1 /******************************************************************************
4 * Unified network-device I/O interface for Xen guest OSes.
6 * Copyright (c) 2003-2004, Keir Fraser
9 #ifndef __XEN_PUBLIC_IO_NETIF_H__
10 #define __XEN_PUBLIC_IO_NETIF_H__
12 #include <xen/interface/io/ring.h>
13 #include <xen/interface/grant_table.h>
16 * Older implementation of Xen network frontend / backend has an
17 * implicit dependency on the MAX_SKB_FRAGS as the maximum number of
18 * ring slots a skb can use. Netfront / netback may not work as
19 * expected when frontend and backend have different MAX_SKB_FRAGS.
21 * A better approach is to add mechanism for netfront / netback to
22 * negotiate this value. However we cannot fix all possible
23 * frontends, so we need to define a value which states the minimum
24 * slots backend must support.
26 * The minimum value derives from older Linux kernel's MAX_SKB_FRAGS
27 * (18), which is proved to work with most frontends. Any new backend
28 * which doesn't negotiate with frontend should expect frontend to
29 * send a valid packet using slots up to this value.
31 #define XEN_NETIF_NR_SLOTS_MIN 18
34 * Notifications after enqueuing any type of message should be conditional on
35 * the appropriate req_event or rsp_event field in the shared ring.
36 * If the client sends notification for rx requests then it should specify
37 * feature 'feature-rx-notify' via xenbus. Otherwise the backend will assume
38 * that it cannot safely queue packets (as it may not be kicked to send them).
42 * "feature-split-event-channels" is introduced to separate guest TX
43 * and RX notificaion. Backend either doesn't support this feature or
44 * advertise it via xenstore as 0 (disabled) or 1 (enabled).
46 * To make use of this feature, frontend should allocate two event
47 * channels for TX and RX, advertise them to backend as
48 * "event-channel-tx" and "event-channel-rx" respectively. If frontend
49 * doesn't want to use this feature, it just writes "event-channel"
54 * "feature-no-csum-offload" should be used to turn IPv4 TCP/UDP checksum
55 * offload off or on. If it is missing then the feature is assumed to be on.
56 * "feature-ipv6-csum-offload" should be used to turn IPv6 TCP/UDP checksum
57 * offload on or off. If it is missing then the feature is assumed to be off.
61 * "feature-gso-tcpv4" and "feature-gso-tcpv6" advertise the capability to
62 * handle large TCP packets (in IPv4 or IPv6 form respectively). Neither
63 * frontends nor backends are assumed to be capable unless the flags are
68 * This is the 'wire' format for packets:
69 * Request 1: xen_netif_tx_request -- XEN_NETTXF_* (any flags)
70 * [Request 2: xen_netif_extra_info] (only if request 1 has XEN_NETTXF_extra_info)
71 * [Request 3: xen_netif_extra_info] (only if request 2 has XEN_NETIF_EXTRA_MORE)
72 * Request 4: xen_netif_tx_request -- XEN_NETTXF_more_data
73 * Request 5: xen_netif_tx_request -- XEN_NETTXF_more_data
75 * Request N: xen_netif_tx_request -- 0
78 /* Protocol checksum field is blank in the packet (hardware offload)? */
79 #define _XEN_NETTXF_csum_blank (0)
80 #define XEN_NETTXF_csum_blank (1U<<_XEN_NETTXF_csum_blank)
82 /* Packet data has been validated against protocol checksum. */
83 #define _XEN_NETTXF_data_validated (1)
84 #define XEN_NETTXF_data_validated (1U<<_XEN_NETTXF_data_validated)
86 /* Packet continues in the next request descriptor. */
87 #define _XEN_NETTXF_more_data (2)
88 #define XEN_NETTXF_more_data (1U<<_XEN_NETTXF_more_data)
90 /* Packet to be followed by extra descriptor(s). */
91 #define _XEN_NETTXF_extra_info (3)
92 #define XEN_NETTXF_extra_info (1U<<_XEN_NETTXF_extra_info)
94 #define XEN_NETIF_MAX_TX_SIZE 0xFFFF
95 struct xen_netif_tx_request {
96 grant_ref_t gref; /* Reference to buffer page */
97 uint16_t offset; /* Offset within buffer page */
98 uint16_t flags; /* XEN_NETTXF_* */
99 uint16_t id; /* Echoed in response message. */
100 uint16_t size; /* Packet size in bytes. */
103 /* Types of xen_netif_extra_info descriptors. */
104 #define XEN_NETIF_EXTRA_TYPE_NONE (0) /* Never used - invalid */
105 #define XEN_NETIF_EXTRA_TYPE_GSO (1) /* u.gso */
106 #define XEN_NETIF_EXTRA_TYPE_MAX (2)
108 /* xen_netif_extra_info flags. */
109 #define _XEN_NETIF_EXTRA_FLAG_MORE (0)
110 #define XEN_NETIF_EXTRA_FLAG_MORE (1U<<_XEN_NETIF_EXTRA_FLAG_MORE)
113 #define XEN_NETIF_GSO_TYPE_TCPV4 (1)
114 #define XEN_NETIF_GSO_TYPE_TCPV6 (2)
117 * This structure needs to fit within both netif_tx_request and
118 * netif_rx_response for compatibility.
120 struct xen_netif_extra_info {
121 uint8_t type; /* XEN_NETIF_EXTRA_TYPE_* */
122 uint8_t flags; /* XEN_NETIF_EXTRA_FLAG_* */
127 * Maximum payload size of each segment. For
128 * example, for TCP this is just the path MSS.
133 * GSO type. This determines the protocol of
134 * the packet and any extra features required
135 * to segment the packet properly.
137 uint8_t type; /* XEN_NETIF_GSO_TYPE_* */
139 /* Future expansion. */
143 * GSO features. This specifies any extra GSO
144 * features required to process this packet,
145 * such as ECN support for TCPv4.
147 uint16_t features; /* XEN_NETIF_GSO_FEAT_* */
154 struct xen_netif_tx_response {
156 int16_t status; /* XEN_NETIF_RSP_* */
159 struct xen_netif_rx_request {
160 uint16_t id; /* Echoed in response message. */
161 grant_ref_t gref; /* Reference to incoming granted frame */
164 /* Packet data has been validated against protocol checksum. */
165 #define _XEN_NETRXF_data_validated (0)
166 #define XEN_NETRXF_data_validated (1U<<_XEN_NETRXF_data_validated)
168 /* Protocol checksum field is blank in the packet (hardware offload)? */
169 #define _XEN_NETRXF_csum_blank (1)
170 #define XEN_NETRXF_csum_blank (1U<<_XEN_NETRXF_csum_blank)
172 /* Packet continues in the next request descriptor. */
173 #define _XEN_NETRXF_more_data (2)
174 #define XEN_NETRXF_more_data (1U<<_XEN_NETRXF_more_data)
176 /* Packet to be followed by extra descriptor(s). */
177 #define _XEN_NETRXF_extra_info (3)
178 #define XEN_NETRXF_extra_info (1U<<_XEN_NETRXF_extra_info)
180 /* GSO Prefix descriptor. */
181 #define _XEN_NETRXF_gso_prefix (4)
182 #define XEN_NETRXF_gso_prefix (1U<<_XEN_NETRXF_gso_prefix)
184 struct xen_netif_rx_response {
186 uint16_t offset; /* Offset in page of start of received packet */
187 uint16_t flags; /* XEN_NETRXF_* */
188 int16_t status; /* -ve: BLKIF_RSP_* ; +ve: Rx'ed pkt size. */
192 * Generate netif ring structures and types.
195 DEFINE_RING_TYPES(xen_netif_tx,
196 struct xen_netif_tx_request,
197 struct xen_netif_tx_response);
198 DEFINE_RING_TYPES(xen_netif_rx,
199 struct xen_netif_rx_request,
200 struct xen_netif_rx_response);
202 #define XEN_NETIF_RSP_DROPPED -2
203 #define XEN_NETIF_RSP_ERROR -1
204 #define XEN_NETIF_RSP_OKAY 0
205 /* No response: used for auxiliary requests (e.g., xen_netif_extra_info). */
206 #define XEN_NETIF_RSP_NULL 1