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net: Proxy netdev_queue_get_dma_dev for leased queues 

Extend netdev_queue_get_dma_dev to return the physical device of the
real rxq for DMA in case the queue was leased. This allows memory
providers like io_uring zero-copy or devmem to bind to the physically
leased rxq via virtual devices such as netkit.

Signed-off-by: David Wei <dw@davidwei.uk>
Co-developed-by: Daniel Borkmann <daniel@iogearbox.net>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Reviewed-by: Nikolay Aleksandrov <razor@blackwall.org>
Link: https://patch.msgid.link/20260402231031.447597-8-daniel@iogearbox.net
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
master
David Wei 2026-04-03 01:10:24 +02:00 committed by Jakub Kicinski
parent 5602ad61eb
commit 222b5566a0
4 changed files with 42 additions and 15 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

4
include/net/netdev_queues.h
View File

@ -380,7 +380,9 @@ static inline unsigned int netif_xmit_timeout_ms(struct netdev_queue *txq)
get_desc, start_thrs); \ get_desc, start_thrs); \
}) })
struct device *netdev_queue_get_dma_dev(struct net_device *dev, int idx); struct device *netdev_queue_get_dma_dev(struct net_device *dev,
unsigned int idx,
enum netdev_queue_type type);
bool netdev_can_create_queue(const struct net_device *dev, bool netdev_can_create_queue(const struct net_device *dev,
struct netlink_ext_ack *extack); struct netlink_ext_ack *extack);
bool netdev_can_lease_queue(const struct net_device *dev, bool netdev_can_lease_queue(const struct net_device *dev,

3
io_uring/zcrx.c
View File

@ -829,7 +829,8 @@ int io_register_zcrx_ifq(struct io_ring_ctx *ctx,
} }
netdev_hold(ifq->netdev, &ifq->netdev_tracker, GFP_KERNEL); netdev_hold(ifq->netdev, &ifq->netdev_tracker, GFP_KERNEL);
ifq->dev = netdev_queue_get_dma_dev(ifq->netdev, reg.if_rxq); ifq->dev = netdev_queue_get_dma_dev(ifq->netdev, reg.if_rxq,
NETDEV_QUEUE_TYPE_RX);
if (!ifq->dev) { if (!ifq->dev) {
ret = -EOPNOTSUPP; ret = -EOPNOTSUPP;
goto netdev_put_unlock; goto netdev_put_unlock;

5
net/core/netdev-genl.c
View File

@ -976,7 +976,8 @@ netdev_nl_get_dma_dev(struct net_device *netdev, unsigned long *rxq_bitmap,
for_each_set_bit(rxq_idx, rxq_bitmap, netdev->real_num_rx_queues) { for_each_set_bit(rxq_idx, rxq_bitmap, netdev->real_num_rx_queues) {
struct device *rxq_dma_dev; struct device *rxq_dma_dev;
rxq_dma_dev = netdev_queue_get_dma_dev(netdev, rxq_idx); rxq_dma_dev = netdev_queue_get_dma_dev(netdev, rxq_idx,
NETDEV_QUEUE_TYPE_RX);
if (dma_dev && rxq_dma_dev != dma_dev) { if (dma_dev && rxq_dma_dev != dma_dev) {
NL_SET_ERR_MSG_FMT(extack, "DMA device mismatch between queue %u and %u (multi-PF device?)", NL_SET_ERR_MSG_FMT(extack, "DMA device mismatch between queue %u and %u (multi-PF device?)",
rxq_idx, prev_rxq_idx); rxq_idx, prev_rxq_idx);
@ -1153,7 +1154,7 @@ int netdev_nl_bind_tx_doit(struct sk_buff *skb, struct genl_info *info)
goto err_unlock_netdev; goto err_unlock_netdev;
} }
dma_dev = netdev_queue_get_dma_dev(netdev, 0); dma_dev = netdev_queue_get_dma_dev(netdev, 0, NETDEV_QUEUE_TYPE_TX);
binding = net_devmem_bind_dmabuf(netdev, dma_dev, DMA_TO_DEVICE, binding = net_devmem_bind_dmabuf(netdev, dma_dev, DMA_TO_DEVICE,
dmabuf_fd, priv, info->extack); dmabuf_fd, priv, info->extack);
if (IS_ERR(binding)) { if (IS_ERR(binding)) {

45
net/core/netdev_queues.c
View File

@ -6,17 +6,8 @@
#include "dev.h" #include "dev.h"
/** static struct device *
* netdev_queue_get_dma_dev() - get dma device for zero-copy operations __netdev_queue_get_dma_dev(struct net_device *dev, unsigned int idx)
* @dev: net_device
* @idx: queue index
*
* Get dma device for zero-copy operations to be used for this queue.
* When such device is not available or valid, the function will return NULL.
*
* Return: Device or NULL on error
*/
struct device *netdev_queue_get_dma_dev(struct net_device *dev, int idx)
{ {
const struct netdev_queue_mgmt_ops *queue_ops = dev->queue_mgmt_ops; const struct netdev_queue_mgmt_ops *queue_ops = dev->queue_mgmt_ops;
struct device *dma_dev; struct device *dma_dev;
@ -29,6 +20,38 @@ struct device *netdev_queue_get_dma_dev(struct net_device *dev, int idx)
return dma_dev && dma_dev->dma_mask ? dma_dev : NULL; return dma_dev && dma_dev->dma_mask ? dma_dev : NULL;
} }
/**
* netdev_queue_get_dma_dev() - get dma device for zero-copy operations
* @dev: net_device
* @idx: queue index
* @type: queue type (RX or TX)
*
* Get dma device for zero-copy operations to be used for this queue. If
* the queue is an RX queue leased from a physical queue, we retrieve the
* physical queue's dma device. When the dma device is not available or
* valid, the function will return NULL.
*
* Return: Device or NULL on error
*/
struct device *netdev_queue_get_dma_dev(struct net_device *dev,
unsigned int idx,
enum netdev_queue_type type)
{
struct net_device *orig_dev = dev;
struct device *dma_dev;
/* Only RX side supports queue leasing today. */
if (type != NETDEV_QUEUE_TYPE_RX || !netif_rxq_is_leased(dev, idx))
return __netdev_queue_get_dma_dev(dev, idx);
if (!netif_get_rx_queue_lease_locked(&dev, &idx))
return NULL;
dma_dev = __netdev_queue_get_dma_dev(dev, idx);
netif_put_rx_queue_lease_locked(orig_dev, dev);
return dma_dev;
}
bool netdev_can_create_queue(const struct net_device *dev, bool netdev_can_create_queue(const struct net_device *dev,
struct netlink_ext_ack *extack) struct netlink_ext_ack *extack)
{ {