| Message ID | 20241221004236.2629280-6-almasrymina@google.com (mailing list archive) |
|---|---|
| State | RFC |
| Delegated to: | Netdev Maintainers |
| Headers | show |
| Series | Device memory TCP TX | expand |
On 12/21, Mina Almasry wrote: > 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 <sdf@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 <sdf@fomichev.me> > Signed-off-by: Kaiyuan Zhang <kaiyuanz@google.com> > Signed-off-by: Mina Almasry <almasrymina@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; For tx, I feel like this needs a copy of binding->tx_iter: struct iov_iter tx_iter = binding->tx_iter; struct iov_iter *from = binding ? &tx_iter : &msg->msg_iter; Or something similar (rewind?). The tx_iter is advanced in zerocopy_fill_skb_from_devmem but never reset back it seems (or I'm missing something). In you case, if you call sendmsg twice with the same offset, the second one will copy from 2*offset. But I'd vote to move away from iov_iter on the tx side. From my initial testing, the perf wasn't great. It's basically O(n_chunks) on every message (iov_iter_advance does linear walk over the chunks). So when we call several sendmsg() with 4k chunks and increasing offset, this blows up to O(n_chunks^2). I tried to "fix" it by caching previous iter position so the next sendmsg can continue without rewinding, but it was a bit messy. I have this simplified constant time version in [1], pls take a look and lmk what you think (zerocopy_fill_skb_from_devmem and net_devmem_get_niov_at). It is significantly faster and much simpler. 1: https://github.com/fomichev/linux/commit/3b3ad4f36771a376c204727e5a167c4993d4c65a#diff-a3bb611c084dada9bcd3ef6c5f9a17f6c5d58eb8e168aa9b07241841e96f6b94R710
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); }