi/qapi-schema.json @@ -53,6 +53,7 @@ { 'include': 'char.json' } { 'include': 'dump.json' } { 'include': 'net.json' } +{ 'include': 'ebpf.json' } { 'include': 'rdma.json' } { 'include': 'rocker.json' } { 'include': 'tpm.json' } -- 2.41.0
