Augment dmabuf binding to be able to handle TX. Additional to all the RX
binding, we also create tx_vec and tx_iter needed for the TX path.

Provide API for sendmsg to be able to send dmabufs bound to this device:

- Provide a new dmabuf_tx_cmsg which includes the dmabuf to send from,
  and the offset into the dmabuf to send from.
- MSG_ZEROCOPY with SCM_DEVMEM_DMABUF cmsg indicates send from dma-buf.

Devmem is uncopyable, so piggyback off the existing MSG_ZEROCOPY
implementation, while disabling instances where MSG_ZEROCOPY falls back
to copying.

We additionally look up the dmabuf to send from by id, then pipe the
binding down to the new zerocopy_fill_skb_from_devmem which fills a TX skb
with net_iov netmems instead of the traditional page netmems.

We also special case skb_frag_dma_map to return the dma-address of these
dmabuf net_iovs instead of attempting to map pages.

Based on work by Stanislav Fomichev <s...@fomichev.me>. A lot of the meat
of the implementation came from devmem TCP RFC v1[1], which included the
TX path, but Stan did all the rebasing on top of netmem/net_iov.

Cc: Stanislav Fomichev <s...@fomichev.me>
Signed-off-by: Kaiyuan Zhang <kaiyu...@google.com>
Signed-off-by: Mina Almasry <almasrym...@google.com>

---
 include/linux/skbuff.h                  | 13 +++-
 include/net/sock.h                      |  2 +
 include/uapi/linux/uio.h                |  5 ++
 net/core/datagram.c                     | 40 ++++++++++-
 net/core/devmem.c                       | 91 +++++++++++++++++++++++--
 net/core/devmem.h                       | 40 +++++++++--
 net/core/netdev-genl.c                  | 65 +++++++++++++++++-
 net/core/skbuff.c                       |  8 ++-
 net/core/sock.c                         |  9 +++
 net/ipv4/tcp.c                          | 36 +++++++---
 net/vmw_vsock/virtio_transport_common.c |  4 +-
 11 files changed, 281 insertions(+), 32 deletions(-)

diff --git a/include/linux/skbuff.h b/include/linux/skbuff.h
index bb2b751d274a..e90dc0c4d542 100644
--- a/include/linux/skbuff.h
+++ b/include/linux/skbuff.h
@@ -1711,9 +1711,10 @@ struct ubuf_info *msg_zerocopy_realloc(struct sock *sk, 
size_t size,
 
 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, bool is_devmem);
 
 int zerocopy_fill_skb_from_iter(struct sk_buff *skb,
                                struct iov_iter *from, size_t length);
@@ -1721,12 +1722,14 @@ 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,
+                                      false);
 }
 
 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 +3700,10 @@ 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/net/sock.h b/include/net/sock.h
index d4bdd3286e03..75bd580fe9c6 100644
--- a/include/net/sock.h
+++ b/include/net/sock.h
@@ -1816,6 +1816,8 @@ struct sockcm_cookie {
        u32 tsflags;
        u32 ts_opt_id;
        u32 priority;
+       u32 dmabuf_id;
+       u64 dmabuf_offset;
 };
 
 static inline void sockcm_init(struct sockcm_cookie *sockc,
diff --git a/include/uapi/linux/uio.h b/include/uapi/linux/uio.h
index 649739e0c404..41490cde95ad 100644
--- a/include/uapi/linux/uio.h
+++ b/include/uapi/linux/uio.h
@@ -38,6 +38,11 @@ struct dmabuf_token {
        __u32 token_count;
 };
 
+struct dmabuf_tx_cmsg {
+       __u32 dmabuf_id;
+       __u64 dmabuf_offset;
+};
+
 /*
  *     UIO_MAXIOV shall be at least 16 1003.1g (5.4.1.1)
  */
diff --git a/net/core/datagram.c b/net/core/datagram.c
index f0693707aece..3b09995db894 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' ?
  */
@@ -692,9 +694,41 @@ int zerocopy_fill_skb_from_iter(struct sk_buff *skb,
        return 0;
 }
 
+static int zerocopy_fill_skb_from_devmem(struct sk_buff *skb,
+                                        struct msghdr *msg,
+                                        struct iov_iter *from, int length)
+{
+       int i = skb_shinfo(skb)->nr_frags;
+       int orig_length = length;
+       netmem_ref netmem;
+       size_t size;
+
+       while (length && iov_iter_count(from)) {
+               if (i == MAX_SKB_FRAGS)
+                       return -EMSGSIZE;
+
+               size = min_t(size_t, iter_iov_len(from), length);
+               if (!size)
+                       return -EFAULT;
+
+               netmem = net_iov_to_netmem(iter_iov(from)->iov_base);
+               get_netmem(netmem);
+               skb_add_rx_frag_netmem(skb, i, netmem, from->iov_offset, size,
+                                      PAGE_SIZE);
+
+               iov_iter_advance(from, size);
+               length -= size;
+               i++;
+       }
+
+       iov_iter_advance(&msg->msg_iter, orig_length);
+
+       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, bool is_devmem)
 {
        unsigned long orig_size = skb->truesize;
        unsigned long truesize;
@@ -702,6 +736,8 @@ 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 (unlikely(is_devmem))
+               ret = zerocopy_fill_skb_from_devmem(skb, msg, from, length);
        else
                ret = zerocopy_fill_skb_from_iter(skb, from, length);
 
@@ -735,7 +771,7 @@ 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/devmem.c b/net/core/devmem.c
index f7e06a8cba01..81f1b715cfa6 100644
--- a/net/core/devmem.c
+++ b/net/core/devmem.c
@@ -15,6 +15,7 @@
 #include <net/netdev_queues.h>
 #include <net/netdev_rx_queue.h>
 #include <net/page_pool/helpers.h>
+#include <net/sock.h>
 #include <trace/events/page_pool.h>
 
 #include "devmem.h"
@@ -63,8 +64,10 @@ 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);
+       kfree(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)
@@ -109,6 +112,13 @@ 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);
 
@@ -122,8 +132,6 @@ void net_devmem_unbind_dmabuf(struct 
net_devmem_dmabuf_binding *binding)
                WARN_ON(netdev_rx_queue_restart(binding->dev, rxq_idx));
        }
 
-       xa_erase(&net_devmem_dmabuf_bindings, binding->id);
-
        net_devmem_dmabuf_binding_put(binding);
 }
 
@@ -174,8 +182,9 @@ int net_devmem_bind_dmabuf_to_queue(struct net_device *dev, 
u32 rxq_idx,
 }
 
 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;
@@ -183,6 +192,7 @@ net_devmem_bind_dmabuf(struct net_device *dev, unsigned int 
dmabuf_fd,
        struct dma_buf *dmabuf;
        unsigned int sg_idx, i;
        unsigned long virtual;
+       struct iovec *iov;
        int err;
 
        dmabuf = dma_buf_get(dmabuf_fd);
@@ -218,13 +228,19 @@ net_devmem_bind_dmabuf(struct net_device *dev, unsigned 
int dmabuf_fd,
        }
 
        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 (!binding->sgt || binding->sgt->nents == 0) {
+               err = -EINVAL;
+               NL_SET_ERR_MSG(extack, "Empty dmabuf attachment");
+               goto err_detach;
+       }
+
        /* 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...
@@ -236,6 +252,19 @@ net_devmem_bind_dmabuf(struct net_device *dev, unsigned 
int dmabuf_fd,
                goto err_unmap;
        }
 
+       if (direction == DMA_TO_DEVICE) {
+               virtual = 0;
+               for_each_sgtable_dma_sg(binding->sgt, sg, sg_idx)
+                       virtual += sg_dma_len(sg);
+
+               binding->tx_vec = kcalloc(virtual / PAGE_SIZE + 1,
+                                         sizeof(struct iovec), GFP_KERNEL);
+               if (!binding->tx_vec) {
+                       err = -ENOMEM;
+                       goto err_unmap;
+               }
+       }
+
        virtual = 0;
        for_each_sgtable_dma_sg(binding->sgt, sg, sg_idx) {
                dma_addr_t dma_addr = sg_dma_address(sg);
@@ -277,11 +306,21 @@ net_devmem_bind_dmabuf(struct net_device *dev, unsigned 
int dmabuf_fd,
                        niov->owner = owner;
                        page_pool_set_dma_addr_netmem(net_iov_to_netmem(niov),
                                                      
net_devmem_get_dma_addr(niov));
+
+                       if (direction == DMA_TO_DEVICE) {
+                               iov = &binding->tx_vec[virtual / PAGE_SIZE + i];
+                               iov->iov_base = niov;
+                               iov->iov_len = PAGE_SIZE;
+                       }
                }
 
                virtual += len;
        }
 
+       if (direction == DMA_TO_DEVICE)
+               iov_iter_init(&binding->tx_iter, WRITE, binding->tx_vec,
+                             virtual / PAGE_SIZE + 1, virtual);
+
        return binding;
 
 err_free_chunks:
@@ -302,6 +341,21 @@ net_devmem_bind_dmabuf(struct net_device *dev, unsigned 
int dmabuf_fd,
        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 dev_dmabuf_uninstall(struct net_device *dev)
 {
        struct net_devmem_dmabuf_binding *binding;
@@ -332,6 +386,33 @@ void net_devmem_put_net_iov(struct net_iov *niov)
        net_devmem_dmabuf_binding_put(niov->owner->binding);
 }
 
+struct net_devmem_dmabuf_binding *
+net_devmem_get_sockc_binding(struct sock *sk, struct sockcm_cookie *sockc)
+{
+       struct net_devmem_dmabuf_binding *binding;
+       int err = 0;
+
+       binding = net_devmem_lookup_dmabuf(sockc->dmabuf_id);
+       if (!binding || !binding->tx_vec) {
+               err = -EINVAL;
+               goto out_err;
+       }
+
+       if (sock_net(sk) != dev_net(binding->dev)) {
+               err = -ENODEV;
+               goto out_err;
+       }
+
+       iov_iter_advance(&binding->tx_iter, sockc->dmabuf_offset);
+       return binding;
+
+out_err:
+       if (binding)
+               net_devmem_dmabuf_binding_put(binding);
+
+       return ERR_PTR(err);
+}
+
 /*** "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 54e30fea80b3..f923c77d9c45 100644
--- a/net/core/devmem.h
+++ b/net/core/devmem.h
@@ -11,6 +11,8 @@
 #define _NET_DEVMEM_H
 
 struct netlink_ext_ack;
+struct sockcm_cookie;
+struct sock;
 
 struct net_devmem_dmabuf_binding {
        struct dma_buf *dmabuf;
@@ -27,6 +29,10 @@ struct net_devmem_dmabuf_binding {
         * 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 that the binding remains alive until all
+        * the net_iovs are no longer used.
         */
        refcount_t ref;
 
@@ -42,6 +48,10 @@ struct net_devmem_dmabuf_binding {
         * active.
         */
        u32 id;
+
+       /* iov_iter representing all possible net_iov chunks in the dmabuf. */
+       struct iov_iter tx_iter;
+       struct iovec *tx_vec;
 };
 
 #if defined(CONFIG_NET_DEVMEM)
@@ -66,8 +76,10 @@ struct dmabuf_genpool_chunk_owner {
 
 void __net_devmem_dmabuf_binding_free(struct net_devmem_dmabuf_binding 
*binding);
 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,
@@ -104,10 +116,10 @@ static inline u32 net_iov_binding_id(const struct net_iov 
*niov)
        return net_iov_owner(niov)->binding->id;
 }
 
-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
@@ -126,6 +138,9 @@ struct net_iov *
 net_devmem_alloc_dmabuf(struct net_devmem_dmabuf_binding *binding);
 void net_devmem_free_dmabuf(struct net_iov *ppiov);
 
+struct net_devmem_dmabuf_binding *
+net_devmem_get_sockc_binding(struct sock *sk, struct sockcm_cookie *sockc);
+
 #else
 struct net_devmem_dmabuf_binding;
 
@@ -144,11 +159,17 @@ __net_devmem_dmabuf_binding_free(struct 
net_devmem_dmabuf_binding *binding)
 
 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)
 {
@@ -186,6 +207,17 @@ static inline u32 net_iov_binding_id(const struct net_iov 
*niov)
 {
        return 0;
 }
+
+static inline void
+net_devmem_dmabuf_binding_put(struct net_devmem_dmabuf_binding *binding)
+{
+}
+
+static inline struct net_devmem_dmabuf_binding *
+net_devmem_get_sockc_binding(struct sock *sk, struct sockcm_cookie *sockc)
+{
+       return ERR_PTR(-EOPNOTSUPP);
+}
 #endif
 
 #endif /* _NET_DEVMEM_H */
diff --git a/net/core/netdev-genl.c b/net/core/netdev-genl.c
index 00d3d5851487..b9928bac94da 100644
--- a/net/core/netdev-genl.c
+++ b/net/core/netdev-genl.c
@@ -850,7 +850,8 @@ 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;
@@ -907,10 +908,68 @@ int netdev_nl_bind_rx_doit(struct sk_buff *skb, struct 
genl_info *info)
        return err;
 }
 
-/* stub */
 int netdev_nl_bind_tx_doit(struct sk_buff *skb, struct genl_info *info)
 {
-       return 0;
+       struct net_devmem_dmabuf_binding *binding;
+       struct list_head *sock_binding_list;
+       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]);
+
+       sock_binding_list =
+               genl_sk_priv_get(&netdev_nl_family, NETLINK_CB(skb).sk);
+       if (IS_ERR(sock_binding_list))
+               return PTR_ERR(sock_binding_list);
+
+       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;
+       }
+
+       rtnl_lock();
+
+       netdev = __dev_get_by_index(genl_info_net(info), ifindex);
+       if (!netdev || !netif_device_present(netdev)) {
+               err = -ENODEV;
+               goto err_unlock;
+       }
+
+       binding = net_devmem_bind_dmabuf(netdev, DMA_TO_DEVICE, dmabuf_fd,
+                                        info->extack);
+       if (IS_ERR(binding)) {
+               err = PTR_ERR(binding);
+               goto err_unlock;
+       }
+
+       list_add(&binding->list, sock_binding_list);
+
+       nla_put_u32(rsp, NETDEV_A_DMABUF_ID, binding->id);
+       genlmsg_end(rsp, hdr);
+
+       rtnl_unlock();
+
+       return genlmsg_reply(rsp, info);
+
+       net_devmem_unbind_dmabuf(binding);
+err_unlock:
+       rtnl_unlock();
+err_genlmsg_free:
+       nlmsg_free(rsp);
+       return err;
 }
 
 void netdev_nl_sock_priv_init(struct list_head *priv)
diff --git a/net/core/skbuff.c b/net/core/skbuff.c
index 815245d5c36b..eb6b41a32524 100644
--- a/net/core/skbuff.c
+++ b/net/core/skbuff.c
@@ -1882,8 +1882,10 @@ 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)
 {
+       struct iov_iter *from = binding ? &binding->tx_iter : &msg->msg_iter;
        int err, orig_len = skb->len;
 
        if (uarg->ops->link_skb) {
@@ -1901,12 +1903,12 @@ 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, from, len, binding != NULL);
        if (err == -EFAULT || (err == -EMSGSIZE && skb->len == orig_len)) {
                struct sock *save_sk = skb->sk;
 
                /* Streams do not free skb on error. Reset to prev state. */
-               iov_iter_revert(&msg->msg_iter, skb->len - orig_len);
+               iov_iter_revert(from, skb->len - orig_len);
                skb->sk = sk;
                ___pskb_trim(skb, orig_len);
                skb->sk = save_sk;
diff --git a/net/core/sock.c b/net/core/sock.c
index e7bcc8952248..ed7089310f0d 100644
--- a/net/core/sock.c
+++ b/net/core/sock.c
@@ -2908,6 +2908,7 @@ EXPORT_SYMBOL(sock_alloc_send_pskb);
 int __sock_cmsg_send(struct sock *sk, struct cmsghdr *cmsg,
                     struct sockcm_cookie *sockc)
 {
+       struct dmabuf_tx_cmsg dmabuf_tx;
        u32 tsflags;
 
        BUILD_BUG_ON(SOF_TIMESTAMPING_LAST == (1 << 31));
@@ -2961,6 +2962,14 @@ int __sock_cmsg_send(struct sock *sk, struct cmsghdr 
*cmsg,
                if (!sk_set_prio_allowed(sk, *(u32 *)CMSG_DATA(cmsg)))
                        return -EPERM;
                sockc->priority = *(u32 *)CMSG_DATA(cmsg);
+               break;
+       case SCM_DEVMEM_DMABUF:
+               if (cmsg->cmsg_len != CMSG_LEN(sizeof(struct dmabuf_tx_cmsg)))
+                       return -EINVAL;
+               dmabuf_tx = *(struct dmabuf_tx_cmsg *)CMSG_DATA(cmsg);
+               sockc->dmabuf_id = dmabuf_tx.dmabuf_id;
+               sockc->dmabuf_offset = dmabuf_tx.dmabuf_offset;
+
                break;
        default:
                return -EINVAL;
diff --git a/net/ipv4/tcp.c b/net/ipv4/tcp.c
index 0d704bda6c41..406dc2993742 100644
--- a/net/ipv4/tcp.c
+++ b/net/ipv4/tcp.c
@@ -1051,6 +1051,7 @@ 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;
@@ -1063,6 +1064,15 @@ int tcp_sendmsg_locked(struct sock *sk, struct msghdr 
*msg, size_t size)
 
        flags = msg->msg_flags;
 
+       sockcm_init(&sockc, sk);
+       if (msg->msg_controllen) {
+               err = sock_cmsg_send(sk, msg, &sockc);
+               if (unlikely(err)) {
+                       err = -EINVAL;
+                       goto out_err;
+               }
+       }
+
        if ((flags & MSG_ZEROCOPY) && size) {
                if (msg->msg_ubuf) {
                        uarg = msg->msg_ubuf;
@@ -1080,6 +1090,15 @@ int tcp_sendmsg_locked(struct sock *sk, struct msghdr 
*msg, size_t size)
                        else
                                uarg_to_msgzc(uarg)->zerocopy = 0;
                }
+
+               if (sockc.dmabuf_id != 0) {
+                       binding = net_devmem_get_sockc_binding(sk, &sockc);
+                       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;
@@ -1123,15 +1142,6 @@ int tcp_sendmsg_locked(struct sock *sk, struct msghdr 
*msg, size_t size)
                /* 'common' sending to sendq */
        }
 
-       sockcm_init(&sockc, sk);
-       if (msg->msg_controllen) {
-               err = sock_cmsg_send(sk, msg, &sockc);
-               if (unlikely(err)) {
-                       err = -EINVAL;
-                       goto out_err;
-               }
-       }
-
        /* This should be in poll */
        sk_clear_bit(SOCKWQ_ASYNC_NOSPACE, sk);
 
@@ -1248,7 +1258,8 @@ int tcp_sendmsg_locked(struct sock *sk, struct msghdr 
*msg, size_t size)
                                        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;
@@ -1329,6 +1340,8 @@ int tcp_sendmsg_locked(struct sock *sk, struct msghdr 
*msg, size_t size)
        /* 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:
@@ -1346,6 +1359,9 @@ int tcp_sendmsg_locked(struct sock *sk, struct msghdr 
*msg, size_t size)
                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/vmw_vsock/virtio_transport_common.c 
b/net/vmw_vsock/virtio_transport_common.c
index 9acc13ab3f82..286e6cd5ad34 100644
--- a/net/vmw_vsock/virtio_transport_common.c
+++ b/net/vmw_vsock/virtio_transport_common.c
@@ -104,8 +104,8 @@ 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,
+                                              false);
 
        return memcpy_from_msg(skb_put(skb, len), info->msg, len);
 }
-- 
2.47.1.613.gc27f4b7a9f-goog


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