9pfs: suppress performance warnings on qtest runs

Don't trigger any performance warning if we're just running test cases,
because tests intentionally run for edge cases.

So far performance warnings were suppressed for the 'synth' fs driver
backend only. This patch suppresses them for all 9p fs driver backends.

Signed-off-by: Christian Schoenebeck <qemu_oss@crudebyte.com>
Reviewed-by: Greg Kurz <groug@kaod.org>
Message-Id: <a2d2ff2163f8853ea782a7a1d4e6f2afd7c29ffe.1603106145.git.qemu_oss@crudebyte.com>
Signed-off-by: Christian Schoenebeck <qemu_oss@crudebyte.com>

hw/9pfs/9p-synth.c

@@ -541,8 +541,6 @@ static int synth_init(FsContext *ctx, Error **errp)
     QLIST_INIT(&synth_root.child);
     qemu_mutex_init(&synth_mutex);
 
-    ctx->export_flags |= V9FS_NO_PERF_WARN;
-
     /* Add "." and ".." entries for root */
     v9fs_add_dir_node(&synth_root, synth_root.attr->mode,
                       "..", synth_root.attr, synth_root.attr->inode);

hw/9pfs/virtio-9p-device.c

@@ -21,6 +21,7 @@
 #include "hw/virtio/virtio-access.h"
 #include "qemu/iov.h"
 #include "qemu/module.h"
+#include "sysemu/qtest.h"
 
 static void virtio_9p_push_and_notify(V9fsPDU *pdu)
 {
@@ -199,6 +200,11 @@ static void virtio_9p_device_realize(DeviceState *dev, Error **errp)
     VirtIODevice *vdev = VIRTIO_DEVICE(dev);
     V9fsVirtioState *v = VIRTIO_9P(dev);
     V9fsState *s = &v->state;
+    FsDriverEntry *fse = get_fsdev_fsentry(s->fsconf.fsdev_id);
+
+    if (qtest_enabled() && fse) {
+        fse->export_flags |= V9FS_NO_PERF_WARN;
+    }
 
     if (v9fs_device_realize_common(s, &virtio_9p_transport, errp)) {
         return;