Re: [PATCH] virtio-net: drop legacy features in virtio 1 mode

Virtio 1.0 spec says VIRTIO_F_ANY_LAYOUT and VIRTIO_NET_F_GSO are
legacy-only feature bits. Do not negotiate them in virtio 1 mode.  Note
this is a spec violation so we need to backport it to stable/downstream
kernels.

Cc: stable@vger.kernel.org
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
---
  drivers/net/virtio_net.c | 30 ++++++++++++++++++++----------
  1 file changed, 20 insertions(+), 10 deletions(-)

diff --git a/drivers/net/virtio_net.c b/drivers/net/virtio_net.c
index 7a00365..b19fb4d 100644
--- a/drivers/net/virtio_net.c
+++ b/drivers/net/virtio_net.c

@@ -2089,23 +2089,33 @@ static struct virtio_device_id id_table[] = {
  	{ 0 },
  };
  
+#define VIRTNET_FEATURES \
+	VIRTIO_NET_F_CSUM, VIRTIO_NET_F_GUEST_CSUM, \
+	VIRTIO_NET_F_MAC, \
+	VIRTIO_NET_F_HOST_TSO4, VIRTIO_NET_F_HOST_UFO, VIRTIO_NET_F_HOST_TSO6, \
+	VIRTIO_NET_F_HOST_ECN, VIRTIO_NET_F_GUEST_TSO4, VIRTIO_NET_F_GUEST_TSO6, \
+	VIRTIO_NET_F_GUEST_ECN, VIRTIO_NET_F_GUEST_UFO, \
+	VIRTIO_NET_F_MRG_RXBUF, VIRTIO_NET_F_STATUS, VIRTIO_NET_F_CTRL_VQ, \
+	VIRTIO_NET_F_CTRL_RX, VIRTIO_NET_F_CTRL_VLAN, \
+	VIRTIO_NET_F_GUEST_ANNOUNCE, VIRTIO_NET_F_MQ, \
+	VIRTIO_NET_F_CTRL_MAC_ADDR, \
+	VIRTIO_NET_F_MTU
+
  static unsigned int features[] = {
-	VIRTIO_NET_F_CSUM, VIRTIO_NET_F_GUEST_CSUM,
-	VIRTIO_NET_F_GSO, VIRTIO_NET_F_MAC,
-	VIRTIO_NET_F_HOST_TSO4, VIRTIO_NET_F_HOST_UFO, VIRTIO_NET_F_HOST_TSO6,
-	VIRTIO_NET_F_HOST_ECN, VIRTIO_NET_F_GUEST_TSO4, VIRTIO_NET_F_GUEST_TSO6,
-	VIRTIO_NET_F_GUEST_ECN, VIRTIO_NET_F_GUEST_UFO,
-	VIRTIO_NET_F_MRG_RXBUF, VIRTIO_NET_F_STATUS, VIRTIO_NET_F_CTRL_VQ,
-	VIRTIO_NET_F_CTRL_RX, VIRTIO_NET_F_CTRL_VLAN,
-	VIRTIO_NET_F_GUEST_ANNOUNCE, VIRTIO_NET_F_MQ,
-	VIRTIO_NET_F_CTRL_MAC_ADDR,
+	VIRTNET_FEATURES,
+};
+
+static unsigned int features_legacy[] = {
+	VIRTNET_FEATURES,
+	VIRTIO_NET_F_GSO,
  	VIRTIO_F_ANY_LAYOUT,
-	VIRTIO_NET_F_MTU,
  };
  
  static struct virtio_driver virtio_net_driver = {
  	.feature_table = features,
  	.feature_table_size = ARRAY_SIZE(features),
+	.feature_table_legacy = features_legacy,
+	.feature_table_size_legacy = ARRAY_SIZE(features_legacy),
  	.driver.name =	KBUILD_MODNAME,
  	.driver.owner =	THIS_MODULE,
  	.id_table =	id_table,