[RFC,4/5] qmp: Added new command to retrieve eBPF blob.

Commit Message

Andrew Melnichenko March 29, 2023, 10:45 a.m. UTC

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.

Signed-off-by: Andrew Melnychenko <[e-mail]>
---
 monitor/qmp-cmds.c | 17 +++++++++++++++++
 qapi/misc.json     | 25 +++++++++++++++++++++++++
 2 files changed, 42 insertions(+)

Patch

diff --git a/monitor/qmp-cmds.c b/monitor/qmp-cmds.c
index b0f948d337..8f2fc3e7ec 100644
--- a/monitor/qmp-cmds.c
+++ b/monitor/qmp-cmds.c
@@ -32,6 +32,7 @@ 
 #include "hw/mem/memory-device.h"
 #include "hw/intc/intc.h"
 #include "hw/rdma/rdma.h"
+#include "ebpf/ebpf.h"
 
 NameInfo *qmp_query_name(Error **errp)
 {
@@ -209,3 +210,19 @@  static void __attribute__((__constructor__)) monitor_init_qmp_commands(void)
                          qmp_marshal_qmp_capabilities,
                          QCO_ALLOW_PRECONFIG, 0);
 }
+
+EbpfObject *qmp_request_ebpf(const char *id, Error **errp)
+{
+    EbpfObject *ret = NULL;
+    size_t size = 0;
+    const guchar *data = ebpf_find_binary_by_id(id, &size);
+
+    if (data) {
+        ret = g_new0(EbpfObject, 1);
+        ret->object = g_base64_encode(data, size);
+    } else {
+        error_setg(errp, "can't find eBPF object with id: %s", id);
+    }
+
+    return ret;
+}
diff --git a/qapi/misc.json b/qapi/misc.json
index 6ddd16ea28..4689802460 100644
--- a/qapi/misc.json
+++ b/qapi/misc.json
@@ -618,3 +618,28 @@ 
 { 'event': 'VFU_CLIENT_HANGUP',
   'data': { 'vfu-id': 'str', 'vfu-qom-path': 'str',
             'dev-id': 'str', 'dev-qom-path': 'str' } }
+
+##
+# @EbpfObject:
+#
+# Structure that holds eBPF ELF object encoded in base64.
+##
+{ 'struct': 'EbpfObject',
+  'data': {'object': 'str'} }
+
+##
+# @request-ebpf:
+#
+# Function 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.
+#
+# Returns: RSS eBPF object encoded in base64.
+#
+# Since: 7.3
+#
+##
+{ 'command': 'request-ebpf',
+  'data': { 'id': 'str' },
+  'returns': 'EbpfObject' }
+