netdev - [PATCH net-next 08/20] net: Proxy net_mp_{open,close}

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Message-ID: <20250919213153.103606-9-daniel@iogearbox.net>
Date: Fri, 19 Sep 2025 23:31:41 +0200
From: Daniel Borkmann <daniel@...earbox.net>
To: netdev@...r.kernel.org
Cc: bpf@...r.kernel.org,
	kuba@...nel.org,
	davem@...emloft.net,
	razor@...ckwall.org,
	pabeni@...hat.com,
	willemb@...gle.com,
	sdf@...ichev.me,
	john.fastabend@...il.com,
	martin.lau@...nel.org,
	jordan@...fe.io,
	maciej.fijalkowski@...el.com,
	magnus.karlsson@...el.com,
	David Wei <dw@...idwei.uk>
Subject: [PATCH net-next 08/20] net: Proxy net_mp_{open,close}_rxq for mapped queues

From: David Wei <dw@...idwei.uk>

When a process in a container wants to setup a memory provider, it will
use the virtual netdev and a mapped rxq, and call net_mp_{open,close}_rxq
to try and restart the queue. At this point, proxy the queue restart on
the real rxq in the physical netdev.

For memory providers (io_uring zero-copy rx and devmem), it causes the
real rxq in the physical netdev to be filled from a memory provider that
has DMA mapped memory from a process within a container.

Signed-off-by: David Wei <dw@...idwei.uk>
Co-developed-by: Daniel Borkmann <daniel@...earbox.net>
Signed-off-by: Daniel Borkmann <daniel@...earbox.net>
---
 net/core/netdev_rx_queue.c | 15 ++++++++++-----
 1 file changed, 10 insertions(+), 5 deletions(-)

diff --git a/net/core/netdev_rx_queue.c b/net/core/netdev_rx_queue.c
index c7d9341b7630..238d3cd9677e 100644
--- a/net/core/netdev_rx_queue.c
+++ b/net/core/netdev_rx_queue.c
@@ -105,13 +105,21 @@ int __net_mp_open_rxq(struct net_device *dev, unsigned int rxq_idx,
 
 	if (!netdev_need_ops_lock(dev))
 		return -EOPNOTSUPP;
-
 	if (rxq_idx >= dev->real_num_rx_queues) {
 		NL_SET_ERR_MSG(extack, "rx queue index out of range");
 		return -ERANGE;
 	}
+
 	rxq_idx = array_index_nospec(rxq_idx, dev->real_num_rx_queues);
+	rxq = __netif_get_rx_queue_peer(&dev, &rxq_idx);
 
+	/* Check again since dev might have changed */
+	if (!netdev_need_ops_lock(dev))
+		return -EOPNOTSUPP;
+	if (!dev->dev.parent) {
+		NL_SET_ERR_MSG(extack, "rx queue is mapped to a virtual netdev");
+		return -EBUSY;
+	}
 	if (dev->cfg->hds_config != ETHTOOL_TCP_DATA_SPLIT_ENABLED) {
 		NL_SET_ERR_MSG(extack, "tcp-data-split is disabled");
 		return -EINVAL;
@@ -124,8 +132,6 @@ int __net_mp_open_rxq(struct net_device *dev, unsigned int rxq_idx,
 		NL_SET_ERR_MSG(extack, "unable to custom memory provider to device with XDP program attached");
 		return -EEXIST;
 	}
-
-	rxq = __netif_get_rx_queue(dev, rxq_idx);
 	if (rxq->mp_params.mp_ops) {
 		NL_SET_ERR_MSG(extack, "designated queue already memory provider bound");
 		return -EEXIST;
@@ -136,7 +142,6 @@ int __net_mp_open_rxq(struct net_device *dev, unsigned int rxq_idx,
 		return -EBUSY;
 	}
 #endif
-
 	rxq->mp_params = *p;
 	ret = netdev_rx_queue_restart(dev, rxq_idx);
 	if (ret) {
@@ -166,7 +171,7 @@ void __net_mp_close_rxq(struct net_device *dev, unsigned int ifq_idx,
 	if (WARN_ON_ONCE(ifq_idx >= dev->real_num_rx_queues))
 		return;
 
-	rxq = __netif_get_rx_queue(dev, ifq_idx);
+	rxq = __netif_get_rx_queue_peer(&dev, &ifq_idx);
 
 	/* Callers holding a netdev ref may get here after we already
 	 * went thru shutdown via dev_memory_provider_uninstall().
-- 
2.43.0