The hwrng core asks for random data in the hwrng_register() call itself from commit d9e7972619. This doesn't play well with virtio -- the DRIVER_OK bit is only set by virtio core on a successful probe, and we're not yet out of our probe routine when this call is made. This causes the host to not acknowledge any requests we put in the virtqueue, and the insmod or kernel boot process just waits for data to arrive from the host, which never happens. The previous commit makes the hwrng core check for the HWRNG_NO_READ_AT_PROBE flag before reading from the device If the flag is set, the request for random data isn't made, and the stall when loading the module doesn't happen. [jac: reworked to use a flag instead of an init function. Reused most of Amit's commit message. ] CC: Kees Cook <keescook@xxxxxxxxxxxx> CC: Jason Cooper <jason@xxxxxxxxxxxxxx> CC: Herbert Xu <herbert@xxxxxxxxxxxxxxxxxxx> CC: <stable@xxxxxxxxxxxxxxx> # v3.15+ Signed-off-by: Amit Shah <amit.shah@xxxxxxxxxx> Signed-off-by: Jason Cooper <jason@xxxxxxxxxxxxxx> --- drivers/char/hw_random/virtio-rng.c | 1 + 1 file changed, 1 insertion(+) diff --git a/drivers/char/hw_random/virtio-rng.c b/drivers/char/hw_random/virtio-rng.c index f3e71501de54..f83433bb1fae 100644 --- a/drivers/char/hw_random/virtio-rng.c +++ b/drivers/char/hw_random/virtio-rng.c @@ -115,6 +115,7 @@ static int probe_common(struct virtio_device *vdev) .cleanup = virtio_cleanup, .priv = (unsigned long)vi, .name = vi->name, + .flags = HWRNG_NO_READ_AT_PROBE, }; vdev->priv = vi; -- 2.0.0 _______________________________________________ Virtualization mailing list Virtualization@xxxxxxxxxxxxxxxxxxxxxxxxxx https://lists.linuxfoundation.org/mailman/listinfo/virtualization
