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igb: add XDP support
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Add XDP support to the IGB driver.
The implementation follows the IXGBE XDP implementation
closely and I used the following patches as basis:

1. commit 9247080 ("ixgbe: add XDP support for pass and drop actions")
2. commit 33fdc82 ("ixgbe: add support for XDP_TX action")
3. commit ed93a39 ("ixgbe: tweak page counting for XDP_REDIRECT")

Due to the hardware constraints of the devices using the
IGB driver we must share the TX queues with XDP which
means locking the TX queue for XDP.

I ran tests on an older device to get better numbers.
Test machine:

Intel(R) Atom(TM) CPU C2338 @ 1.74GHz (2 Cores)
2x Intel I211

Routing Original Driver Network Stack: 382 Kpps

Routing XDP Redirect (xdp_fwd_kern): 1.48 Mpps
XDP Drop: 1.48 Mpps

Using XDP we can achieve line rate forwarding even on
an older Intel Atom CPU.

Signed-off-by: Sven Auhagen <sven.auhagen@voleatech.de>
Tested-by: Sandeep Penigalapati <sandeep.penigalapati@intel.com>
Signed-off-by: Tony Nguyen <anthony.l.nguyen@intel.com>
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svenauhagen authored and anguy11 committed Sep 28, 2020
1 parent bcbf1be commit 9cbc948
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Showing 3 changed files with 481 additions and 36 deletions.
80 changes: 74 additions & 6 deletions drivers/net/ethernet/intel/igb/igb.h
Original file line number Diff line number Diff line change
Expand Up @@ -19,6 +19,8 @@
#include <linux/pci.h>
#include <linux/mdio.h>

#include <net/xdp.h>

struct igb_adapter;

#define E1000_PCS_CFG_IGN_SD 1
Expand Down Expand Up @@ -79,6 +81,12 @@ struct igb_adapter;
#define IGB_I210_RX_LATENCY_100 2213
#define IGB_I210_RX_LATENCY_1000 448

/* XDP */
#define IGB_XDP_PASS 0
#define IGB_XDP_CONSUMED BIT(0)
#define IGB_XDP_TX BIT(1)
#define IGB_XDP_REDIR BIT(2)

struct vf_data_storage {
unsigned char vf_mac_addresses[ETH_ALEN];
u16 vf_mc_hashes[IGB_MAX_VF_MC_ENTRIES];
Expand Down Expand Up @@ -132,17 +140,62 @@ struct vf_mac_filter {

/* Supported Rx Buffer Sizes */
#define IGB_RXBUFFER_256 256
#define IGB_RXBUFFER_1536 1536
#define IGB_RXBUFFER_2048 2048
#define IGB_RXBUFFER_3072 3072
#define IGB_RX_HDR_LEN IGB_RXBUFFER_256
#define IGB_TS_HDR_LEN 16

#define IGB_SKB_PAD (NET_SKB_PAD + NET_IP_ALIGN)
/* Attempt to maximize the headroom available for incoming frames. We
* use a 2K buffer for receives and need 1536/1534 to store the data for
* the frame. This leaves us with 512 bytes of room. From that we need
* to deduct the space needed for the shared info and the padding needed
* to IP align the frame.
*
* Note: For cache line sizes 256 or larger this value is going to end
* up negative. In these cases we should fall back to the 3K
* buffers.
*/
#if (PAGE_SIZE < 8192)
#define IGB_MAX_FRAME_BUILD_SKB \
(SKB_WITH_OVERHEAD(IGB_RXBUFFER_2048) - IGB_SKB_PAD - IGB_TS_HDR_LEN)
#define IGB_MAX_FRAME_BUILD_SKB (IGB_RXBUFFER_1536 - NET_IP_ALIGN)
#define IGB_2K_TOO_SMALL_WITH_PADDING \
((NET_SKB_PAD + IGB_TS_HDR_LEN + IGB_RXBUFFER_1536) > SKB_WITH_OVERHEAD(IGB_RXBUFFER_2048))

static inline int igb_compute_pad(int rx_buf_len)
{
int page_size, pad_size;

page_size = ALIGN(rx_buf_len, PAGE_SIZE / 2);
pad_size = SKB_WITH_OVERHEAD(page_size) - rx_buf_len;

return pad_size;
}

static inline int igb_skb_pad(void)
{
int rx_buf_len;

/* If a 2K buffer cannot handle a standard Ethernet frame then
* optimize padding for a 3K buffer instead of a 1.5K buffer.
*
* For a 3K buffer we need to add enough padding to allow for
* tailroom due to NET_IP_ALIGN possibly shifting us out of
* cache-line alignment.
*/
if (IGB_2K_TOO_SMALL_WITH_PADDING)
rx_buf_len = IGB_RXBUFFER_3072 + SKB_DATA_ALIGN(NET_IP_ALIGN);
else
rx_buf_len = IGB_RXBUFFER_1536;

/* if needed make room for NET_IP_ALIGN */
rx_buf_len -= NET_IP_ALIGN;

return igb_compute_pad(rx_buf_len);
}

#define IGB_SKB_PAD igb_skb_pad()
#else
#define IGB_MAX_FRAME_BUILD_SKB (IGB_RXBUFFER_2048 - IGB_TS_HDR_LEN)
#define IGB_SKB_PAD (NET_SKB_PAD + NET_IP_ALIGN)
#endif

/* How many Rx Buffers do we bundle into one write to the hardware ? */
Expand Down Expand Up @@ -194,13 +247,22 @@ enum igb_tx_flags {
#define IGB_SFF_ADDRESSING_MODE 0x4
#define IGB_SFF_8472_UNSUP 0x00

enum igb_tx_buf_type {
IGB_TYPE_SKB = 0,
IGB_TYPE_XDP,
};

/* wrapper around a pointer to a socket buffer,
* so a DMA handle can be stored along with the buffer
*/
struct igb_tx_buffer {
union e1000_adv_tx_desc *next_to_watch;
unsigned long time_stamp;
struct sk_buff *skb;
enum igb_tx_buf_type type;
union {
struct sk_buff *skb;
struct xdp_frame *xdpf;
};
unsigned int bytecount;
u16 gso_segs;
__be16 protocol;
Expand Down Expand Up @@ -248,6 +310,7 @@ struct igb_ring_container {
struct igb_ring {
struct igb_q_vector *q_vector; /* backlink to q_vector */
struct net_device *netdev; /* back pointer to net_device */
struct bpf_prog *xdp_prog;
struct device *dev; /* device pointer for dma mapping */
union { /* array of buffer info structs */
struct igb_tx_buffer *tx_buffer_info;
Expand Down Expand Up @@ -288,6 +351,7 @@ struct igb_ring {
struct u64_stats_sync rx_syncp;
};
};
struct xdp_rxq_info xdp_rxq;
} ____cacheline_internodealigned_in_smp;

struct igb_q_vector {
Expand Down Expand Up @@ -339,7 +403,7 @@ static inline unsigned int igb_rx_bufsz(struct igb_ring *ring)
return IGB_RXBUFFER_3072;

if (ring_uses_build_skb(ring))
return IGB_MAX_FRAME_BUILD_SKB + IGB_TS_HDR_LEN;
return IGB_MAX_FRAME_BUILD_SKB;
#endif
return IGB_RXBUFFER_2048;
}
Expand Down Expand Up @@ -467,6 +531,7 @@ struct igb_adapter {
unsigned long active_vlans[BITS_TO_LONGS(VLAN_N_VID)];

struct net_device *netdev;
struct bpf_prog *xdp_prog;

unsigned long state;
unsigned int flags;
Expand Down Expand Up @@ -643,6 +708,9 @@ enum igb_boards {

extern char igb_driver_name[];

int igb_xmit_xdp_ring(struct igb_adapter *adapter,
struct igb_ring *ring,
struct xdp_frame *xdpf);
int igb_open(struct net_device *netdev);
int igb_close(struct net_device *netdev);
int igb_up(struct igb_adapter *);
Expand Down
4 changes: 4 additions & 0 deletions drivers/net/ethernet/intel/igb/igb_ethtool.c
Original file line number Diff line number Diff line change
Expand Up @@ -961,6 +961,10 @@ static int igb_set_ringparam(struct net_device *netdev,
memcpy(&temp_ring[i], adapter->rx_ring[i],
sizeof(struct igb_ring));

/* Clear copied XDP RX-queue info */
memset(&temp_ring[i].xdp_rxq, 0,
sizeof(temp_ring[i].xdp_rxq));

temp_ring[i].count = new_rx_count;
err = igb_setup_rx_resources(&temp_ring[i]);
if (err) {
Expand Down

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