[PATCH] virtio-net: Remove more stack DMA

From: Andy Lutomirski
Date: Mon Jul 11 2016 - 17:31:08 EST


VLAN and MQ control was doing DMA from the stack. Fix it.

Cc: Michael S. Tsirkin <mst@xxxxxxxxxx>
Cc: "netdev@xxxxxxxxxxxxxxx" <netdev@xxxxxxxxxxxxxxx>
Signed-off-by: Andy Lutomirski <luto@xxxxxxxxxx>
---

I tested VLAN addition and removal with CONFIG_VMAP_STACK=y,
CONFIG_DEBUG_SG=y and it got rid of the warnings I saw. I haven't
tested the MQ part because I don't know how to enable it in the first
place (I'm guessing it needs me to enable some QEMU feature I don't
know about.)

Michael, can you double-check this? DaveM, is it okay for this to go
in via -tip?

drivers/net/virtio_net.c | 13 ++++++++-----
1 file changed, 8 insertions(+), 5 deletions(-)

diff --git a/drivers/net/virtio_net.c b/drivers/net/virtio_net.c
index e0638e556fe7..5044ca37d725 100644
--- a/drivers/net/virtio_net.c
+++ b/drivers/net/virtio_net.c
@@ -144,8 +144,10 @@ struct virtnet_info {
/* Control VQ buffers: protected by the rtnl lock */
struct virtio_net_ctrl_hdr ctrl_hdr;
virtio_net_ctrl_ack ctrl_status;
+ struct virtio_net_ctrl_mq ctrl_mq;
u8 ctrl_promisc;
u8 ctrl_allmulti;
+ u16 ctrl_vid;

/* Ethtool settings */
u8 duplex;
@@ -1116,14 +1118,13 @@ static void virtnet_ack_link_announce(struct virtnet_info *vi)
static int virtnet_set_queues(struct virtnet_info *vi, u16 queue_pairs)
{
struct scatterlist sg;
- struct virtio_net_ctrl_mq s;
struct net_device *dev = vi->dev;

if (!vi->has_cvq || !virtio_has_feature(vi->vdev, VIRTIO_NET_F_MQ))
return 0;

- s.virtqueue_pairs = cpu_to_virtio16(vi->vdev, queue_pairs);
- sg_init_one(&sg, &s, sizeof(s));
+ vi->ctrl_mq.virtqueue_pairs = cpu_to_virtio16(vi->vdev, queue_pairs);
+ sg_init_one(&sg, &vi->ctrl_mq, sizeof(vi->ctrl_mq));

if (!virtnet_send_command(vi, VIRTIO_NET_CTRL_MQ,
VIRTIO_NET_CTRL_MQ_VQ_PAIRS_SET, &sg)) {
@@ -1230,7 +1231,8 @@ static int virtnet_vlan_rx_add_vid(struct net_device *dev,
struct virtnet_info *vi = netdev_priv(dev);
struct scatterlist sg;

- sg_init_one(&sg, &vid, sizeof(vid));
+ vi->ctrl_vid = vid;
+ sg_init_one(&sg, &vi->ctrl_vid, sizeof(vi->ctrl_vid));

if (!virtnet_send_command(vi, VIRTIO_NET_CTRL_VLAN,
VIRTIO_NET_CTRL_VLAN_ADD, &sg))
@@ -1244,7 +1246,8 @@ static int virtnet_vlan_rx_kill_vid(struct net_device *dev,
struct virtnet_info *vi = netdev_priv(dev);
struct scatterlist sg;

- sg_init_one(&sg, &vid, sizeof(vid));
+ vi->ctrl_vid = vid;
+ sg_init_one(&sg, &vi->ctrl_vid, sizeof(vi->ctrl_vid));

if (!virtnet_send_command(vi, VIRTIO_NET_CTRL_VLAN,
VIRTIO_NET_CTRL_VLAN_DEL, &sg))
--
2.7.4