Re: [dpdk-dev] [PATCH v4 1/5] net/af_xdp: introduce AF XDP PMD driver

[Maxime Coquelin <maxime.coquelin@redhat.com>]

On 3/22/19 2:01 PM, Xiaolong Ye wrote:
> Add a new PMD driver for AF_XDP which is a proposed faster version of
> AF_PACKET interface in Linux. More info about AF_XDP, please refer to [1]
> [2].
> 
> This is the vanilla version PMD which just uses a raw buffer registered as
> the umem.
> 
> [1] https://fosdem.org/2018/schedule/event/af_xdp/
> [2] https://lwn.net/Articles/745934/
> 
> Signed-off-by: Xiaolong Ye <xiaolong.ye@intel.com>
> ---
>   MAINTAINERS                                   |   6 +
>   config/common_base                            |   5 +
>   config/common_linux                           |   1 +
>   doc/guides/nics/af_xdp.rst                    |  45 +
>   doc/guides/nics/features/af_xdp.ini           |  11 +
>   doc/guides/nics/index.rst                     |   1 +
>   doc/guides/rel_notes/release_19_05.rst        |   7 +
>   drivers/net/Makefile                          |   1 +
>   drivers/net/af_xdp/Makefile                   |  32 +
>   drivers/net/af_xdp/meson.build                |  21 +
>   drivers/net/af_xdp/rte_eth_af_xdp.c           | 940 ++++++++++++++++++
>   drivers/net/af_xdp/rte_pmd_af_xdp_version.map |   3 +
>   drivers/net/meson.build                       |   1 +
>   mk/rte.app.mk                                 |   1 +
>   14 files changed, 1075 insertions(+)
>   create mode 100644 doc/guides/nics/af_xdp.rst
>   create mode 100644 doc/guides/nics/features/af_xdp.ini
>   create mode 100644 drivers/net/af_xdp/Makefile
>   create mode 100644 drivers/net/af_xdp/meson.build
>   create mode 100644 drivers/net/af_xdp/rte_eth_af_xdp.c
>   create mode 100644 drivers/net/af_xdp/rte_pmd_af_xdp_version.map
> 

...

> diff --git a/config/common_base b/config/common_base
> index 0b09a9348..4044de205 100644
> --- a/config/common_base
> +++ b/config/common_base
> @@ -416,6 +416,11 @@ CONFIG_RTE_LIBRTE_VMXNET3_DEBUG_TX_FREE=n
>   #
>   CONFIG_RTE_LIBRTE_PMD_AF_PACKET=n
>   
> +#
> +# Compile software PMD backed by AF_XDP sockets (Linux only)
> +#
> +CONFIG_RTE_LIBRTE_PMD_AF_XDP=n
> +
>   #
>   # Compile link bonding PMD library
>   #
> diff --git a/config/common_linux b/config/common_linux
> index 75334273d..0b1249da0 100644
> --- a/config/common_linux
> +++ b/config/common_linux
> @@ -19,6 +19,7 @@ CONFIG_RTE_LIBRTE_VHOST_POSTCOPY=n
>   CONFIG_RTE_LIBRTE_PMD_VHOST=y
>   CONFIG_RTE_LIBRTE_IFC_PMD=y
>   CONFIG_RTE_LIBRTE_PMD_AF_PACKET=y
> +CONFIG_RTE_LIBRTE_PMD_AF_XDP=y

It has to be disabled by default as it requires headers from kernels
more recent than minimum kernel version supported by DPDK.

>   CONFIG_RTE_LIBRTE_PMD_SOFTNIC=y
>   CONFIG_RTE_LIBRTE_PMD_TAP=y
>   CONFIG_RTE_LIBRTE_AVP_PMD=y

...

> diff --git a/drivers/net/af_xdp/meson.build b/drivers/net/af_xdp/meson.build
> new file mode 100644
> index 000000000..635e67483
> --- /dev/null
> +++ b/drivers/net/af_xdp/meson.build
> @@ -0,0 +1,21 @@
> +# SPDX-License-Identifier: BSD-3-Clause
> +# Copyright(c) 2018 Intel Corporation
> +
> +if host_machine.system() != 'linux'
> +	build = false
> +endif
> +
> +bpf_dep = dependency('libbpf', required: false)
> +if bpf_dep.found()
> +	build = true
> +else
> +	bpf_dep = cc.find_library('libbpf', required: false)
> +	if bpf_dep.found() and cc.has_header('xsk.h', dependencies: bpf_dep)
> +		build = true
> +		pkgconfig_extra_libs += '-lbpf'
> +	else
> +		build = false
> +	endif
> +endif

I think you need to add more checks, as above does not cover
linux/if_xdp.h header IIUC.

> +sources = files('rte_eth_af_xdp.c')
> +ext_deps += bpf_dep
> diff --git a/drivers/net/af_xdp/rte_eth_af_xdp.c b/drivers/net/af_xdp/rte_eth_af_xdp.c
> new file mode 100644
> index 000000000..9f0012347
> --- /dev/null
> +++ b/drivers/net/af_xdp/rte_eth_af_xdp.c
> @@ -0,0 +1,940 @@
> +/* SPDX-License-Identifier: BSD-3-Clause
> + * Copyright(c) 2019 Intel Corporation.
> + */
> +
> +#include <rte_mbuf.h>
> +#include <rte_ethdev_driver.h>
> +#include <rte_ethdev_vdev.h>
> +#include <rte_malloc.h>
> +#include <rte_kvargs.h>
> +#include <rte_bus_vdev.h>
> +#include <rte_string_fns.h>
> +
> +#include <linux/if_ether.h>
> +#include <linux/if_xdp.h>
> +#include <linux/if_link.h>
> +#include <asm/barrier.h>
> +#include <arpa/inet.h>
> +#include <net/if.h>
> +#include <sys/types.h>
> +#include <sys/socket.h>
> +#include <sys/ioctl.h>
> +#include <sys/mman.h>
> +#include <unistd.h>
> +#include <poll.h>
> +#include <bpf/bpf.h>
> +#include <xsk.h>
> +
> +#ifndef SOL_XDP
> +#define SOL_XDP 283
> +#endif
> +
> +#ifndef AF_XDP
> +#define AF_XDP 44
> +#endif
> +
> +#ifndef PF_XDP
> +#define PF_XDP AF_XDP
> +#endif
> +
> +static int af_xdp_logtype;
> +
> +#define AF_XDP_LOG(level, fmt, args...)			\
> +	rte_log(RTE_LOG_ ## level, af_xdp_logtype,	\
> +		"%s(): " fmt "\n", __func__, ##args)
> +
> +#define ETH_AF_XDP_IFACE_ARG			"iface"
> +#define ETH_AF_XDP_QUEUE_IDX_ARG		"queue"
> +
> +#define ETH_AF_XDP_FRAME_SIZE		XSK_UMEM__DEFAULT_FRAME_SIZE
> +#define ETH_AF_XDP_NUM_BUFFERS		4096
> +#define ETH_AF_XDP_DATA_HEADROOM	0
> +#define ETH_AF_XDP_DFLT_NUM_DESCS	XSK_RING_CONS__DEFAULT_NUM_DESCS
> +#define ETH_AF_XDP_DFLT_QUEUE_IDX	0
> +
> +#define ETH_AF_XDP_RX_BATCH_SIZE	32
> +#define ETH_AF_XDP_TX_BATCH_SIZE	32
> +
> +#define ETH_AF_XDP_MAX_QUEUE_PAIRS     16
> +
> +struct xsk_umem_info {
> +	struct xsk_ring_prod fq;
> +	struct xsk_ring_cons cq;
> +	struct xsk_umem *umem;
> +	struct rte_ring *buf_ring;
> +	void *buffer;
> +};
> +
> +struct rx_stats {
> +	uint64_t rx_pkts;
> +	uint64_t rx_bytes;
> +	uint64_t rx_dropped;
> +};
> +
> +struct pkt_rx_queue {
> +	struct xsk_ring_cons rx;
> +	struct xsk_umem_info *umem;
> +	struct xsk_socket *xsk;
> +	struct rte_mempool *mb_pool;
> +
> +	struct rx_stats stats;
> +
> +	struct pkt_tx_queue *pair;
> +	uint16_t queue_idx;
> +};
> +
> +struct tx_stats {
> +	uint64_t tx_pkts;
> +	uint64_t err_pkts;
> +	uint64_t tx_bytes;
> +};
> +
> +struct pkt_tx_queue {
> +	struct xsk_ring_prod tx;
> +
> +	struct tx_stats stats;
> +
> +	struct pkt_rx_queue *pair;
> +	uint16_t queue_idx;
> +};
> +
> +struct pmd_internals {
> +	int if_index;
> +	char if_name[IFNAMSIZ];
> +	uint16_t queue_idx;
> +	struct ether_addr eth_addr;
> +	struct xsk_umem_info *umem;
> +	struct rte_mempool *mb_pool_share;
> +
> +	struct pkt_rx_queue rx_queues[ETH_AF_XDP_MAX_QUEUE_PAIRS];
> +	struct pkt_tx_queue tx_queues[ETH_AF_XDP_MAX_QUEUE_PAIRS];
> +};
> +
> +static const char * const valid_arguments[] = {
> +	ETH_AF_XDP_IFACE_ARG,
> +	ETH_AF_XDP_QUEUE_IDX_ARG,
> +	NULL
> +};
> +
> +static struct rte_eth_link pmd_link = {
> +	.link_speed = ETH_SPEED_NUM_10G,
> +	.link_duplex = ETH_LINK_FULL_DUPLEX,
> +	.link_status = ETH_LINK_DOWN,
> +	.link_autoneg = ETH_LINK_AUTONEG
> +};
> +
> +static inline int
> +reserve_fill_queue(struct xsk_umem_info *umem, int reserve_size)
> +{
> +	struct xsk_ring_prod *fq = &umem->fq;
> +	uint32_t idx;
> +	void *addr = NULL;
> +	int i, ret;
> +
> +	ret = xsk_ring_prod__reserve(fq, reserve_size, &idx);
> +	if (!ret) {

You could use unlikely() here as it is called in the hot path.

> +		AF_XDP_LOG(ERR, "Failed to reserve enough fq descs.\n");
> +		return ret;
> +	}
> +
> +	for (i = 0; i < reserve_size; i++) {
> +		__u64 *fq_addr;

For consistency, you could either declare addr here, or fq_addr at the
top of the function.

> +		if (rte_ring_dequeue(umem->buf_ring, &addr)) {
> +			i--;
> +			break;
> +		}
> +		fq_addr = xsk_ring_prod__fill_addr(fq, idx++);
> +		*fq_addr = (uint64_t)addr;
> +	}
> +
> +	xsk_ring_prod__submit(fq, i);
> +
> +	return 0;
> +}
> +
> +static uint16_t
> +eth_af_xdp_rx(void *queue, struct rte_mbuf **bufs, uint16_t nb_pkts)
> +{
> +	struct pkt_rx_queue *rxq = queue;
> +	struct xsk_ring_cons *rx = &rxq->rx;
> +	struct xsk_umem_info *umem = rxq->umem;
> +	struct xsk_ring_prod *fq = &umem->fq;
> +	uint32_t idx_rx;
> +	uint32_t free_thresh = fq->size >> 1;
> +	struct rte_mbuf *mbufs[ETH_AF_XDP_TX_BATCH_SIZE];
> +	unsigned long dropped = 0;
> +	unsigned long rx_bytes = 0;
> +	uint16_t count = 0;
> +	int rcvd, i;
> +
> +	nb_pkts = RTE_MIN(nb_pkts, ETH_AF_XDP_TX_BATCH_SIZE);
> +
> +	rcvd = xsk_ring_cons__peek(rx, nb_pkts, &idx_rx);
> +	if (rcvd == 0)
> +		return 0;
> +
> +	if (xsk_prod_nb_free(fq, free_thresh) >= free_thresh)
> +		(void)reserve_fill_queue(umem, ETH_AF_XDP_RX_BATCH_SIZE);
> +
> +	if (rte_pktmbuf_alloc_bulk(rxq->mb_pool, mbufs, rcvd) != 0)
unlikely()?
> +		return 0;
> +
> +	for (i = 0; i < rcvd; i++) {
> +		const struct xdp_desc *desc;
> +		uint64_t addr;
> +		uint32_t len;
> +		void *pkt;
> +
> +		desc = xsk_ring_cons__rx_desc(rx, idx_rx++);
> +		addr = desc->addr;
> +		len = desc->len;
> +		pkt = xsk_umem__get_data(rxq->umem->buffer, addr);
> +
> +		rte_memcpy(rte_pktmbuf_mtod(mbufs[i], void *), pkt, len);
> +		rte_pktmbuf_pkt_len(mbufs[i]) = len;
> +		rte_pktmbuf_data_len(mbufs[i]) = len;
> +		rx_bytes += len;
> +		bufs[count++] = mbufs[i];
> +
> +		rte_ring_enqueue(umem->buf_ring, (void *)addr);
> +	}
> +
> +	xsk_ring_cons__release(rx, rcvd);
> +
> +	/* statistics */
> +	rxq->stats.rx_pkts += (rcvd - dropped);
> +	rxq->stats.rx_bytes += rx_bytes;
> +
> +	return count;
> +}
> +

...

> +
> +/* This function gets called when the current port gets stopped. */
> +static void
> +eth_dev_stop(struct rte_eth_dev *dev)
> +{
> +	dev->data->dev_link.link_status = ETH_LINK_DOWN;
> +}
> +
> +static int
> +eth_dev_configure(struct rte_eth_dev *dev __rte_unused)

Remove __rte_unused.

> +{
> +	/* rx/tx must be paired */
> +	if (dev->data->nb_rx_queues != dev->data->nb_tx_queues)
> +		return -EINVAL;
> +
> +	return 0;
> +}
> +

...

> +
> +static int
> +xsk_configure(struct pmd_internals *internals, struct pkt_rx_queue *rxq,
> +	      int ring_size)
> +{
> +	struct xsk_socket_config cfg;
> +	struct pkt_tx_queue *txq = rxq->pair;
> +	int ret = 0;
> +	int reserve_size;
> +
> +	rxq->umem = xdp_umem_configure();
> +	if (rxq->umem == NULL) {
> +		ret = -ENOMEM;
> +		goto err;
You can return directly here as umem == NULL.

> +	}
> +
> +	cfg.rx_size = ring_size;
> +	cfg.tx_size = ring_size;
> +	cfg.libbpf_flags = 0;
> +	cfg.xdp_flags = XDP_FLAGS_UPDATE_IF_NOEXIST;
> +	cfg.bind_flags = 0;
> +	ret = xsk_socket__create(&rxq->xsk, internals->if_name,
> +			internals->queue_idx, rxq->umem->umem, &rxq->rx,
> +			&txq->tx, &cfg);
> +	if (ret) {
> +		AF_XDP_LOG(ERR, "Failed to create xsk socket.\n");
> +		goto err;
> +	}
> +
> +	reserve_size = ETH_AF_XDP_DFLT_NUM_DESCS / 2;
> +	ret = reserve_fill_queue(rxq->umem, reserve_size);
> +	if (ret) {
> +		AF_XDP_LOG(ERR, "Failed to reserve fill queue.\n");
> +		goto err;

Shouldn't you call xsk_socket__delete(rxq->xsk) here?

> +	}
> +
> +	return 0;
> +
> +err:
> +	xdp_umem_destroy(rxq->umem);
> +
> +	return ret;
> +}
> +
> +static void
> +queue_reset(struct pmd_internals *internals, uint16_t queue_idx)
> +{
> +	struct pkt_rx_queue *rxq = &internals->rx_queues[queue_idx];
> +	struct pkt_tx_queue *txq = rxq->pair;
> +	int xsk_fd = xsk_socket__fd(rxq->xsk);
> +
> +	if (xsk_fd) {
> +		close(xsk_fd);
> +		if (internals->umem != NULL) {

Moving this condition out would work and be cleaner.

Anyway, it seems to never enter this condition as internal->umem is not
set yet when queue_reset() is called.

> +			xdp_umem_destroy(internals->umem);
> +			internals->umem = NULL;
> +		}
> +	}
> +	memset(rxq, 0, sizeof(*rxq));
> +	memset(txq, 0, sizeof(*txq));
> +	rxq->pair = txq;
> +	txq->pair = rxq;
> +	rxq->queue_idx = queue_idx;
> +	txq->queue_idx = queue_idx;
> +}
> +
> +static int
> +eth_rx_queue_setup(struct rte_eth_dev *dev,
> +		   uint16_t rx_queue_id,
> +		   uint16_t nb_rx_desc,
> +		   unsigned int socket_id __rte_unused,
> +		   const struct rte_eth_rxconf *rx_conf __rte_unused,
> +		   struct rte_mempool *mb_pool)
> +{
> +	struct pmd_internals *internals = dev->data->dev_private;
> +	uint32_t buf_size, data_size;
> +	struct pkt_rx_queue *rxq;
> +	int ret;
> +
> +	rxq = &internals->rx_queues[rx_queue_id];
> +	queue_reset(internals, rx_queue_id);
> +
> +	/* Now get the space available for data in the mbuf */
> +	buf_size = rte_pktmbuf_data_room_size(mb_pool) -
> +		RTE_PKTMBUF_HEADROOM;
> +	data_size = ETH_AF_XDP_FRAME_SIZE - ETH_AF_XDP_DATA_HEADROOM;
> +
> +	if (data_size > buf_size) {
> +		AF_XDP_LOG(ERR, "%s: %d bytes will not fit in mbuf (%d bytes)\n",
> +			dev->device->name, data_size, buf_size);
> +		ret = -ENOMEM;
> +		goto err;
> +	}
> +
> +	rxq->mb_pool = mb_pool;
> +
> +	if (xsk_configure(internals, rxq, nb_rx_desc)) {
> +		AF_XDP_LOG(ERR, "Failed to configure xdp socket\n");
> +		ret = -EINVAL;
> +		goto err;
> +	}
> +
> +	internals->umem = rxq->umem;

If my previous comment is wrong, i.e. internals->umem may be already set
when queue_reset() is called, then it means you might have a leak here.

> +
> +	dev->data->rx_queues[rx_queue_id] = rxq;
> +	return 0;
> +
> +err:
> +	queue_reset(internals, rx_queue_id);
> +	return ret;
> +}
> +