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 * This is the 'wire' format for packets:
62 * Request 1: xen_netif_tx_request -- XEN_NETTXF_* (any flags)
63 * [Request 2: xen_netif_extra_info] (only if request 1 has XEN_NETTXF_extra_info)
64 * [Request 3: xen_netif_extra_info] (only if request 2 has XEN_NETIF_EXTRA_MORE)
65 * Request 4: xen_netif_tx_request -- XEN_NETTXF_more_data
66 * Request 5: xen_netif_tx_request -- XEN_NETTXF_more_data
68 * Request N: xen_netif_tx_request -- 0
71 /* Protocol checksum field is blank in the packet (hardware offload)? */
72 #define _XEN_NETTXF_csum_blank (0)
73 #define XEN_NETTXF_csum_blank (1U<<_XEN_NETTXF_csum_blank)
75 /* Packet data has been validated against protocol checksum. */
76 #define _XEN_NETTXF_data_validated (1)
77 #define XEN_NETTXF_data_validated (1U<<_XEN_NETTXF_data_validated)
79 /* Packet continues in the next request descriptor. */
80 #define _XEN_NETTXF_more_data (2)
81 #define XEN_NETTXF_more_data (1U<<_XEN_NETTXF_more_data)
83 /* Packet to be followed by extra descriptor(s). */
84 #define _XEN_NETTXF_extra_info (3)
85 #define XEN_NETTXF_extra_info (1U<<_XEN_NETTXF_extra_info)
87 #define XEN_NETIF_MAX_TX_SIZE 0xFFFF
88 struct xen_netif_tx_request {
89 grant_ref_t gref; /* Reference to buffer page */
90 uint16_t offset; /* Offset within buffer page */
91 uint16_t flags; /* XEN_NETTXF_* */
92 uint16_t id; /* Echoed in response message. */
93 uint16_t size; /* Packet size in bytes. */
96 /* Types of xen_netif_extra_info descriptors. */
97 #define XEN_NETIF_EXTRA_TYPE_NONE (0) /* Never used - invalid */
98 #define XEN_NETIF_EXTRA_TYPE_GSO (1) /* u.gso */
99 #define XEN_NETIF_EXTRA_TYPE_MAX (2)
101 /* xen_netif_extra_info flags. */
102 #define _XEN_NETIF_EXTRA_FLAG_MORE (0)
103 #define XEN_NETIF_EXTRA_FLAG_MORE (1U<<_XEN_NETIF_EXTRA_FLAG_MORE)
105 /* GSO types - only TCPv4 currently supported. */
106 #define XEN_NETIF_GSO_TYPE_TCPV4 (1)
109 * This structure needs to fit within both netif_tx_request and
110 * netif_rx_response for compatibility.
112 struct xen_netif_extra_info {
113 uint8_t type; /* XEN_NETIF_EXTRA_TYPE_* */
114 uint8_t flags; /* XEN_NETIF_EXTRA_FLAG_* */
119 * Maximum payload size of each segment. For
120 * example, for TCP this is just the path MSS.
125 * GSO type. This determines the protocol of
126 * the packet and any extra features required
127 * to segment the packet properly.
129 uint8_t type; /* XEN_NETIF_GSO_TYPE_* */
131 /* Future expansion. */
135 * GSO features. This specifies any extra GSO
136 * features required to process this packet,
137 * such as ECN support for TCPv4.
139 uint16_t features; /* XEN_NETIF_GSO_FEAT_* */
146 struct xen_netif_tx_response {
148 int16_t status; /* XEN_NETIF_RSP_* */
151 struct xen_netif_rx_request {
152 uint16_t id; /* Echoed in response message. */
153 grant_ref_t gref; /* Reference to incoming granted frame */
156 /* Packet data has been validated against protocol checksum. */
157 #define _XEN_NETRXF_data_validated (0)
158 #define XEN_NETRXF_data_validated (1U<<_XEN_NETRXF_data_validated)
160 /* Protocol checksum field is blank in the packet (hardware offload)? */
161 #define _XEN_NETRXF_csum_blank (1)
162 #define XEN_NETRXF_csum_blank (1U<<_XEN_NETRXF_csum_blank)
164 /* Packet continues in the next request descriptor. */
165 #define _XEN_NETRXF_more_data (2)
166 #define XEN_NETRXF_more_data (1U<<_XEN_NETRXF_more_data)
168 /* Packet to be followed by extra descriptor(s). */
169 #define _XEN_NETRXF_extra_info (3)
170 #define XEN_NETRXF_extra_info (1U<<_XEN_NETRXF_extra_info)
172 /* GSO Prefix descriptor. */
173 #define _XEN_NETRXF_gso_prefix (4)
174 #define XEN_NETRXF_gso_prefix (1U<<_XEN_NETRXF_gso_prefix)
176 struct xen_netif_rx_response {
178 uint16_t offset; /* Offset in page of start of received packet */
179 uint16_t flags; /* XEN_NETRXF_* */
180 int16_t status; /* -ve: BLKIF_RSP_* ; +ve: Rx'ed pkt size. */
184 * Generate netif ring structures and types.
187 DEFINE_RING_TYPES(xen_netif_tx,
188 struct xen_netif_tx_request,
189 struct xen_netif_tx_response);
190 DEFINE_RING_TYPES(xen_netif_rx,
191 struct xen_netif_rx_request,
192 struct xen_netif_rx_response);
194 #define XEN_NETIF_RSP_DROPPED -2
195 #define XEN_NETIF_RSP_ERROR -1
196 #define XEN_NETIF_RSP_OKAY 0
197 /* No response: used for auxiliary requests (e.g., xen_netif_extra_info). */
198 #define XEN_NETIF_RSP_NULL 1