From: Maxime Coquelin Date: Wed, 19 Dec 2018 08:21:11 +0000 (+0100) Subject: vhost: enforce desc flags and content read ordering X-Git-Url: http://git.droids-corp.org/?a=commitdiff_plain;h=33e12d63d156b99aed2733e6aae97d53931e8e43;p=dpdk.git vhost: enforce desc flags and content read ordering A read barrier is required to ensure that the ordering between descriptor's flags and content reads is enforced. 1. read flags = desc->flags if (flags & AVAIL_BIT) 2. read desc->id There is a control dependency between steps 1 and step 2. 2 could be speculatively executed before 1, which could result in 'id' to not be updated yet. Fixes: 2f3225a7d69b ("vhost: add vector filling support for packed ring") Cc: stable@dpdk.org Reported-by: Jason Wang Signed-off-by: Maxime Coquelin Acked-by: Ilya Maximets Acked-by: Michael S. Tsirkin Acked-by: Tiwei Bie --- diff --git a/lib/librte_vhost/virtio_net.c b/lib/librte_vhost/virtio_net.c index 7f37bbbed6..a9b1bc55f6 100644 --- a/lib/librte_vhost/virtio_net.c +++ b/lib/librte_vhost/virtio_net.c @@ -481,6 +481,12 @@ fill_vec_buf_packed(struct virtio_net *dev, struct vhost_virtqueue *vq, if (unlikely(!desc_is_avail(&descs[avail_idx], wrap_counter))) return -1; + /* + * The ordering between desc flags and desc + * content reads need to be enforced. + */ + rte_smp_rmb(); + *desc_count = 0; *len = 0;