Merge branch 'device-memory-tcp-tx'

Mina Almasry says:

====================
Device memory TCP TX

The TX path had been dropped from the Device Memory TCP patch series
post RFCv1 [1], to make that series slightly easier to review. This
series rebases the implementation of the TX path on top of the
net_iov/netmem framework agreed upon and merged. The motivation for
the feature is thoroughly described in the docs & cover letter of the
original proposal, so I don't repeat the lengthy descriptions here, but
they are available in [1].

Full outline on usage of the TX path is detailed in the documentation
included with this series.

Test example is available via the kselftest included in the series as well.

The series is relatively small, as the TX path for this feature largely
piggybacks on the existing MSG_ZEROCOPY implementation.

Patch Overview:
---------------

1. Documentation & tests to give high level overview of the feature
   being added.

1. Add netmem refcounting needed for the TX path.

2. Devmem TX netlink API.

3. Devmem TX net stack implementation.

4. Make dma-buf unbinding scheduled work to handle TX cases where it gets
   freed from contexts where we can't sleep.

5. Add devmem TX documentation.

6. Add scaffolding enabling driver support for netmem_tx. Add helpers, driver
feature flag, and docs to enable drivers to declare netmem_tx support.

7. Guard netmem_tx against being enabled against drivers that don't
   support it.

8. Add devmem_tx selftests. Add TX path to ncdevmem and add a test to
   devmem.py.

Testing:
--------

Testing is very similar to devmem TCP RX path. The ncdevmem test used
for the RX path is now augemented with client functionality to test TX
path.

* Test Setup:

Kernel: net-next with this RFC and memory provider API cherry-picked
locally.

Hardware: Google Cloud A3 VMs.

NIC: GVE with header split & RSS & flow steering support.

Performance results are not included with this version, unfortunately.
I'm having issues running the dma-buf exporter driver against the
upstream kernel on my test setup. The issues are specific to that
dma-buf exporter and do not affect this patch series. I plan to follow
up this series with perf fixes if the tests point to issues once they're
up and running.

Special thanks to Stan who took a stab at rebasing the TX implementation
on top of the netmem/net_iov framework merged. Parts of his proposal [2]
that are reused as-is are forked off into their own patches to give full
credit.

[1] https://lore.kernel.org/netdev/20240909054318.1809580-1-almasrymina@google.com/
[2] https://lore.kernel.org/netdev/20240913150913.1280238-2-sdf@fomichev.me/T/#m066dd407fbed108828e2c40ae50e3f4376ef57fd

Cc: sdf@fomichev.me
Cc: asml.silence@gmail.com
Cc: dw@davidwei.uk
Cc: Jamal Hadi Salim <jhs@mojatatu.com>
Cc: Victor Nogueira <victor@mojatatu.com>
Cc: Pedro Tammela <pctammela@mojatatu.com>
Cc: Samiullah Khawaja <skhawaja@google.com>
Cc: Kuniyuki Iwashima <kuniyu@amazon.com>

v14: https://lore.kernel.org/netdev/20250429032645.363766-1-almasrymina@google.com/
v13: https://lore.kernel.org/netdev/20250425204743.617260-1-almasrymina@google.com/
v12: https://lore.kernel.org/netdev/20250423031117.907681-1-almasrymina@google.com/
v11: https://lore.kernel.org/netdev/20250423031117.907681-1-almasrymina@google.com/
v10: https://lore.kernel.org/netdev/20250417231540.2780723-1-almasrymina@google.com/
v9: https://lore.kernel.org/netdev/20250415224756.152002-1-almasrymina@google.com/
v8: https://lore.kernel.org/netdev/20250308214045.1160445-1-almasrymina@google.com/
v7: https://lore.kernel.org/netdev/20250227041209.2031104-1-almasrymina@google.com/
v6: https://lore.kernel.org/netdev/20250222191517.743530-1-almasrymina@google.com/
v5: https://lore.kernel.org/netdev/20250220020914.895431-1-almasrymina@google.com/
v4: https://lore.kernel.org/netdev/20250203223916.1064540-1-almasrymina@google.com/
v3: https://patchwork.kernel.org/project/netdevbpf/list/?series=929401&state=*
RFC v2: https://patchwork.kernel.org/project/netdevbpf/list/?series=920056&state=*
====================

Link: https://patch.msgid.link/20250508004830.4100853-1-almasrymina@google.com
Signed-off-by: Paolo Abeni <pabeni@redhat.com>

30 files changed, 1007 insertions, 86 deletions

diff --git a/Documentation/netlink/specs/netdev.yaml b/Documentation/netlink/specs/netdev.yaml
index f5e0750ab71d..c0ef6d0d7786 100644
--- a/Documentation/netlink/specs/netdev.yaml
+++ b/Documentation/netlink/specs/netdev.yaml
@@ -743,6 +743,18 @@ operations:
             - defer-hard-irqs
             - gro-flush-timeout
             - irq-suspend-timeout
+    -
+      name: bind-tx
+      doc: Bind dmabuf to netdev for TX
+      attribute-set: dmabuf
+      do:
+        request:
+          attributes:
+            - ifindex
+            - fd
+        reply:
+          attributes:
+            - id
 
 kernel-family:
   headers: [ "net/netdev_netlink.h"]
diff --git a/Documentation/networking/devmem.rst b/Documentation/networking/devmem.rst
index eb678ca45496..a6cd7236bfbd 100644
--- a/Documentation/networking/devmem.rst
+++ b/Documentation/networking/devmem.rst
@@ -62,15 +62,15 @@ More Info
     https://lore.kernel.org/netdev/20240831004313.3713467-1-almasrymina@google.com/
 
 
-Interface
-=========
+RX Interface
+============
 
 
 Example
 -------
 
-tools/testing/selftests/net/ncdevmem.c:do_server shows an example of setting up
-the RX path of this API.
+./tools/testing/selftests/drivers/net/hw/ncdevmem:do_server shows an example of
+setting up the RX path of this API.
 
 
 NIC Setup
@@ -235,6 +235,148 @@ can be less than the tokens provided by the user in case of:
 (a) an internal kernel leak bug.
 (b) the user passed more than 1024 frags.
 
+TX Interface
+============
+
+
+Example
+-------
+
+./tools/testing/selftests/drivers/net/hw/ncdevmem:do_client shows an example of
+setting up the TX path of this API.
+
+
+NIC Setup
+---------
+
+The user must bind a TX dmabuf to a given NIC using the netlink API::
+
+        struct netdev_bind_tx_req *req = NULL;
+        struct netdev_bind_tx_rsp *rsp = NULL;
+        struct ynl_error yerr;
+
+        *ys = ynl_sock_create(&ynl_netdev_family, &yerr);
+
+        req = netdev_bind_tx_req_alloc();
+        netdev_bind_tx_req_set_ifindex(req, ifindex);
+        netdev_bind_tx_req_set_fd(req, dmabuf_fd);
+
+        rsp = netdev_bind_tx(*ys, req);
+
+        tx_dmabuf_id = rsp->id;
+
+
+The netlink API returns a dmabuf_id: a unique ID that refers to this dmabuf
+that has been bound.
+
+The user can unbind the dmabuf from the netdevice by closing the netlink socket
+that established the binding. We do this so that the binding is automatically
+unbound even if the userspace process crashes.
+
+Note that any reasonably well-behaved dmabuf from any exporter should work with
+devmem TCP, even if the dmabuf is not actually backed by devmem. An example of
+this is udmabuf, which wraps user memory (non-devmem) in a dmabuf.
+
+Socket Setup
+------------
+
+The user application must use MSG_ZEROCOPY flag when sending devmem TCP. Devmem
+cannot be copied by the kernel, so the semantics of the devmem TX are similar
+to the semantics of MSG_ZEROCOPY::
+
+	setsockopt(socket_fd, SOL_SOCKET, SO_ZEROCOPY, &opt, sizeof(opt));
+
+It is also recommended that the user binds the TX socket to the same interface
+the dma-buf has been bound to via SO_BINDTODEVICE::
+
+	setsockopt(socket_fd, SOL_SOCKET, SO_BINDTODEVICE, ifname, strlen(ifname) + 1);
+
+
+Sending data
+------------
+
+Devmem data is sent using the SCM_DEVMEM_DMABUF cmsg.
+
+The user should create a msghdr where,
+
+* iov_base is set to the offset into the dmabuf to start sending from
+* iov_len is set to the number of bytes to be sent from the dmabuf
+
+The user passes the dma-buf id to send from via the dmabuf_tx_cmsg.dmabuf_id.
+
+The example below sends 1024 bytes from offset 100 into the dmabuf, and 2048
+from offset 2000 into the dmabuf. The dmabuf to send from is tx_dmabuf_id::
+
+       char ctrl_data[CMSG_SPACE(sizeof(struct dmabuf_tx_cmsg))];
+       struct dmabuf_tx_cmsg ddmabuf;
+       struct msghdr msg = {};
+       struct cmsghdr *cmsg;
+       struct iovec iov[2];
+
+       iov[0].iov_base = (void*)100;
+       iov[0].iov_len = 1024;
+       iov[1].iov_base = (void*)2000;
+       iov[1].iov_len = 2048;
+
+       msg.msg_iov = iov;
+       msg.msg_iovlen = 2;
+
+       msg.msg_control = ctrl_data;
+       msg.msg_controllen = sizeof(ctrl_data);
+
+       cmsg = CMSG_FIRSTHDR(&msg);
+       cmsg->cmsg_level = SOL_SOCKET;
+       cmsg->cmsg_type = SCM_DEVMEM_DMABUF;
+       cmsg->cmsg_len = CMSG_LEN(sizeof(struct dmabuf_tx_cmsg));
+
+       ddmabuf.dmabuf_id = tx_dmabuf_id;
+
+       *((struct dmabuf_tx_cmsg *)CMSG_DATA(cmsg)) = ddmabuf;
+
+       sendmsg(socket_fd, &msg, MSG_ZEROCOPY);
+
+
+Reusing TX dmabufs
+------------------
+
+Similar to MSG_ZEROCOPY with regular memory, the user should not modify the
+contents of the dma-buf while a send operation is in progress. This is because
+the kernel does not keep a copy of the dmabuf contents. Instead, the kernel
+will pin and send data from the buffer available to the userspace.
+
+Just as in MSG_ZEROCOPY, the kernel notifies the userspace of send completions
+using MSG_ERRQUEUE::
+
+        int64_t tstop = gettimeofday_ms() + waittime_ms;
+        char control[CMSG_SPACE(100)] = {};
+        struct sock_extended_err *serr;
+        struct msghdr msg = {};
+        struct cmsghdr *cm;
+        int retries = 10;
+        __u32 hi, lo;
+
+        msg.msg_control = control;
+        msg.msg_controllen = sizeof(control);
+
+        while (gettimeofday_ms() < tstop) {
+                if (!do_poll(fd)) continue;
+
+                ret = recvmsg(fd, &msg, MSG_ERRQUEUE);
+
+                for (cm = CMSG_FIRSTHDR(&msg); cm; cm = CMSG_NXTHDR(&msg, cm)) {
+                        serr = (void *)CMSG_DATA(cm);
+
+                        hi = serr->ee_data;
+                        lo = serr->ee_info;
+
+                        fprintf(stdout, "tx complete [%d,%d]\n", lo, hi);
+                }
+        }
+
+After the associated sendmsg has been completed, the dmabuf can be reused by
+the userspace.
+
+
 Implementation & Caveats
 ========================
 
diff --git a/Documentation/networking/net_cachelines/net_device.rst b/Documentation/networking/net_cachelines/net_device.rst
index ca8605eb82ff..c69cc89c958e 100644
--- a/Documentation/networking/net_cachelines/net_device.rst
+++ b/Documentation/networking/net_cachelines/net_device.rst
@@ -10,6 +10,7 @@ Type                                Name                        fastpath_tx_acce
 =================================== =========================== =================== =================== ===================================================================================
 unsigned_long:32                    priv_flags                  read_mostly                             __dev_queue_xmit(tx)
 unsigned_long:1                     lltx                        read_mostly                             HARD_TX_LOCK,HARD_TX_TRYLOCK,HARD_TX_UNLOCK(tx)
+unsigned long:1                     netmem_tx:1;                read_mostly
 char                                name[16]
 struct netdev_name_node*            name_node
 struct dev_ifalias*                 ifalias
diff --git a/Documentation/networking/netdev-features.rst b/Documentation/networking/netdev-features.rst
index 5014f7cc1398..02bd7536fc0c 100644
--- a/Documentation/networking/netdev-features.rst
+++ b/Documentation/networking/netdev-features.rst
@@ -188,3 +188,8 @@ Redundancy) frames from one port to another in hardware.
 This should be set for devices which duplicate outgoing HSR (High-availability
 Seamless Redundancy) or PRP (Parallel Redundancy Protocol) tags automatically
 frames in hardware.
+
+* netmem-tx
+
+This should be set for devices which support netmem TX. See
+Documentation/networking/netmem.rst
diff --git a/Documentation/networking/netmem.rst b/Documentation/networking/netmem.rst
index 7de21ddb5412..b63aded46337 100644
--- a/Documentation/networking/netmem.rst
+++ b/Documentation/networking/netmem.rst
@@ -19,8 +19,8 @@ Benefits of Netmem :
 * Simplified Development: Drivers interact with a consistent API,
   regardless of the underlying memory implementation.
 
-Driver Requirements
-===================
+Driver RX Requirements
+======================
 
 1. The driver must support page_pool.
 
@@ -77,3 +77,22 @@ Driver Requirements
    that purpose, but be mindful that some netmem types might have longer
    circulation times, such as when userspace holds a reference in zerocopy
    scenarios.
+
+Driver TX Requirements
+======================
+
+1. The Driver must not pass the netmem dma_addr to any of the dma-mapping APIs
+   directly. This is because netmem dma_addrs may come from a source like
+   dma-buf that is not compatible with the dma-mapping APIs.
+
+   Helpers like netmem_dma_unmap_page_attrs() & netmem_dma_unmap_addr_set()
+   should be used in lieu of dma_unmap_page[_attrs](), dma_unmap_addr_set().
+   The netmem variants will handle netmem dma_addrs correctly regardless of the
+   source, delegating to the dma-mapping APIs when appropriate.
+
+   Not all dma-mapping APIs have netmem equivalents at the moment. If your
+   driver relies on a missing netmem API, feel free to add and propose to
+   netdev@, or reach out to the maintainers and/or almasrymina@google.com for
+   help adding the netmem API.
+
+2. Driver should declare support by setting `netdev->netmem_tx = true`
diff --git a/drivers/net/ethernet/google/gve/gve_main.c b/drivers/net/ethernet/google/gve/gve_main.c
index 446e4b6fd3f1..e1ffbd561fac 100644
--- a/drivers/net/ethernet/google/gve/gve_main.c
+++ b/drivers/net/ethernet/google/gve/gve_main.c
@@ -2659,6 +2659,9 @@ static int gve_probe(struct pci_dev *pdev, const struct pci_device_id *ent)
 	if (err)
 		goto abort_with_wq;
 
+	if (!gve_is_gqi(priv) && !gve_is_qpl(priv))
+		dev->netmem_tx = true;
+
 	err = register_netdev(dev);
 	if (err)
 		goto abort_with_gve_init;
diff --git a/drivers/net/ethernet/google/gve/gve_tx_dqo.c b/drivers/net/ethernet/google/gve/gve_tx_dqo.c
index 2eba868d8037..a27f1574a733 100644
--- a/drivers/net/ethernet/google/gve/gve_tx_dqo.c
+++ b/drivers/net/ethernet/google/gve/gve_tx_dqo.c
@@ -660,7 +660,8 @@ static int gve_tx_add_skb_no_copy_dqo(struct gve_tx_ring *tx,
 			goto err;
 
 		dma_unmap_len_set(pkt, len[pkt->num_bufs], len);
-		dma_unmap_addr_set(pkt, dma[pkt->num_bufs], addr);
+		netmem_dma_unmap_addr_set(skb_frag_netmem(frag), pkt,
+					  dma[pkt->num_bufs], addr);
 		++pkt->num_bufs;
 
 		gve_tx_fill_pkt_desc_dqo(tx, desc_idx, skb, len, addr,
@@ -1038,8 +1039,9 @@ static void gve_unmap_packet(struct device *dev,
 	dma_unmap_single(dev, dma_unmap_addr(pkt, dma[0]),
 			 dma_unmap_len(pkt, len[0]), DMA_TO_DEVICE);
 	for (i = 1; i < pkt->num_bufs; i++) {
-		dma_unmap_page(dev, dma_unmap_addr(pkt, dma[i]),
-			       dma_unmap_len(pkt, len[i]), DMA_TO_DEVICE);
+		netmem_dma_unmap_page_attrs(dev, dma_unmap_addr(pkt, dma[i]),
+					    dma_unmap_len(pkt, len[i]),
+					    DMA_TO_DEVICE, 0);
 	}
 	pkt->num_bufs = 0;
 }
diff --git a/include/linux/netdevice.h b/include/linux/netdevice.h
index 773167508c82..32a1e41636a9 100644
--- a/include/linux/netdevice.h
+++ b/include/linux/netdevice.h
@@ -1772,6 +1772,7 @@ enum netdev_reg_state {
  *	@lltx:		device supports lockless Tx. Deprecated for real HW
  *			drivers. Mainly used by logical interfaces, such as
  *			bonding and tunnels
+ *	@netmem_tx:	device support netmem_tx.
  *
  *	@name:	This is the first field of the "visible" part of this structure
  *		(i.e. as seen by users in the "Space.c" file).  It is the name
@@ -2087,6 +2088,7 @@ struct net_device {
 	struct_group(priv_flags_fast,
 		unsigned long		priv_flags:32;
 		unsigned long		lltx:1;
+		unsigned long		netmem_tx:1;
 	);
 	const struct net_device_ops *netdev_ops;
 	const struct header_ops *header_ops;
diff --git a/include/linux/skbuff.h b/include/linux/skbuff.h
index f3e72be6f634..c7397b17bb08 100644
--- a/include/linux/skbuff.h
+++ b/include/linux/skbuff.h
@@ -1707,13 +1707,16 @@ static inline void skb_set_end_offset(struct sk_buff *skb, unsigned int offset)
 extern const struct ubuf_info_ops msg_zerocopy_ubuf_ops;
 
 struct ubuf_info *msg_zerocopy_realloc(struct sock *sk, size_t size,
-				       struct ubuf_info *uarg);
+				       struct ubuf_info *uarg, bool devmem);
 
 void msg_zerocopy_put_abort(struct ubuf_info *uarg, bool have_uref);
 
+struct net_devmem_dmabuf_binding;
+
 int __zerocopy_sg_from_iter(struct msghdr *msg, struct sock *sk,
 			    struct sk_buff *skb, struct iov_iter *from,
-			    size_t length);
+			    size_t length,
+			    struct net_devmem_dmabuf_binding *binding);
 
 int zerocopy_fill_skb_from_iter(struct sk_buff *skb,
 				struct iov_iter *from, size_t length);
@@ -1721,12 +1724,14 @@ int zerocopy_fill_skb_from_iter(struct sk_buff *skb,
 static inline int skb_zerocopy_iter_dgram(struct sk_buff *skb,
 					  struct msghdr *msg, int len)
 {
-	return __zerocopy_sg_from_iter(msg, skb->sk, skb, &msg->msg_iter, len);
+	return __zerocopy_sg_from_iter(msg, skb->sk, skb, &msg->msg_iter, len,
+				       NULL);
 }
 
 int skb_zerocopy_iter_stream(struct sock *sk, struct sk_buff *skb,
 			     struct msghdr *msg, int len,
-			     struct ubuf_info *uarg);
+			     struct ubuf_info *uarg,
+			     struct net_devmem_dmabuf_binding *binding);
 
 /* Internal */
 #define skb_shinfo(SKB)	((struct skb_shared_info *)(skb_end_pointer(SKB)))
@@ -3697,6 +3702,10 @@ static inline dma_addr_t __skb_frag_dma_map(struct device *dev,
 					    size_t offset, size_t size,
 					    enum dma_data_direction dir)
 {
+	if (skb_frag_is_net_iov(frag)) {
+		return netmem_to_net_iov(frag->netmem)->dma_addr + offset +
+		       frag->offset;
+	}
 	return dma_map_page(dev, skb_frag_page(frag),
 			    skb_frag_off(frag) + offset, size, dir);
 }
diff --git a/include/linux/skbuff_ref.h b/include/linux/skbuff_ref.h
index 0f3c58007488..9e49372ef1a0 100644
--- a/include/linux/skbuff_ref.h
+++ b/include/linux/skbuff_ref.h
@@ -17,7 +17,7 @@
  */
 static inline void __skb_frag_ref(skb_frag_t *frag)
 {
-	get_page(skb_frag_page(frag));
+	get_netmem(skb_frag_netmem(frag));
 }
 
 /**
@@ -40,7 +40,7 @@ static inline void skb_page_unref(netmem_ref netmem, bool recycle)
 	if (recycle && napi_pp_put_page(netmem))
 		return;
 #endif
-	put_page(netmem_to_page(netmem));
+	put_netmem(netmem);
 }
 
 /**
diff --git a/include/net/netmem.h b/include/net/netmem.h
index c61d5b21e7b4..386164fb9c18 100644
--- a/include/net/netmem.h
+++ b/include/net/netmem.h
@@ -8,6 +8,7 @@
 #ifndef _NET_NETMEM_H
 #define _NET_NETMEM_H
 
+#include <linux/dma-mapping.h>
 #include <linux/mm.h>
 #include <net/net_debug.h>
 
@@ -20,8 +21,17 @@ DECLARE_STATIC_KEY_FALSE(page_pool_mem_providers);
  */
 #define NET_IOV 0x01UL
 
+enum net_iov_type {
+	NET_IOV_DMABUF,
+	NET_IOV_IOURING,
+
+	/* Force size to unsigned long to make the NET_IOV_ASSERTS below pass.
+	 */
+	NET_IOV_MAX = ULONG_MAX
+};
+
 struct net_iov {
-	unsigned long __unused_padding;
+	enum net_iov_type type;
 	unsigned long pp_magic;
 	struct page_pool *pp;
 	struct net_iov_area *owner;
@@ -264,4 +274,26 @@ static inline unsigned long netmem_get_dma_addr(netmem_ref netmem)
 	return __netmem_clear_lsb(netmem)->dma_addr;
 }
 
+void get_netmem(netmem_ref netmem);
+void put_netmem(netmem_ref netmem);
+
+#define netmem_dma_unmap_addr_set(NETMEM, PTR, ADDR_NAME, VAL)   \
+	do {                                                     \
+		if (!netmem_is_net_iov(NETMEM))                  \
+			dma_unmap_addr_set(PTR, ADDR_NAME, VAL); \
+		else                                             \
+			dma_unmap_addr_set(PTR, ADDR_NAME, 0);   \
+	} while (0)
+
+static inline void netmem_dma_unmap_page_attrs(struct device *dev,
+					       dma_addr_t addr, size_t size,
+					       enum dma_data_direction dir,
+					       unsigned long attrs)
+{
+	if (!addr)
+		return;
+
+	dma_unmap_page_attrs(dev, addr, size, dir, attrs);
+}
+
 #endif /* _NET_NETMEM_H */
diff --git a/include/net/sock.h b/include/net/sock.h
index f0fabb9fd28a..3e15d7105ad2 100644
--- a/include/net/sock.h
+++ b/include/net/sock.h
@@ -1851,6 +1851,7 @@ struct sockcm_cookie {
 	u32 tsflags;
 	u32 ts_opt_id;
 	u32 priority;
+	u32 dmabuf_id;
 };
 
 static inline void sockcm_init(struct sockcm_cookie *sockc,
diff --git a/include/uapi/linux/netdev.h b/include/uapi/linux/netdev.h
index 7600bf62dbdf..7eb9571786b8 100644
--- a/include/uapi/linux/netdev.h
+++ b/include/uapi/linux/netdev.h
@@ -219,6 +219,7 @@ enum {
 	NETDEV_CMD_QSTATS_GET,
 	NETDEV_CMD_BIND_RX,
 	NETDEV_CMD_NAPI_SET,
+	NETDEV_CMD_BIND_TX,
 
 	__NETDEV_CMD_MAX,
 	NETDEV_CMD_MAX = (__NETDEV_CMD_MAX - 1)
diff --git a/io_uring/zcrx.c b/io_uring/zcrx.c
index fe86606b9f30..0c64129f5d50 100644
--- a/io_uring/zcrx.c
+++ b/io_uring/zcrx.c
@@ -259,6 +259,7 @@ static int io_zcrx_create_area(struct io_zcrx_ifq *ifq,
 		niov->owner = &area->nia;
 		area->freelist[i] = i;
 		atomic_set(&area->user_refs[i], 0);
+		niov->type = NET_IOV_IOURING;
 	}
 
 	area->free_count = nr_iovs;
@@ -809,7 +810,7 @@ static int io_zcrx_recv_frag(struct io_kiocb *req, struct io_zcrx_ifq *ifq,
 		return io_zcrx_copy_frag(req, ifq, frag, off, len);
 
 	niov = netmem_to_net_iov(frag->netmem);
-	if (niov->pp->mp_ops != &io_uring_pp_zc_ops ||
+	if (!niov->pp || niov->pp->mp_ops != &io_uring_pp_zc_ops ||
 	    io_pp_to_ifq(niov->pp) != ifq)
 		return -EFAULT;
 
diff --git a/net/core/datagram.c b/net/core/datagram.c
index f0634f0cb834..9ef5442536f5 100644
--- a/net/core/datagram.c
+++ b/net/core/datagram.c
@@ -63,6 +63,8 @@
 #include <net/busy_poll.h>
 #include <crypto/hash.h>
 
+#include "devmem.h"
+
 /*
  *	Is a socket 'connection oriented' ?
  */
@@ -691,9 +693,49 @@ int zerocopy_fill_skb_from_iter(struct sk_buff *skb,
 	return 0;
 }
 
+static int
+zerocopy_fill_skb_from_devmem(struct sk_buff *skb, struct iov_iter *from,
+			      int length,
+			      struct net_devmem_dmabuf_binding *binding)
+{
+	int i = skb_shinfo(skb)->nr_frags;
+	size_t virt_addr, size, off;
+	struct net_iov *niov;
+
+	/* Devmem filling works by taking an IOVEC from the user where the
+	 * iov_addrs are interpreted as an offset in bytes into the dma-buf to
+	 * send from. We do not support other iter types.
+	 */
+	if (iov_iter_type(from) != ITER_IOVEC)
+		return -EFAULT;
+
+	while (length && iov_iter_count(from)) {
+		if (i == MAX_SKB_FRAGS)
+			return -EMSGSIZE;
+
+		virt_addr = (size_t)iter_iov_addr(from);
+		niov = net_devmem_get_niov_at(binding, virt_addr, &off, &size);
+		if (!niov)
+			return -EFAULT;
+
+		size = min_t(size_t, size, length);
+		size = min_t(size_t, size, iter_iov_len(from));
+
+		get_netmem(net_iov_to_netmem(niov));
+		skb_add_rx_frag_netmem(skb, i, net_iov_to_netmem(niov), off,
+				       size, PAGE_SIZE);
+		iov_iter_advance(from, size);
+		length -= size;
+		i++;
+	}
+
+	return 0;
+}
+
 int __zerocopy_sg_from_iter(struct msghdr *msg, struct sock *sk,
 			    struct sk_buff *skb, struct iov_iter *from,
-			    size_t length)
+			    size_t length,
+			    struct net_devmem_dmabuf_binding *binding)
 {
 	unsigned long orig_size = skb->truesize;
 	unsigned long truesize;
@@ -701,6 +743,8 @@ int __zerocopy_sg_from_iter(struct msghdr *msg, struct sock *sk,
 
 	if (msg && msg->msg_ubuf && msg->sg_from_iter)
 		ret = msg->sg_from_iter(skb, from, length);
+	else if (binding)
+		ret = zerocopy_fill_skb_from_devmem(skb, from, length, binding);
 	else
 		ret = zerocopy_fill_skb_from_iter(skb, from, length);
 
@@ -734,7 +778,7 @@ int zerocopy_sg_from_iter(struct sk_buff *skb, struct iov_iter *from)
 	if (skb_copy_datagram_from_iter(skb, 0, from, copy))
 		return -EFAULT;
 
-	return __zerocopy_sg_from_iter(NULL, NULL, skb, from, ~0U);
+	return __zerocopy_sg_from_iter(NULL, NULL, skb, from, ~0U, NULL);
 }
 EXPORT_SYMBOL(zerocopy_sg_from_iter);
 
diff --git a/net/core/dev.c b/net/core/dev.c
index c9013632296f..33d5e95209cb 100644
--- a/net/core/dev.c
+++ b/net/core/dev.c
@@ -3896,12 +3896,42 @@ sw_checksum:
 }
 EXPORT_SYMBOL(skb_csum_hwoffload_help);
 
+static struct sk_buff *validate_xmit_unreadable_skb(struct sk_buff *skb,
+						    struct net_device *dev)
+{
+	struct skb_shared_info *shinfo;
+	struct net_iov *niov;
+
+	if (likely(skb_frags_readable(skb)))
+		goto out;
+
+	if (!dev->netmem_tx)
+		goto out_free;
+
+	shinfo = skb_shinfo(skb);
+
+	if (shinfo->nr_frags > 0) {
+		niov = netmem_to_net_iov(skb_frag_netmem(&shinfo->frags[0]));
+		if (net_is_devmem_iov(niov) &&
+		    net_devmem_iov_binding(niov)->dev != dev)
+			goto out_free;
+	}
+
+out:
+	return skb;
+
+out_free:
+	kfree_skb(skb);
+	return NULL;
+}
+
 static struct sk_buff *validate_xmit_skb(struct sk_buff *skb, struct net_device *dev, bool *again)
 {
 	netdev_features_t features;
 
-	if (!skb_frags_readable(skb))
-		goto out_kfree_skb;
+	skb = validate_xmit_unreadable_skb(skb, dev);
+	if (unlikely(!skb))
+		goto out_null;
 
 	features = netif_skb_features(skb);
 	skb = validate_xmit_vlan(skb, features);
diff --git a/net/core/devmem.c b/net/core/devmem.c
index 6e27a47d0493..88065e5ef651 100644
--- a/net/core/devmem.c
+++ b/net/core/devmem.c
@@ -16,6 +16,7 @@
 #include <net/netdev_rx_queue.h>
 #include <net/page_pool/helpers.h>
 #include <net/page_pool/memory_provider.h>
+#include <net/sock.h>
 #include <trace/events/page_pool.h>
 
 #include "devmem.h"
@@ -30,7 +31,7 @@ static const struct memory_provider_ops dmabuf_devmem_ops;
 
 bool net_is_devmem_iov(struct net_iov *niov)
 {
-	return niov->pp->mp_ops == &dmabuf_devmem_ops;
+	return niov->type == NET_IOV_DMABUF;
 }
 
 static void net_devmem_dmabuf_free_chunk_owner(struct gen_pool *genpool,
@@ -52,8 +53,10 @@ static dma_addr_t net_devmem_get_dma_addr(const struct net_iov *niov)
 	       ((dma_addr_t)net_iov_idx(niov) << PAGE_SHIFT);
 }
 
-void __net_devmem_dmabuf_binding_free(struct net_devmem_dmabuf_binding *binding)
+void __net_devmem_dmabuf_binding_free(struct work_struct *wq)
 {
+	struct net_devmem_dmabuf_binding *binding = container_of(wq, typeof(*binding), unbind_w);
+
 	size_t size, avail;
 
 	gen_pool_for_each_chunk(binding->chunk_pool,
@@ -71,8 +74,10 @@ void __net_devmem_dmabuf_binding_free(struct net_devmem_dmabuf_binding *binding)
 	dma_buf_detach(binding->dmabuf, binding->attachment);
 	dma_buf_put(binding->dmabuf);
 	xa_destroy(&binding->bound_rxqs);
+	kvfree(binding->tx_vec);
 	kfree(binding);
 }
+EXPORT_SYMBOL(__net_devmem_dmabuf_binding_free);
 
 struct net_iov *
 net_devmem_alloc_dmabuf(struct net_devmem_dmabuf_binding *binding)
@@ -117,6 +122,13 @@ void net_devmem_unbind_dmabuf(struct net_devmem_dmabuf_binding *binding)
 	unsigned long xa_idx;
 	unsigned int rxq_idx;
 
+	xa_erase(&net_devmem_dmabuf_bindings, binding->id);
+
+	/* Ensure no tx net_devmem_lookup_dmabuf() are in flight after the
+	 * erase.
+	 */
+	synchronize_net();
+
 	if (binding->list.next)
 		list_del(&binding->list);
 
@@ -131,8 +143,6 @@ void net_devmem_unbind_dmabuf(struct net_devmem_dmabuf_binding *binding)
 		__net_mp_close_rxq(binding->dev, rxq_idx, &mp_params);
 	}
 
-	xa_erase(&net_devmem_dmabuf_bindings, binding->id);
-
 	net_devmem_dmabuf_binding_put(binding);
 }
 
@@ -166,8 +176,9 @@ err_close_rxq:
 }
 
 struct net_devmem_dmabuf_binding *
-net_devmem_bind_dmabuf(struct net_device *dev, unsigned int dmabuf_fd,
-		       struct netlink_ext_ack *extack)
+net_devmem_bind_dmabuf(struct net_device *dev,
+		       enum dma_data_direction direction,
+		       unsigned int dmabuf_fd, struct netlink_ext_ack *extack)
 {
 	struct net_devmem_dmabuf_binding *binding;
 	static u32 id_alloc_next;
@@ -189,13 +200,6 @@ net_devmem_bind_dmabuf(struct net_device *dev, unsigned int dmabuf_fd,
 	}
 
 	binding->dev = dev;
-
-	err = xa_alloc_cyclic(&net_devmem_dmabuf_bindings, &binding->id,
-			      binding, xa_limit_32b, &id_alloc_next,
-			      GFP_KERNEL);
-	if (err < 0)
-		goto err_free_binding;
-
 	xa_init_flags(&binding->bound_rxqs, XA_FLAGS_ALLOC);
 
 	refcount_set(&binding->ref, 1);
@@ -206,26 +210,36 @@ net_devmem_bind_dmabuf(struct net_device *dev, unsigned int dmabuf_fd,
 	if (IS_ERR(binding->attachment)) {
 		err = PTR_ERR(binding->attachment);
 		NL_SET_ERR_MSG(extack, "Failed to bind dmabuf to device");
-		goto err_free_id;
+		goto err_free_binding;
 	}
 
 	binding->sgt = dma_buf_map_attachment_unlocked(binding->attachment,
-						       DMA_FROM_DEVICE);
+						       direction);
 	if (IS_ERR(binding->sgt)) {
 		err = PTR_ERR(binding->sgt);
 		NL_SET_ERR_MSG(extack, "Failed to map dmabuf attachment");
 		goto err_detach;
 	}
 
+	if (direction == DMA_TO_DEVICE) {
+		binding->tx_vec = kvmalloc_array(dmabuf->size / PAGE_SIZE,
+						 sizeof(struct net_iov *),
+						 GFP_KERNEL);
+		if (!binding->tx_vec) {
+			err = -ENOMEM;
+			goto err_unmap;
+		}
+	}
+
 	/* For simplicity we expect to make PAGE_SIZE allocations, but the
 	 * binding can be much more flexible than that. We may be able to
 	 * allocate MTU sized chunks here. Leave that for future work...
 	 */
-	binding->chunk_pool =
-		gen_pool_create(PAGE_SHIFT, dev_to_node(&dev->dev));
+	binding->chunk_pool = gen_pool_create(PAGE_SHIFT,
+					      dev_to_node(&dev->dev));
 	if (!binding->chunk_pool) {
 		err = -ENOMEM;
-		goto err_unmap;
+		goto err_tx_vec;
 	}
 
 	virtual = 0;
@@ -266,27 +280,36 @@ net_devmem_bind_dmabuf(struct net_device *dev, unsigned int dmabuf_fd,
 
 		for (i = 0; i < owner->area.num_niovs; i++) {
 			niov = &owner->area.niovs[i];
+			niov->type = NET_IOV_DMABUF;
 			niov->owner = &owner->area;
 			page_pool_set_dma_addr_netmem(net_iov_to_netmem(niov),
 						      net_devmem_get_dma_addr(niov));
+			if (direction == DMA_TO_DEVICE)
+				binding->tx_vec[owner->area.base_virtual / PAGE_SIZE + i] = niov;
 		}
 
 		virtual += len;
 	}
 
+	err = xa_alloc_cyclic(&net_devmem_dmabuf_bindings, &binding->id,
+			      binding, xa_limit_32b, &id_alloc_next,
+			      GFP_KERNEL);
+	if (err < 0)
+		goto err_free_chunks;
+
 	return binding;
 
 err_free_chunks:
 	gen_pool_for_each_chunk(binding->chunk_pool,
 				net_devmem_dmabuf_free_chunk_owner, NULL);
 	gen_pool_destroy(binding->chunk_pool);
+err_tx_vec:
+	kvfree(binding->tx_vec);
 err_unmap:
 	dma_buf_unmap_attachment_unlocked(binding->attachment, binding->sgt,
 					  DMA_FROM_DEVICE);
 err_detach:
 	dma_buf_detach(dmabuf, binding->attachment);
-err_free_id:
-	xa_erase(&net_devmem_dmabuf_bindings, binding->id);
 err_free_binding:
 	kfree(binding);
 err_put_dmabuf:
@@ -294,6 +317,74 @@ err_put_dmabuf:
 	return ERR_PTR(err);
 }
 
+struct net_devmem_dmabuf_binding *net_devmem_lookup_dmabuf(u32 id)
+{
+	struct net_devmem_dmabuf_binding *binding;
+
+	rcu_read_lock();
+	binding = xa_load(&net_devmem_dmabuf_bindings, id);
+	if (binding) {
+		if (!net_devmem_dmabuf_binding_get(binding))
+			binding = NULL;
+	}
+	rcu_read_unlock();
+
+	return binding;
+}
+
+void net_devmem_get_net_iov(struct net_iov *niov)
+{
+	net_devmem_dmabuf_binding_get(net_devmem_iov_binding(niov));
+}
+
+void net_devmem_put_net_iov(struct net_iov *niov)
+{
+	net_devmem_dmabuf_binding_put(net_devmem_iov_binding(niov));
+}
+
+struct net_devmem_dmabuf_binding *net_devmem_get_binding(struct sock *sk,
+							 unsigned int dmabuf_id)
+{
+	struct net_devmem_dmabuf_binding *binding;
+	struct dst_entry *dst = __sk_dst_get(sk);
+	int err = 0;
+
+	binding = net_devmem_lookup_dmabuf(dmabuf_id);
+	if (!binding || !binding->tx_vec) {
+		err = -EINVAL;
+		goto out_err;
+	}
+
+	/* The dma-addrs in this binding are only reachable to the corresponding
+	 * net_device.
+	 */
+	if (!dst || !dst->dev || dst->dev->ifindex != binding->dev->ifindex) {
+		err = -ENODEV;
+		goto out_err;
+	}
+
+	return binding;
+
+out_err:
+	if (binding)
+		net_devmem_dmabuf_binding_put(binding);
+
+	return ERR_PTR(err);
+}
+
+struct net_iov *
+net_devmem_get_niov_at(struct net_devmem_dmabuf_binding *binding,
+		       size_t virt_addr, size_t *off, size_t *size)
+{
+	if (virt_addr >= binding->dmabuf->size)
+		return NULL;
+
+	*off = virt_addr % PAGE_SIZE;
+	*size = PAGE_SIZE - *off;
+
+	return binding->tx_vec[virt_addr / PAGE_SIZE];
+}
+
 /*** "Dmabuf devmem memory provider" ***/
 
 int mp_dmabuf_devmem_init(struct page_pool *pool)
diff --git a/net/core/devmem.h b/net/core/devmem.h
index 7fc158d52729..919e6ed28fdc 100644
--- a/net/core/devmem.h
+++ b/net/core/devmem.h
@@ -23,12 +23,20 @@ struct net_devmem_dmabuf_binding {
 
 	/* The user holds a ref (via the netlink API) for as long as they want
 	 * the binding to remain alive. Each page pool using this binding holds
-	 * a ref to keep the binding alive. Each allocated net_iov holds a
-	 * ref.
+	 * a ref to keep the binding alive. The page_pool does not release the
+	 * ref until all the net_iovs allocated from this binding are released
+	 * back to the page_pool.
 	 *
 	 * The binding undos itself and unmaps the underlying dmabuf once all
 	 * those refs are dropped and the binding is no longer desired or in
 	 * use.
+	 *
+	 * net_devmem_get_net_iov() on dmabuf net_iovs will increment this
+	 * reference, making sure that the binding remains alive until all the
+	 * net_iovs are no longer used. net_iovs allocated from this binding
+	 * that are stuck in the TX path for any reason (such as awaiting
+	 * retransmits) hold a reference to the binding until the skb holding
+	 * them is freed.
 	 */
 	refcount_t ref;
 
@@ -44,6 +52,14 @@ struct net_devmem_dmabuf_binding {
 	 * active.
 	 */
 	u32 id;
+
+	/* Array of net_iov pointers for this binding, sorted by virtual
+	 * address. This array is convenient to map the virtual addresses to
+	 * net_iovs in the TX path.
+	 */
+	struct net_iov **tx_vec;
+
+	struct work_struct unbind_w;
 };
 
 #if defined(CONFIG_NET_DEVMEM)
@@ -60,14 +76,17 @@ struct dmabuf_genpool_chunk_owner {
 	dma_addr_t base_dma_addr;
 };
 
-void __net_devmem_dmabuf_binding_free(struct net_devmem_dmabuf_binding *binding);
+void __net_devmem_dmabuf_binding_free(struct work_struct *wq);
 struct net_devmem_dmabuf_binding *
-net_devmem_bind_dmabuf(struct net_device *dev, unsigned int dmabuf_fd,
-		       struct netlink_ext_ack *extack);
+net_devmem_bind_dmabuf(struct net_device *dev,
+		       enum dma_data_direction direction,
+		       unsigned int dmabuf_fd, struct netlink_ext_ack *extack);
+struct net_devmem_dmabuf_binding *net_devmem_lookup_dmabuf(u32 id);
 void net_devmem_unbind_dmabuf(struct net_devmem_dmabuf_binding *binding);
 int net_devmem_bind_dmabuf_to_queue(struct net_device *dev, u32 rxq_idx,
 				    struct net_devmem_dmabuf_binding *binding,
 				    struct netlink_ext_ack *extack);
+void net_devmem_bind_tx_release(struct sock *sk);
 
 static inline struct dmabuf_genpool_chunk_owner *
 net_devmem_iov_to_chunk_owner(const struct net_iov *niov)
@@ -96,10 +115,10 @@ static inline unsigned long net_iov_virtual_addr(const struct net_iov *niov)
 	       ((unsigned long)net_iov_idx(niov) << PAGE_SHIFT);
 }
 
-static inline void
+static inline bool
 net_devmem_dmabuf_binding_get(struct net_devmem_dmabuf_binding *binding)
 {
-	refcount_inc(&binding->ref);
+	return refcount_inc_not_zero(&binding->ref);
 }
 
 static inline void
@@ -108,30 +127,57 @@ net_devmem_dmabuf_binding_put(struct net_devmem_dmabuf_binding *binding)
 	if (!refcount_dec_and_test(&binding->ref))
 		return;
 
-	__net_devmem_dmabuf_binding_free(binding);
+	INIT_WORK(&binding->unbind_w, __net_devmem_dmabuf_binding_free);
+	schedule_work(&binding->unbind_w);
 }
 
+void net_devmem_get_net_iov(struct net_iov *niov);
+void net_devmem_put_net_iov(struct net_iov *niov);
+
 struct net_iov *
 net_devmem_alloc_dmabuf(struct net_devmem_dmabuf_binding *binding);
 void net_devmem_free_dmabuf(struct net_iov *ppiov);
 
 bool net_is_devmem_iov(struct net_iov *niov);
+struct net_devmem_dmabuf_binding *
+net_devmem_get_binding(struct sock *sk, unsigned int dmabuf_id);
+struct net_iov *
+net_devmem_get_niov_at(struct net_devmem_dmabuf_binding *binding, size_t addr,
+		       size_t *off, size_t *size);
 
 #else
 struct net_devmem_dmabuf_binding;
 
 static inline void
-__net_devmem_dmabuf_binding_free(struct net_devmem_dmabuf_binding *binding)
+net_devmem_dmabuf_binding_put(struct net_devmem_dmabuf_binding *binding)
+{
+}
+
+static inline void net_devmem_get_net_iov(struct net_iov *niov)
+{
+}
+
+static inline void net_devmem_put_net_iov(struct net_iov *niov)
+{
+}
+
+static inline void __net_devmem_dmabuf_binding_free(struct work_struct *wq)
 {
 }
 
 static inline struct net_devmem_dmabuf_binding *
 net_devmem_bind_dmabuf(struct net_device *dev, unsigned int dmabuf_fd,
+		       enum dma_data_direction direction,
 		       struct netlink_ext_ack *extack)
 {
 	return ERR_PTR(-EOPNOTSUPP);
 }
 
+static inline struct net_devmem_dmabuf_binding *net_devmem_lookup_dmabuf(u32 id)
+{
+	return NULL;
+}
+
 static inline void
 net_devmem_unbind_dmabuf(struct net_devmem_dmabuf_binding *binding)
 {
@@ -170,6 +216,25 @@ static inline bool net_is_devmem_iov(struct net_iov *niov)
 {
 	return false;
 }
+
+static inline struct net_devmem_dmabuf_binding *
+net_devmem_get_binding(struct sock *sk, unsigned int dmabuf_id)
+{
+	return ERR_PTR(-EOPNOTSUPP);
+}
+
+static inline struct net_iov *
+net_devmem_get_niov_at(struct net_devmem_dmabuf_binding *binding, size_t addr,
+		       size_t *off, size_t *size)
+{
+	return NULL;
+}
+
+static inline struct net_devmem_dmabuf_binding *
+net_devmem_iov_binding(const struct net_iov *niov)
+{
+	return NULL;
+}
 #endif
 
 #endif /* _NET_DEVMEM_H */
diff --git a/net/core/netdev-genl-gen.c b/net/core/netdev-genl-gen.c
index 739f7b6506a6..4fc44587f493 100644
--- a/net/core/netdev-genl-gen.c
+++ b/net/core/netdev-genl-gen.c
@@ -99,6 +99,12 @@ static const struct nla_policy netdev_napi_set_nl_policy[NETDEV_A_NAPI_IRQ_SUSPE
 	[NETDEV_A_NAPI_IRQ_SUSPEND_TIMEOUT] = { .type = NLA_UINT, },
 };
 
+/* NETDEV_CMD_BIND_TX - do */
+static const struct nla_policy netdev_bind_tx_nl_policy[NETDEV_A_DMABUF_FD + 1] = {
+	[NETDEV_A_DMABUF_IFINDEX] = NLA_POLICY_MIN(NLA_U32, 1),
+	[NETDEV_A_DMABUF_FD] = { .type = NLA_U32, },
+};
+
 /* Ops table for netdev */
 static const struct genl_split_ops netdev_nl_ops[] = {
 	{
@@ -190,6 +196,13 @@ static const struct genl_split_ops netdev_nl_ops[] = {
 		.maxattr	= NETDEV_A_NAPI_IRQ_SUSPEND_TIMEOUT,
 		.flags		= GENL_ADMIN_PERM | GENL_CMD_CAP_DO,
 	},
+	{
+		.cmd		= NETDEV_CMD_BIND_TX,
+		.doit		= netdev_nl_bind_tx_doit,
+		.policy		= netdev_bind_tx_nl_policy,
+		.maxattr	= NETDEV_A_DMABUF_FD,
+		.flags		= GENL_CMD_CAP_DO,
+	},
 };
 
 static const struct genl_multicast_group netdev_nl_mcgrps[] = {
diff --git a/net/core/netdev-genl-gen.h b/net/core/netdev-genl-gen.h
index 17d39fd64c94..cf3fad74511f 100644
--- a/net/core/netdev-genl-gen.h
+++ b/net/core/netdev-genl-gen.h
@@ -34,6 +34,7 @@ int netdev_nl_qstats_get_dumpit(struct sk_buff *skb,
 				struct netlink_callback *cb);
 int netdev_nl_bind_rx_doit(struct sk_buff *skb, struct genl_info *info);
 int netdev_nl_napi_set_doit(struct sk_buff *skb, struct genl_info *info);
+int netdev_nl_bind_tx_doit(struct sk_buff *skb, struct genl_info *info);
 
 enum {
 	NETDEV_NLGRP_MGMT,
diff --git a/net/core/netdev-genl.c b/net/core/netdev-genl.c
index 17aa9e42e8d5..cfcf1654d4fb 100644
--- a/net/core/netdev-genl.c
+++ b/net/core/netdev-genl.c
@@ -907,7 +907,8 @@ int netdev_nl_bind_rx_doit(struct sk_buff *skb, struct genl_info *info)
 		goto err_unlock;
 	}
 
-	binding = net_devmem_bind_dmabuf(netdev, dmabuf_fd, info->extack);
+	binding = net_devmem_bind_dmabuf(netdev, DMA_FROM_DEVICE, dmabuf_fd,
+					 info->extack);
 	if (IS_ERR(binding)) {
 		err = PTR_ERR(binding);
 		goto err_unlock;
@@ -968,6 +969,83 @@ err_genlmsg_free:
 	return err;
 }
 
+int netdev_nl_bind_tx_doit(struct sk_buff *skb, struct genl_info *info)
+{
+	struct net_devmem_dmabuf_binding *binding;
+	struct netdev_nl_sock *priv;
+	struct net_device *netdev;
+	u32 ifindex, dmabuf_fd;
+	struct sk_buff *rsp;
+	int err = 0;
+	void *hdr;
+
+	if (GENL_REQ_ATTR_CHECK(info, NETDEV_A_DEV_IFINDEX) ||
+	    GENL_REQ_ATTR_CHECK(info, NETDEV_A_DMABUF_FD))
+		return -EINVAL;
+
+	ifindex = nla_get_u32(info->attrs[NETDEV_A_DEV_IFINDEX]);
+	dmabuf_fd = nla_get_u32(info->attrs[NETDEV_A_DMABUF_FD]);
+
+	priv = genl_sk_priv_get(&netdev_nl_family, NETLINK_CB(skb).sk);
+	if (IS_ERR(priv))
+		return PTR_ERR(priv);
+
+	rsp = genlmsg_new(GENLMSG_DEFAULT_SIZE, GFP_KERNEL);
+	if (!rsp)
+		return -ENOMEM;
+
+	hdr = genlmsg_iput(rsp, info);
+	if (!hdr) {
+		err = -EMSGSIZE;
+		goto err_genlmsg_free;
+	}
+
+	mutex_lock(&priv->lock);
+
+	netdev = netdev_get_by_index_lock(genl_info_net(info), ifindex);
+	if (!netdev) {
+		err = -ENODEV;
+		goto err_unlock_sock;
+	}
+
+	if (!netif_device_present(netdev)) {
+		err = -ENODEV;
+		goto err_unlock_netdev;
+	}
+
+	if (!netdev->netmem_tx) {
+		err = -EOPNOTSUPP;
+		NL_SET_ERR_MSG(info->extack,
+			       "Driver does not support netmem TX");
+		goto err_unlock_netdev;
+	}
+
+	binding = net_devmem_bind_dmabuf(netdev, DMA_TO_DEVICE, dmabuf_fd,
+					 info->extack);
+	if (IS_ERR(binding)) {
+		err = PTR_ERR(binding);
+		goto err_unlock_netdev;
+	}
+
+	list_add(&binding->list, &priv->bindings);
+
+	nla_put_u32(rsp, NETDEV_A_DMABUF_ID, binding->id);
+	genlmsg_end(rsp, hdr);
+
+	netdev_unlock(netdev);
+	mutex_unlock(&priv->lock);
+
+	return genlmsg_reply(rsp, info);
+
+err_unlock_netdev:
+	netdev_unlock(netdev);
+err_unlock_sock:
+	mutex_unlock(&priv->lock);
+err_genlmsg_free:
+	nlmsg_free(rsp);
+	return err;
+}
+
 void netdev_nl_sock_priv_init(struct netdev_nl_sock *priv)
 {
 	INIT_LIST_HEAD(&priv->bindings);
diff --git a/net/core/skbuff.c b/net/core/skbuff.c
index d73ad79fe739..4159107f1666 100644
--- a/net/core/skbuff.c
+++ b/net/core/skbuff.c
@@ -89,6 +89,7 @@
 #include <linux/textsearch.h>
 
 #include "dev.h"
+#include "devmem.h"
 #include "netmem_priv.h"
 #include "sock_destructor.h"
 
@@ -1654,7 +1655,8 @@ void mm_unaccount_pinned_pages(struct mmpin *mmp)
 }
 EXPORT_SYMBOL_GPL(mm_unaccount_pinned_pages);
 
-static struct ubuf_info *msg_zerocopy_alloc(struct sock *sk, size_t size)
+static struct ubuf_info *msg_zerocopy_alloc(struct sock *sk, size_t size,
+					    bool devmem)
 {
 	struct ubuf_info_msgzc *uarg;
 	struct sk_buff *skb;
@@ -1669,7 +1671,7 @@ static struct ubuf_info *msg_zerocopy_alloc(struct sock *sk, size_t size)
 	uarg = (void *)skb->cb;
 	uarg->mmp.user = NULL;
 
-	if (mm_account_pinned_pages(&uarg->mmp, size)) {
+	if (likely(!devmem) && mm_account_pinned_pages(&uarg->mmp, size)) {
 		kfree_skb(skb);
 		return NULL;
 	}
@@ -1692,7 +1694,7 @@ static inline struct sk_buff *skb_from_uarg(struct ubuf_info_msgzc *uarg)
 }
 
 struct ubuf_info *msg_zerocopy_realloc(struct sock *sk, size_t size,
-				       struct ubuf_info *uarg)
+				       struct ubuf_info *uarg, bool devmem)
 {
 	if (uarg) {
 		struct ubuf_info_msgzc *uarg_zc;
@@ -1722,7 +1724,8 @@ struct ubuf_info *msg_zerocopy_realloc(struct sock *sk, size_t size,
 
 		next = (u32)atomic_read(&sk->sk_zckey);
 		if ((u32)(uarg_zc->id + uarg_zc->len) == next) {
-			if (mm_account_pinned_pages(&uarg_zc->mmp, size))
+			if (likely(!devmem) &&
+			    mm_account_pinned_pages(&uarg_zc->mmp, size))
 				return NULL;
 			uarg_zc->len++;
 			uarg_zc->bytelen = bytelen;
@@ -1737,7 +1740,7 @@ struct ubuf_info *msg_zerocopy_realloc(struct sock *sk, size_t size,
 	}
 
 new_alloc:
-	return msg_zerocopy_alloc(sk, size);
+	return msg_zerocopy_alloc(sk, size, devmem);
 }
 EXPORT_SYMBOL_GPL(msg_zerocopy_realloc);
 
@@ -1841,7 +1844,8 @@ EXPORT_SYMBOL_GPL(msg_zerocopy_ubuf_ops);
 
 int skb_zerocopy_iter_stream(struct sock *sk, struct sk_buff *skb,
 			     struct msghdr *msg, int len,
-			     struct ubuf_info *uarg)
+			     struct ubuf_info *uarg,
+			     struct net_devmem_dmabuf_binding *binding)
 {
 	int err, orig_len = skb->len;
 
@@ -1860,7 +1864,8 @@ int skb_zerocopy_iter_stream(struct sock *sk, struct sk_buff *skb,
 			return -EEXIST;
 	}
 
-	err = __zerocopy_sg_from_iter(msg, sk, skb, &msg->msg_iter, len);
+	err = __zerocopy_sg_from_iter(msg, sk, skb, &msg->msg_iter, len,
+				      binding);
 	if (err == -EFAULT || (err == -EMSGSIZE && skb->len == orig_len)) {
 		struct sock *save_sk = skb->sk;
 
@@ -7313,3 +7318,32 @@ bool csum_and_copy_from_iter_full(void *addr, size_t bytes,
 	return false;
 }
 EXPORT_SYMBOL(csum_and_copy_from_iter_full);
+
+void get_netmem(netmem_ref netmem)
+{
+	struct net_iov *niov;
+
+	if (netmem_is_net_iov(netmem)) {
+		niov = netmem_to_net_iov(netmem);
+		if (net_is_devmem_iov(niov))
+			net_devmem_get_net_iov(netmem_to_net_iov(netmem));
+		return;
+	}
+	get_page(netmem_to_page(netmem));
+}
+EXPORT_SYMBOL(get_netmem);
+
+void put_netmem(netmem_ref netmem)
+{
+	struct net_iov *niov;
+
+	if (netmem_is_net_iov(netmem)) {
+		niov = netmem_to_net_iov(netmem);
+		if (net_is_devmem_iov(niov))
+			net_devmem_put_net_iov(netmem_to_net_iov(netmem));
+		return;
+	}
+
+	put_page(netmem_to_page(netmem));
+}
+EXPORT_SYMBOL(put_netmem);
diff --git a/net/core/sock.c b/net/core/sock.c
index b64df2463300..347ce75482f5 100644
--- a/net/core/sock.c
+++ b/net/core/sock.c
@@ -3018,6 +3018,11 @@ int __sock_cmsg_send(struct sock *sk, struct cmsghdr *cmsg,
 			return -EPERM;
 		sockc->priority = *(u32 *)CMSG_DATA(cmsg);
 		break;
+	case SCM_DEVMEM_DMABUF:
+		if (cmsg->cmsg_len != CMSG_LEN(sizeof(u32)))
+			return -EINVAL;
+		sockc->dmabuf_id = *(u32 *)CMSG_DATA(cmsg);
+		break;
 	default:
 		return -EINVAL;
 	}
diff --git a/net/ipv4/ip_output.c b/net/ipv4/ip_output.c
index 6e18d7ec5062..a2705d454fd6 100644
--- a/net/ipv4/ip_output.c
+++ b/net/ipv4/ip_output.c
@@ -1014,7 +1014,8 @@ static int __ip_append_data(struct sock *sk,
 				uarg = msg->msg_ubuf;
 			}
 		} else if (sock_flag(sk, SOCK_ZEROCOPY)) {
-			uarg = msg_zerocopy_realloc(sk, length, skb_zcopy(skb));
+			uarg = msg_zerocopy_realloc(sk, length, skb_zcopy(skb),
+						    false);
 			if (!uarg)
 				return -ENOBUFS;
 			extra_uref = !skb_zcopy(skb);	/* only ref on new uarg */
diff --git a/net/ipv4/tcp.c b/net/ipv4/tcp.c
index 86c427f16636..0ae265d39184 100644
--- a/net/ipv4/tcp.c
+++ b/net/ipv4/tcp.c
@@ -1059,6 +1059,7 @@ int tcp_sendmsg_fastopen(struct sock *sk, struct msghdr *msg, int *copied,
 
 int tcp_sendmsg_locked(struct sock *sk, struct msghdr *msg, size_t size)
 {
+	struct net_devmem_dmabuf_binding *binding = NULL;
 	struct tcp_sock *tp = tcp_sk(sk);
 	struct ubuf_info *uarg = NULL;
 	struct sk_buff *skb;
@@ -1066,11 +1067,23 @@ int tcp_sendmsg_locked(struct sock *sk, struct msghdr *msg, size_t size)
 	int flags, err, copied = 0;
 	int mss_now = 0, size_goal, copied_syn = 0;
 	int process_backlog = 0;
+	bool sockc_valid = true;
 	int zc = 0;
 	long timeo;
 
 	flags = msg->msg_flags;
 
+	sockc = (struct sockcm_cookie){ .tsflags = READ_ONCE(sk->sk_tsflags) };
+	if (msg->msg_controllen) {
+		err = sock_cmsg_send(sk, msg, &sockc);
+		if (unlikely(err))
+			/* Don't return error until MSG_FASTOPEN has been
+			 * processed; that may succeed even if the cmsg is
+			 * invalid.
+			 */
+			sockc_valid = false;
+	}
+
 	if ((flags & MSG_ZEROCOPY) && size) {
 		if (msg->msg_ubuf) {
 			uarg = msg->msg_ubuf;
@@ -1078,7 +1091,8 @@ int tcp_sendmsg_locked(struct sock *sk, struct msghdr *msg, size_t size)
 				zc = MSG_ZEROCOPY;
 		} else if (sock_flag(sk, SOCK_ZEROCOPY)) {
 			skb = tcp_write_queue_tail(sk);
-			uarg = msg_zerocopy_realloc(sk, size, skb_zcopy(skb));
+			uarg = msg_zerocopy_realloc(sk, size, skb_zcopy(skb),
+						    sockc_valid && !!sockc.dmabuf_id);
 			if (!uarg) {
 				err = -ENOBUFS;
 				goto out_err;
@@ -1087,12 +1101,27 @@ int tcp_sendmsg_locked(struct sock *sk, struct msghdr *msg, size_t size)
 				zc = MSG_ZEROCOPY;
 			else
 				uarg_to_msgzc(uarg)->zerocopy = 0;
+
+			if (sockc_valid && sockc.dmabuf_id) {
+				binding = net_devmem_get_binding(sk, sockc.dmabuf_id);
+				if (IS_ERR(binding)) {
+					err = PTR_ERR(binding);
+					binding = NULL;
+					goto out_err;
+				}
+			}
 		}
 	} else if (unlikely(msg->msg_flags & MSG_SPLICE_PAGES) && size) {
 		if (sk->sk_route_caps & NETIF_F_SG)
 			zc = MSG_SPLICE_PAGES;
 	}
 
+	if (sockc_valid && sockc.dmabuf_id &&
+	    (!(flags & MSG_ZEROCOPY) || !sock_flag(sk, SOCK_ZEROCOPY))) {
+		err = -EINVAL;
+		goto out_err;
+	}
+
 	if (unlikely(flags & MSG_FASTOPEN ||
 		     inet_test_bit(DEFER_CONNECT, sk)) &&
 	    !tp->repair) {
@@ -1131,13 +1160,10 @@ int tcp_sendmsg_locked(struct sock *sk, struct msghdr *msg, size_t size)
 		/* 'common' sending to sendq */
 	}
 
-	sockc = (struct sockcm_cookie) { .tsflags = READ_ONCE(sk->sk_tsflags)};
-	if (msg->msg_controllen) {
-		err = sock_cmsg_send(sk, msg, &sockc);
-		if (unlikely(err)) {
+	if (!sockc_valid) {
+		if (!err)
 			err = -EINVAL;
-			goto out_err;
-		}
+		goto out_err;
 	}
 
 	/* This should be in poll */
@@ -1258,7 +1284,8 @@ new_segment:
 					goto wait_for_space;
 			}
 
-			err = skb_zerocopy_iter_stream(sk, skb, msg, copy, uarg);
+			err = skb_zerocopy_iter_stream(sk, skb, msg, copy, uarg,
+						       binding);
 			if (err == -EMSGSIZE || err == -EEXIST) {
 				tcp_mark_push(tp, skb);
 				goto new_segment;
@@ -1339,6 +1366,8 @@ out_nopush:
 	/* msg->msg_ubuf is pinned by the caller so we don't take extra refs */
 	if (uarg && !msg->msg_ubuf)
 		net_zcopy_put(uarg);
+	if (binding)
+		net_devmem_dmabuf_binding_put(binding);
 	return copied + copied_syn;
 
 do_error:
@@ -1356,6 +1385,9 @@ out_err:
 		sk->sk_write_space(sk);
 		tcp_chrono_stop(sk, TCP_CHRONO_SNDBUF_LIMITED);
 	}
+	if (binding)
+		net_devmem_dmabuf_binding_put(binding);
+
 	return err;
 }
 EXPORT_SYMBOL_GPL(tcp_sendmsg_locked);
diff --git a/net/ipv6/ip6_output.c b/net/ipv6/ip6_output.c
index ef052ccd9380..7bd29a9ff0db 100644
--- a/net/ipv6/ip6_output.c
+++ b/net/ipv6/ip6_output.c
@@ -1524,7 +1524,8 @@ emsgsize:
 				uarg = msg->msg_ubuf;
 			}
 		} else if (sock_flag(sk, SOCK_ZEROCOPY)) {
-			uarg = msg_zerocopy_realloc(sk, length, skb_zcopy(skb));
+			uarg = msg_zerocopy_realloc(sk, length, skb_zcopy(skb),
+						    false);
 			if (!uarg)
 				return -ENOBUFS;
 			extra_uref = !skb_zcopy(skb);	/* only ref on new uarg */
diff --git a/net/vmw_vsock/virtio_transport_common.c b/net/vmw_vsock/virtio_transport_common.c
index 7f7de6d88096..6e7b727c781c 100644
--- a/net/vmw_vsock/virtio_transport_common.c
+++ b/net/vmw_vsock/virtio_transport_common.c
@@ -87,7 +87,7 @@ static int virtio_transport_init_zcopy_skb(struct vsock_sock *vsk,
 
 		uarg = msg_zerocopy_realloc(sk_vsock(vsk),
 					    iter->count,
-					    NULL);
+					    NULL, false);
 		if (!uarg)
 			return -1;
 
@@ -107,8 +107,7 @@ static int virtio_transport_fill_skb(struct sk_buff *skb,
 {
 	if (zcopy)
 		return __zerocopy_sg_from_iter(info->msg, NULL, skb,
-					       &info->msg->msg_iter,
-					       len);
+					       &info->msg->msg_iter, len, NULL);
 
 	return memcpy_from_msg(skb_put(skb, len), info->msg, len);
 }
diff --git a/tools/include/uapi/linux/netdev.h b/tools/include/uapi/linux/netdev.h
index 7600bf62dbdf..7eb9571786b8 100644
--- a/tools/include/uapi/linux/netdev.h
+++ b/tools/include/uapi/linux/netdev.h
@@ -219,6 +219,7 @@ enum {
 	NETDEV_CMD_QSTATS_GET,
 	NETDEV_CMD_BIND_RX,
 	NETDEV_CMD_NAPI_SET,
+	NETDEV_CMD_BIND_TX,
 
 	__NETDEV_CMD_MAX,
 	NETDEV_CMD_MAX = (__NETDEV_CMD_MAX - 1)
diff --git a/tools/testing/selftests/drivers/net/hw/devmem.py b/tools/testing/selftests/drivers/net/hw/devmem.py
index 3947e9157115..7fc686cf47a2 100755
--- a/tools/testing/selftests/drivers/net/hw/devmem.py
+++ b/tools/testing/selftests/drivers/net/hw/devmem.py
@@ -1,6 +1,7 @@
 #!/usr/bin/env python3
 # SPDX-License-Identifier: GPL-2.0
 
+from os import path
 from lib.py import ksft_run, ksft_exit
 from lib.py import ksft_eq, KsftSkipEx
 from lib.py import NetDrvEpEnv
@@ -10,8 +11,7 @@ from lib.py import ksft_disruptive
 
 def require_devmem(cfg):
     if not hasattr(cfg, "_devmem_probed"):
-        port = rand_port()
-        probe_command = f"./ncdevmem -f {cfg.ifname}"
+        probe_command = f"{cfg.bin_local} -f {cfg.ifname}"
         cfg._devmem_supported = cmd(probe_command, fail=False, shell=True).ret == 0
         cfg._devmem_probed = True
 
@@ -25,7 +25,7 @@ def check_rx(cfg) -> None:
     require_devmem(cfg)
 
     port = rand_port()
-    listen_cmd = f"./ncdevmem -l -f {cfg.ifname} -s {cfg.addr_v['6']} -p {port}"
+    listen_cmd = f"{cfg.bin_local} -l -f {cfg.ifname} -s {cfg.addr_v['6']} -p {port}"
 
     with bkg(listen_cmd) as socat:
         wait_port_listen(port)
@@ -34,9 +34,27 @@ def check_rx(cfg) -> None:
     ksft_eq(socat.stdout.strip(), "hello\nworld")
 
 
+@ksft_disruptive
+def check_tx(cfg) -> None:
+    cfg.require_ipver("6")
+    require_devmem(cfg)
+
+    port = rand_port()
+    listen_cmd = f"socat -U - TCP6-LISTEN:{port}"
+
+    with bkg(listen_cmd, exit_wait=True) as socat:
+        wait_port_listen(port)
+        cmd(f"echo -e \"hello\\nworld\"| {cfg.bin_remote} -f {cfg.ifname} -s {cfg.addr_v['6']} -p {port}", host=cfg.remote, shell=True)
+
+    ksft_eq(socat.stdout.strip(), "hello\nworld")
+
+
 def main() -> None:
     with NetDrvEpEnv(__file__) as cfg:
-        ksft_run([check_rx],
+        cfg.bin_local = path.abspath(path.dirname(__file__) + "/ncdevmem")
+        cfg.bin_remote = cfg.remote.deploy(cfg.bin_local)
+
+        ksft_run([check_rx, check_tx],
                  args=(cfg, ))
     ksft_exit()
 
diff --git a/tools/testing/selftests/drivers/net/hw/ncdevmem.c b/tools/testing/selftests/drivers/net/hw/ncdevmem.c
index 2bf14ac2b8c6..f801a1b3545f 100644
--- a/tools/testing/selftests/drivers/net/hw/ncdevmem.c
+++ b/tools/testing/selftests/drivers/net/hw/ncdevmem.c
@@ -9,22 +9,31 @@
  *     ncdevmem -s <server IP> [-c <client IP>] -f eth1 -l -p 5201
  *
  *     On client:
- *     echo -n "hello\nworld" | nc -s <server IP> 5201 -p 5201
+ *     echo -n "hello\nworld" | \
+ *		ncdevmem -s <server IP> [-c <client IP>] -p 5201 -f eth1
  *
- * Test data validation:
+ * Note this is compatible with regular netcat. i.e. the sender or receiver can
+ * be replaced with regular netcat to test the RX or TX path in isolation.
+ *
+ * Test data validation (devmem TCP on RX only):
  *
  *     On server:
  *     ncdevmem -s <server IP> [-c <client IP>] -f eth1 -l -p 5201 -v 7
  *
  *     On client:
  *     yes $(echo -e \\x01\\x02\\x03\\x04\\x05\\x06) | \
- *             tr \\n \\0 | \
- *             head -c 5G | \
+ *             head -c 1G | \
  *             nc <server IP> 5201 -p 5201
  *
+ * Test data validation (devmem TCP on RX and TX, validation happens on RX):
  *
- * Note this is compatible with regular netcat. i.e. the sender or receiver can
- * be replaced with regular netcat to test the RX or TX path in isolation.
+ *	On server:
+ *	ncdevmem -s <server IP> [-c <client IP>] -l -p 5201 -v 8 -f eth1
+ *
+ *	On client:
+ *	yes $(echo -e \\x01\\x02\\x03\\x04\\x05\\x06\\x07) | \
+ *		head -c 1M | \
+ *		ncdevmem -s <server IP> [-c <client IP>] -p 5201 -f eth1
  */
 #define _GNU_SOURCE
 #define __EXPORTED_HEADERS__
@@ -40,15 +49,18 @@
 #include <fcntl.h>
 #include <malloc.h>
 #include <error.h>
+#include <poll.h>
 
 #include <arpa/inet.h>
 #include <sys/socket.h>
 #include <sys/mman.h>
 #include <sys/ioctl.h>
 #include <sys/syscall.h>
+#include <sys/time.h>
 
 #include <linux/memfd.h>
 #include <linux/dma-buf.h>
+#include <linux/errqueue.h>
 #include <linux/udmabuf.h>
 #include <linux/types.h>
 #include <linux/netlink.h>
@@ -79,6 +91,8 @@ static int num_queues = -1;
 static char *ifname;
 static unsigned int ifindex;
 static unsigned int dmabuf_id;
+static uint32_t tx_dmabuf_id;
+static int waittime_ms = 500;
 
 struct memory_buffer {
 	int fd;
@@ -92,6 +106,8 @@ struct memory_buffer {
 struct memory_provider {
 	struct memory_buffer *(*alloc)(size_t size);
 	void (*free)(struct memory_buffer *ctx);
+	void (*memcpy_to_device)(struct memory_buffer *dst, size_t off,
+				 void *src, int n);
 	void (*memcpy_from_device)(void *dst, struct memory_buffer *src,
 				   size_t off, int n);
 };
@@ -152,6 +168,20 @@ static void udmabuf_free(struct memory_buffer *ctx)
 	free(ctx);
 }
 
+static void udmabuf_memcpy_to_device(struct memory_buffer *dst, size_t off,
+				     void *src, int n)
+{
+	struct dma_buf_sync sync = {};
+
+	sync.flags = DMA_BUF_SYNC_START | DMA_BUF_SYNC_WRITE;
+	ioctl(dst->fd, DMA_BUF_IOCTL_SYNC, &sync);
+
+	memcpy(dst->buf_mem + off, src, n);
+
+	sync.flags = DMA_BUF_SYNC_END | DMA_BUF_SYNC_WRITE;
+	ioctl(dst->fd, DMA_BUF_IOCTL_SYNC, &sync);
+}
+
 static void udmabuf_memcpy_from_device(void *dst, struct memory_buffer *src,
 				       size_t off, int n)
 {
@@ -169,6 +199,7 @@ static void udmabuf_memcpy_from_device(void *dst, struct memory_buffer *src,
 static struct memory_provider udmabuf_memory_provider = {
 	.alloc = udmabuf_alloc,
 	.free = udmabuf_free,
+	.memcpy_to_device = udmabuf_memcpy_to_device,
 	.memcpy_from_device = udmabuf_memcpy_from_device,
 };
 
@@ -187,14 +218,16 @@ void validate_buffer(void *line, size_t size)
 {
 	static unsigned char seed = 1;
 	unsigned char *ptr = line;
-	int errors = 0;
+	unsigned char expected;
+	static int errors;
 	size_t i;
 
 	for (i = 0; i < size; i++) {
-		if (ptr[i] != seed) {
+		expected = seed ? seed : '\n';
+		if (ptr[i] != expected) {
 			fprintf(stderr,
 				"Failed validation: expected=%u, actual=%u, index=%lu\n",
-				seed, ptr[i], i);
+				expected, ptr[i], i);
 			errors++;
 			if (errors > 20)
 				error(1, 0, "validation failed.");
@@ -393,6 +426,49 @@ err_close:
 	return -1;
 }
 
+static int bind_tx_queue(unsigned int ifindex, unsigned int dmabuf_fd,
+			 struct ynl_sock **ys)
+{
+	struct netdev_bind_tx_req *req = NULL;
+	struct netdev_bind_tx_rsp *rsp = NULL;
+	struct ynl_error yerr;
+
+	*ys = ynl_sock_create(&ynl_netdev_family, &yerr);
+	if (!*ys) {
+		fprintf(stderr, "YNL: %s\n", yerr.msg);
+		return -1;
+	}
+
+	req = netdev_bind_tx_req_alloc();
+	netdev_bind_tx_req_set_ifindex(req, ifindex);
+	netdev_bind_tx_req_set_fd(req, dmabuf_fd);
+
+	rsp = netdev_bind_tx(*ys, req);
+	if (!rsp) {
+		perror("netdev_bind_tx");
+		goto err_close;
+	}
+
+	if (!rsp->_present.id) {
+		perror("id not present");
+		goto err_close;
+	}
+
+	fprintf(stderr, "got tx dmabuf id=%d\n", rsp->id);
+	tx_dmabuf_id = rsp->id;
+
+	netdev_bind_tx_req_free(req);
+	netdev_bind_tx_rsp_free(rsp);
+
+	return 0;
+
+err_close:
+	fprintf(stderr, "YNL failed: %s\n", (*ys)->err.msg);
+	netdev_bind_tx_req_free(req);
+	ynl_sock_destroy(*ys);
+	return -1;
+}
+
 static void enable_reuseaddr(int fd)
 {
 	int opt = 1;
@@ -431,7 +507,7 @@ static int parse_address(const char *str, int port, struct sockaddr_in6 *sin6)
 	return 0;
 }
 
-int do_server(struct memory_buffer *mem)
+static int do_server(struct memory_buffer *mem)
 {
 	char ctrl_data[sizeof(int) * 20000];
 	struct netdev_queue_id *queues;
@@ -685,6 +761,206 @@ void run_devmem_tests(void)
 	provider->free(mem);
 }
 
+static uint64_t gettimeofday_ms(void)
+{
+	struct timeval tv;
+
+	gettimeofday(&tv, NULL);
+	return (tv.tv_sec * 1000ULL) + (tv.tv_usec / 1000ULL);
+}
+
+static int do_poll(int fd)
+{
+	struct pollfd pfd;
+	int ret;
+
+	pfd.revents = 0;
+	pfd.fd = fd;
+
+	ret = poll(&pfd, 1, waittime_ms);
+	if (ret == -1)
+		error(1, errno, "poll");
+
+	return ret && (pfd.revents & POLLERR);
+}
+
+static void wait_compl(int fd)
+{
+	int64_t tstop = gettimeofday_ms() + waittime_ms;
+	char control[CMSG_SPACE(100)] = {};
+	struct sock_extended_err *serr;
+	struct msghdr msg = {};
+	struct cmsghdr *cm;
+	__u32 hi, lo;
+	int ret;
+
+	msg.msg_control = control;
+	msg.msg_controllen = sizeof(control);
+
+	while (gettimeofday_ms() < tstop) {
+		if (!do_poll(fd))
+			continue;
+
+		ret = recvmsg(fd, &msg, MSG_ERRQUEUE);
+		if (ret < 0) {
+			if (errno == EAGAIN)
+				continue;
+			error(1, errno, "recvmsg(MSG_ERRQUEUE)");
+			return;
+		}
+		if (msg.msg_flags & MSG_CTRUNC)
+			error(1, 0, "MSG_CTRUNC\n");
+
+		for (cm = CMSG_FIRSTHDR(&msg); cm; cm = CMSG_NXTHDR(&msg, cm)) {
+			if (cm->cmsg_level != SOL_IP &&
+			    cm->cmsg_level != SOL_IPV6)
+				continue;
+			if (cm->cmsg_level == SOL_IP &&
+			    cm->cmsg_type != IP_RECVERR)
+				continue;
+			if (cm->cmsg_level == SOL_IPV6 &&
+			    cm->cmsg_type != IPV6_RECVERR)
+				continue;
+
+			serr = (void *)CMSG_DATA(cm);
+			if (serr->ee_origin != SO_EE_ORIGIN_ZEROCOPY)
+				error(1, 0, "wrong origin %u", serr->ee_origin);
+			if (serr->ee_errno != 0)
+				error(1, 0, "wrong errno %d", serr->ee_errno);
+
+			hi = serr->ee_data;
+			lo = serr->ee_info;
+
+			fprintf(stderr, "tx complete [%d,%d]\n", lo, hi);
+			return;
+		}
+	}
+
+	error(1, 0, "did not receive tx completion");
+}
+
+static int do_client(struct memory_buffer *mem)
+{
+	char ctrl_data[CMSG_SPACE(sizeof(__u32))];
+	struct sockaddr_in6 server_sin;
+	struct sockaddr_in6 client_sin;
+	struct ynl_sock *ys = NULL;
+	struct msghdr msg = {};
+	ssize_t line_size = 0;
+	struct cmsghdr *cmsg;
+	struct iovec iov[2];
+	char *line = NULL;
+	unsigned long mid;
+	size_t len = 0;
+	int socket_fd;
+	__u32 ddmabuf;
+	int opt = 1;
+	int ret;
+
+	ret = parse_address(server_ip, atoi(port), &server_sin);
+	if (ret < 0)
+		error(1, 0, "parse server address");
+
+	socket_fd = socket(AF_INET6, SOCK_STREAM, 0);
+	if (socket_fd < 0)
+		error(1, socket_fd, "create socket");
+
+	enable_reuseaddr(socket_fd);
+
+	ret = setsockopt(socket_fd, SOL_SOCKET, SO_BINDTODEVICE, ifname,
+			 strlen(ifname) + 1);
+	if (ret)
+		error(1, errno, "bindtodevice");
+
+	if (bind_tx_queue(ifindex, mem->fd, &ys))
+		error(1, 0, "Failed to bind\n");
+
+	if (client_ip) {
+		ret = parse_address(client_ip, atoi(port), &client_sin);
+		if (ret < 0)
+			error(1, 0, "parse client address");
+
+		ret = bind(socket_fd, &client_sin, sizeof(client_sin));
+		if (ret)
+			error(1, errno, "bind");
+	}
+
+	ret = setsockopt(socket_fd, SOL_SOCKET, SO_ZEROCOPY, &opt, sizeof(opt));
+	if (ret)
+		error(1, errno, "set sock opt");
+
+	fprintf(stderr, "Connect to %s %d (via %s)\n", server_ip,
+		ntohs(server_sin.sin6_port), ifname);
+
+	ret = connect(socket_fd, &server_sin, sizeof(server_sin));
+	if (ret)
+		error(1, errno, "connect");
+
+	while (1) {
+		free(line);
+		line = NULL;
+		line_size = getline(&line, &len, stdin);
+
+		if (line_size < 0)
+			break;
+
+		mid = (line_size / 2) + 1;
+
+		iov[0].iov_base = (void *)1;
+		iov[0].iov_len = mid;
+		iov[1].iov_base = (void *)(mid + 2);
+		iov[1].iov_len = line_size - mid;
+
+		provider->memcpy_to_device(mem, (size_t)iov[0].iov_base, line,
+					   iov[0].iov_len);
+		provider->memcpy_to_device(mem, (size_t)iov[1].iov_base,
+					   line + iov[0].iov_len,
+					   iov[1].iov_len);
+
+		fprintf(stderr,
+			"read line_size=%ld iov[0].iov_base=%lu, iov[0].iov_len=%lu, iov[1].iov_base=%lu, iov[1].iov_len=%lu\n",
+			line_size, (unsigned long)iov[0].iov_base,
+			iov[0].iov_len, (unsigned long)iov[1].iov_base,
+			iov[1].iov_len);
+
+		msg.msg_iov = iov;
+		msg.msg_iovlen = 2;
+
+		msg.msg_control = ctrl_data;
+		msg.msg_controllen = sizeof(ctrl_data);
+
+		cmsg = CMSG_FIRSTHDR(&msg);
+		cmsg->cmsg_level = SOL_SOCKET;
+		cmsg->cmsg_type = SCM_DEVMEM_DMABUF;
+		cmsg->cmsg_len = CMSG_LEN(sizeof(__u32));
+
+		ddmabuf = tx_dmabuf_id;
+
+		*((__u32 *)CMSG_DATA(cmsg)) = ddmabuf;
+
+		ret = sendmsg(socket_fd, &msg, MSG_ZEROCOPY);
+		if (ret < 0)
+			error(1, errno, "Failed sendmsg");
+
+		fprintf(stderr, "sendmsg_ret=%d\n", ret);
+
+		if (ret != line_size)
+			error(1, errno, "Did not send all bytes");
+
+		wait_compl(socket_fd);
+	}
+
+	fprintf(stderr, "%s: tx ok\n", TEST_PREFIX);
+
+	free(line);
+	close(socket_fd);
+
+	if (ys)
+		ynl_sock_destroy(ys);
+
+	return 0;
+}
+
 int main(int argc, char *argv[])
 {
 	struct memory_buffer *mem;
@@ -728,6 +1004,8 @@ int main(int argc, char *argv[])
 
 	ifindex = if_nametoindex(ifname);
 
+	fprintf(stderr, "using ifindex=%u\n", ifindex);
+
 	if (!server_ip && !client_ip) {
 		if (start_queue < 0 && num_queues < 0) {
 			num_queues = rxq_num(ifindex);
@@ -778,7 +1056,7 @@ int main(int argc, char *argv[])
 		error(1, 0, "Missing -p argument\n");
 
 	mem = provider->alloc(getpagesize() * NUM_PAGES);
-	ret = is_server ? do_server(mem) : 1;
+	ret = is_server ? do_server(mem) : do_client(mem);
 	provider->free(mem);
 
 	return ret;