[PATCH v4 05/10] net/ioring: implement secondary process support

Stephen Hemminger
2025-03-13T21:52:38Z

Add support for communicating fd's from primary to secondary.

Signed-off-by: Stephen Hemminger <stephen@networkplumber.org>
---
doc/guides/nics/features/ioring.ini | 1 +
doc/guides/nics/ioring.rst | 6 --
drivers/net/ioring/rte_eth_ioring.c | 136 +++++++++++++++++++++++++++-
3 files changed, 135 insertions(+), 8 deletions(-)

diff --git a/doc/guides/nics/features/ioring.ini b/doc/guides/nics/features/ioring.ini
index 199c7cd31c..da47062adb 100644
--- a/doc/guides/nics/features/ioring.ini
+++ b/doc/guides/nics/features/ioring.ini
@@ -8,6 +8,7 @@ Link status = Y
MTU update = Y
Promiscuous mode = Y
Allmulticast mode = Y
+Multiprocess aware = Y
Linux = Y
x86-64 = Y
Usage doc = Y
diff --git a/doc/guides/nics/ioring.rst b/doc/guides/nics/ioring.rst
index 7d37a6bb37..69102a5b38 100644
--- a/doc/guides/nics/ioring.rst
+++ b/doc/guides/nics/ioring.rst
@@ -46,12 +46,6 @@ But this behavior can be overridden by the use of the persist flag, example::
--vdev=net_ioring0,iface=io0,persist ...

-Multi-process sharing
----------------------
-
-The IORING device does not support secondary process (yet).
-
-
Limitations
-----------

diff --git a/drivers/net/ioring/rte_eth_ioring.c b/drivers/net/ioring/rte_eth_ioring.c
index b5b5ffdee3..f01db960a7 100644
--- a/drivers/net/ioring/rte_eth_ioring.c
+++ b/drivers/net/ioring/rte_eth_ioring.c
@@ -28,6 +28,7 @@
#include <rte_log.h>

#define IORING_DEFAULT_IFNAME "itap%d"
+#define IORING_MP_KEY "ioring_mp_send_fds"

RTE_LOG_REGISTER_DEFAULT(ioring_logtype, NOTICE);
#define RTE_LOGTYPE_IORING ioring_logtype
@@ -400,6 +401,84 @@ parse_iface_arg(const char *key __rte_unused, const char *value, void *extra_arg
return 0;
}

+/* Secondary process requests rxq fds from primary. */
+static int
+ioring_request_fds(const char *name, struct rte_eth_dev *dev)
+{
+ struct rte_mp_msg request = { };
+
+ strlcpy(request.name, IORING_MP_KEY, sizeof(request.name));
+ strlcpy((char *)request.param, name, RTE_MP_MAX_PARAM_LEN);
+ request.len_param = strlen(name);
+
+ /* Send the request and receive the reply */
+ PMD_LOG(DEBUG, "Sending multi-process IPC request for %s", name);
+
+ struct timespec timeout = {.tv_sec = 1, .tv_nsec = 0};
+ struct rte_mp_reply replies;
+ int ret = rte_mp_request_sync(&request, &replies, &timeout);
+ if (ret < 0 || replies.nb_received != 1) {
+ PMD_LOG(ERR, "Failed to request fds from primary: %s",
+ rte_strerror(rte_errno));
+ return -1;
+ }
+
+ struct rte_mp_msg *reply = replies.msgs;
+ PMD_LOG(DEBUG, "Received multi-process IPC reply for %s", name);
+ if (dev->data->nb_rx_queues != reply->num_fds) {
+ PMD_LOG(ERR, "Incorrect number of fds received: %d != %d",
+ reply->num_fds, dev->data->nb_rx_queues);
+ return -EINVAL;
+ }
+
+ int *fds = dev->process_private;
+ for (int i = 0; i < reply->num_fds; i++)
+ fds[i] = reply->fds[i];
+
+ free(reply);
+ return 0;
+}
+
+/* Primary process sends rxq fds to secondary. */
+static int
+ioring_mp_send_fds(const struct rte_mp_msg *request, const void *peer)
+{
+ const char *request_name = (const char *)request->param;
+
+ PMD_LOG(DEBUG, "Received multi-process IPC request for %s", request_name);
+
+ /* Find the requested port */
+ struct rte_eth_dev *dev = rte_eth_dev_get_by_name(request_name);
+ if (!dev) {
+ PMD_LOG(ERR, "Failed to get port id for %s", request_name);
+ return -1;
+ }
+
+ /* Populate the reply with the xsk fd for each queue */
+ struct rte_mp_msg reply = { };
+ if (dev->data->nb_rx_queues > RTE_MP_MAX_FD_NUM) {
+ PMD_LOG(ERR, "Number of rx queues (%d) exceeds max number of fds (%d)",
+ dev->data->nb_rx_queues, RTE_MP_MAX_FD_NUM);
+ return -EINVAL;
+ }
+
+ int *fds = dev->process_private;
+ for (uint16_t i = 0; i < dev->data->nb_rx_queues; i++)
+ reply.fds[reply.num_fds++] = fds[i];
+
+ /* Send the reply */
+ strlcpy(reply.name, request->name, sizeof(reply.name));
+ strlcpy((char *)reply.param, request_name, RTE_MP_MAX_PARAM_LEN);
+ reply.len_param = strlen(request_name);
+
+ PMD_LOG(DEBUG, "Sending multi-process IPC reply for %s", request_name);
+ if (rte_mp_reply(&reply, peer) < 0) {
+ PMD_LOG(ERR, "Failed to reply to multi-process IPC request");
+ return -1;
+ }
+ return 0;
+}
+
static int
ioring_probe(struct rte_vdev_device *vdev)
{
@@ -407,14 +486,43 @@ ioring_probe(struct rte_vdev_device *vdev)
const char *params = rte_vdev_device_args(vdev);
struct rte_kvargs *kvlist = NULL;
struct rte_eth_dev *eth_dev = NULL;
+ int *fds = NULL;
char tap_name[IFNAMSIZ] = IORING_DEFAULT_IFNAME;
uint8_t persist = 0;
int ret;

PMD_LOG(INFO, "Initializing %s", name);

- if (rte_eal_process_type() == RTE_PROC_SECONDARY)
- return -1; /* TODO */
+ if (rte_eal_process_type() == RTE_PROC_SECONDARY) {
+ struct rte_eth_dev *eth_dev;
+
+ eth_dev = rte_eth_dev_attach_secondary(name);
+ if (!eth_dev) {
+ PMD_LOG(ERR, "Failed to probe %s", name);
+ return -1;
+ }
+ eth_dev->dev_ops = &ops;
+ eth_dev->device = &vdev->device;
+
+ if (!rte_eal_primary_proc_alive(NULL)) {
+ PMD_LOG(ERR, "Primary process is missing");
+ return -1;
+ }
+
+ fds = calloc(RTE_MAX_QUEUES_PER_PORT, sizeof(int));
+ if (fds == NULL) {
+ PMD_LOG(ERR, "Failed to alloc memory for process private");
+ return -1;
+ }
+
+ eth_dev->process_private = fds;
+
+ if (ioring_request_fds(name, eth_dev))
+ return -1;
+
+ rte_eth_dev_probing_finish(eth_dev);
+ return 0;
+ }

if (params != NULL) {
kvlist = rte_kvargs_parse(params, valid_arguments);
@@ -432,21 +540,45 @@ ioring_probe(struct rte_vdev_device *vdev)
persist = 1;
}

+ /* Per-queue tap fd's (for primary process) */
+ fds = calloc(RTE_MAX_QUEUES_PER_PORT, sizeof(int));
+ if (fds == NULL) {
+ PMD_LOG(ERR, "Unable to allocate fd array");
+ return -1;
+ }
+ for (unsigned int i = 0; i < RTE_MAX_QUEUES_PER_PORT; i++)
+ fds[i] = -1;
+
eth_dev = rte_eth_vdev_allocate(vdev, sizeof(struct pmd_internals));
if (eth_dev == NULL) {
PMD_LOG(ERR, "%s Unable to allocate device struct", tap_name);
goto error;
}

+ eth_dev->data->dev_flags = RTE_ETH_DEV_AUTOFILL_QUEUE_XSTATS;
+ eth_dev->dev_ops = &ops;
+ eth_dev->process_private = fds;
+
if (ioring_create(eth_dev, tap_name, persist) < 0)
goto error;

+ /* register the MP server on the first device */
+ static unsigned int ioring_dev_count;
+ if (ioring_dev_count == 0) {
+ if (rte_mp_action_register(IORING_MP_KEY, ioring_mp_send_fds) < 0) {
+ PMD_LOG(ERR, "Failed to register multi-process callback: %s",
+ rte_strerror(rte_errno));
+ goto error;
+ }
+ }
+ ++ioring_dev_count;
rte_eth_dev_probing_finish(eth_dev);
return 0;

error:
if (eth_dev != NULL)
rte_eth_dev_release_port(eth_dev);
+ free(fds);
rte_kvargs_free(kvlist);
return -1;
}
--
2.47.2