From: Jason Wang <jasowang@redhat.com>
To: mst@redhat.com, jasowang@redhat.com, kvm@vger.kernel.org,
virtualization@lists.linux-foundation.org,
netdev@vger.kernel.org, linux-kernel@vger.kernel.org
Subject: [PATCH net V3 1/3] vhost: make sure used idx is seen before log in vhost_add_used_n()
Date: Thu, 13 Dec 2018 10:53:37 +0800 [thread overview]
Message-ID: <20181213025339.14023-2-jasowang@redhat.com> (raw)
In-Reply-To: <20181213025339.14023-1-jasowang@redhat.com>
We miss a write barrier that guarantees used idx is updated and seen
before log. This will let userspace sync and copy used ring before
used idx is update. Fix this by adding a barrier before log_write().
Fixes: 8dd014adfea6f ("vhost-net: mergeable buffers support")
Acked-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Jason Wang <jasowang@redhat.com>
---
drivers/vhost/vhost.c | 2 ++
1 file changed, 2 insertions(+)
diff --git a/drivers/vhost/vhost.c b/drivers/vhost/vhost.c
index 6b98d8e3a5bf..5915f240275a 100644
--- a/drivers/vhost/vhost.c
+++ b/drivers/vhost/vhost.c
@@ -2220,6 +2220,8 @@ int vhost_add_used_n(struct vhost_virtqueue *vq, struct vring_used_elem *heads,
return -EFAULT;
}
if (unlikely(vq->log_used)) {
+ /* Make sure used idx is seen before log. */
+ smp_wmb();
/* Log used index update. */
log_write(vq->log_base,
vq->log_addr + offsetof(struct vring_used, idx),
--
2.17.1
next prev parent reply other threads:[~2018-12-13 2:53 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-12-13 2:53 [PATCH net V3 0/3] Fix various issue of vhost Jason Wang
2018-12-13 2:53 ` Jason Wang [this message]
2018-12-13 2:53 ` [PATCH net V3 2/3] vhost_net: switch to use mutex_trylock() in vhost_net_busy_poll() Jason Wang
2018-12-13 2:53 ` [PATCH net V3 3/3] Revert "net: vhost: lock the vqs one by one" Jason Wang
2018-12-13 5:57 ` [PATCH net V3 0/3] Fix various issue of vhost David Miller
2018-12-13 14:32 ` Michael S. Tsirkin
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