virtio: disable ioeventfd for record/replay

virtio devices support separate iothreads waiting for
events from file descriptors. These are asynchronous
events that can't be recorded and replayed, therefore
this patch disables ioeventfd for all devices when
record or replay is enabled.

Signed-off-by: Pavel Dovgalyuk <Pavel.Dovgalyuk@ispras.ru>
Message-Id: <162125678869.1252810.4317416444097392406.stgit@pasha-ThinkPad-X280>
Reviewed-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
diff --git a/hw/virtio/virtio-mmio.c b/hw/virtio/virtio-mmio.c
index 5952471..1af48a1 100644
--- a/hw/virtio/virtio-mmio.c
+++ b/hw/virtio/virtio-mmio.c
@@ -29,6 +29,7 @@
 #include "qemu/host-utils.h"
 #include "qemu/module.h"
 #include "sysemu/kvm.h"
+#include "sysemu/replay.h"
 #include "hw/virtio/virtio-mmio.h"
 #include "qemu/error-report.h"
 #include "qemu/log.h"
@@ -740,6 +741,11 @@
         proxy->flags &= ~VIRTIO_IOMMIO_FLAG_USE_IOEVENTFD;
     }
 
+    /* fd-based ioevents can't be synchronized in record/replay */
+    if (replay_mode != REPLAY_MODE_NONE) {
+        proxy->flags &= ~VIRTIO_IOMMIO_FLAG_USE_IOEVENTFD;
+    }
+
     if (proxy->legacy) {
         memory_region_init_io(&proxy->iomem, OBJECT(d),
                               &virtio_legacy_mem_ops, proxy,