[RFC PATCH 1/4] qemu_monitor: Added QEMU's "request-ebpf" support.

[Andrew Melnychenko]

Added code for monitor and monitor_json.
The "request-ebpf" return's eBPF binary object encoded in base64.
The function qemuMonitorGetEbpf() returns a decoded blob.

QEMU provides eBPF that can be loaded and passed to it from Libvirt.
QEMU requires exact eBPF program/maps, so it can be retrieved using QAPI.
To load eBPF program - administrative capabilities are required, so Libvirt may load it and pass it to the QEMU instance.
For now, there is only "RSS"(Receive Side Scaling) for virtio-net eBPF program and maps.

Signed-off-by: Andrew Melnychenko <andrew at daynix.com>
---
 src/qemu/qemu_monitor.c      | 23 +++++++++++++++++++++++
 src/qemu/qemu_monitor.h      |  3 +++
 src/qemu/qemu_monitor_json.c | 21 +++++++++++++++++++++
 src/qemu/qemu_monitor_json.h |  3 +++
 4 files changed, 50 insertions(+)

diff --git a/src/qemu/qemu_monitor.c b/src/qemu/qemu_monitor.c
index 320729f067..07596c78ee 100644
--- a/src/qemu/qemu_monitor.c
+++ b/src/qemu/qemu_monitor.c
@@ -4512,3 +4512,26 @@ qemuMonitorGetStatsByQOMPath(virJSONValue *arr,
 
     return NULL;
 }
+
+void *
+qemuMonitorGetEbpf(qemuMonitor *mon, const char *ebpfName, size_t *size)
+{
+    QEMU_CHECK_MONITOR_NULL(mon);
+    g_autoptr(virJSONValue) reply = NULL;
+    const char *ebpfBase64 = NULL;
+    void *ebpfObject = NULL;
+
+    if (ebpfName == NULL || size == NULL)
+        return NULL;
+
+    reply = qemuMonitorJSONGetEbpf(mon, ebpfName);
+
+    if (reply == NULL)
+        return NULL;
+
+    ebpfBase64 = virJSONValueObjectGetString(reply, "object");
+
+    ebpfObject = g_base64_decode(ebpfBase64, size);
+
+    return ebpfObject;
+}
diff --git a/src/qemu/qemu_monitor.h b/src/qemu/qemu_monitor.h
index 6c590933aa..15f32f105c 100644
--- a/src/qemu/qemu_monitor.h
+++ b/src/qemu/qemu_monitor.h
@@ -1579,3 +1579,6 @@ qemuMonitorExtractQueryStats(virJSONValue *info);
 virJSONValue *
 qemuMonitorGetStatsByQOMPath(virJSONValue *arr,
                              char *qom_path);
+
+void *
+qemuMonitorGetEbpf(qemuMonitor *mon, const char *ebpfName, size_t *size);
diff --git a/src/qemu/qemu_monitor_json.c b/src/qemu/qemu_monitor_json.c
index 8152eea9a0..a7d0865ddc 100644
--- a/src/qemu/qemu_monitor_json.c
+++ b/src/qemu/qemu_monitor_json.c
@@ -8851,3 +8851,24 @@ qemuMonitorJSONQueryStats(qemuMonitor *mon,
 
     return virJSONValueObjectStealArray(reply, "return");
 }
+
+
+virJSONValue *
+qemuMonitorJSONGetEbpf(qemuMonitor *mon, const char *ebpfName)
+{
+    g_autoptr(virJSONValue) cmd = NULL;
+    g_autoptr(virJSONValue) reply = NULL;
+
+    if (!(cmd = qemuMonitorJSONMakeCommand("request-ebpf",
+                                           "s:id", ebpfName, NULL)))
+        return NULL;
+
+    if (qemuMonitorJSONCommand(mon, cmd, &reply) < 0)
+        return NULL;
+
+    /* return empty hash */
+    if (qemuMonitorJSONHasError(reply, "CommandNotFound"))
+        return NULL;
+
+    return virJSONValueObjectStealObject(reply, "return");
+}
diff --git a/src/qemu/qemu_monitor_json.h b/src/qemu/qemu_monitor_json.h
index 06023b98ea..6a2fc963ba 100644
--- a/src/qemu/qemu_monitor_json.h
+++ b/src/qemu/qemu_monitor_json.h
@@ -825,3 +825,6 @@ qemuMonitorJSONQueryStats(qemuMonitor *mon,
                           qemuMonitorQueryStatsTargetType target,
                           char **vcpus,
                           GPtrArray *providers);
+
+virJSONValue *
+qemuMonitorJSONGetEbpf(qemuMonitor *mon, const char *ebpfName);
-- 
2.42.0