runtime: Start QEMU undaemonized

QEMU has always been started daemonized since the beginning. I
could not find any justification for that though, but it certainly
introduces a problem : QEMU stops logging errors when started this
way, which isn't accaptable from a support standpoint. The QEMU
community discourages the use of -daemonize ; mostly because
libvirt, QEMU's primary consummer, doesn't use this option and
prefers getting errors from QEMU's stderr through a pipe in order
to enforce rollover.

Now that virtcontainers knows how to start QEMU with a pre-
established QMP connection, let's start QEMU without -daemonize.
This requires to handle the reaping of QEMU when it terminates.
Since cmd.Wait() is blocking, call it from a goroutine.

Signed-off-by: Greg Kurz <groug@kaod.org>

src/runtime/virtcontainers/qemu.go

@@ -531,7 +531,7 @@ func (q *qemu) CreateVM(ctx context.Context, id string, network Network, hypervi
 		NoDefaults:    true,
 		NoGraphic:     true,
 		NoReboot:      true,
-		Daemonize:     true,
+		Daemonize:     false,
 		MemPrealloc:   q.config.MemPrealloc,
 		HugePages:     q.config.HugePages,
 		IOMMUPlatform: q.config.IOMMUPlatform,
@@ -951,6 +951,11 @@ func (q *qemu) StartVM(ctx context.Context, timeout int) error {
 		// Wait for it to exit to assume that the QEMU daemon was
 		// actually started.
 		qemuCmd.Wait()
+	} else {
+		// Ensure the QEMU process is reaped after termination
+		go func() {
+			qemuCmd.Wait()
+		}()
 	}
 
 	err = q.waitVM(ctx, qmpConn, timeout)