virtio: rng: add derating factor for use by hwrng core
The khwrngd thread is started when a hwrng device of sufficient
quality is registered. The virtio-rng device is backed by the
hypervisor, and we trust the hypervisor to provide real entropy.
A malicious or badly-implemented hypervisor is a scenario that's
irrelevant -- such a setup is bound to cause all sorts of badness, and a
compromised hwrng is the least of the user's worries.
Given this, we might as well assume that the quality of randomness we
receive is perfectly trustworthy. Hence, we use 100% for the factor,
indicating maximum confidence in the source.
Signed-off-by: Amit Shah <amit.shah@redhat.com>
Reviewed-by: H. Peter Anvin <hpa@linux.intel.com>
Reviewed-by: Amos Kong <akong@redhat.com>
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
diff --git a/drivers/char/hw_random/virtio-rng.c b/drivers/char/hw_random/virtio-rng.c
index 0027137..2e3139e 100644
--- a/drivers/char/hw_random/virtio-rng.c
+++ b/drivers/char/hw_random/virtio-rng.c
@@ -116,6 +116,7 @@
.cleanup = virtio_cleanup,
.priv = (unsigned long)vi,
.name = vi->name,
+ .quality = 1000,
};
vdev->priv = vi;