1 files changed, 245 insertions, 0 deletions
diff --git a/net/core/devmem.h b/net/core/devmem.h
new file mode 100644
index 000000000000..e7ba77050b8f
--- /dev/null
+++ b/net/core/devmem.h
@@ -0,0 +1,245 @@
+/* SPDX-License-Identifier: GPL-2.0-or-later */
+/*
+ * Device memory TCP support
+ *
+ * Authors:	Mina Almasry <almasrymina@google.com>
+ *		Willem de Bruijn <willemb@google.com>
+ *		Kaiyuan Zhang <kaiyuanz@google.com>
+ *
+ */
+#ifndef _NET_DEVMEM_H
+#define _NET_DEVMEM_H
+
+#include <net/netmem.h>
+#include <net/netdev_netlink.h>
+
+struct netlink_ext_ack;
+
+struct net_devmem_dmabuf_binding {
+	struct dma_buf *dmabuf;
+	struct dma_buf_attachment *attachment;
+	struct sg_table *sgt;
+	struct net_device *dev;
+	struct gen_pool *chunk_pool;
+	/* Protect dev */
+	struct mutex lock;
+
+	/* 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. 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;
+
+	/* The list of bindings currently active. Used for netlink to notify us
+	 * of the user dropping the bind.
+	 */
+	struct list_head list;
+
+	/* rxq's this binding is active on. */
+	struct xarray bound_rxqs;
+
+	/* ID of this binding. Globally unique to all bindings currently
+	 * 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)
+/* Owner of the dma-buf chunks inserted into the gen pool. Each scatterlist
+ * entry from the dmabuf is inserted into the genpool as a chunk, and needs
+ * this owner struct to keep track of some metadata necessary to create
+ * allocations from this chunk.
+ */
+struct dmabuf_genpool_chunk_owner {
+	struct net_iov_area area;
+	struct net_devmem_dmabuf_binding *binding;
+
+	/* dma_addr of the start of the chunk.  */
+	dma_addr_t base_dma_addr;
+};
+
+void __net_devmem_dmabuf_binding_free(struct work_struct *wq);
+struct net_devmem_dmabuf_binding *
+net_devmem_bind_dmabuf(struct net_device *dev,
+		       enum dma_data_direction direction,
+		       unsigned int dmabuf_fd, struct netdev_nl_sock *priv,
+		       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)
+{
+	struct net_iov_area *owner = net_iov_owner(niov);
+
+	return container_of(owner, struct dmabuf_genpool_chunk_owner, area);
+}
+
+static inline struct net_devmem_dmabuf_binding *
+net_devmem_iov_binding(const struct net_iov *niov)
+{
+	return net_devmem_iov_to_chunk_owner(niov)->binding;
+}
+
+static inline u32 net_devmem_iov_binding_id(const struct net_iov *niov)
+{
+	return net_devmem_iov_binding(niov)->id;
+}
+
+static inline unsigned long net_iov_virtual_addr(const struct net_iov *niov)
+{
+	struct net_iov_area *owner = net_iov_owner(niov);
+
+	return owner->base_virtual +
+	       ((unsigned long)net_iov_idx(niov) << PAGE_SHIFT);
+}
+
+static inline bool
+net_devmem_dmabuf_binding_get(struct net_devmem_dmabuf_binding *binding)
+{
+	return refcount_inc_not_zero(&binding->ref);
+}
+
+static inline void
+net_devmem_dmabuf_binding_put(struct net_devmem_dmabuf_binding *binding)
+{
+	if (!refcount_dec_and_test(&binding->ref))
+		return;
+
+	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_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 netdev_nl_sock *priv,
+		       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)
+{
+}
+
+static inline 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)
+
+{
+	return -EOPNOTSUPP;
+}
+
+static inline struct net_iov *
+net_devmem_alloc_dmabuf(struct net_devmem_dmabuf_binding *binding)
+{
+	return NULL;
+}
+
+static inline void net_devmem_free_dmabuf(struct net_iov *ppiov)
+{
+}
+
+static inline unsigned long net_iov_virtual_addr(const struct net_iov *niov)
+{
+	return 0;
+}
+
+static inline u32 net_devmem_iov_binding_id(const struct net_iov *niov)
+{
+	return 0;
+}
+
+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 */