Re: [PATCH net-next v2 6/9] net: use core MTU range checking in virt drivers

From: Michael S. Tsirkin
Date: Thu Oct 20 2016 - 16:25:15 EST


On Thu, Oct 20, 2016 at 01:55:21PM -0400, Jarod Wilson wrote:
> hyperv_net:
> - set min/max_mtu, per Haiyang, after rndis_filter_device_add
>
> virtio_net:
> - set min/max_mtu
> - remove virtnet_change_mtu
> vmxnet3:
> - set min/max_mtu
>
> xen-netback:
> - min_mtu = 0, max_mtu = 65517
>
> xen-netfront:
> - min_mtu = 0, max_mtu = 65535
>
> unisys/visor:
> - clean up defines a little to not clash with network core or add
> redundat definitions
>
> CC: netdev@xxxxxxxxxxxxxxx
> CC: virtualization@xxxxxxxxxxxxxxxxxxxxxxxxxx
> CC: "K. Y. Srinivasan" <kys@xxxxxxxxxxxxx>
> CC: Haiyang Zhang <haiyangz@xxxxxxxxxxxxx>
> CC: "Michael S. Tsirkin" <mst@xxxxxxxxxx>
> CC: Shrikrishna Khare <skhare@xxxxxxxxxx>
> CC: "VMware, Inc." <pv-drivers@xxxxxxxxxx>
> CC: Wei Liu <wei.liu2@xxxxxxxxxx>
> CC: Paul Durrant <paul.durrant@xxxxxxxxxx>
> CC: David Kershner <david.kershner@xxxxxxxxxx>
> Signed-off-by: Jarod Wilson <jarod@xxxxxxxxxx>
> ---
> drivers/net/hyperv/hyperv_net.h | 4 ++--
> drivers/net/hyperv/netvsc_drv.c | 14 +++++++-------
> drivers/net/virtio_net.c | 23 ++++++++++-------------
> drivers/net/vmxnet3/vmxnet3_drv.c | 7 ++++---
> drivers/net/xen-netback/interface.c | 5 ++++-
> drivers/net/xen-netfront.c | 2 ++
> drivers/staging/unisys/include/iochannel.h | 10 ++++------
> drivers/staging/unisys/visornic/visornic_main.c | 4 ++--
> 8 files changed, 35 insertions(+), 34 deletions(-)
>
> diff --git a/drivers/net/hyperv/hyperv_net.h b/drivers/net/hyperv/hyperv_net.h
> index f4fbcb5..3958ada 100644
> --- a/drivers/net/hyperv/hyperv_net.h
> +++ b/drivers/net/hyperv/hyperv_net.h
> @@ -606,8 +606,8 @@ struct nvsp_message {
> } __packed;
>
>
> -#define NETVSC_MTU 65536
> -#define NETVSC_MTU_MIN 68
> +#define NETVSC_MTU 65535
> +#define NETVSC_MTU_MIN ETH_MIN_MTU
>
> #define NETVSC_RECEIVE_BUFFER_SIZE (1024*1024*16) /* 16MB */
> #define NETVSC_RECEIVE_BUFFER_SIZE_LEGACY (1024*1024*15) /* 15MB */
> diff --git a/drivers/net/hyperv/netvsc_drv.c b/drivers/net/hyperv/netvsc_drv.c
> index f0919bd..3b28cf1 100644
> --- a/drivers/net/hyperv/netvsc_drv.c
> +++ b/drivers/net/hyperv/netvsc_drv.c
> @@ -872,19 +872,12 @@ static int netvsc_change_mtu(struct net_device *ndev, int mtu)
> struct netvsc_device *nvdev = ndevctx->nvdev;
> struct hv_device *hdev = ndevctx->device_ctx;
> struct netvsc_device_info device_info;
> - int limit = ETH_DATA_LEN;
> u32 num_chn;
> int ret = 0;
>
> if (ndevctx->start_remove || !nvdev || nvdev->destroy)
> return -ENODEV;
>
> - if (nvdev->nvsp_version >= NVSP_PROTOCOL_VERSION_2)
> - limit = NETVSC_MTU - ETH_HLEN;
> -
> - if (mtu < NETVSC_MTU_MIN || mtu > limit)
> - return -EINVAL;
> -
> ret = netvsc_close(ndev);
> if (ret)
> goto out;
> @@ -1402,6 +1395,13 @@ static int netvsc_probe(struct hv_device *dev,
> netif_set_real_num_tx_queues(net, nvdev->num_chn);
> netif_set_real_num_rx_queues(net, nvdev->num_chn);
>
> + /* MTU range: 68 - 1500 or 65521 */
> + net->min_mtu = NETVSC_MTU_MIN;
> + if (nvdev->nvsp_version >= NVSP_PROTOCOL_VERSION_2)
> + net->max_mtu = NETVSC_MTU - ETH_HLEN;
> + else
> + net->max_mtu = ETH_DATA_LEN;
> +
> ret = register_netdev(net);
> if (ret != 0) {
> pr_err("Unable to register netdev.\n");
> diff --git a/drivers/net/virtio_net.c b/drivers/net/virtio_net.c
> index fad84f3..720809f 100644
> --- a/drivers/net/virtio_net.c
> +++ b/drivers/net/virtio_net.c
> @@ -1419,17 +1419,6 @@ static const struct ethtool_ops virtnet_ethtool_ops = {
> .set_settings = virtnet_set_settings,
> };
>
> -#define MIN_MTU 68
> -#define MAX_MTU 65535
> -
> -static int virtnet_change_mtu(struct net_device *dev, int new_mtu)
> -{
> - if (new_mtu < MIN_MTU || new_mtu > MAX_MTU)
> - return -EINVAL;
> - dev->mtu = new_mtu;
> - return 0;
> -}
> -
> static const struct net_device_ops virtnet_netdev = {
> .ndo_open = virtnet_open,
> .ndo_stop = virtnet_close,
> @@ -1437,7 +1426,6 @@ static const struct net_device_ops virtnet_netdev = {
> .ndo_validate_addr = eth_validate_addr,
> .ndo_set_mac_address = virtnet_set_mac_address,
> .ndo_set_rx_mode = virtnet_set_rx_mode,
> - .ndo_change_mtu = virtnet_change_mtu,
> .ndo_get_stats64 = virtnet_stats,
> .ndo_vlan_rx_add_vid = virtnet_vlan_rx_add_vid,
> .ndo_vlan_rx_kill_vid = virtnet_vlan_rx_kill_vid,
> @@ -1748,6 +1736,9 @@ static bool virtnet_validate_features(struct virtio_device *vdev)
> return true;
> }
>
> +#define MIN_MTU ETH_MIN_MTU
> +#define MAX_MTU ETH_MAX_MTU
> +

Can we drop these btw?

> static int virtnet_probe(struct virtio_device *vdev)
> {
> int i, err;
> @@ -1821,6 +1812,10 @@ static int virtnet_probe(struct virtio_device *vdev)
>
> dev->vlan_features = dev->features;
>
> + /* MTU range: 68 - 65535 */
> + dev->min_mtu = MIN_MTU;
> + dev->max_mtu = MAX_MTU;
> +
> /* Configuration may specify what MAC to use. Otherwise random. */
> if (virtio_has_feature(vdev, VIRTIO_NET_F_MAC))
> virtio_cread_bytes(vdev,
> @@ -1875,8 +1870,10 @@ static int virtnet_probe(struct virtio_device *vdev)
> mtu = virtio_cread16(vdev,
> offsetof(struct virtio_net_config,
> mtu));
> - if (virtnet_change_mtu(dev, mtu))
> + if (mtu < dev->min_mtu || mtu > dev->max_mtu)

In fact the > max_mtu branch does not make sense since a 16 bit
value can't exceed MAX_MTU.

> __virtio_clear_bit(vdev, VIRTIO_NET_F_MTU);
> + else
> + dev->mtu = mtu;
> }
>
> if (vi->any_header_sg)
> diff --git a/drivers/net/vmxnet3/vmxnet3_drv.c b/drivers/net/vmxnet3/vmxnet3_drv.c
> index b5554f2..0c36de1 100644
> --- a/drivers/net/vmxnet3/vmxnet3_drv.c
> +++ b/drivers/net/vmxnet3/vmxnet3_drv.c
> @@ -2969,9 +2969,6 @@ vmxnet3_change_mtu(struct net_device *netdev, int new_mtu)
> struct vmxnet3_adapter *adapter = netdev_priv(netdev);
> int err = 0;
>
> - if (new_mtu < VMXNET3_MIN_MTU || new_mtu > VMXNET3_MAX_MTU)
> - return -EINVAL;
> -
> netdev->mtu = new_mtu;
>
> /*
> @@ -3428,6 +3425,10 @@ vmxnet3_probe_device(struct pci_dev *pdev,
> vmxnet3_set_ethtool_ops(netdev);
> netdev->watchdog_timeo = 5 * HZ;
>
> + /* MTU range: 60 - 9000 */
> + netdev->min_mtu = VMXNET3_MIN_MTU;
> + netdev->max_mtu = VMXNET3_MAX_MTU;
> +
> INIT_WORK(&adapter->work, vmxnet3_reset_work);
> set_bit(VMXNET3_STATE_BIT_QUIESCED, &adapter->state);
>
> diff --git a/drivers/net/xen-netback/interface.c b/drivers/net/xen-netback/interface.c
> index 74dc2bf..e30ffd2 100644
> --- a/drivers/net/xen-netback/interface.c
> +++ b/drivers/net/xen-netback/interface.c
> @@ -302,7 +302,7 @@ static int xenvif_close(struct net_device *dev)
> static int xenvif_change_mtu(struct net_device *dev, int mtu)
> {
> struct xenvif *vif = netdev_priv(dev);
> - int max = vif->can_sg ? 65535 - VLAN_ETH_HLEN : ETH_DATA_LEN;
> + int max = vif->can_sg ? ETH_MAX_MTU - VLAN_ETH_HLEN : ETH_DATA_LEN;
>
> if (mtu > max)
> return -EINVAL;
> @@ -471,6 +471,9 @@ struct xenvif *xenvif_alloc(struct device *parent, domid_t domid,
>
> dev->tx_queue_len = XENVIF_QUEUE_LENGTH;
>
> + dev->min_mtu = 0;
> + dev->max_mtu = ETH_MAX_MTU - VLAN_ETH_HLEN;
> +
> /*
> * Initialise a dummy MAC address. We choose the numerically
> * largest non-broadcast address to prevent the address getting
> diff --git a/drivers/net/xen-netfront.c b/drivers/net/xen-netfront.c
> index e17879d..7d616b0 100644
> --- a/drivers/net/xen-netfront.c
> +++ b/drivers/net/xen-netfront.c
> @@ -1329,6 +1329,8 @@ static struct net_device *xennet_create_dev(struct xenbus_device *dev)
> netdev->features |= netdev->hw_features;
>
> netdev->ethtool_ops = &xennet_ethtool_ops;
> + netdev->min_mtu = 0;
> + netdev->max_mtu = XEN_NETIF_MAX_TX_SIZE;
> SET_NETDEV_DEV(netdev, &dev->dev);
>
> np->netdev = netdev;
> diff --git a/drivers/staging/unisys/include/iochannel.h b/drivers/staging/unisys/include/iochannel.h
> index cba4433..9081b3f 100644
> --- a/drivers/staging/unisys/include/iochannel.h
> +++ b/drivers/staging/unisys/include/iochannel.h
> @@ -113,12 +113,10 @@ enum net_types {
>
> };
>
> -#define ETH_HEADER_SIZE 14 /* size of ethernet header */
> -
> #define ETH_MIN_DATA_SIZE 46 /* minimum eth data size */
> -#define ETH_MIN_PACKET_SIZE (ETH_HEADER_SIZE + ETH_MIN_DATA_SIZE)
> +#define ETH_MIN_PACKET_SIZE (ETH_HLEN + ETH_MIN_DATA_SIZE)
>
> -#define ETH_MAX_MTU 16384 /* maximum data size */
> +#define VISOR_ETH_MAX_MTU 16384 /* maximum data size */
>
> #ifndef MAX_MACADDR_LEN
> #define MAX_MACADDR_LEN 6 /* number of bytes in MAC address */
> @@ -288,7 +286,7 @@ struct net_pkt_xmt {
> int len; /* full length of data in the packet */
> int num_frags; /* number of fragments in frags containing data */
> struct phys_info frags[MAX_PHYS_INFO]; /* physical page information */
> - char ethhdr[ETH_HEADER_SIZE]; /* the ethernet header */
> + char ethhdr[ETH_HLEN]; /* the ethernet header */
> struct {
> /* these are needed for csum at uisnic end */
> u8 valid; /* 1 = struct is valid - else ignore */
> @@ -323,7 +321,7 @@ struct net_pkt_xmtdone {
> */
> #define RCVPOST_BUF_SIZE 4032
> #define MAX_NET_RCV_CHAIN \
> - ((ETH_MAX_MTU + ETH_HEADER_SIZE + RCVPOST_BUF_SIZE - 1) \
> + ((VISOR_ETH_MAX_MTU + ETH_HLEN + RCVPOST_BUF_SIZE - 1) \
> / RCVPOST_BUF_SIZE)
>
> struct net_pkt_rcvpost {
> diff --git a/drivers/staging/unisys/visornic/visornic_main.c b/drivers/staging/unisys/visornic/visornic_main.c
> index 1367007..f8a584b 100644
> --- a/drivers/staging/unisys/visornic/visornic_main.c
> +++ b/drivers/staging/unisys/visornic/visornic_main.c
> @@ -791,7 +791,7 @@ visornic_xmit(struct sk_buff *skb, struct net_device *netdev)
> * pointing to
> */
> firstfraglen = skb->len - skb->data_len;
> - if (firstfraglen < ETH_HEADER_SIZE) {
> + if (firstfraglen < ETH_HLEN) {
> spin_unlock_irqrestore(&devdata->priv_lock, flags);
> devdata->busy_cnt++;
> dev_err(&netdev->dev,
> @@ -864,7 +864,7 @@ visornic_xmit(struct sk_buff *skb, struct net_device *netdev)
> /* copy ethernet header from first frag into ocmdrsp
> * - everything else will be pass in frags & DMA'ed
> */
> - memcpy(cmdrsp->net.xmt.ethhdr, skb->data, ETH_HEADER_SIZE);
> + memcpy(cmdrsp->net.xmt.ethhdr, skb->data, ETH_HLEN);
> /* copy frags info - from skb->data we need to only provide access
> * beyond eth header
> */
> --
> 2.10.0