virtio-rng: trigger timer only when guest requests for entropy

This patch triggers timer only when guest requests for
entropy. As soon as first request from guest for entropy
comes we set the timer. Timer bumps up the quota value
when it gets triggered.

Signed-off-by: Pankaj Gupta <pagupta@redhat.com>
Reviewed-by: Amit Shah <amit.shah@redhat.com>
Message-Id: <1436962608-9961-2-git-send-email-pagupta@redhat.com>

[Re-worded patch subject, removed extra whitespace -- Amit]

Signed-off-by: Amit Shah <amit.shah@redhat.com>

diff --git a/hw/virtio/virtio-rng.c b/hw/virtio/virtio-rng.c
index 740ed3102bce1f83b6a0df823037a3a9a21e2209..6e5f02230141bd6228e91cb4bff478f78d279ccf 100644 (file)
--- a/hw/virtio/virtio-rng.c
+++ b/hw/virtio/virtio-rng.c
@@ -77,6 +77,12 @@ static void virtio_rng_process(VirtIORNG *vrng)
         return;
     }
 
+    if (vrng->activate_timer) {
+        timer_mod(vrng->rate_limit_timer,
+                  qemu_clock_get_ms(QEMU_CLOCK_VIRTUAL) + vrng->conf.period_ms);
+        vrng->activate_timer = false;
+    }
+
     if (vrng->quota_remaining < 0) {
         quota = 0;
     } else {
@@ -138,8 +144,7 @@ static void check_rate_limit(void *opaque)
 
     vrng->quota_remaining = vrng->conf.max_bytes;
     virtio_rng_process(vrng);
-    timer_mod(vrng->rate_limit_timer,
-                   qemu_clock_get_ms(QEMU_CLOCK_VIRTUAL) + vrng->conf.period_ms);
+    vrng->activate_timer = true;
 }
 
 static void virtio_rng_device_realize(DeviceState *dev, Error **errp)
@@ -195,13 +200,9 @@ static void virtio_rng_device_realize(DeviceState *dev, Error **errp)
 
     vrng->vq = virtio_add_queue(vdev, 8, handle_input);
     vrng->quota_remaining = vrng->conf.max_bytes;
-
     vrng->rate_limit_timer = timer_new_ms(QEMU_CLOCK_VIRTUAL,
                                                check_rate_limit, vrng);
-
-    timer_mod(vrng->rate_limit_timer,
-                   qemu_clock_get_ms(QEMU_CLOCK_VIRTUAL) + vrng->conf.period_ms);
-
+    vrng->activate_timer = true;
     register_savevm(dev, "virtio-rng", -1, 1, virtio_rng_save,
                     virtio_rng_load, vrng);
 }

diff --git a/include/hw/virtio/virtio-rng.h b/include/hw/virtio/virtio-rng.h
index 03164887335905d0ac03d3501daa0dd4deb57936..3f07de70c783e7c7de3aa7c4f1d9e4d53464e56a 100644 (file)
--- a/include/hw/virtio/virtio-rng.h
+++ b/include/hw/virtio/virtio-rng.h
@@ -44,6 +44,7 @@ typedef struct VirtIORNG {
      */
     QEMUTimer *rate_limit_timer;
     int64_t quota_remaining;
+    bool activate_timer;
 } VirtIORNG;
 
 #endif