lkml.org 
[lkml]   [2020]   [Jan]   [5]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
Patch in this message
/
Date
From
Subject[PATCH v2] virtio_net: CTRL_GUEST_OFFLOADS depends on CTRL_VQ
The only way for guest to control offloads (as enabled by
VIRTIO_NET_F_CTRL_GUEST_OFFLOADS) is by sending commands
through CTRL_VQ. So it does not make sense to
acknowledge VIRTIO_NET_F_CTRL_GUEST_OFFLOADS without
VIRTIO_NET_F_CTRL_VQ.

The spec does not outlaw devices with such a configuration, so we have
to support it. Simply clear VIRTIO_NET_F_CTRL_GUEST_OFFLOADS.
Note that Linux is still crashing if it tries to
change the offloads when there's no control vq.
That needs to be fixed by another patch.

Reported-by: Alistair Delva <adelva@google.com>
Reported-by: Willem de Bruijn <willemdebruijn.kernel@gmail.com>
Fixes: 3f93522ffab2 ("virtio-net: switch off offloads on demand if possible on XDP set")
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
---

Same patch as v1 but update documentation so it's clear it's not
enough to fix the crash.

drivers/net/virtio_net.c | 9 +++++++++
1 file changed, 9 insertions(+)

diff --git a/drivers/net/virtio_net.c b/drivers/net/virtio_net.c
index 4d7d5434cc5d..7b8805b47f0d 100644
--- a/drivers/net/virtio_net.c
+++ b/drivers/net/virtio_net.c
@@ -2971,6 +2971,15 @@ static int virtnet_validate(struct virtio_device *vdev)
if (!virtnet_validate_features(vdev))
return -EINVAL;

+ /* VIRTIO_NET_F_CTRL_GUEST_OFFLOADS does not work without
+ * VIRTIO_NET_F_CTRL_VQ. Unfortunately spec forgot to
+ * specify that VIRTIO_NET_F_CTRL_GUEST_OFFLOADS depends
+ * on VIRTIO_NET_F_CTRL_VQ so devices can set the later but
+ * not the former.
+ */
+ if (!virtio_has_feature(vdev, VIRTIO_NET_F_CTRL_VQ))
+ __virtio_clear_bit(vdev, VIRTIO_NET_F_CTRL_GUEST_OFFLOADS);
+
if (virtio_has_feature(vdev, VIRTIO_NET_F_MTU)) {
int mtu = virtio_cread16(vdev,
offsetof(struct virtio_net_config,
--
MST
\
 
 \ /
  Last update: 2020-01-05 14:23    [W:0.108 / U:0.100 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site