virtio attempts to clear the MTU feature bit if the value is out of the
supported range, but this has no real effect since FEATURES_OK has
already been set.
Fix this up by checking the MTU in the new validate callback.
Fixes: 14de9d114a82 ("virtio-net: Add initial MTU advice feature")
Signed-off-by: Michael S. Tsirkin <mst@xxxxxxxxxx>
---
drivers/net/virtio_net.c | 41 ++++++++++++++++++++++++++++++-----------
1 file changed, 30 insertions(+), 11 deletions(-)
diff --git a/drivers/net/virtio_net.c b/drivers/net/virtio_net.c
index f6a379d..6aba098 100644
--- a/drivers/net/virtio_net.c
+++ b/drivers/net/virtio_net.c
@@ -2312,14 +2312,8 @@ static bool virtnet_validate_features(struct virtio_device *vdev)
#define MIN_MTU ETH_MIN_MTU
#define MAX_MTU ETH_MAX_MTU
-static int virtnet_probe(struct virtio_device *vdev)
+static int virtnet_validate(struct virtio_device *vdev)
{
- int i, err;
- struct net_device *dev;
- struct virtnet_info *vi;
- u16 max_queue_pairs;
- int mtu;
-
if (!vdev->config->get) {
dev_err(&vdev->dev, "%s failure: config access disabled\n",
__func__);
@@ -2329,6 +2323,25 @@ static int virtnet_probe(struct virtio_device *vdev)
if (!virtnet_validate_features(vdev))
return -EINVAL;
+ if (virtio_has_feature(vdev, VIRTIO_NET_F_MTU)) {
+ int mtu = virtio_cread16(vdev,
+ offsetof(struct virtio_net_config,
+ mtu));
+ if (mtu < MIN_MTU)
+ __virtio_clear_bit(vdev, VIRTIO_NET_F_MTU);
+ }
+
+ return 0;
+}
+
+static int virtnet_probe(struct virtio_device *vdev)
+{
+ int i, err;
+ struct net_device *dev;
+ struct virtnet_info *vi;
+ u16 max_queue_pairs;
+ int mtu;
+
/* Find if host supports multiqueue virtio_net device */
err = virtio_cread_feature(vdev, VIRTIO_NET_F_MQ,
struct virtio_net_config,
@@ -2444,12 +2457,17 @@ static int virtnet_probe(struct virtio_device *vdev)
offsetof(struct virtio_net_config,
mtu));
if (mtu < dev->min_mtu) {
- __virtio_clear_bit(vdev, VIRTIO_NET_F_MTU);
- } else {
- dev->mtu = mtu;
- dev->max_mtu = mtu;
+ /* Should never trigger: MTU was previously validated
+ * in virtnet_validate.
+ */
+ dev_err(&vdev->dev, "device MTU appears to have changed "
+ "it is now %d < %d", mtu, dev->min_mtu);
+ goto free_stats;
}
+ dev->mtu = mtu;
+ dev->max_mtu = mtu;
+
/* TODO: size buffers correctly in this case. */
if (dev->mtu > ETH_DATA_LEN)
vi->big_packets = true;
@@ -2630,6 +2648,7 @@ static struct virtio_driver virtio_net_driver = {
.driver.name = KBUILD_MODNAME,
.driver.owner = THIS_MODULE,
.id_table = id_table,
+ .validate = virtnet_validate,
.probe = virtnet_probe,
.remove = virtnet_remove,
.config_changed = virtnet_config_changed,
--
MST
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