Subject: Re: [net-next PATCH v2 5/6] i40e: Add TX and RX support in switchdev mode.

From: "Samudrala, Sridhar" <[email-masked]>
Date: Thu, 05 Jan 2017 16:27:13 -0800

On 1/5/2017 4:56 AM, Jiri Pirko wrote:
> Tue, Jan 03, 2017 at 07:07:53PM CET, [email-masked] wrote:
>> In switchdev mode, broadcast filter is not enabled on VFs. The broadcasts and
>> unknown frames from VFs are received by the PF and passed to corresponding VF
>> port representator netdev.
>> A host based switching entity like a linux bridge or OVS redirects these frames
>> to the right VFs via VFPR netdevs. Any frames sent via VFPR netdevs are sent as
>> directed transmits to the corresponding VFs. To enable directed transmit, skb
>> metadata dst is used to pass the VF id and the frame is requeued to call the PFs
>> transmit routine.
>>
>> Small script to demonstrate inter VF pings in switchdev mode.
>> PF: enp5s0f0, VFs: enp5s2,enp5s2f1 VFPRs:enp5s0f0-vf0, enp5s0f0-vf1
>>
>> # rmmod i40e; modprobe i40e
>> # devlink dev eswitch set pci/0000:05:00.0 mode switchdev
>> # echo 2 > /sys/class/net/enp5s0f0/device/sriov_numvfs
>> # ip link set enp5s0f0 vf 0 mac 00:11:22:33:44:55
>> # ip link set enp5s0f0 vf 1 mac 00:11:22:33:44:56
>> # rmmod i40evf; modprobe i40evf
>>
>> /* Create 2 namespaces and move the VFs to the corresponding ns. */
>> # ip netns add ns0
>> # ip link set enp5s2 netns ns0
>> # ip netns exec ns0 ip addr add 192.168.1.10/24 dev enp5s2
>> # ip netns exec ns0 ip link set enp5s2 up
>> # ip netns add ns1
>> # ip link set enp5s2f1 netns ns1
>> # ip netns exec ns1 ip addr add 192.168.1.11/24 dev enp5s2f1
>> # ip netns exec ns1 ip link set enp5s2f1 up
>>
>> /* bring up pf and vfpr netdevs */
>> # ip link set enp5s0f0 up
>> # ip link set enp5s0f0-vf0 up
>> # ip link set enp5s0f0-vf1 up
>>
>> /* Create a linux bridge and add vfpr netdevs to it. */
>> # ip link add vfpr-br type bridge
>> # ip link set enp5s0f0-vf0 master vfpr-br
>> # ip link set enp5s0f0-vf1 master vfpr-br
>> # ip addr add 192.168.1.1/24 dev vfpr-br
>> # ip link set vfpr-br up
>>
>> # ip netns exec ns0 ping -c3 192.168.1.11
>> # ip netns exec ns1 ping -c3 192.168.1.10
>>
>> Signed-off-by: Sridhar Samudrala <[email-masked]>
> [...]
>
>> diff --git a/drivers/net/ethernet/intel/i40e/i40e_txrx.c b/drivers/net/ethernet/intel/i40e/i40e_txrx.c
>> index 352cf7c..b46ddaa 100644
>> --- a/drivers/net/ethernet/intel/i40e/i40e_txrx.c
>> +++ b/drivers/net/ethernet/intel/i40e/i40e_txrx.c
>> @@ -1176,16 +1176,37 @@ static bool i40e_alloc_mapped_page(struct i40e_ring *rx_ring,
>>   * @rx_ring:  rx ring in play
>>   * @skb: packet to send up
>>   * @vlan_tag: vlan tag for packet
>> + * @lpbk: is it a loopback frame?
>>   **/
>> static void i40e_receive_skb(struct i40e_ring *rx_ring,
>> -			     struct sk_buff *skb, u16 vlan_tag)
>> +			     struct sk_buff *skb, u16 vlan_tag, bool lpbk)
>> {
>> 	struct i40e_q_vector *q_vector = rx_ring->q_vector;
>> +	struct i40e_pf *pf = rx_ring->vsi->back;
>> +	struct i40e_vf *vf;
>> +	struct ethhdr *eth;
>> +	int vf_id;
>>
>> 	if ((rx_ring->netdev->features & NETIF_F_HW_VLAN_CTAG_RX) &&
>> 	    (vlan_tag & VLAN_VID_MASK))
>> 		__vlan_hwaccel_put_tag(skb, htons(ETH_P_8021Q), vlan_tag);
>>
>> +	if ((pf->eswitch_mode == DEVLINK_ESWITCH_MODE_LEGACY) || !lpbk)
>> +		goto gro_receive;
>> +
>> +	/* If a loopback packet is received from a VF in switchdev mode, pass the
>> +	 * frame to the corresponding VFPR netdev based on the source MAC in the frame.
>> +	 */
>> +	eth = (struct ethhdr *)skb_mac_header(skb);
>> +	for (vf_id = 0; vf_id < pf->num_alloc_vfs; vf_id++) {
>> +		vf = &pf->vf[vf_id];
>> +		if (ether_addr_equal(eth->h_source, vf->default_lan_addr.addr)) {
>> +			skb->dev = vf->vfpr_netdev;
> This sucks :( Is't there any identification coming from rx ring that
> would tell you what vf this is? To match vrpr according to a single MAC
> address seems a bit awkward. What if there is a macvlan configured
> on the VF?
Unfortunately, with the current HW, RX descriptor only indicates if it 
is a loopback packet from a VF,
but not the specific id of the VF.
Multiple macs on VF are not supported with the current patchset.
At this point we are not making switchdev as the default mode because of 
these limitations.

>
>
>
>> +			break;
>> +		}
>> +	}
>> +
>> +gro_receive:
>> 	napi_gro_receive(&q_vector->napi, skb);
>> }
>>
> [...]
>
>> @@ -2998,3 +3064,19 @@ netdev_tx_t i40e_lan_xmit_frame(struct sk_buff *skb, struct net_device *netdev)
>>
>> 	return i40e_xmit_frame_ring(skb, tx_ring);
>> }
>> +
>> +netdev_tx_t i40e_vfpr_netdev_start_xmit(struct sk_buff *skb,
>> +				        struct net_device *dev)
>> +{
>> +	struct i40e_vfpr_netdev_priv *priv = netdev_priv(dev);
>> +	struct i40e_vf *vf = priv->vf;
>> +	struct i40e_pf *pf = vf->pf;
>> +	struct i40e_vsi *vsi = pf->vsi[pf->lan_vsi];
>> +
>> +	skb_dst_drop(skb);
>> +	dst_hold(&priv->vfpr_dst->dst);
>> +	skb_dst_set(skb, &priv->vfpr_dst->dst);
>> +	skb->dev = vsi->netdev;
> This dst dance seems a bit odd to me. Why don't you just call
> i40e_xmit_frame_ring with an extra arg holding the needed metadata?

We don't have TX/RX queues associated with VFPR netdevs, so we need to 
set the dev to PF netdev and requeue the skb.

>
>
>> +
>> +	return dev_queue_xmit(skb);
>> +}
>> diff --git a/drivers/net/ethernet/intel/i40e/i40e_txrx.h b/drivers/net/ethernet/intel/i40e/i40e_txrx.h
>> index e065321..850723f 100644
>> --- a/drivers/net/ethernet/intel/i40e/i40e_txrx.h
>> +++ b/drivers/net/ethernet/intel/i40e/i40e_txrx.h
>> @@ -366,6 +366,7 @@ struct i40e_ring_container {
>>
>> bool i40e_alloc_rx_buffers(struct i40e_ring *rxr, u16 cleaned_count);
>> netdev_tx_t i40e_lan_xmit_frame(struct sk_buff *skb, struct net_device *netdev);
>> +netdev_tx_t i40e_vfpr_netdev_start_xmit(struct sk_buff *skb, struct net_device *netdev);
>> void i40e_clean_tx_ring(struct i40e_ring *tx_ring);
>> void i40e_clean_rx_ring(struct i40e_ring *rx_ring);
>> int i40e_setup_tx_descriptors(struct i40e_ring *tx_ring);
>> diff --git a/drivers/net/ethernet/intel/i40e/i40e_type.h b/drivers/net/ethernet/intel/i40e/i40e_type.h
>> index edc0abd..c136cc9 100644
>> --- a/drivers/net/ethernet/intel/i40e/i40e_type.h
>> +++ b/drivers/net/ethernet/intel/i40e/i40e_type.h
>> @@ -728,6 +728,9 @@ enum i40e_rx_desc_status_bits {
>> #define I40E_RXD_QW1_STATUS_TSYNVALID_SHIFT  I40E_RX_DESC_STATUS_TSYNVALID_SHIFT
>> #define I40E_RXD_QW1_STATUS_TSYNVALID_MASK \
>> 				    BIT_ULL(I40E_RXD_QW1_STATUS_TSYNVALID_SHIFT)
>> +#define I40E_RXD_QW1_STATUS_LPBK_SHIFT  I40E_RX_DESC_STATUS_LPBK_SHIFT
>> +#define I40E_RXD_QW1_STATUS_LPBK_MASK \
>> +				BIT_ULL(I40E_RXD_QW1_STATUS_LPBK_SHIFT)
>>
>> enum i40e_rx_desc_fltstat_values {
>> 	I40E_RX_DESC_FLTSTAT_NO_DATA	= 0,
>> diff --git a/drivers/net/ethernet/intel/i40e/i40e_virtchnl_pf.c b/drivers/net/ethernet/intel/i40e/i40e_virtchnl_pf.c
>> index 0c8687d..f0860ef 100644
>> --- a/drivers/net/ethernet/intel/i40e/i40e_virtchnl_pf.c
>> +++ b/drivers/net/ethernet/intel/i40e/i40e_virtchnl_pf.c
>> @@ -1062,6 +1062,7 @@ static int i40e_vfpr_netdev_stop(struct net_device *dev)
>> static const struct net_device_ops i40e_vfpr_netdev_ops = {
>> 	.ndo_open       	= i40e_vfpr_netdev_open,
>> 	.ndo_stop       	= i40e_vfpr_netdev_stop,
>> +	.ndo_start_xmit		= i40e_vfpr_netdev_start_xmit,
>> };
>>
>> /**
>> @@ -1121,16 +1122,22 @@ int i40e_alloc_vfpr_netdev(struct i40e_vf *vf, u16 vf_num)
>>
>> 	priv = netdev_priv(vfpr_netdev);
>> 	priv->vf = &(pf->vf[vf_num]);
>> +	priv->vfpr_dst = metadata_dst_alloc(0, METADATA_HW_PORT_MUX, GFP_KERNEL);
> I'm missing a patch here. In net-next, metadata_dst_alloc has 2 args.

Somehow that patch didn't make it to netdev. You can find it here on 
intel-wired-lan archives.
http://lists.osuosl.org/pipermail/intel-wired-lan/Week-of-Mon-20170102/007723.html
I will CC you when i submit V3.