1 /******************************************************************************
2 * netif.h
3 *
4 * Unified network-device I/O interface for Xen guest OSes.
5 *
6 * Permission is hereby granted, free of charge, to any person obtaining a copy
7 * of this software and associated documentation files (the "Software"), to
8 * deal in the Software without restriction, including without limitation the
9 * rights to use, copy, modify, merge, publish, distribute, sublicense, and/or
10 * sell copies of the Software, and to permit persons to whom the Software is
11 * furnished to do so, subject to the following conditions:
12 *
13 * The above copyright notice and this permission notice shall be included in
14 * all copies or substantial portions of the Software.
15 *
16 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
17 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
18 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
19 * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
20 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
21 * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
22 * DEALINGS IN THE SOFTWARE.
23 *
24 * Copyright (c) 2003-2004, Keir Fraser
25 */
26
27 #ifndef __XEN_PUBLIC_IO_NETIF_H__
28 #define __XEN_PUBLIC_IO_NETIF_H__
29
30 #include "ring.h"
31 #include "../grant_table.h"
32
33 /*
34 * Older implementation of Xen network frontend / backend has an
35 * implicit dependency on the MAX_SKB_FRAGS as the maximum number of
36 * ring slots a skb can use. Netfront / netback may not work as
37 * expected when frontend and backend have different MAX_SKB_FRAGS.
38 *
39 * A better approach is to add mechanism for netfront / netback to
40 * negotiate this value. However we cannot fix all possible
41 * frontends, so we need to define a value which states the minimum
42 * slots backend must support.
43 *
44 * The minimum value derives from older Linux kernel's MAX_SKB_FRAGS
45 * (18), which is proved to work with most frontends. Any new backend
46 * which doesn't negotiate with frontend should expect frontend to
47 * send a valid packet using slots up to this value.
48 */
49 #define XEN_NETIF_NR_SLOTS_MIN 18
50
51 /*
52 * Notifications after enqueuing any type of message should be conditional on
53 * the appropriate req_event or rsp_event field in the shared ring.
54 * If the client sends notification for rx requests then it should specify
55 * feature 'feature-rx-notify' via xenbus. Otherwise the backend will assume
56 * that it cannot safely queue packets (as it may not be kicked to send them).
57 */
58
59 /*
60 * "feature-split-event-channels" is introduced to separate guest TX
61 * and RX notification. Backend either doesn't support this feature or
62 * advertises it via xenstore as 0 (disabled) or 1 (enabled).
63 *
64 * To make use of this feature, frontend should allocate two event
65 * channels for TX and RX, advertise them to backend as
66 * "event-channel-tx" and "event-channel-rx" respectively. If frontend
67 * doesn't want to use this feature, it just writes "event-channel"
68 * node as before.
69 */
70
71 /*
72 * Multiple transmit and receive queues:
73 * If supported, the backend will write the key "multi-queue-max-queues" to
74 * the directory for that vif, and set its value to the maximum supported
75 * number of queues.
76 * Frontends that are aware of this feature and wish to use it can write the
77 * key "multi-queue-num-queues", set to the number they wish to use, which
78 * must be greater than zero, and no more than the value reported by the backend
79 * in "multi-queue-max-queues".
80 *
81 * Queues replicate the shared rings and event channels.
82 * "feature-split-event-channels" may optionally be used when using
83 * multiple queues, but is not mandatory.
84 *
85 * Each queue consists of one shared ring pair, i.e. there must be the same
86 * number of tx and rx rings.
87 *
88 * For frontends requesting just one queue, the usual event-channel and
89 * ring-ref keys are written as before, simplifying the backend processing
90 * to avoid distinguishing between a frontend that doesn't understand the
91 * multi-queue feature, and one that does, but requested only one queue.
92 *
93 * Frontends requesting two or more queues must not write the toplevel
94 * event-channel (or event-channel-{tx,rx}) and {tx,rx}-ring-ref keys,
95 * instead writing those keys under sub-keys having the name "queue-N" where
96 * N is the integer ID of the queue for which those keys belong. Queues
97 * are indexed from zero. For example, a frontend with two queues and split
98 * event channels must write the following set of queue-related keys:
99 *
100 * /local/domain/1/device/vif/0/multi-queue-num-queues = "2"
101 * /local/domain/1/device/vif/0/queue-0 = ""
102 * /local/domain/1/device/vif/0/queue-0/tx-ring-ref = "<ring-ref-tx0>"
103 * /local/domain/1/device/vif/0/queue-0/rx-ring-ref = "<ring-ref-rx0>"
104 * /local/domain/1/device/vif/0/queue-0/event-channel-tx = "<evtchn-tx0>"
105 * /local/domain/1/device/vif/0/queue-0/event-channel-rx = "<evtchn-rx0>"
106 * /local/domain/1/device/vif/0/queue-1 = ""
107 * /local/domain/1/device/vif/0/queue-1/tx-ring-ref = "<ring-ref-tx1>"
108 * /local/domain/1/device/vif/0/queue-1/rx-ring-ref = "<ring-ref-rx1"
109 * /local/domain/1/device/vif/0/queue-1/event-channel-tx = "<evtchn-tx1>"
110 * /local/domain/1/device/vif/0/queue-1/event-channel-rx = "<evtchn-rx1>"
111 *
112 * If there is any inconsistency in the XenStore data, the backend may
113 * choose not to connect any queues, instead treating the request as an
114 * error. This includes scenarios where more (or fewer) queues were
115 * requested than the frontend provided details for.
116 *
117 * Mapping of packets to queues is considered to be a function of the
118 * transmitting system (backend or frontend) and is not negotiated
119 * between the two. Guests are free to transmit packets on any queue
120 * they choose, provided it has been set up correctly. Guests must be
121 * prepared to receive packets on any queue they have requested be set up.
122 */
123
124 /*
125 * "feature-no-csum-offload" should be used to turn IPv4 TCP/UDP checksum
126 * offload off or on. If it is missing then the feature is assumed to be on.
127 * "feature-ipv6-csum-offload" should be used to turn IPv6 TCP/UDP checksum
128 * offload on or off. If it is missing then the feature is assumed to be off.
129 */
130
131 /*
132 * "feature-gso-tcpv4" and "feature-gso-tcpv6" advertise the capability to
133 * handle large TCP packets (in IPv4 or IPv6 form respectively). Neither
134 * frontends nor backends are assumed to be capable unless the flags are
135 * present.
136 */
137
138 /*
139 * "feature-multicast-control" advertises the capability to filter ethernet
140 * multicast packets in the backend. To enable use of this capability the
141 * frontend must set "request-multicast-control" before moving into the
142 * connected state.
143 *
144 * If "request-multicast-control" is set then the backend transmit side should
145 * no longer flood multicast packets to the frontend, it should instead drop any
146 * multicast packet that does not match in a filter list. The list is
147 * amended by the frontend by sending dummy transmit requests containing
148 * XEN_NETIF_EXTRA_TYPE_MCAST_{ADD,DEL} extra-info fragments as specified below.
149 * Once enabled by the frontend, the feature cannot be disabled except by
150 * closing and re-connecting to the backend.
151 */
152
153 /*
154 * This is the 'wire' format for packets:
155 * Request 1: netif_tx_request_t -- NETTXF_* (any flags)
156 * [Request 2: netif_extra_info_t] (only if request 1 has NETTXF_extra_info)
157 * [Request 3: netif_extra_info_t] (only if request 2 has XEN_NETIF_EXTRA_MORE)
158 * Request 4: netif_tx_request_t -- NETTXF_more_data
159 * Request 5: netif_tx_request_t -- NETTXF_more_data
160 * ...
161 * Request N: netif_tx_request_t -- 0
162 */
163
164 /*
165 * Guest transmit
166 * ==============
167 *
168 * Ring slot size is 12 octets, however not all request/response
169 * structs use the full size.
170 *
171 * tx request data (netif_tx_request_t)
172 * ------------------------------------
173 *
174 * 0 1 2 3 4 5 6 7 octet
175 * +-----+-----+-----+-----+-----+-----+-----+-----+
176 * | grant ref | offset | flags |
177 * +-----+-----+-----+-----+-----+-----+-----+-----+
178 * | id | size |
179 * +-----+-----+-----+-----+
180 *
181 * grant ref: Reference to buffer page.
182 * offset: Offset within buffer page.
183 * flags: NETTXF_*.
184 * id: request identifier, echoed in response.
185 * size: packet size in bytes.
186 *
187 * tx response (netif_tx_response_t)
188 * ---------------------------------
189 *
190 * 0 1 2 3 4 5 6 7 octet
191 * +-----+-----+-----+-----+-----+-----+-----+-----+
192 * | id | status | unused |
193 * +-----+-----+-----+-----+-----+-----+-----+-----+
194 * | unused |
195 * +-----+-----+-----+-----+
196 *
197 * id: reflects id in transmit request
198 * status: NETIF_RSP_*
199 *
200 * Guest receive
201 * =============
202 *
203 * Ring slot size is 8 octets.
204 *
205 * rx request (netif_rx_request_t)
206 * -------------------------------
207 *
208 * 0 1 2 3 4 5 6 7 octet
209 * +-----+-----+-----+-----+-----+-----+-----+-----+
210 * | id | pad | gref |
211 * +-----+-----+-----+-----+-----+-----+-----+-----+
212 *
213 * id: request identifier, echoed in response.
214 * gref: reference to incoming granted frame.
215 *
216 * rx response (netif_rx_response_t)
217 * ---------------------------------
218 *
219 * 0 1 2 3 4 5 6 7 octet
220 * +-----+-----+-----+-----+-----+-----+-----+-----+
221 * | id | offset | flags | status |
222 * +-----+-----+-----+-----+-----+-----+-----+-----+
223 *
224 * id: reflects id in receive request
225 * offset: offset in page of start of received packet
226 * flags: NETRXF_*
227 * status: -ve: NETIF_RSP_*; +ve: Rx'ed pkt size.
228 *
229 * Extra Info
230 * ==========
231 *
232 * Can be present if initial request has NET{T,R}XF_extra_info, or
233 * previous extra request has XEN_NETIF_EXTRA_MORE.
234 *
235 * The struct therefore needs to fit into either a tx or rx slot and
236 * is therefore limited to 8 octets.
237 *
238 * extra info (netif_extra_info_t)
239 * -------------------------------
240 *
241 * General format:
242 *
243 * 0 1 2 3 4 5 6 7 octet
244 * +-----+-----+-----+-----+-----+-----+-----+-----+
245 * |type |flags| type specfic data |
246 * +-----+-----+-----+-----+-----+-----+-----+-----+
247 * | padding for tx |
248 * +-----+-----+-----+-----+
249 *
250 * type: XEN_NETIF_EXTRA_TYPE_*
251 * flags: XEN_NETIF_EXTRA_FLAG_*
252 * padding for tx: present only in the tx case due to 8 octet limit
253 * from rx case. Not shown in type specific entries below.
254 *
255 * XEN_NETIF_EXTRA_TYPE_GSO:
256 *
257 * 0 1 2 3 4 5 6 7 octet
258 * +-----+-----+-----+-----+-----+-----+-----+-----+
259 * |type |flags| size |type | pad | features |
260 * +-----+-----+-----+-----+-----+-----+-----+-----+
261 *
262 * type: Must be XEN_NETIF_EXTRA_TYPE_GSO
263 * flags: XEN_NETIF_EXTRA_FLAG_*
264 * size: Maximum payload size of each segment.
265 * type: XEN_NETIF_GSO_TYPE_*
266 * features: EN_NETIF_GSO_FEAT_*
267 *
268 * XEN_NETIF_EXTRA_TYPE_MCAST_{ADD,DEL}:
269 *
270 * 0 1 2 3 4 5 6 7 octet
271 * +-----+-----+-----+-----+-----+-----+-----+-----+
272 * |type |flags| addr |
273 * +-----+-----+-----+-----+-----+-----+-----+-----+
274 *
275 * type: Must be XEN_NETIF_EXTRA_TYPE_MCAST_{ADD,DEL}
276 * flags: XEN_NETIF_EXTRA_FLAG_*
277 * addr: address to add/remove
278 */
279
280 /* Protocol checksum field is blank in the packet (hardware offload)? */
281 #define _NETTXF_csum_blank (0)
282 #define NETTXF_csum_blank (1U<<_NETTXF_csum_blank)
283
284 /* Packet data has been validated against protocol checksum. */
285 #define _NETTXF_data_validated (1)
286 #define NETTXF_data_validated (1U<<_NETTXF_data_validated)
287
288 /* Packet continues in the next request descriptor. */
289 #define _NETTXF_more_data (2)
290 #define NETTXF_more_data (1U<<_NETTXF_more_data)
291
292 /* Packet to be followed by extra descriptor(s). */
293 #define _NETTXF_extra_info (3)
294 #define NETTXF_extra_info (1U<<_NETTXF_extra_info)
295
296 #define XEN_NETIF_MAX_TX_SIZE 0xFFFF
297 struct netif_tx_request {
298 grant_ref_t gref; /* Reference to buffer page */
299 uint16_t offset; /* Offset within buffer page */
300 uint16_t flags; /* NETTXF_* */
301 uint16_t id; /* Echoed in response message. */
302 uint16_t size; /* Packet size in bytes. */
303 };
304 typedef struct netif_tx_request netif_tx_request_t;
305
306 /* Types of netif_extra_info descriptors. */
307 #define XEN_NETIF_EXTRA_TYPE_NONE (0) /* Never used - invalid */
308 #define XEN_NETIF_EXTRA_TYPE_GSO (1) /* u.gso */
309 #define XEN_NETIF_EXTRA_TYPE_MCAST_ADD (2) /* u.mcast */
310 #define XEN_NETIF_EXTRA_TYPE_MCAST_DEL (3) /* u.mcast */
311 #define XEN_NETIF_EXTRA_TYPE_MAX (4)
312
313 /* netif_extra_info_t flags. */
314 #define _XEN_NETIF_EXTRA_FLAG_MORE (0)
315 #define XEN_NETIF_EXTRA_FLAG_MORE (1U<<_XEN_NETIF_EXTRA_FLAG_MORE)
316
317 /* GSO types */
318 #define XEN_NETIF_GSO_TYPE_NONE (0)
319 #define XEN_NETIF_GSO_TYPE_TCPV4 (1)
320 #define XEN_NETIF_GSO_TYPE_TCPV6 (2)
321
322 /*
323 * This structure needs to fit within both netif_tx_request_t and
324 * netif_rx_response_t for compatibility.
325 */
326 struct netif_extra_info {
327 uint8_t type; /* XEN_NETIF_EXTRA_TYPE_* */
328 uint8_t flags; /* XEN_NETIF_EXTRA_FLAG_* */
329
330 union {
331 /*
332 * XEN_NETIF_EXTRA_TYPE_GSO:
333 */
334 struct {
335 /*
336 * Maximum payload size of each segment. For example, for TCP this
337 * is just the path MSS.
338 */
339 uint16_t size;
340
341 /*
342 * GSO type. This determines the protocol of the packet and any
343 * extra features required to segment the packet properly.
344 */
345 uint8_t type; /* XEN_NETIF_GSO_TYPE_* */
346
347 /* Future expansion. */
348 uint8_t pad;
349
350 /*
351 * GSO features. This specifies any extra GSO features required
352 * to process this packet, such as ECN support for TCPv4.
353 */
354 uint16_t features; /* XEN_NETIF_GSO_FEAT_* */
355 } gso;
356
357 /*
358 * XEN_NETIF_EXTRA_TYPE_MCAST_{ADD,DEL}:
359 */
360 struct {
361 uint8_t addr[6]; /* Address to add/remove. */
362 } mcast;
363
364 uint16_t pad[3];
365 } u;
366 };
367 typedef struct netif_extra_info netif_extra_info_t;
368
369 struct netif_tx_response {
370 uint16_t id;
371 int16_t status; /* NETIF_RSP_* */
372 };
373 typedef struct netif_tx_response netif_tx_response_t;
374
375 struct netif_rx_request {
376 uint16_t id; /* Echoed in response message. */
377 uint16_t pad;
378 grant_ref_t gref; /* Reference to incoming granted frame */
379 };
380 typedef struct netif_rx_request netif_rx_request_t;
381
382 /* Packet data has been validated against protocol checksum. */
383 #define _NETRXF_data_validated (0)
384 #define NETRXF_data_validated (1U<<_NETRXF_data_validated)
385
386 /* Protocol checksum field is blank in the packet (hardware offload)? */
387 #define _NETRXF_csum_blank (1)
388 #define NETRXF_csum_blank (1U<<_NETRXF_csum_blank)
389
390 /* Packet continues in the next request descriptor. */
391 #define _NETRXF_more_data (2)
392 #define NETRXF_more_data (1U<<_NETRXF_more_data)
393
394 /* Packet to be followed by extra descriptor(s). */
395 #define _NETRXF_extra_info (3)
396 #define NETRXF_extra_info (1U<<_NETRXF_extra_info)
397
398 struct netif_rx_response {
399 uint16_t id;
400 uint16_t offset; /* Offset in page of start of received packet */
401 uint16_t flags; /* NETRXF_* */
402 int16_t status; /* -ve: NETIF_RSP_* ; +ve: Rx'ed pkt size. */
403 };
404 typedef struct netif_rx_response netif_rx_response_t;
405
406 /*
407 * Generate netif ring structures and types.
408 */
409
410 DEFINE_RING_TYPES(netif_tx, struct netif_tx_request, struct netif_tx_response);
411 DEFINE_RING_TYPES(netif_rx, struct netif_rx_request, struct netif_rx_response);
412
413 #define NETIF_RSP_DROPPED -2
414 #define NETIF_RSP_ERROR -1
415 #define NETIF_RSP_OKAY 0
416 /* No response: used for auxiliary requests (e.g., netif_extra_info_t). */
417 #define NETIF_RSP_NULL 1
418
419 #endif
420
421 /*
422 * Local variables:
423 * mode: C
424 * c-file-style: "BSD"
425 * c-basic-offset: 4
426 * tab-width: 4
427 * indent-tabs-mode: nil
428 * End:
429 */
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