virtio-rng: add some trace events

Add some trace events to virtio-rng for easier debugging
Signed-off-by: NAmit Shah <amit.shah@redhat.com>
Reviewed-by: NAmos Kong <akong@redhat.com>
Signed-off-by: NStefan Hajnoczi <stefanha@redhat.com>

hw/virtio/virtio-rng.c

@@ -16,6 +16,7 @@
 #include "hw/virtio/virtio-rng.h"
 #include "sysemu/rng.h"
 #include "qom/object_interfaces.h"
+#include "trace.h"
 
 static bool is_guest_ready(VirtIORNG *vrng)
 {
@@ -24,6 +25,7 @@ static bool is_guest_ready(VirtIORNG *vrng)
         && (vdev->status & VIRTIO_CONFIG_S_DRIVER_OK)) {
         return true;
     }
+    trace_virtio_rng_guest_not_ready(vrng);
     return false;
 }
 
@@ -62,6 +64,7 @@ static void chr_read(void *opaque, const void *buf, size_t size)
         offset += len;
 
         virtqueue_push(vrng->vq, &elem, len);
+        trace_virtio_rng_pushed(vrng, len);
     }
     virtio_notify(vdev, vrng->vq);
 }
@@ -81,6 +84,9 @@ static void virtio_rng_process(VirtIORNG *vrng)
         quota = MIN((uint64_t)vrng->quota_remaining, (uint64_t)UINT32_MAX);
     }
     size = get_request_size(vrng->vq, quota);
+
+    trace_virtio_rng_request(vrng, size, quota);
+
     size = MIN(vrng->quota_remaining, size);
     if (size) {
         rng_backend_request_entropy(vrng->rng, size, chr_read, vrng);

trace-events

@@ -41,6 +41,11 @@ virtio_irq(void *vq) "vq %p"
 virtio_notify(void *vdev, void *vq) "vdev %p vq %p"
 virtio_set_status(void *vdev, uint8_t val) "vdev %p val %u"
 
+# hw/virtio/virtio-rng.c
+virtio_rng_guest_not_ready(void *rng) "rng %p: guest not ready"
+virtio_rng_pushed(void *rng, size_t len) "rng %p: %zd bytes pushed"
+virtio_rng_request(void *rng, size_t size, unsigned quota) "rng %p: %zd bytes requested, %u bytes quota left"
+
 # hw/char/virtio-serial-bus.c
 virtio_serial_send_control_event(unsigned int port, uint16_t event, uint16_t value) "port %u, event %u, value %u"
 virtio_serial_throttle_port(unsigned int port, bool throttle) "port %u, throttle %d"