net/core/devmem.h

   1 /* SPDX-License-Identifier: GPL-2.0-or-later */
   2 /*
   3  * Device memory TCP support
   4  *
   5  * Authors:     Mina Almasry <almasrymina@google.com>
   6  *              Willem de Bruijn <willemb@google.com>
   7  *              Kaiyuan Zhang <kaiyuanz@google.com>
   8  *
   9  */
  10 #ifndef _NET_DEVMEM_H
  11 #define _NET_DEVMEM_H
  12
  13 struct netlink_ext_ack;
  14
  15 struct net_devmem_dmabuf_binding {
  16         struct dma_buf *dmabuf;
  17         struct dma_buf_attachment *attachment;
  18         struct sg_table *sgt;
  19         struct net_device *dev;
  20         struct gen_pool *chunk_pool;
  21
  22         /* The user holds a ref (via the netlink API) for as long as they want
  23          * the binding to remain alive. Each page pool using this binding holds
  24          * a ref to keep the binding alive. Each allocated net_iov holds a
  25          * ref.
  26          *
  27          * The binding undos itself and unmaps the underlying dmabuf once all
  28          * those refs are dropped and the binding is no longer desired or in
  29          * use.
  30          */
  31         refcount_t ref;
  32
  33         /* The list of bindings currently active. Used for netlink to notify us
  34          * of the user dropping the bind.
  35          */
  36         struct list_head list;
  37
  38         /* rxq's this binding is active on. */
  39         struct xarray bound_rxqs;
  40
  41         /* ID of this binding. Globally unique to all bindings currently
  42          * active.
  43          */
  44         u32 id;
  45 };
  46
  47 #if defined(CONFIG_NET_DEVMEM)
  48 /* Owner of the dma-buf chunks inserted into the gen pool. Each scatterlist
  49  * entry from the dmabuf is inserted into the genpool as a chunk, and needs
  50  * this owner struct to keep track of some metadata necessary to create
  51  * allocations from this chunk.
  52  */
  53 struct dmabuf_genpool_chunk_owner {
  54         /* Offset into the dma-buf where this chunk starts.  */
  55         unsigned long base_virtual;
  56
  57         /* dma_addr of the start of the chunk.  */
  58         dma_addr_t base_dma_addr;
  59
  60         /* Array of net_iovs for this chunk. */
  61         struct net_iov *niovs;
  62         size_t num_niovs;
  63
  64         struct net_devmem_dmabuf_binding *binding;
  65 };
  66
  67 void __net_devmem_dmabuf_binding_free(struct net_devmem_dmabuf_binding *binding);
  68 struct net_devmem_dmabuf_binding *
  69 net_devmem_bind_dmabuf(struct net_device *dev, unsigned int dmabuf_fd,
  70                        struct netlink_ext_ack *extack);
  71 void net_devmem_unbind_dmabuf(struct net_devmem_dmabuf_binding *binding);
  72 int net_devmem_bind_dmabuf_to_queue(struct net_device *dev, u32 rxq_idx,
  73                                     struct net_devmem_dmabuf_binding *binding,
  74                                     struct netlink_ext_ack *extack);
  75 void dev_dmabuf_uninstall(struct net_device *dev);
  76
  77 static inline struct dmabuf_genpool_chunk_owner *
  78 net_iov_owner(const struct net_iov *niov)
  79 {
  80         return niov->owner;
  81 }
  82
  83 static inline unsigned int net_iov_idx(const struct net_iov *niov)
  84 {
  85         return niov - net_iov_owner(niov)->niovs;
  86 }
  87
  88 static inline struct net_devmem_dmabuf_binding *
  89 net_iov_binding(const struct net_iov *niov)
  90 {
  91         return net_iov_owner(niov)->binding;
  92 }
  93
  94 static inline unsigned long net_iov_virtual_addr(const struct net_iov *niov)
  95 {
  96         struct dmabuf_genpool_chunk_owner *owner = net_iov_owner(niov);
  97
  98         return owner->base_virtual +
  99                ((unsigned long)net_iov_idx(niov) << PAGE_SHIFT);
 100 }
 101
 102 static inline u32 net_iov_binding_id(const struct net_iov *niov)
 103 {
 104         return net_iov_owner(niov)->binding->id;
 105 }
 106
 107 static inline void
 108 net_devmem_dmabuf_binding_get(struct net_devmem_dmabuf_binding *binding)
 109 {
 110         refcount_inc(&binding->ref);
 111 }
 112
 113 static inline void
 114 net_devmem_dmabuf_binding_put(struct net_devmem_dmabuf_binding *binding)
 115 {
 116         if (!refcount_dec_and_test(&binding->ref))
 117                 return;
 118
 119         __net_devmem_dmabuf_binding_free(binding);
 120 }
 121
 122 struct net_iov *
 123 net_devmem_alloc_dmabuf(struct net_devmem_dmabuf_binding *binding);
 124 void net_devmem_free_dmabuf(struct net_iov *ppiov);
 125
 126 #else
 127 struct net_devmem_dmabuf_binding;
 128
 129 static inline void
 130 __net_devmem_dmabuf_binding_free(struct net_devmem_dmabuf_binding *binding)
 131 {
 132 }
 133
 134 static inline struct net_devmem_dmabuf_binding *
 135 net_devmem_bind_dmabuf(struct net_device *dev, unsigned int dmabuf_fd,
 136                        struct netlink_ext_ack *extack)
 137 {
 138         return ERR_PTR(-EOPNOTSUPP);
 139 }
 140
 141 static inline void
 142 net_devmem_unbind_dmabuf(struct net_devmem_dmabuf_binding *binding)
 143 {
 144 }
 145
 146 static inline int
 147 net_devmem_bind_dmabuf_to_queue(struct net_device *dev, u32 rxq_idx,
 148                                 struct net_devmem_dmabuf_binding *binding,
 149                                 struct netlink_ext_ack *extack)
 150
 151 {
 152         return -EOPNOTSUPP;
 153 }
 154
 155 static inline void dev_dmabuf_uninstall(struct net_device *dev)
 156 {
 157 }
 158
 159 static inline struct net_iov *
 160 net_devmem_alloc_dmabuf(struct net_devmem_dmabuf_binding *binding)
 161 {
 162         return NULL;
 163 }
 164
 165 static inline void net_devmem_free_dmabuf(struct net_iov *ppiov)
 166 {
 167 }
 168
 169 static inline unsigned long net_iov_virtual_addr(const struct net_iov *niov)
 170 {
 171         return 0;
 172 }
 173
 174 static inline u32 net_iov_binding_id(const struct net_iov *niov)
 175 {
 176         return 0;
 177 }
 178 #endif
 179
 180 #endif /* _NET_DEVMEM_H */