net: pass queue rx page size from memory provider

Allow memory providers to configure rx queues with a custom receive
page size. It's passed in struct pp_memory_provider_params, which is
copied into the queue, so it's preserved across queue restarts. Then,
it's propagated to the driver in a new queue config parameter.

Drivers should explicitly opt into using it by setting
QCFG_RX_PAGE_SIZE, in which case they should implement ndo_default_qcfg,
validate the size on queue restart and honour the current config in case
of a reset.

Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>

Author: isilence

include/net/netdev_queues.h

@@ -15,6 +15,7 @@ struct netdev_config {
 };
 
 struct netdev_queue_config {
+	u32	rx_page_size;
 };
 
 /* See the netdev.yaml spec for definition of each statistic */
@@ -114,6 +115,11 @@ void netdev_stat_queue_sum(struct net_device *netdev,
 			   int tx_start, int tx_end,
 			   struct netdev_queue_stats_tx *tx_sum);
 
+enum {
+	/* The queue checks and honours the page size qcfg parameter */
+	QCFG_RX_PAGE_SIZE	= 0x1,
+};
+
 /**
  * struct netdev_queue_mgmt_ops - netdev ops for queue management
  *
@@ -135,6 +141,8 @@ void netdev_stat_queue_sum(struct net_device *netdev,
  *
  * @ndo_default_qcfg:	Populate queue config struct with defaults. Optional.
  *
+ * @supported_params:	Bitmask of supported parameters, see QCFG_*.
+ *
  * Note that @ndo_queue_mem_alloc and @ndo_queue_mem_free may be called while
  * the interface is closed. @ndo_queue_start and @ndo_queue_stop will only
  * be called for an interface which is open.
@@ -158,6 +166,8 @@ struct netdev_queue_mgmt_ops {
 				    struct netdev_queue_config *qcfg);
 	struct device *	(*ndo_queue_get_dma_dev)(struct net_device *dev,
 						 int idx);
+
+	unsigned int supported_params;
 };
 
 bool netif_rxq_has_unreadable_mp(struct net_device *dev, int idx);

include/net/page_pool/types.h

@@ -161,6 +161,7 @@ struct memory_provider_ops;
 struct pp_memory_provider_params {
 	void *mp_priv;
 	const struct memory_provider_ops *mp_ops;
+	u32 rx_page_size;
 };
 
 struct page_pool {

net/core/netdev_rx_queue.c

@@ -30,12 +30,21 @@ int netdev_rx_queue_restart(struct net_device *dev, unsigned int rxq_idx)
 	    !qops->ndo_queue_mem_alloc || !qops->ndo_queue_start)
 		return -EOPNOTSUPP;
 
+	if (WARN_ON_ONCE(qops->supported_params && !qops->ndo_default_qcfg))
+		return -EINVAL;
+
 	netdev_assert_locked(dev);
 
 	memset(&qcfg, 0, sizeof(qcfg));
 	if (qops->ndo_default_qcfg)
 		qops->ndo_default_qcfg(dev, &qcfg);
 
+	if (rxq->mp_params.rx_page_size) {
+		if (!(qops->supported_params & QCFG_RX_PAGE_SIZE))
+			return -EOPNOTSUPP;
+		qcfg.rx_page_size = rxq->mp_params.rx_page_size;
+	}
+
 	new_mem = kvzalloc(qops->ndo_queue_mem_size, GFP_KERNEL);
 	if (!new_mem)
 		return -ENOMEM;