1 /* SPDX-License-Identifier: GPL-2.0 2 * 3 * Network memory 4 * 5 * Author: Mina Almasry <almasrymina@google.com> 6 */ 7 8 #ifndef _NET_NETMEM_H 9 #define _NET_NETMEM_H 10 11 #include <linux/dma-mapping.h> 12 #include <linux/mm.h> 13 #include <net/net_debug.h> 14 15 /* net_iov */ 16 17 DECLARE_STATIC_KEY_FALSE(page_pool_mem_providers); 18 19 /* We overload the LSB of the struct page pointer to indicate whether it's 20 * a page or net_iov. 21 */ 22 #define NET_IOV 0x01UL 23 24 enum net_iov_type { 25 NET_IOV_DMABUF, 26 NET_IOV_IOURING, 27 28 /* Force size to unsigned long to make the NET_IOV_ASSERTS below pass. 29 */ 30 NET_IOV_MAX = ULONG_MAX 31 }; 32 33 struct net_iov { 34 enum net_iov_type type; 35 unsigned long pp_magic; 36 struct page_pool *pp; 37 struct net_iov_area *owner; 38 unsigned long dma_addr; 39 atomic_long_t pp_ref_count; 40 }; 41 42 struct net_iov_area { 43 /* Array of net_iovs for this area. */ 44 struct net_iov *niovs; 45 size_t num_niovs; 46 47 /* Offset into the dma-buf where this chunk starts. */ 48 unsigned long base_virtual; 49 }; 50 51 /* These fields in struct page are used by the page_pool and net stack: 52 * 53 * struct { 54 * unsigned long pp_magic; 55 * struct page_pool *pp; 56 * unsigned long _pp_mapping_pad; 57 * unsigned long dma_addr; 58 * atomic_long_t pp_ref_count; 59 * }; 60 * 61 * We mirror the page_pool fields here so the page_pool can access these fields 62 * without worrying whether the underlying fields belong to a page or net_iov. 63 * 64 * The non-net stack fields of struct page are private to the mm stack and must 65 * never be mirrored to net_iov. 66 */ 67 #define NET_IOV_ASSERT_OFFSET(pg, iov) \ 68 static_assert(offsetof(struct page, pg) == \ 69 offsetof(struct net_iov, iov)) 70 NET_IOV_ASSERT_OFFSET(pp_magic, pp_magic); 71 NET_IOV_ASSERT_OFFSET(pp, pp); 72 NET_IOV_ASSERT_OFFSET(dma_addr, dma_addr); 73 NET_IOV_ASSERT_OFFSET(pp_ref_count, pp_ref_count); 74 #undef NET_IOV_ASSERT_OFFSET 75 76 static inline struct net_iov_area *net_iov_owner(const struct net_iov *niov) 77 { 78 return niov->owner; 79 } 80 81 static inline unsigned int net_iov_idx(const struct net_iov *niov) 82 { 83 return niov - net_iov_owner(niov)->niovs; 84 } 85 86 /* netmem */ 87 88 /** 89 * typedef netmem_ref - a nonexistent type marking a reference to generic 90 * network memory. 91 * 92 * A netmem_ref currently is always a reference to a struct page. This 93 * abstraction is introduced so support for new memory types can be added. 94 * 95 * Use the supplied helpers to obtain the underlying memory pointer and fields. 96 */ 97 typedef unsigned long __bitwise netmem_ref; 98 99 static inline bool netmem_is_net_iov(const netmem_ref netmem) 100 { 101 return (__force unsigned long)netmem & NET_IOV; 102 } 103 104 /** 105 * __netmem_to_page - unsafely get pointer to the &page backing @netmem 106 * @netmem: netmem reference to convert 107 * 108 * Unsafe version of netmem_to_page(). When @netmem is always page-backed, 109 * e.g. when it's a header buffer, performs faster and generates smaller 110 * object code (no check for the LSB, no WARN). When @netmem points to IOV, 111 * provokes undefined behaviour. 112 * 113 * Return: pointer to the &page (garbage if @netmem is not page-backed). 114 */ 115 static inline struct page *__netmem_to_page(netmem_ref netmem) 116 { 117 return (__force struct page *)netmem; 118 } 119 120 /* This conversion fails (returns NULL) if the netmem_ref is not struct page 121 * backed. 122 */ 123 static inline struct page *netmem_to_page(netmem_ref netmem) 124 { 125 if (WARN_ON_ONCE(netmem_is_net_iov(netmem))) 126 return NULL; 127 128 return __netmem_to_page(netmem); 129 } 130 131 static inline struct net_iov *netmem_to_net_iov(netmem_ref netmem) 132 { 133 if (netmem_is_net_iov(netmem)) 134 return (struct net_iov *)((__force unsigned long)netmem & 135 ~NET_IOV); 136 137 DEBUG_NET_WARN_ON_ONCE(true); 138 return NULL; 139 } 140 141 static inline netmem_ref net_iov_to_netmem(struct net_iov *niov) 142 { 143 return (__force netmem_ref)((unsigned long)niov | NET_IOV); 144 } 145 146 static inline netmem_ref page_to_netmem(struct page *page) 147 { 148 return (__force netmem_ref)page; 149 } 150 151 /** 152 * virt_to_netmem - convert virtual memory pointer to a netmem reference 153 * @data: host memory pointer to convert 154 * 155 * Return: netmem reference to the &page backing this virtual address. 156 */ 157 static inline netmem_ref virt_to_netmem(const void *data) 158 { 159 return page_to_netmem(virt_to_page(data)); 160 } 161 162 static inline int netmem_ref_count(netmem_ref netmem) 163 { 164 /* The non-pp refcount of net_iov is always 1. On net_iov, we only 165 * support pp refcounting which uses the pp_ref_count field. 166 */ 167 if (netmem_is_net_iov(netmem)) 168 return 1; 169 170 return page_ref_count(netmem_to_page(netmem)); 171 } 172 173 static inline unsigned long netmem_pfn_trace(netmem_ref netmem) 174 { 175 if (netmem_is_net_iov(netmem)) 176 return 0; 177 178 return page_to_pfn(netmem_to_page(netmem)); 179 } 180 181 static inline struct net_iov *__netmem_clear_lsb(netmem_ref netmem) 182 { 183 return (struct net_iov *)((__force unsigned long)netmem & ~NET_IOV); 184 } 185 186 /** 187 * __netmem_get_pp - unsafely get pointer to the &page_pool backing @netmem 188 * @netmem: netmem reference to get the pointer from 189 * 190 * Unsafe version of netmem_get_pp(). When @netmem is always page-backed, 191 * e.g. when it's a header buffer, performs faster and generates smaller 192 * object code (avoids clearing the LSB). When @netmem points to IOV, 193 * provokes invalid memory access. 194 * 195 * Return: pointer to the &page_pool (garbage if @netmem is not page-backed). 196 */ 197 static inline struct page_pool *__netmem_get_pp(netmem_ref netmem) 198 { 199 return __netmem_to_page(netmem)->pp; 200 } 201 202 static inline struct page_pool *netmem_get_pp(netmem_ref netmem) 203 { 204 return __netmem_clear_lsb(netmem)->pp; 205 } 206 207 static inline atomic_long_t *netmem_get_pp_ref_count_ref(netmem_ref netmem) 208 { 209 return &__netmem_clear_lsb(netmem)->pp_ref_count; 210 } 211 212 static inline bool netmem_is_pref_nid(netmem_ref netmem, int pref_nid) 213 { 214 /* NUMA node preference only makes sense if we're allocating 215 * system memory. Memory providers (which give us net_iovs) 216 * choose for us. 217 */ 218 if (netmem_is_net_iov(netmem)) 219 return true; 220 221 return page_to_nid(netmem_to_page(netmem)) == pref_nid; 222 } 223 224 static inline netmem_ref netmem_compound_head(netmem_ref netmem) 225 { 226 /* niov are never compounded */ 227 if (netmem_is_net_iov(netmem)) 228 return netmem; 229 230 return page_to_netmem(compound_head(netmem_to_page(netmem))); 231 } 232 233 /** 234 * __netmem_address - unsafely get pointer to the memory backing @netmem 235 * @netmem: netmem reference to get the pointer for 236 * 237 * Unsafe version of netmem_address(). When @netmem is always page-backed, 238 * e.g. when it's a header buffer, performs faster and generates smaller 239 * object code (no check for the LSB). When @netmem points to IOV, provokes 240 * undefined behaviour. 241 * 242 * Return: pointer to the memory (garbage if @netmem is not page-backed). 243 */ 244 static inline void *__netmem_address(netmem_ref netmem) 245 { 246 return page_address(__netmem_to_page(netmem)); 247 } 248 249 static inline void *netmem_address(netmem_ref netmem) 250 { 251 if (netmem_is_net_iov(netmem)) 252 return NULL; 253 254 return __netmem_address(netmem); 255 } 256 257 /** 258 * netmem_is_pfmemalloc - check if @netmem was allocated under memory pressure 259 * @netmem: netmem reference to check 260 * 261 * Return: true if @netmem is page-backed and the page was allocated under 262 * memory pressure, false otherwise. 263 */ 264 static inline bool netmem_is_pfmemalloc(netmem_ref netmem) 265 { 266 if (netmem_is_net_iov(netmem)) 267 return false; 268 269 return page_is_pfmemalloc(netmem_to_page(netmem)); 270 } 271 272 static inline unsigned long netmem_get_dma_addr(netmem_ref netmem) 273 { 274 return __netmem_clear_lsb(netmem)->dma_addr; 275 } 276 277 void get_netmem(netmem_ref netmem); 278 void put_netmem(netmem_ref netmem); 279 280 #define netmem_dma_unmap_addr_set(NETMEM, PTR, ADDR_NAME, VAL) \ 281 do { \ 282 if (!netmem_is_net_iov(NETMEM)) \ 283 dma_unmap_addr_set(PTR, ADDR_NAME, VAL); \ 284 else \ 285 dma_unmap_addr_set(PTR, ADDR_NAME, 0); \ 286 } while (0) 287 288 static inline void netmem_dma_unmap_page_attrs(struct device *dev, 289 dma_addr_t addr, size_t size, 290 enum dma_data_direction dir, 291 unsigned long attrs) 292 { 293 if (!addr) 294 return; 295 296 dma_unmap_page_attrs(dev, addr, size, dir, attrs); 297 } 298 299 #endif /* _NET_NETMEM_H */ 300