diff mbox series

[v2] net/af_xdp: re-enable secondary process support

Message ID 20220204125436.30397-1-ciara.loftus@intel.com (mailing list archive)
State Superseded, archived
Delegated to: Ferruh Yigit
Headers show
Series [v2] net/af_xdp: re-enable secondary process support | expand

Checks

Context Check Description
ci/intel-Testing success Testing PASS
ci/Intel-compilation success Compilation OK
ci/iol-testing warning apply patch failure
ci/checkpatch success coding style OK

Commit Message

Ciara Loftus Feb. 4, 2022, 12:54 p.m. UTC
Secondary process support had been disabled for the AF_XDP PMD
because there was no logic in place to share the AF_XDP socket
file descriptors between the processes. This commit introduces
this logic using the IPC APIs.

Since AF_XDP rings are single-producer single-consumer, rx/tx
in the secondary process is disabled. However other operations
including retrieval of stats are permitted.

Signed-off-by: Ciara Loftus <ciara.loftus@intel.com>

---
v1 -> v2:
* Rebase to next-net

RFC -> v1:
* Added newline to af_xdp.rst
* Fixed spelling errors
* Fixed potential NULL dereference in init_internals
* Fixed potential free of address-of expression in afxdp_mp_request_fds
---
 doc/guides/nics/af_xdp.rst             |   9 ++
 doc/guides/nics/features/af_xdp.ini    |   1 +
 doc/guides/rel_notes/release_22_03.rst |   1 +
 drivers/net/af_xdp/rte_eth_af_xdp.c    | 210 +++++++++++++++++++++++--
 4 files changed, 207 insertions(+), 14 deletions(-)

Comments

Ferruh Yigit Feb. 4, 2022, 2:18 p.m. UTC | #1
On 2/4/2022 12:54 PM, Ciara Loftus wrote:
> Secondary process support had been disabled for the AF_XDP PMD
> because there was no logic in place to share the AF_XDP socket
> file descriptors between the processes. This commit introduces
> this logic using the IPC APIs.
> 
> Since AF_XDP rings are single-producer single-consumer, rx/tx
> in the secondary process is disabled. However other operations
> including retrieval of stats are permitted.
> 
> Signed-off-by: Ciara Loftus <ciara.loftus@intel.com>
> 
> ---
> v1 -> v2:
> * Rebase to next-net
> 
> RFC -> v1:
> * Added newline to af_xdp.rst
> * Fixed spelling errors
> * Fixed potential NULL dereference in init_internals
> * Fixed potential free of address-of expression in afxdp_mp_request_fds
> ---
>   doc/guides/nics/af_xdp.rst             |   9 ++
>   doc/guides/nics/features/af_xdp.ini    |   1 +
>   doc/guides/rel_notes/release_22_03.rst |   1 +
>   drivers/net/af_xdp/rte_eth_af_xdp.c    | 210 +++++++++++++++++++++++--
>   4 files changed, 207 insertions(+), 14 deletions(-)
> 
> diff --git a/doc/guides/nics/af_xdp.rst b/doc/guides/nics/af_xdp.rst
> index db02ea1984..eb4eab28a8 100644
> --- a/doc/guides/nics/af_xdp.rst
> +++ b/doc/guides/nics/af_xdp.rst
> @@ -141,4 +141,13 @@ Limitations
>     NAPI context from a watchdog timer instead of from softirqs. More information
>     on this feature can be found at [1].
>   
> +- **Secondary Processes**
> +
> +  Rx and Tx are not supported for secondary processes due to the single-producer
> +  single-consumer nature of the AF_XDP rings. However other operations including
> +  statistics retrieval are permitted.

Hi Ciara,

Isn't this limitation same for all PMDs, like not both primary & secondary can Rx/Tx
from same queue at the same time.
But primary can initiallize the PMD and secondary can do the datapath,
or isn't af_xdp supports multiple queue, if so some queues can be used by
primary and some by secondary for datapath.

Is there anyhing special for af_xdp that prevents it?

> +  The maximum number of queues permitted for PMDs operating in this model is 8
> +  as this is the maximum number of fds that can be sent through the IPC APIs as
> +  defined by RTE_MP_MAX_FD_NUM.
> +
>     [1] https://lwn.net/Articles/837010/
> diff --git a/doc/guides/nics/features/af_xdp.ini b/doc/guides/nics/features/af_xdp.ini
> index 54b738e616..8e7e075aaf 100644
> --- a/doc/guides/nics/features/af_xdp.ini
> +++ b/doc/guides/nics/features/af_xdp.ini
> @@ -9,4 +9,5 @@ Power mgmt address monitor = Y
>   MTU update           = Y
>   Promiscuous mode     = Y
>   Stats per queue      = Y
> +Multiprocess aware   = Y
>   x86-64               = Y
> diff --git a/doc/guides/rel_notes/release_22_03.rst b/doc/guides/rel_notes/release_22_03.rst
> index bf2e3f78a9..dfd2cbbccf 100644
> --- a/doc/guides/rel_notes/release_22_03.rst
> +++ b/doc/guides/rel_notes/release_22_03.rst
> @@ -58,6 +58,7 @@ New Features
>   * **Updated AF_XDP PMD**
>   
>     * Added support for libxdp >=v1.2.2.
> +  * Re-enabled secondary process support. RX/TX is not supported.
>   
>   * **Updated Cisco enic driver.**
>   
> diff --git a/drivers/net/af_xdp/rte_eth_af_xdp.c b/drivers/net/af_xdp/rte_eth_af_xdp.c
> index 1b6192fa44..407f6d8dbe 100644
> --- a/drivers/net/af_xdp/rte_eth_af_xdp.c
> +++ b/drivers/net/af_xdp/rte_eth_af_xdp.c
> @@ -80,6 +80,18 @@ RTE_LOG_REGISTER_DEFAULT(af_xdp_logtype, NOTICE);
>   
>   #define ETH_AF_XDP_ETH_OVERHEAD		(RTE_ETHER_HDR_LEN + RTE_ETHER_CRC_LEN)
>   
> +#define ETH_AF_XDP_MP_KEY "afxdp_mp_send_fds"
> +
> +static int afxdp_dev_count;
> +
> +/* Message header to synchronize fds via IPC */
> +struct ipc_hdr {
> +	char port_name[RTE_DEV_NAME_MAX_LEN];
> +	/* The file descriptors are in the dedicated part
> +	 * of the Unix message to be translated by the kernel.
> +	 */
> +};
> +
>   struct xsk_umem_info {
>   	struct xsk_umem *umem;
>   	struct rte_ring *buf_ring;
> @@ -147,6 +159,10 @@ struct pmd_internals {
>   	struct pkt_tx_queue *tx_queues;
>   };
>   
> +struct pmd_process_private {
> +	int rxq_xsk_fds[RTE_MAX_QUEUES_PER_PORT];
> +};
> +
>   #define ETH_AF_XDP_IFACE_ARG			"iface"
>   #define ETH_AF_XDP_START_QUEUE_ARG		"start_queue"
>   #define ETH_AF_XDP_QUEUE_COUNT_ARG		"queue_count"
> @@ -795,11 +811,12 @@ static int
>   eth_stats_get(struct rte_eth_dev *dev, struct rte_eth_stats *stats)
>   {
>   	struct pmd_internals *internals = dev->data->dev_private;
> +	struct pmd_process_private *process_private = dev->process_private;
>   	struct xdp_statistics xdp_stats;
>   	struct pkt_rx_queue *rxq;
>   	struct pkt_tx_queue *txq;
>   	socklen_t optlen;
> -	int i, ret;
> +	int i, ret, fd;
>   
>   	for (i = 0; i < dev->data->nb_rx_queues; i++) {
>   		optlen = sizeof(struct xdp_statistics);
> @@ -815,8 +832,9 @@ eth_stats_get(struct rte_eth_dev *dev, struct rte_eth_stats *stats)
>   		stats->ibytes += stats->q_ibytes[i];
>   		stats->imissed += rxq->stats.rx_dropped;
>   		stats->oerrors += txq->stats.tx_dropped;
> -		ret = getsockopt(xsk_socket__fd(rxq->xsk), SOL_XDP,
> -				XDP_STATISTICS, &xdp_stats, &optlen);
> +		fd = process_private->rxq_xsk_fds[i];
> +		ret = fd >= 0 ? getsockopt(fd, SOL_XDP, XDP_STATISTICS,
> +					   &xdp_stats, &optlen) : -1;
>   		if (ret != 0) {
>   			AF_XDP_LOG(ERR, "getsockopt() failed for XDP_STATISTICS.\n");
>   			return -1;
> @@ -883,8 +901,10 @@ eth_dev_close(struct rte_eth_dev *dev)
>   	struct pkt_rx_queue *rxq;
>   	int i;
>   
> -	if (rte_eal_process_type() != RTE_PROC_PRIMARY)
> +	if (rte_eal_process_type() != RTE_PROC_PRIMARY) {
> +		rte_free(dev->process_private);
>   		return 0;
> +	}
>   
>   	AF_XDP_LOG(INFO, "Closing AF_XDP ethdev on numa socket %u\n",
>   		rte_socket_id());
> @@ -1349,6 +1369,7 @@ eth_rx_queue_setup(struct rte_eth_dev *dev,
>   		   struct rte_mempool *mb_pool)
>   {
>   	struct pmd_internals *internals = dev->data->dev_private;
> +	struct pmd_process_private *process_private = dev->process_private;
>   	struct pkt_rx_queue *rxq;
>   	int ret;
>   
> @@ -1387,6 +1408,8 @@ eth_rx_queue_setup(struct rte_eth_dev *dev,
>   	rxq->fds[0].fd = xsk_socket__fd(rxq->xsk);
>   	rxq->fds[0].events = POLLIN;
>   
> +	process_private->rxq_xsk_fds[rx_queue_id] = rxq->fds[0].fd;
> +
>   	dev->data->rx_queues[rx_queue_id] = rxq;
>   	return 0;
>   
> @@ -1688,6 +1711,7 @@ init_internals(struct rte_vdev_device *dev, const char *if_name,
>   {
>   	const char *name = rte_vdev_device_name(dev);
>   	const unsigned int numa_node = dev->device.numa_node;
> +	struct pmd_process_private *process_private;
>   	struct pmd_internals *internals;
>   	struct rte_eth_dev *eth_dev;
>   	int ret;
> @@ -1753,9 +1777,17 @@ init_internals(struct rte_vdev_device *dev, const char *if_name,
>   	if (ret)
>   		goto err_free_tx;
>   
> +	process_private = (struct pmd_process_private *)
> +		rte_zmalloc_socket(name, sizeof(struct pmd_process_private),
> +				   RTE_CACHE_LINE_SIZE, numa_node);
> +	if (process_private == NULL) {
> +		AF_XDP_LOG(ERR, "Failed to alloc memory for process private\n");
> +		goto err_free_tx;
> +	}

Need to free 'process_private' in the PMD, in 'close()' and 'remove()' paths.

> +
>   	eth_dev = rte_eth_vdev_allocate(dev, 0);
>   	if (eth_dev == NULL)
> -		goto err_free_tx;
> +		goto err_free_pp;
>   
>   	eth_dev->data->dev_private = internals;
>   	eth_dev->data->dev_link = pmd_link;
> @@ -1764,6 +1796,10 @@ init_internals(struct rte_vdev_device *dev, const char *if_name,
>   	eth_dev->dev_ops = &ops;
>   	eth_dev->rx_pkt_burst = eth_af_xdp_rx;
>   	eth_dev->tx_pkt_burst = eth_af_xdp_tx;
> +	eth_dev->process_private = process_private;
> +
> +	for (i = 0; i < queue_cnt; i++)
> +		process_private->rxq_xsk_fds[i] = -1;
>   
>   #if defined(XDP_UMEM_UNALIGNED_CHUNK_FLAG)
>   	AF_XDP_LOG(INFO, "Zero copy between umem and mbuf enabled.\n");
> @@ -1771,6 +1807,8 @@ init_internals(struct rte_vdev_device *dev, const char *if_name,
>   
>   	return eth_dev;
>   
> +err_free_pp:
> +	rte_free(process_private);
>   err_free_tx:
>   	rte_free(internals->tx_queues);
>   err_free_rx:
> @@ -1780,6 +1818,115 @@ init_internals(struct rte_vdev_device *dev, const char *if_name,
>   	return NULL;
>   }
>   
> +/* Secondary process requests rxq fds from primary. */
> +static int
> +afxdp_mp_request_fds(const char *name, struct rte_eth_dev *dev)
> +{
> +	struct pmd_process_private *process_private = dev->process_private;
> +	struct timespec timeout = {.tv_sec = 1, .tv_nsec = 0};
> +	struct rte_mp_msg request, *reply;
> +	struct rte_mp_reply replies;
> +	struct ipc_hdr *request_param = (struct ipc_hdr *)request.param;
> +	int i, ret;
> +
> +	/* Prepare the request */
> +	memset(&request, 0, sizeof(request));
> +	strlcpy(request.name, ETH_AF_XDP_MP_KEY, sizeof(request.name));
> +	strlcpy(request_param->port_name, name,
> +		sizeof(request_param->port_name));
> +	request.len_param = sizeof(*request_param);
> +
> +	/* Send the request and receive the reply */
> +	AF_XDP_LOG(DEBUG, "Sending IPC request for %s\n", name);
> +	ret = rte_mp_request_sync(&request, &replies, &timeout);
> +	if (ret < 0 || replies.nb_received != 1) {
> +		AF_XDP_LOG(ERR, "Failed to request fds from primary: %d",
> +			   rte_errno);
> +		return -1;
> +	}
> +	reply = replies.msgs;
> +	AF_XDP_LOG(DEBUG, "Received IPC reply for %s\n", name);

I think message can mention "multi-process IPC" for clarification.

> +	if (dev->data->nb_rx_queues != reply->num_fds) {
> +		AF_XDP_LOG(ERR, "Incorrect number of fds received: %d != %d\n",
> +			   reply->num_fds, dev->data->nb_rx_queues);
> +		return -EINVAL;
> +	}
> +
> +	for (i = 0; i < reply->num_fds; i++)
> +		process_private->rxq_xsk_fds[i] = reply->fds[i];
> +
> +	free(reply);
> +	return 0;
> +}
> +
> +/* Primary process sends rxq fds to secondary. */
> +static int
> +afxdp_mp_send_fds(const struct rte_mp_msg *request, const void *peer)
> +{
> +	struct rte_eth_dev *dev;
> +	struct pmd_process_private *process_private;
> +	struct rte_mp_msg reply;
> +	const struct ipc_hdr *request_param =
> +		(const struct ipc_hdr *)request->param;
> +	struct ipc_hdr *reply_param =
> +		(struct ipc_hdr *)reply.param;
> +	const char *request_name = request_param->port_name;
> +	uint16_t port_id;
> +	int i, ret;
> +
> +	AF_XDP_LOG(DEBUG, "Received IPC request for %s\n", request_name);
> +
> +	/* Find the requested port */
> +	ret = rte_eth_dev_get_port_by_name(request_name, &port_id);
> +	if (ret) {
> +		AF_XDP_LOG(ERR, "Failed to get port id for %s\n", request_name);
> +		return -1;
> +	}
> +	dev = &rte_eth_devices[port_id];

Better to not access the global array, there is a new API and a cleanup
already done [1] in other PMDs, can you please apply the same here.

[1]
https://patches.dpdk.org/project/dpdk/patch/20220203082412.79028-1-kumaraparamesh92@gmail.com/

> +	process_private = dev->process_private;
> +
> +	/* Populate the reply with the xsk fd for each queue */
> +	reply.num_fds = 0;
> +	if (dev->data->nb_rx_queues > RTE_MP_MAX_FD_NUM) {
> +		AF_XDP_LOG(ERR, "Number of rx queues (%d) exceeds max number of fds (%d)\n",
> +			   dev->data->nb_rx_queues, RTE_MP_MAX_FD_NUM);
> +		return -EINVAL;
> +	}
> +
> +	for (i = 0; i < dev->data->nb_rx_queues; i++)
> +		reply.fds[reply.num_fds++] = process_private->rxq_xsk_fds[i];
> +
> +	/* Send the reply */
> +	strlcpy(reply.name, request->name, sizeof(reply.name));
> +	strlcpy(reply_param->port_name, request_name,
> +		sizeof(reply_param->port_name));
> +	reply.len_param = sizeof(*reply_param);
> +	AF_XDP_LOG(DEBUG, "Sending IPC reply for %s\n", reply_param->port_name);
> +	if (rte_mp_reply(&reply, peer) < 0) {
> +		AF_XDP_LOG(ERR, "Failed to reply to IPC request\n");
> +		return -1;
> +	}
> +	return 0;
> +}
> +
> +/* Secondary process rx function. RX is disabled because rings are SPSC */
> +static uint16_t
> +eth_af_xdp_rx_noop(void *queue __rte_unused,
> +		struct rte_mbuf **bufs __rte_unused,
> +		uint16_t nb_pkts __rte_unused)
> +{
> +	return 0;
> +}
> +
> +/* Secondary process tx function. TX is disabled because rings are SPSC */
> +static uint16_t
> +eth_af_xdp_tx_noop(void *queue __rte_unused,
> +			struct rte_mbuf **bufs __rte_unused,
> +			uint16_t nb_pkts __rte_unused)
> +{
> +	return 0;
> +}
> +

Now there are multiple PMDs using noop/dummy Rx/Tx burst functions,
what do you think to add static inline functions in the 'ethdev_driver.h'
(and clean existing drivers to use it) with a separate patch, later in this
patch use those functions?


>   static int
>   rte_pmd_af_xdp_probe(struct rte_vdev_device *dev)
>   {
> @@ -1789,19 +1936,39 @@ rte_pmd_af_xdp_probe(struct rte_vdev_device *dev)
>   	int xsk_queue_cnt = ETH_AF_XDP_DFLT_QUEUE_COUNT;
>   	int shared_umem = 0;
>   	char prog_path[PATH_MAX] = {'\0'};
> -	int busy_budget = -1;
> +	int busy_budget = -1, ret;
>   	struct rte_eth_dev *eth_dev = NULL;
> -	const char *name;
> +	const char *name = rte_vdev_device_name(dev);
>   
> -	AF_XDP_LOG(INFO, "Initializing pmd_af_xdp for %s\n",
> -		rte_vdev_device_name(dev));
> +	AF_XDP_LOG(INFO, "Initializing pmd_af_xdp for %s\n", name);
>   
> -	name = rte_vdev_device_name(dev);
>   	if (rte_eal_process_type() == RTE_PROC_SECONDARY) {
> -		AF_XDP_LOG(ERR, "Failed to probe %s. "
> -				"AF_XDP PMD does not support secondary processes.\n",
> -				name);
> -		return -ENOTSUP;
> +		eth_dev = rte_eth_dev_attach_secondary(name);
> +		if (eth_dev == NULL) {
> +			AF_XDP_LOG(ERR, "Failed to probe %s\n", name);
> +			return -EINVAL;
> +		}
> +		eth_dev->dev_ops = &ops;
> +		eth_dev->device = &dev->device;
> +		eth_dev->rx_pkt_burst = eth_af_xdp_rx_noop;
> +		eth_dev->tx_pkt_burst = eth_af_xdp_tx_noop;
> +		eth_dev->process_private = (struct pmd_process_private *)
> +			rte_zmalloc_socket(name,
> +					   sizeof(struct pmd_process_private),
> +					   RTE_CACHE_LINE_SIZE,
> +					   eth_dev->device->numa_node);
> +		if (eth_dev->process_private == NULL) {
> +			AF_XDP_LOG(ERR,
> +				"Failed to alloc memory for process private\n");
> +			return -ENOMEM;
> +		}
> +
> +		/* Obtain the xsk fds from the primary process. */
> +		if (afxdp_mp_request_fds(name, eth_dev))
> +			return -1;
> +
> +		rte_eth_dev_probing_finish(eth_dev);
> +		return 0;
>   	}
>   
>   	kvlist = rte_kvargs_parse(rte_vdev_device_args(dev), valid_arguments);
> @@ -1836,6 +2003,17 @@ rte_pmd_af_xdp_probe(struct rte_vdev_device *dev)
>   		return -1;
>   	}
>   
> +	/* Register IPC callback which shares xsk fds from primary to secondary */
> +	if (!afxdp_dev_count) {
> +		ret = rte_mp_action_register(ETH_AF_XDP_MP_KEY, afxdp_mp_send_fds);
> +		if (ret < 0) {
> +			AF_XDP_LOG(ERR, "%s: Failed to register IPC callback: %s",
> +				   name, strerror(rte_errno));
> +			return -1;
> +		}
> +	}
> +	afxdp_dev_count++;
> +
>   	rte_eth_dev_probing_finish(eth_dev);
>   
>   	return 0;
> @@ -1858,6 +2036,10 @@ rte_pmd_af_xdp_remove(struct rte_vdev_device *dev)
>   		return 0;
>   
>   	eth_dev_close(eth_dev);
> +	rte_free(eth_dev->process_private);
> +	if (afxdp_dev_count == 1)
> +		rte_mp_action_unregister(ETH_AF_XDP_MP_KEY);
> +	afxdp_dev_count--;
>   	rte_eth_dev_release_port(eth_dev);
>   
>
Ciara Loftus Feb. 7, 2022, 7:49 a.m. UTC | #2
> 
> On 2/4/2022 12:54 PM, Ciara Loftus wrote:
> > Secondary process support had been disabled for the AF_XDP PMD
> > because there was no logic in place to share the AF_XDP socket
> > file descriptors between the processes. This commit introduces
> > this logic using the IPC APIs.
> >
> > Since AF_XDP rings are single-producer single-consumer, rx/tx
> > in the secondary process is disabled. However other operations
> > including retrieval of stats are permitted.
> >
> > Signed-off-by: Ciara Loftus <ciara.loftus@intel.com>
> >
> > ---
> > v1 -> v2:
> > * Rebase to next-net
> >
> > RFC -> v1:
> > * Added newline to af_xdp.rst
> > * Fixed spelling errors
> > * Fixed potential NULL dereference in init_internals
> > * Fixed potential free of address-of expression in afxdp_mp_request_fds
> > ---
> >   doc/guides/nics/af_xdp.rst             |   9 ++
> >   doc/guides/nics/features/af_xdp.ini    |   1 +
> >   doc/guides/rel_notes/release_22_03.rst |   1 +
> >   drivers/net/af_xdp/rte_eth_af_xdp.c    | 210
> +++++++++++++++++++++++--
> >   4 files changed, 207 insertions(+), 14 deletions(-)
> >
> > diff --git a/doc/guides/nics/af_xdp.rst b/doc/guides/nics/af_xdp.rst
> > index db02ea1984..eb4eab28a8 100644
> > --- a/doc/guides/nics/af_xdp.rst
> > +++ b/doc/guides/nics/af_xdp.rst
> > @@ -141,4 +141,13 @@ Limitations
> >     NAPI context from a watchdog timer instead of from softirqs. More
> information
> >     on this feature can be found at [1].
> >
> > +- **Secondary Processes**
> > +
> > +  Rx and Tx are not supported for secondary processes due to the single-
> producer
> > +  single-consumer nature of the AF_XDP rings. However other operations
> including
> > +  statistics retrieval are permitted.
> 
> Hi Ciara,
> 
> Isn't this limitation same for all PMDs, like not both primary & secondary can
> Rx/Tx
> from same queue at the same time.
> But primary can initiallize the PMD and secondary can do the datapath,
> or isn't af_xdp supports multiple queue, if so some queues can be used by
> primary and some by secondary for datapath.
> 
> Is there anyhing special for af_xdp that prevents it?

Hi Ferruh,

Thanks for the review.
Each queue of the PMD corresponds to a new AF_XDP socket.
Each socket has an RX and TX ring that is mmapped from the kernel to userspace and this mapping is only valid for the primary process.
I did not figure out a way to share that mapping with the secondary process successfully. Can you think of anything that might work?

> 
> > +  The maximum number of queues permitted for PMDs operating in this
> model is 8
> > +  as this is the maximum number of fds that can be sent through the IPC
> APIs as
> > +  defined by RTE_MP_MAX_FD_NUM.
> > +
> >     [1] https://lwn.net/Articles/837010/
> > diff --git a/doc/guides/nics/features/af_xdp.ini
> b/doc/guides/nics/features/af_xdp.ini
> > index 54b738e616..8e7e075aaf 100644
> > --- a/doc/guides/nics/features/af_xdp.ini
> > +++ b/doc/guides/nics/features/af_xdp.ini
> > @@ -9,4 +9,5 @@ Power mgmt address monitor = Y
> >   MTU update           = Y
> >   Promiscuous mode     = Y
> >   Stats per queue      = Y
> > +Multiprocess aware   = Y
> >   x86-64               = Y
> > diff --git a/doc/guides/rel_notes/release_22_03.rst
> b/doc/guides/rel_notes/release_22_03.rst
> > index bf2e3f78a9..dfd2cbbccf 100644
> > --- a/doc/guides/rel_notes/release_22_03.rst
> > +++ b/doc/guides/rel_notes/release_22_03.rst
> > @@ -58,6 +58,7 @@ New Features
> >   * **Updated AF_XDP PMD**
> >
> >     * Added support for libxdp >=v1.2.2.
> > +  * Re-enabled secondary process support. RX/TX is not supported.
> >
> >   * **Updated Cisco enic driver.**
> >
> > diff --git a/drivers/net/af_xdp/rte_eth_af_xdp.c
> b/drivers/net/af_xdp/rte_eth_af_xdp.c
> > index 1b6192fa44..407f6d8dbe 100644
> > --- a/drivers/net/af_xdp/rte_eth_af_xdp.c
> > +++ b/drivers/net/af_xdp/rte_eth_af_xdp.c
> > @@ -80,6 +80,18 @@ RTE_LOG_REGISTER_DEFAULT(af_xdp_logtype,
> NOTICE);
> >
> >   #define ETH_AF_XDP_ETH_OVERHEAD
> 	(RTE_ETHER_HDR_LEN + RTE_ETHER_CRC_LEN)
> >
> > +#define ETH_AF_XDP_MP_KEY "afxdp_mp_send_fds"
> > +
> > +static int afxdp_dev_count;
> > +
> > +/* Message header to synchronize fds via IPC */
> > +struct ipc_hdr {
> > +	char port_name[RTE_DEV_NAME_MAX_LEN];
> > +	/* The file descriptors are in the dedicated part
> > +	 * of the Unix message to be translated by the kernel.
> > +	 */
> > +};
> > +
> >   struct xsk_umem_info {
> >   	struct xsk_umem *umem;
> >   	struct rte_ring *buf_ring;
> > @@ -147,6 +159,10 @@ struct pmd_internals {
> >   	struct pkt_tx_queue *tx_queues;
> >   };
> >
> > +struct pmd_process_private {
> > +	int rxq_xsk_fds[RTE_MAX_QUEUES_PER_PORT];
> > +};
> > +
> >   #define ETH_AF_XDP_IFACE_ARG			"iface"
> >   #define ETH_AF_XDP_START_QUEUE_ARG		"start_queue"
> >   #define ETH_AF_XDP_QUEUE_COUNT_ARG
> 	"queue_count"
> > @@ -795,11 +811,12 @@ static int
> >   eth_stats_get(struct rte_eth_dev *dev, struct rte_eth_stats *stats)
> >   {
> >   	struct pmd_internals *internals = dev->data->dev_private;
> > +	struct pmd_process_private *process_private = dev-
> >process_private;
> >   	struct xdp_statistics xdp_stats;
> >   	struct pkt_rx_queue *rxq;
> >   	struct pkt_tx_queue *txq;
> >   	socklen_t optlen;
> > -	int i, ret;
> > +	int i, ret, fd;
> >
> >   	for (i = 0; i < dev->data->nb_rx_queues; i++) {
> >   		optlen = sizeof(struct xdp_statistics);
> > @@ -815,8 +832,9 @@ eth_stats_get(struct rte_eth_dev *dev, struct
> rte_eth_stats *stats)
> >   		stats->ibytes += stats->q_ibytes[i];
> >   		stats->imissed += rxq->stats.rx_dropped;
> >   		stats->oerrors += txq->stats.tx_dropped;
> > -		ret = getsockopt(xsk_socket__fd(rxq->xsk), SOL_XDP,
> > -				XDP_STATISTICS, &xdp_stats, &optlen);
> > +		fd = process_private->rxq_xsk_fds[i];
> > +		ret = fd >= 0 ? getsockopt(fd, SOL_XDP, XDP_STATISTICS,
> > +					   &xdp_stats, &optlen) : -1;
> >   		if (ret != 0) {
> >   			AF_XDP_LOG(ERR, "getsockopt() failed for
> XDP_STATISTICS.\n");
> >   			return -1;
> > @@ -883,8 +901,10 @@ eth_dev_close(struct rte_eth_dev *dev)
> >   	struct pkt_rx_queue *rxq;
> >   	int i;
> >
> > -	if (rte_eal_process_type() != RTE_PROC_PRIMARY)
> > +	if (rte_eal_process_type() != RTE_PROC_PRIMARY) {
> > +		rte_free(dev->process_private);
> >   		return 0;
> > +	}
> >
> >   	AF_XDP_LOG(INFO, "Closing AF_XDP ethdev on numa socket %u\n",
> >   		rte_socket_id());
> > @@ -1349,6 +1369,7 @@ eth_rx_queue_setup(struct rte_eth_dev *dev,
> >   		   struct rte_mempool *mb_pool)
> >   {
> >   	struct pmd_internals *internals = dev->data->dev_private;
> > +	struct pmd_process_private *process_private = dev-
> >process_private;
> >   	struct pkt_rx_queue *rxq;
> >   	int ret;
> >
> > @@ -1387,6 +1408,8 @@ eth_rx_queue_setup(struct rte_eth_dev *dev,
> >   	rxq->fds[0].fd = xsk_socket__fd(rxq->xsk);
> >   	rxq->fds[0].events = POLLIN;
> >
> > +	process_private->rxq_xsk_fds[rx_queue_id] = rxq->fds[0].fd;
> > +
> >   	dev->data->rx_queues[rx_queue_id] = rxq;
> >   	return 0;
> >
> > @@ -1688,6 +1711,7 @@ init_internals(struct rte_vdev_device *dev, const
> char *if_name,
> >   {
> >   	const char *name = rte_vdev_device_name(dev);
> >   	const unsigned int numa_node = dev->device.numa_node;
> > +	struct pmd_process_private *process_private;
> >   	struct pmd_internals *internals;
> >   	struct rte_eth_dev *eth_dev;
> >   	int ret;
> > @@ -1753,9 +1777,17 @@ init_internals(struct rte_vdev_device *dev,
> const char *if_name,
> >   	if (ret)
> >   		goto err_free_tx;
> >
> > +	process_private = (struct pmd_process_private *)
> > +		rte_zmalloc_socket(name, sizeof(struct
> pmd_process_private),
> > +				   RTE_CACHE_LINE_SIZE, numa_node);
> > +	if (process_private == NULL) {
> > +		AF_XDP_LOG(ERR, "Failed to alloc memory for process
> private\n");
> > +		goto err_free_tx;
> > +	}
> 
> Need to free 'process_private' in the PMD, in 'close()' and 'remove()' paths.

+1

> 
> > +
> >   	eth_dev = rte_eth_vdev_allocate(dev, 0);
> >   	if (eth_dev == NULL)
> > -		goto err_free_tx;
> > +		goto err_free_pp;
> >
> >   	eth_dev->data->dev_private = internals;
> >   	eth_dev->data->dev_link = pmd_link;
> > @@ -1764,6 +1796,10 @@ init_internals(struct rte_vdev_device *dev,
> const char *if_name,
> >   	eth_dev->dev_ops = &ops;
> >   	eth_dev->rx_pkt_burst = eth_af_xdp_rx;
> >   	eth_dev->tx_pkt_burst = eth_af_xdp_tx;
> > +	eth_dev->process_private = process_private;
> > +
> > +	for (i = 0; i < queue_cnt; i++)
> > +		process_private->rxq_xsk_fds[i] = -1;
> >
> >   #if defined(XDP_UMEM_UNALIGNED_CHUNK_FLAG)
> >   	AF_XDP_LOG(INFO, "Zero copy between umem and mbuf
> enabled.\n");
> > @@ -1771,6 +1807,8 @@ init_internals(struct rte_vdev_device *dev, const
> char *if_name,
> >
> >   	return eth_dev;
> >
> > +err_free_pp:
> > +	rte_free(process_private);
> >   err_free_tx:
> >   	rte_free(internals->tx_queues);
> >   err_free_rx:
> > @@ -1780,6 +1818,115 @@ init_internals(struct rte_vdev_device *dev,
> const char *if_name,
> >   	return NULL;
> >   }
> >
> > +/* Secondary process requests rxq fds from primary. */
> > +static int
> > +afxdp_mp_request_fds(const char *name, struct rte_eth_dev *dev)
> > +{
> > +	struct pmd_process_private *process_private = dev-
> >process_private;
> > +	struct timespec timeout = {.tv_sec = 1, .tv_nsec = 0};
> > +	struct rte_mp_msg request, *reply;
> > +	struct rte_mp_reply replies;
> > +	struct ipc_hdr *request_param = (struct ipc_hdr *)request.param;
> > +	int i, ret;
> > +
> > +	/* Prepare the request */
> > +	memset(&request, 0, sizeof(request));
> > +	strlcpy(request.name, ETH_AF_XDP_MP_KEY,
> sizeof(request.name));
> > +	strlcpy(request_param->port_name, name,
> > +		sizeof(request_param->port_name));
> > +	request.len_param = sizeof(*request_param);
> > +
> > +	/* Send the request and receive the reply */
> > +	AF_XDP_LOG(DEBUG, "Sending IPC request for %s\n", name);
> > +	ret = rte_mp_request_sync(&request, &replies, &timeout);
> > +	if (ret < 0 || replies.nb_received != 1) {
> > +		AF_XDP_LOG(ERR, "Failed to request fds from primary: %d",
> > +			   rte_errno);
> > +		return -1;
> > +	}
> > +	reply = replies.msgs;
> > +	AF_XDP_LOG(DEBUG, "Received IPC reply for %s\n", name);
> 
> I think message can mention "multi-process IPC" for clarification.

+1

> 
> > +	if (dev->data->nb_rx_queues != reply->num_fds) {
> > +		AF_XDP_LOG(ERR, "Incorrect number of fds received: %d !=
> %d\n",
> > +			   reply->num_fds, dev->data->nb_rx_queues);
> > +		return -EINVAL;
> > +	}
> > +
> > +	for (i = 0; i < reply->num_fds; i++)
> > +		process_private->rxq_xsk_fds[i] = reply->fds[i];
> > +
> > +	free(reply);
> > +	return 0;
> > +}
> > +
> > +/* Primary process sends rxq fds to secondary. */
> > +static int
> > +afxdp_mp_send_fds(const struct rte_mp_msg *request, const void
> *peer)
> > +{
> > +	struct rte_eth_dev *dev;
> > +	struct pmd_process_private *process_private;
> > +	struct rte_mp_msg reply;
> > +	const struct ipc_hdr *request_param =
> > +		(const struct ipc_hdr *)request->param;
> > +	struct ipc_hdr *reply_param =
> > +		(struct ipc_hdr *)reply.param;
> > +	const char *request_name = request_param->port_name;
> > +	uint16_t port_id;
> > +	int i, ret;
> > +
> > +	AF_XDP_LOG(DEBUG, "Received IPC request for %s\n",
> request_name);
> > +
> > +	/* Find the requested port */
> > +	ret = rte_eth_dev_get_port_by_name(request_name, &port_id);
> > +	if (ret) {
> > +		AF_XDP_LOG(ERR, "Failed to get port id for %s\n",
> request_name);
> > +		return -1;
> > +	}
> > +	dev = &rte_eth_devices[port_id];
> 
> Better to not access the global array, there is a new API and a cleanup
> already done [1] in other PMDs, can you please apply the same here.
> 
> [1]
> https://patches.dpdk.org/project/dpdk/patch/20220203082412.79028-1-
> kumaraparamesh92@gmail.com/

Thanks for sharing, I wasn't aware of this API. I'll add it in the v3.

> 
> > +	process_private = dev->process_private;
> > +
> > +	/* Populate the reply with the xsk fd for each queue */
> > +	reply.num_fds = 0;
> > +	if (dev->data->nb_rx_queues > RTE_MP_MAX_FD_NUM) {
> > +		AF_XDP_LOG(ERR, "Number of rx queues (%d) exceeds max
> number of fds (%d)\n",
> > +			   dev->data->nb_rx_queues,
> RTE_MP_MAX_FD_NUM);
> > +		return -EINVAL;
> > +	}
> > +
> > +	for (i = 0; i < dev->data->nb_rx_queues; i++)
> > +		reply.fds[reply.num_fds++] = process_private-
> >rxq_xsk_fds[i];
> > +
> > +	/* Send the reply */
> > +	strlcpy(reply.name, request->name, sizeof(reply.name));
> > +	strlcpy(reply_param->port_name, request_name,
> > +		sizeof(reply_param->port_name));
> > +	reply.len_param = sizeof(*reply_param);
> > +	AF_XDP_LOG(DEBUG, "Sending IPC reply for %s\n", reply_param-
> >port_name);
> > +	if (rte_mp_reply(&reply, peer) < 0) {
> > +		AF_XDP_LOG(ERR, "Failed to reply to IPC request\n");
> > +		return -1;
> > +	}
> > +	return 0;
> > +}
> > +
> > +/* Secondary process rx function. RX is disabled because rings are SPSC */
> > +static uint16_t
> > +eth_af_xdp_rx_noop(void *queue __rte_unused,
> > +		struct rte_mbuf **bufs __rte_unused,
> > +		uint16_t nb_pkts __rte_unused)
> > +{
> > +	return 0;
> > +}
> > +
> > +/* Secondary process tx function. TX is disabled because rings are SPSC */
> > +static uint16_t
> > +eth_af_xdp_tx_noop(void *queue __rte_unused,
> > +			struct rte_mbuf **bufs __rte_unused,
> > +			uint16_t nb_pkts __rte_unused)
> > +{
> > +	return 0;
> > +}
> > +
> 
> Now there are multiple PMDs using noop/dummy Rx/Tx burst functions,
> what do you think to add static inline functions in the 'ethdev_driver.h'
> (and clean existing drivers to use it) with a separate patch, later in this
> patch use those functions?

+1

> 
> 
> >   static int
> >   rte_pmd_af_xdp_probe(struct rte_vdev_device *dev)
> >   {
> > @@ -1789,19 +1936,39 @@ rte_pmd_af_xdp_probe(struct
> rte_vdev_device *dev)
> >   	int xsk_queue_cnt = ETH_AF_XDP_DFLT_QUEUE_COUNT;
> >   	int shared_umem = 0;
> >   	char prog_path[PATH_MAX] = {'\0'};
> > -	int busy_budget = -1;
> > +	int busy_budget = -1, ret;
> >   	struct rte_eth_dev *eth_dev = NULL;
> > -	const char *name;
> > +	const char *name = rte_vdev_device_name(dev);
> >
> > -	AF_XDP_LOG(INFO, "Initializing pmd_af_xdp for %s\n",
> > -		rte_vdev_device_name(dev));
> > +	AF_XDP_LOG(INFO, "Initializing pmd_af_xdp for %s\n", name);
> >
> > -	name = rte_vdev_device_name(dev);
> >   	if (rte_eal_process_type() == RTE_PROC_SECONDARY) {
> > -		AF_XDP_LOG(ERR, "Failed to probe %s. "
> > -				"AF_XDP PMD does not support secondary
> processes.\n",
> > -				name);
> > -		return -ENOTSUP;
> > +		eth_dev = rte_eth_dev_attach_secondary(name);
> > +		if (eth_dev == NULL) {
> > +			AF_XDP_LOG(ERR, "Failed to probe %s\n", name);
> > +			return -EINVAL;
> > +		}
> > +		eth_dev->dev_ops = &ops;
> > +		eth_dev->device = &dev->device;
> > +		eth_dev->rx_pkt_burst = eth_af_xdp_rx_noop;
> > +		eth_dev->tx_pkt_burst = eth_af_xdp_tx_noop;
> > +		eth_dev->process_private = (struct pmd_process_private *)
> > +			rte_zmalloc_socket(name,
> > +					   sizeof(struct
> pmd_process_private),
> > +					   RTE_CACHE_LINE_SIZE,
> > +					   eth_dev->device->numa_node);
> > +		if (eth_dev->process_private == NULL) {
> > +			AF_XDP_LOG(ERR,
> > +				"Failed to alloc memory for process
> private\n");
> > +			return -ENOMEM;
> > +		}
> > +
> > +		/* Obtain the xsk fds from the primary process. */
> > +		if (afxdp_mp_request_fds(name, eth_dev))
> > +			return -1;
> > +
> > +		rte_eth_dev_probing_finish(eth_dev);
> > +		return 0;
> >   	}
> >
> >   	kvlist = rte_kvargs_parse(rte_vdev_device_args(dev),
> valid_arguments);
> > @@ -1836,6 +2003,17 @@ rte_pmd_af_xdp_probe(struct rte_vdev_device
> *dev)
> >   		return -1;
> >   	}
> >
> > +	/* Register IPC callback which shares xsk fds from primary to
> secondary */
> > +	if (!afxdp_dev_count) {
> > +		ret = rte_mp_action_register(ETH_AF_XDP_MP_KEY,
> afxdp_mp_send_fds);
> > +		if (ret < 0) {
> > +			AF_XDP_LOG(ERR, "%s: Failed to register IPC
> callback: %s",
> > +				   name, strerror(rte_errno));
> > +			return -1;
> > +		}
> > +	}
> > +	afxdp_dev_count++;
> > +
> >   	rte_eth_dev_probing_finish(eth_dev);
> >
> >   	return 0;
> > @@ -1858,6 +2036,10 @@ rte_pmd_af_xdp_remove(struct
> rte_vdev_device *dev)
> >   		return 0;
> >
> >   	eth_dev_close(eth_dev);
> > +	rte_free(eth_dev->process_private);
> > +	if (afxdp_dev_count == 1)
> > +		rte_mp_action_unregister(ETH_AF_XDP_MP_KEY);
> > +	afxdp_dev_count--;
> >   	rte_eth_dev_release_port(eth_dev);
> >
> >
Ferruh Yigit Feb. 7, 2022, 10:27 a.m. UTC | #3
On 2/7/2022 7:49 AM, Loftus, Ciara wrote:
>>
>> On 2/4/2022 12:54 PM, Ciara Loftus wrote:
>>> Secondary process support had been disabled for the AF_XDP PMD
>>> because there was no logic in place to share the AF_XDP socket
>>> file descriptors between the processes. This commit introduces
>>> this logic using the IPC APIs.
>>>
>>> Since AF_XDP rings are single-producer single-consumer, rx/tx
>>> in the secondary process is disabled. However other operations
>>> including retrieval of stats are permitted.
>>>
>>> Signed-off-by: Ciara Loftus <ciara.loftus@intel.com>
>>>
>>> ---
>>> v1 -> v2:
>>> * Rebase to next-net
>>>
>>> RFC -> v1:
>>> * Added newline to af_xdp.rst
>>> * Fixed spelling errors
>>> * Fixed potential NULL dereference in init_internals
>>> * Fixed potential free of address-of expression in afxdp_mp_request_fds
>>> ---
>>>    doc/guides/nics/af_xdp.rst             |   9 ++
>>>    doc/guides/nics/features/af_xdp.ini    |   1 +
>>>    doc/guides/rel_notes/release_22_03.rst |   1 +
>>>    drivers/net/af_xdp/rte_eth_af_xdp.c    | 210
>> +++++++++++++++++++++++--
>>>    4 files changed, 207 insertions(+), 14 deletions(-)
>>>
>>> diff --git a/doc/guides/nics/af_xdp.rst b/doc/guides/nics/af_xdp.rst
>>> index db02ea1984..eb4eab28a8 100644
>>> --- a/doc/guides/nics/af_xdp.rst
>>> +++ b/doc/guides/nics/af_xdp.rst
>>> @@ -141,4 +141,13 @@ Limitations
>>>      NAPI context from a watchdog timer instead of from softirqs. More
>> information
>>>      on this feature can be found at [1].
>>>
>>> +- **Secondary Processes**
>>> +
>>> +  Rx and Tx are not supported for secondary processes due to the single-
>> producer
>>> +  single-consumer nature of the AF_XDP rings. However other operations
>> including
>>> +  statistics retrieval are permitted.
>>
>> Hi Ciara,
>>
>> Isn't this limitation same for all PMDs, like not both primary & secondary can
>> Rx/Tx
>> from same queue at the same time.
>> But primary can initiallize the PMD and secondary can do the datapath,
>> or isn't af_xdp supports multiple queue, if so some queues can be used by
>> primary and some by secondary for datapath.
>>
>> Is there anyhing special for af_xdp that prevents it?
> 
> Hi Ferruh,
> 
> Thanks for the review.
> Each queue of the PMD corresponds to a new AF_XDP socket.
> Each socket has an RX and TX ring that is mmapped from the kernel to userspace and this mapping is only valid for the primary process.
> I did not figure out a way to share that mapping with the secondary process successfully. Can you think of anything that might work?
> 

Does the application knows the buffer address for the Rx/Tx, or is
abstracted to the 'fd'?
If only 'fd' is used, this patch already converts 'fd' between
processes.
cc'ed Anatoly, but what I understand is after MP fd conversion:
Primary process: FD=x
Secondary process: FD=y
And both x & y points to exact same socket in the kernel side.

At least this is how it works for the 'tap' interface, and that is
why 'fs' are in the process_private area and converted between primary
and secondary, I thought it will be same for the xdp socket.

Did you test the secondary Rx/Tx in the secondary after this patch?
Ciara Loftus Feb. 7, 2022, 11:39 a.m. UTC | #4
> >>
> >> On 2/4/2022 12:54 PM, Ciara Loftus wrote:
> >>> Secondary process support had been disabled for the AF_XDP PMD
> >>> because there was no logic in place to share the AF_XDP socket
> >>> file descriptors between the processes. This commit introduces
> >>> this logic using the IPC APIs.
> >>>
> >>> Since AF_XDP rings are single-producer single-consumer, rx/tx
> >>> in the secondary process is disabled. However other operations
> >>> including retrieval of stats are permitted.
> >>>
> >>> Signed-off-by: Ciara Loftus <ciara.loftus@intel.com>
> >>>
> >>> ---
> >>> v1 -> v2:
> >>> * Rebase to next-net
> >>>
> >>> RFC -> v1:
> >>> * Added newline to af_xdp.rst
> >>> * Fixed spelling errors
> >>> * Fixed potential NULL dereference in init_internals
> >>> * Fixed potential free of address-of expression in
> afxdp_mp_request_fds
> >>> ---
> >>>    doc/guides/nics/af_xdp.rst             |   9 ++
> >>>    doc/guides/nics/features/af_xdp.ini    |   1 +
> >>>    doc/guides/rel_notes/release_22_03.rst |   1 +
> >>>    drivers/net/af_xdp/rte_eth_af_xdp.c    | 210
> >> +++++++++++++++++++++++--
> >>>    4 files changed, 207 insertions(+), 14 deletions(-)
> >>>
> >>> diff --git a/doc/guides/nics/af_xdp.rst b/doc/guides/nics/af_xdp.rst
> >>> index db02ea1984..eb4eab28a8 100644
> >>> --- a/doc/guides/nics/af_xdp.rst
> >>> +++ b/doc/guides/nics/af_xdp.rst
> >>> @@ -141,4 +141,13 @@ Limitations
> >>>      NAPI context from a watchdog timer instead of from softirqs. More
> >> information
> >>>      on this feature can be found at [1].
> >>>
> >>> +- **Secondary Processes**
> >>> +
> >>> +  Rx and Tx are not supported for secondary processes due to the
> single-
> >> producer
> >>> +  single-consumer nature of the AF_XDP rings. However other
> operations
> >> including
> >>> +  statistics retrieval are permitted.
> >>
> >> Hi Ciara,
> >>
> >> Isn't this limitation same for all PMDs, like not both primary & secondary
> can
> >> Rx/Tx
> >> from same queue at the same time.
> >> But primary can initiallize the PMD and secondary can do the datapath,
> >> or isn't af_xdp supports multiple queue, if so some queues can be used
> by
> >> primary and some by secondary for datapath.
> >>
> >> Is there anyhing special for af_xdp that prevents it?
> >
> > Hi Ferruh,
> >
> > Thanks for the review.
> > Each queue of the PMD corresponds to a new AF_XDP socket.
> > Each socket has an RX and TX ring that is mmapped from the kernel to
> userspace and this mapping is only valid for the primary process.
> > I did not figure out a way to share that mapping with the secondary process
> successfully. Can you think of anything that might work?
> >
> 
> Does the application knows the buffer address for the Rx/Tx, or is
> abstracted to the 'fd'?

The application knows the buffer address of the Rx/Tx rings.
We pass a pointer to these rings to the libbpf xsk_socket__create API, which sets up the mappings:
http://code.dpdk.org/dpdk/v21.11/source/drivers/net/af_xdp/rte_eth_af_xdp.c#L1291
Then later on in the datapath we operate directly on those rings:
http://code.dpdk.org/dpdk/v21.11/source/drivers/net/af_xdp/rte_eth_af_xdp.c#L268
The fd is used in the datapath, but just for the syscalls (recvfrom/poll/send).

> If only 'fd' is used, this patch already converts 'fd' between
> processes.
> cc'ed Anatoly, but what I understand is after MP fd conversion:
> Primary process: FD=x
> Secondary process: FD=y
> And both x & y points to exact same socket in the kernel side.
> 
> At least this is how it works for the 'tap' interface, and that is
> why 'fs' are in the process_private area and converted between primary
> and secondary, I thought it will be same for the xdp socket.
> 
> Did you test the secondary Rx/Tx in the secondary after this patch?
Ferruh Yigit Feb. 8, 2022, 10:58 a.m. UTC | #5
On 2/7/2022 11:39 AM, Loftus, Ciara wrote:
>>>>
>>>> On 2/4/2022 12:54 PM, Ciara Loftus wrote:
>>>>> Secondary process support had been disabled for the AF_XDP PMD
>>>>> because there was no logic in place to share the AF_XDP socket
>>>>> file descriptors between the processes. This commit introduces
>>>>> this logic using the IPC APIs.
>>>>>
>>>>> Since AF_XDP rings are single-producer single-consumer, rx/tx
>>>>> in the secondary process is disabled. However other operations
>>>>> including retrieval of stats are permitted.
>>>>>
>>>>> Signed-off-by: Ciara Loftus <ciara.loftus@intel.com>
>>>>>
>>>>> ---
>>>>> v1 -> v2:
>>>>> * Rebase to next-net
>>>>>
>>>>> RFC -> v1:
>>>>> * Added newline to af_xdp.rst
>>>>> * Fixed spelling errors
>>>>> * Fixed potential NULL dereference in init_internals
>>>>> * Fixed potential free of address-of expression in
>> afxdp_mp_request_fds
>>>>> ---
>>>>>     doc/guides/nics/af_xdp.rst             |   9 ++
>>>>>     doc/guides/nics/features/af_xdp.ini    |   1 +
>>>>>     doc/guides/rel_notes/release_22_03.rst |   1 +
>>>>>     drivers/net/af_xdp/rte_eth_af_xdp.c    | 210
>>>> +++++++++++++++++++++++--
>>>>>     4 files changed, 207 insertions(+), 14 deletions(-)
>>>>>
>>>>> diff --git a/doc/guides/nics/af_xdp.rst b/doc/guides/nics/af_xdp.rst
>>>>> index db02ea1984..eb4eab28a8 100644
>>>>> --- a/doc/guides/nics/af_xdp.rst
>>>>> +++ b/doc/guides/nics/af_xdp.rst
>>>>> @@ -141,4 +141,13 @@ Limitations
>>>>>       NAPI context from a watchdog timer instead of from softirqs. More
>>>> information
>>>>>       on this feature can be found at [1].
>>>>>
>>>>> +- **Secondary Processes**
>>>>> +
>>>>> +  Rx and Tx are not supported for secondary processes due to the
>> single-
>>>> producer
>>>>> +  single-consumer nature of the AF_XDP rings. However other
>> operations
>>>> including
>>>>> +  statistics retrieval are permitted.
>>>>
>>>> Hi Ciara,
>>>>
>>>> Isn't this limitation same for all PMDs, like not both primary & secondary
>> can
>>>> Rx/Tx
>>>> from same queue at the same time.
>>>> But primary can initiallize the PMD and secondary can do the datapath,
>>>> or isn't af_xdp supports multiple queue, if so some queues can be used
>> by
>>>> primary and some by secondary for datapath.
>>>>
>>>> Is there anyhing special for af_xdp that prevents it?
>>>
>>> Hi Ferruh,
>>>
>>> Thanks for the review.
>>> Each queue of the PMD corresponds to a new AF_XDP socket.
>>> Each socket has an RX and TX ring that is mmapped from the kernel to
>> userspace and this mapping is only valid for the primary process.
>>> I did not figure out a way to share that mapping with the secondary process
>> successfully. Can you think of anything that might work?
>>>
>>
>> Does the application knows the buffer address for the Rx/Tx, or is
>> abstracted to the 'fd'?
> 
> The application knows the buffer address of the Rx/Tx rings.
> We pass a pointer to these rings to the libbpf xsk_socket__create API, which sets up the mappings:
> http://code.dpdk.org/dpdk/v21.11/source/drivers/net/af_xdp/rte_eth_af_xdp.c#L1291
> Then later on in the datapath we operate directly on those rings:
> http://code.dpdk.org/dpdk/v21.11/source/drivers/net/af_xdp/rte_eth_af_xdp.c#L268
> The fd is used in the datapath, but just for the syscalls (recvfrom/poll/send).
> 

Got it, if the buffer address is explicitly required for datapath, fd conversion
is not enough.

Primary/secondary process works by mapping memory to same virtual address
on two different process. The same method can be used for af_xdp multi
process support, again @Anatoly can comment better.
But this method is fragile, not sure if we should implement it in more
places...

Anyway, agree to continue this patch without datapath support in secondary.

>> If only 'fd' is used, this patch already converts 'fd' between
>> processes.
>> cc'ed Anatoly, but what I understand is after MP fd conversion:
>> Primary process: FD=x
>> Secondary process: FD=y
>> And both x & y points to exact same socket in the kernel side.
>>
>> At least this is how it works for the 'tap' interface, and that is
>> why 'fs' are in the process_private area and converted between primary
>> and secondary, I thought it will be same for the xdp socket.
>>
>> Did you test the secondary Rx/Tx in the secondary after this patch?
diff mbox series

Patch

diff --git a/doc/guides/nics/af_xdp.rst b/doc/guides/nics/af_xdp.rst
index db02ea1984..eb4eab28a8 100644
--- a/doc/guides/nics/af_xdp.rst
+++ b/doc/guides/nics/af_xdp.rst
@@ -141,4 +141,13 @@  Limitations
   NAPI context from a watchdog timer instead of from softirqs. More information
   on this feature can be found at [1].
 
+- **Secondary Processes**
+
+  Rx and Tx are not supported for secondary processes due to the single-producer
+  single-consumer nature of the AF_XDP rings. However other operations including
+  statistics retrieval are permitted.
+  The maximum number of queues permitted for PMDs operating in this model is 8
+  as this is the maximum number of fds that can be sent through the IPC APIs as
+  defined by RTE_MP_MAX_FD_NUM.
+
   [1] https://lwn.net/Articles/837010/
diff --git a/doc/guides/nics/features/af_xdp.ini b/doc/guides/nics/features/af_xdp.ini
index 54b738e616..8e7e075aaf 100644
--- a/doc/guides/nics/features/af_xdp.ini
+++ b/doc/guides/nics/features/af_xdp.ini
@@ -9,4 +9,5 @@  Power mgmt address monitor = Y
 MTU update           = Y
 Promiscuous mode     = Y
 Stats per queue      = Y
+Multiprocess aware   = Y
 x86-64               = Y
diff --git a/doc/guides/rel_notes/release_22_03.rst b/doc/guides/rel_notes/release_22_03.rst
index bf2e3f78a9..dfd2cbbccf 100644
--- a/doc/guides/rel_notes/release_22_03.rst
+++ b/doc/guides/rel_notes/release_22_03.rst
@@ -58,6 +58,7 @@  New Features
 * **Updated AF_XDP PMD**
 
   * Added support for libxdp >=v1.2.2.
+  * Re-enabled secondary process support. RX/TX is not supported.
 
 * **Updated Cisco enic driver.**
 
diff --git a/drivers/net/af_xdp/rte_eth_af_xdp.c b/drivers/net/af_xdp/rte_eth_af_xdp.c
index 1b6192fa44..407f6d8dbe 100644
--- a/drivers/net/af_xdp/rte_eth_af_xdp.c
+++ b/drivers/net/af_xdp/rte_eth_af_xdp.c
@@ -80,6 +80,18 @@  RTE_LOG_REGISTER_DEFAULT(af_xdp_logtype, NOTICE);
 
 #define ETH_AF_XDP_ETH_OVERHEAD		(RTE_ETHER_HDR_LEN + RTE_ETHER_CRC_LEN)
 
+#define ETH_AF_XDP_MP_KEY "afxdp_mp_send_fds"
+
+static int afxdp_dev_count;
+
+/* Message header to synchronize fds via IPC */
+struct ipc_hdr {
+	char port_name[RTE_DEV_NAME_MAX_LEN];
+	/* The file descriptors are in the dedicated part
+	 * of the Unix message to be translated by the kernel.
+	 */
+};
+
 struct xsk_umem_info {
 	struct xsk_umem *umem;
 	struct rte_ring *buf_ring;
@@ -147,6 +159,10 @@  struct pmd_internals {
 	struct pkt_tx_queue *tx_queues;
 };
 
+struct pmd_process_private {
+	int rxq_xsk_fds[RTE_MAX_QUEUES_PER_PORT];
+};
+
 #define ETH_AF_XDP_IFACE_ARG			"iface"
 #define ETH_AF_XDP_START_QUEUE_ARG		"start_queue"
 #define ETH_AF_XDP_QUEUE_COUNT_ARG		"queue_count"
@@ -795,11 +811,12 @@  static int
 eth_stats_get(struct rte_eth_dev *dev, struct rte_eth_stats *stats)
 {
 	struct pmd_internals *internals = dev->data->dev_private;
+	struct pmd_process_private *process_private = dev->process_private;
 	struct xdp_statistics xdp_stats;
 	struct pkt_rx_queue *rxq;
 	struct pkt_tx_queue *txq;
 	socklen_t optlen;
-	int i, ret;
+	int i, ret, fd;
 
 	for (i = 0; i < dev->data->nb_rx_queues; i++) {
 		optlen = sizeof(struct xdp_statistics);
@@ -815,8 +832,9 @@  eth_stats_get(struct rte_eth_dev *dev, struct rte_eth_stats *stats)
 		stats->ibytes += stats->q_ibytes[i];
 		stats->imissed += rxq->stats.rx_dropped;
 		stats->oerrors += txq->stats.tx_dropped;
-		ret = getsockopt(xsk_socket__fd(rxq->xsk), SOL_XDP,
-				XDP_STATISTICS, &xdp_stats, &optlen);
+		fd = process_private->rxq_xsk_fds[i];
+		ret = fd >= 0 ? getsockopt(fd, SOL_XDP, XDP_STATISTICS,
+					   &xdp_stats, &optlen) : -1;
 		if (ret != 0) {
 			AF_XDP_LOG(ERR, "getsockopt() failed for XDP_STATISTICS.\n");
 			return -1;
@@ -883,8 +901,10 @@  eth_dev_close(struct rte_eth_dev *dev)
 	struct pkt_rx_queue *rxq;
 	int i;
 
-	if (rte_eal_process_type() != RTE_PROC_PRIMARY)
+	if (rte_eal_process_type() != RTE_PROC_PRIMARY) {
+		rte_free(dev->process_private);
 		return 0;
+	}
 
 	AF_XDP_LOG(INFO, "Closing AF_XDP ethdev on numa socket %u\n",
 		rte_socket_id());
@@ -1349,6 +1369,7 @@  eth_rx_queue_setup(struct rte_eth_dev *dev,
 		   struct rte_mempool *mb_pool)
 {
 	struct pmd_internals *internals = dev->data->dev_private;
+	struct pmd_process_private *process_private = dev->process_private;
 	struct pkt_rx_queue *rxq;
 	int ret;
 
@@ -1387,6 +1408,8 @@  eth_rx_queue_setup(struct rte_eth_dev *dev,
 	rxq->fds[0].fd = xsk_socket__fd(rxq->xsk);
 	rxq->fds[0].events = POLLIN;
 
+	process_private->rxq_xsk_fds[rx_queue_id] = rxq->fds[0].fd;
+
 	dev->data->rx_queues[rx_queue_id] = rxq;
 	return 0;
 
@@ -1688,6 +1711,7 @@  init_internals(struct rte_vdev_device *dev, const char *if_name,
 {
 	const char *name = rte_vdev_device_name(dev);
 	const unsigned int numa_node = dev->device.numa_node;
+	struct pmd_process_private *process_private;
 	struct pmd_internals *internals;
 	struct rte_eth_dev *eth_dev;
 	int ret;
@@ -1753,9 +1777,17 @@  init_internals(struct rte_vdev_device *dev, const char *if_name,
 	if (ret)
 		goto err_free_tx;
 
+	process_private = (struct pmd_process_private *)
+		rte_zmalloc_socket(name, sizeof(struct pmd_process_private),
+				   RTE_CACHE_LINE_SIZE, numa_node);
+	if (process_private == NULL) {
+		AF_XDP_LOG(ERR, "Failed to alloc memory for process private\n");
+		goto err_free_tx;
+	}
+
 	eth_dev = rte_eth_vdev_allocate(dev, 0);
 	if (eth_dev == NULL)
-		goto err_free_tx;
+		goto err_free_pp;
 
 	eth_dev->data->dev_private = internals;
 	eth_dev->data->dev_link = pmd_link;
@@ -1764,6 +1796,10 @@  init_internals(struct rte_vdev_device *dev, const char *if_name,
 	eth_dev->dev_ops = &ops;
 	eth_dev->rx_pkt_burst = eth_af_xdp_rx;
 	eth_dev->tx_pkt_burst = eth_af_xdp_tx;
+	eth_dev->process_private = process_private;
+
+	for (i = 0; i < queue_cnt; i++)
+		process_private->rxq_xsk_fds[i] = -1;
 
 #if defined(XDP_UMEM_UNALIGNED_CHUNK_FLAG)
 	AF_XDP_LOG(INFO, "Zero copy between umem and mbuf enabled.\n");
@@ -1771,6 +1807,8 @@  init_internals(struct rte_vdev_device *dev, const char *if_name,
 
 	return eth_dev;
 
+err_free_pp:
+	rte_free(process_private);
 err_free_tx:
 	rte_free(internals->tx_queues);
 err_free_rx:
@@ -1780,6 +1818,115 @@  init_internals(struct rte_vdev_device *dev, const char *if_name,
 	return NULL;
 }
 
+/* Secondary process requests rxq fds from primary. */
+static int
+afxdp_mp_request_fds(const char *name, struct rte_eth_dev *dev)
+{
+	struct pmd_process_private *process_private = dev->process_private;
+	struct timespec timeout = {.tv_sec = 1, .tv_nsec = 0};
+	struct rte_mp_msg request, *reply;
+	struct rte_mp_reply replies;
+	struct ipc_hdr *request_param = (struct ipc_hdr *)request.param;
+	int i, ret;
+
+	/* Prepare the request */
+	memset(&request, 0, sizeof(request));
+	strlcpy(request.name, ETH_AF_XDP_MP_KEY, sizeof(request.name));
+	strlcpy(request_param->port_name, name,
+		sizeof(request_param->port_name));
+	request.len_param = sizeof(*request_param);
+
+	/* Send the request and receive the reply */
+	AF_XDP_LOG(DEBUG, "Sending IPC request for %s\n", name);
+	ret = rte_mp_request_sync(&request, &replies, &timeout);
+	if (ret < 0 || replies.nb_received != 1) {
+		AF_XDP_LOG(ERR, "Failed to request fds from primary: %d",
+			   rte_errno);
+		return -1;
+	}
+	reply = replies.msgs;
+	AF_XDP_LOG(DEBUG, "Received IPC reply for %s\n", name);
+	if (dev->data->nb_rx_queues != reply->num_fds) {
+		AF_XDP_LOG(ERR, "Incorrect number of fds received: %d != %d\n",
+			   reply->num_fds, dev->data->nb_rx_queues);
+		return -EINVAL;
+	}
+
+	for (i = 0; i < reply->num_fds; i++)
+		process_private->rxq_xsk_fds[i] = reply->fds[i];
+
+	free(reply);
+	return 0;
+}
+
+/* Primary process sends rxq fds to secondary. */
+static int
+afxdp_mp_send_fds(const struct rte_mp_msg *request, const void *peer)
+{
+	struct rte_eth_dev *dev;
+	struct pmd_process_private *process_private;
+	struct rte_mp_msg reply;
+	const struct ipc_hdr *request_param =
+		(const struct ipc_hdr *)request->param;
+	struct ipc_hdr *reply_param =
+		(struct ipc_hdr *)reply.param;
+	const char *request_name = request_param->port_name;
+	uint16_t port_id;
+	int i, ret;
+
+	AF_XDP_LOG(DEBUG, "Received IPC request for %s\n", request_name);
+
+	/* Find the requested port */
+	ret = rte_eth_dev_get_port_by_name(request_name, &port_id);
+	if (ret) {
+		AF_XDP_LOG(ERR, "Failed to get port id for %s\n", request_name);
+		return -1;
+	}
+	dev = &rte_eth_devices[port_id];
+	process_private = dev->process_private;
+
+	/* Populate the reply with the xsk fd for each queue */
+	reply.num_fds = 0;
+	if (dev->data->nb_rx_queues > RTE_MP_MAX_FD_NUM) {
+		AF_XDP_LOG(ERR, "Number of rx queues (%d) exceeds max number of fds (%d)\n",
+			   dev->data->nb_rx_queues, RTE_MP_MAX_FD_NUM);
+		return -EINVAL;
+	}
+
+	for (i = 0; i < dev->data->nb_rx_queues; i++)
+		reply.fds[reply.num_fds++] = process_private->rxq_xsk_fds[i];
+
+	/* Send the reply */
+	strlcpy(reply.name, request->name, sizeof(reply.name));
+	strlcpy(reply_param->port_name, request_name,
+		sizeof(reply_param->port_name));
+	reply.len_param = sizeof(*reply_param);
+	AF_XDP_LOG(DEBUG, "Sending IPC reply for %s\n", reply_param->port_name);
+	if (rte_mp_reply(&reply, peer) < 0) {
+		AF_XDP_LOG(ERR, "Failed to reply to IPC request\n");
+		return -1;
+	}
+	return 0;
+}
+
+/* Secondary process rx function. RX is disabled because rings are SPSC */
+static uint16_t
+eth_af_xdp_rx_noop(void *queue __rte_unused,
+		struct rte_mbuf **bufs __rte_unused,
+		uint16_t nb_pkts __rte_unused)
+{
+	return 0;
+}
+
+/* Secondary process tx function. TX is disabled because rings are SPSC */
+static uint16_t
+eth_af_xdp_tx_noop(void *queue __rte_unused,
+			struct rte_mbuf **bufs __rte_unused,
+			uint16_t nb_pkts __rte_unused)
+{
+	return 0;
+}
+
 static int
 rte_pmd_af_xdp_probe(struct rte_vdev_device *dev)
 {
@@ -1789,19 +1936,39 @@  rte_pmd_af_xdp_probe(struct rte_vdev_device *dev)
 	int xsk_queue_cnt = ETH_AF_XDP_DFLT_QUEUE_COUNT;
 	int shared_umem = 0;
 	char prog_path[PATH_MAX] = {'\0'};
-	int busy_budget = -1;
+	int busy_budget = -1, ret;
 	struct rte_eth_dev *eth_dev = NULL;
-	const char *name;
+	const char *name = rte_vdev_device_name(dev);
 
-	AF_XDP_LOG(INFO, "Initializing pmd_af_xdp for %s\n",
-		rte_vdev_device_name(dev));
+	AF_XDP_LOG(INFO, "Initializing pmd_af_xdp for %s\n", name);
 
-	name = rte_vdev_device_name(dev);
 	if (rte_eal_process_type() == RTE_PROC_SECONDARY) {
-		AF_XDP_LOG(ERR, "Failed to probe %s. "
-				"AF_XDP PMD does not support secondary processes.\n",
-				name);
-		return -ENOTSUP;
+		eth_dev = rte_eth_dev_attach_secondary(name);
+		if (eth_dev == NULL) {
+			AF_XDP_LOG(ERR, "Failed to probe %s\n", name);
+			return -EINVAL;
+		}
+		eth_dev->dev_ops = &ops;
+		eth_dev->device = &dev->device;
+		eth_dev->rx_pkt_burst = eth_af_xdp_rx_noop;
+		eth_dev->tx_pkt_burst = eth_af_xdp_tx_noop;
+		eth_dev->process_private = (struct pmd_process_private *)
+			rte_zmalloc_socket(name,
+					   sizeof(struct pmd_process_private),
+					   RTE_CACHE_LINE_SIZE,
+					   eth_dev->device->numa_node);
+		if (eth_dev->process_private == NULL) {
+			AF_XDP_LOG(ERR,
+				"Failed to alloc memory for process private\n");
+			return -ENOMEM;
+		}
+
+		/* Obtain the xsk fds from the primary process. */
+		if (afxdp_mp_request_fds(name, eth_dev))
+			return -1;
+
+		rte_eth_dev_probing_finish(eth_dev);
+		return 0;
 	}
 
 	kvlist = rte_kvargs_parse(rte_vdev_device_args(dev), valid_arguments);
@@ -1836,6 +2003,17 @@  rte_pmd_af_xdp_probe(struct rte_vdev_device *dev)
 		return -1;
 	}
 
+	/* Register IPC callback which shares xsk fds from primary to secondary */
+	if (!afxdp_dev_count) {
+		ret = rte_mp_action_register(ETH_AF_XDP_MP_KEY, afxdp_mp_send_fds);
+		if (ret < 0) {
+			AF_XDP_LOG(ERR, "%s: Failed to register IPC callback: %s",
+				   name, strerror(rte_errno));
+			return -1;
+		}
+	}
+	afxdp_dev_count++;
+
 	rte_eth_dev_probing_finish(eth_dev);
 
 	return 0;
@@ -1858,6 +2036,10 @@  rte_pmd_af_xdp_remove(struct rte_vdev_device *dev)
 		return 0;
 
 	eth_dev_close(eth_dev);
+	rte_free(eth_dev->process_private);
+	if (afxdp_dev_count == 1)
+		rte_mp_action_unregister(ETH_AF_XDP_MP_KEY);
+	afxdp_dev_count--;
 	rte_eth_dev_release_port(eth_dev);