[RFC PATCH v3 10/20] io_uring: setup ZC for an Rx queue when registering an ifq

[David Wei <dw@davidwei.uk>]

From: David Wei <davidhwei@meta.com>

This patch sets up ZC for an Rx queue in a net device when an ifq is
registered with io_uring. The Rx queue is specified in the registration
struct.

For now since there is only one ifq, its destruction is implicit during
io_uring cleanup.

Signed-off-by: David Wei <dw@davidwei.uk>
---
 io_uring/zc_rx.c | 45 +++++++++++++++++++++++++++++++++++++++++++--
 1 file changed, 43 insertions(+), 2 deletions(-)

diff --git a/io_uring/zc_rx.c b/io_uring/zc_rx.c
index 7e3e6f6d446b..259e08a34ab2 100644
--- a/io_uring/zc_rx.c
+++ b/io_uring/zc_rx.c
@@ -4,6 +4,7 @@
 #include <linux/errno.h>
 #include <linux/mm.h>
 #include <linux/io_uring.h>
+#include <linux/netdevice.h>
 
 #include <uapi/linux/io_uring.h>
 
@@ -11,6 +12,34 @@
 #include "kbuf.h"
 #include "zc_rx.h"
 
+typedef int (*bpf_op_t)(struct net_device *dev, struct netdev_bpf *bpf);
+
+static int __io_queue_mgmt(struct net_device *dev, struct io_zc_rx_ifq *ifq,
+			   u16 queue_id)
+{
+	struct netdev_bpf cmd;
+	bpf_op_t ndo_bpf;
+
+	ndo_bpf = dev->netdev_ops->ndo_bpf;
+	if (!ndo_bpf)
+		return -EINVAL;
+
+	cmd.command = XDP_SETUP_ZC_RX;
+	cmd.zc_rx.ifq = ifq;
+	cmd.zc_rx.queue_id = queue_id;
+	return ndo_bpf(dev, &cmd);
+}
+
+static int io_open_zc_rxq(struct io_zc_rx_ifq *ifq)
+{
+	return __io_queue_mgmt(ifq->dev, ifq, ifq->if_rxq_id);
+}
+
+static int io_close_zc_rxq(struct io_zc_rx_ifq *ifq)
+{
+	return __io_queue_mgmt(ifq->dev, NULL, ifq->if_rxq_id);
+}
+
 static int io_allocate_rbuf_ring(struct io_zc_rx_ifq *ifq,
 				 struct io_uring_zc_rx_ifq_reg *reg)
 {
@@ -52,6 +81,10 @@ static struct io_zc_rx_ifq *io_zc_rx_ifq_alloc(struct io_ring_ctx *ctx)
 
 static void io_zc_rx_ifq_free(struct io_zc_rx_ifq *ifq)
 {
+	if (ifq->if_rxq_id != -1)
+		io_close_zc_rxq(ifq);
+	if (ifq->dev)
+		dev_put(ifq->dev);
 	io_free_rbuf_ring(ifq);
 	kfree(ifq);
 }
@@ -77,18 +110,25 @@ int io_register_zc_rx_ifq(struct io_ring_ctx *ctx,
 	if (!ifq)
 		return -ENOMEM;
 
-	/* TODO: initialise network interface */
-
 	ret = io_allocate_rbuf_ring(ifq, &reg);
 	if (ret)
 		goto err;
 
+	ret = -ENODEV;
+	ifq->dev = dev_get_by_index(current->nsproxy->net_ns, reg.if_idx);
+	if (!ifq->dev)
+		goto err;
+
 	/* TODO: map zc region and initialise zc pool */
 
 	ifq->rq_entries = reg.rq_entries;
 	ifq->cq_entries = reg.cq_entries;
 	ifq->if_rxq_id = reg.if_rxq_id;
 
+	ret = io_open_zc_rxq(ifq);
+	if (ret)
+		goto err;
+
 	ring_sz = sizeof(struct io_rbuf_ring);
 	rqes_sz = sizeof(struct io_uring_rbuf_rqe) * ifq->rq_entries;
 	cqes_sz = sizeof(struct io_uring_rbuf_cqe) * ifq->cq_entries;
@@ -101,6 +141,7 @@ int io_register_zc_rx_ifq(struct io_ring_ctx *ctx,
 	reg.cq_off.tail = offsetof(struct io_rbuf_ring, cq.tail);
 
 	if (copy_to_user(arg, &reg, sizeof(reg))) {
+		io_close_zc_rxq(ifq);
 		ret = -EFAULT;
 		goto err;
 	}
-- 
2.39.3