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 * This is the 'wire' format for packets:
43 * Request 1: xen_netif_tx_request -- XEN_NETTXF_* (any flags)
44 * [Request 2: xen_netif_extra_info] (only if request 1 has XEN_NETTXF_extra_info)
45 * [Request 3: xen_netif_extra_info] (only if request 2 has XEN_NETIF_EXTRA_MORE)
46 * Request 4: xen_netif_tx_request -- XEN_NETTXF_more_data
47 * Request 5: xen_netif_tx_request -- XEN_NETTXF_more_data
49 * Request N: xen_netif_tx_request -- 0
52 /* Protocol checksum field is blank in the packet (hardware offload)? */
53 #define _XEN_NETTXF_csum_blank (0)
54 #define XEN_NETTXF_csum_blank (1U<<_XEN_NETTXF_csum_blank)
56 /* Packet data has been validated against protocol checksum. */
57 #define _XEN_NETTXF_data_validated (1)
58 #define XEN_NETTXF_data_validated (1U<<_XEN_NETTXF_data_validated)
60 /* Packet continues in the next request descriptor. */
61 #define _XEN_NETTXF_more_data (2)
62 #define XEN_NETTXF_more_data (1U<<_XEN_NETTXF_more_data)
64 /* Packet to be followed by extra descriptor(s). */
65 #define _XEN_NETTXF_extra_info (3)
66 #define XEN_NETTXF_extra_info (1U<<_XEN_NETTXF_extra_info)
68 #define XEN_NETIF_MAX_TX_SIZE 0xFFFF
69 struct xen_netif_tx_request {
70 grant_ref_t gref; /* Reference to buffer page */
71 uint16_t offset; /* Offset within buffer page */
72 uint16_t flags; /* XEN_NETTXF_* */
73 uint16_t id; /* Echoed in response message. */
74 uint16_t size; /* Packet size in bytes. */
77 /* Types of xen_netif_extra_info descriptors. */
78 #define XEN_NETIF_EXTRA_TYPE_NONE (0) /* Never used - invalid */
79 #define XEN_NETIF_EXTRA_TYPE_GSO (1) /* u.gso */
80 #define XEN_NETIF_EXTRA_TYPE_MAX (2)
82 /* xen_netif_extra_info flags. */
83 #define _XEN_NETIF_EXTRA_FLAG_MORE (0)
84 #define XEN_NETIF_EXTRA_FLAG_MORE (1U<<_XEN_NETIF_EXTRA_FLAG_MORE)
86 /* GSO types - only TCPv4 currently supported. */
87 #define XEN_NETIF_GSO_TYPE_TCPV4 (1)
90 * This structure needs to fit within both netif_tx_request and
91 * netif_rx_response for compatibility.
93 struct xen_netif_extra_info {
94 uint8_t type; /* XEN_NETIF_EXTRA_TYPE_* */
95 uint8_t flags; /* XEN_NETIF_EXTRA_FLAG_* */
100 * Maximum payload size of each segment. For
101 * example, for TCP this is just the path MSS.
106 * GSO type. This determines the protocol of
107 * the packet and any extra features required
108 * to segment the packet properly.
110 uint8_t type; /* XEN_NETIF_GSO_TYPE_* */
112 /* Future expansion. */
116 * GSO features. This specifies any extra GSO
117 * features required to process this packet,
118 * such as ECN support for TCPv4.
120 uint16_t features; /* XEN_NETIF_GSO_FEAT_* */
127 struct xen_netif_tx_response {
129 int16_t status; /* XEN_NETIF_RSP_* */
132 struct xen_netif_rx_request {
133 uint16_t id; /* Echoed in response message. */
134 grant_ref_t gref; /* Reference to incoming granted frame */
137 /* Packet data has been validated against protocol checksum. */
138 #define _XEN_NETRXF_data_validated (0)
139 #define XEN_NETRXF_data_validated (1U<<_XEN_NETRXF_data_validated)
141 /* Protocol checksum field is blank in the packet (hardware offload)? */
142 #define _XEN_NETRXF_csum_blank (1)
143 #define XEN_NETRXF_csum_blank (1U<<_XEN_NETRXF_csum_blank)
145 /* Packet continues in the next request descriptor. */
146 #define _XEN_NETRXF_more_data (2)
147 #define XEN_NETRXF_more_data (1U<<_XEN_NETRXF_more_data)
149 /* Packet to be followed by extra descriptor(s). */
150 #define _XEN_NETRXF_extra_info (3)
151 #define XEN_NETRXF_extra_info (1U<<_XEN_NETRXF_extra_info)
153 /* GSO Prefix descriptor. */
154 #define _XEN_NETRXF_gso_prefix (4)
155 #define XEN_NETRXF_gso_prefix (1U<<_XEN_NETRXF_gso_prefix)
157 struct xen_netif_rx_response {
159 uint16_t offset; /* Offset in page of start of received packet */
160 uint16_t flags; /* XEN_NETRXF_* */
161 int16_t status; /* -ve: BLKIF_RSP_* ; +ve: Rx'ed pkt size. */
165 * Generate netif ring structures and types.
168 DEFINE_RING_TYPES(xen_netif_tx,
169 struct xen_netif_tx_request,
170 struct xen_netif_tx_response);
171 DEFINE_RING_TYPES(xen_netif_rx,
172 struct xen_netif_rx_request,
173 struct xen_netif_rx_response);
175 #define XEN_NETIF_RSP_DROPPED -2
176 #define XEN_NETIF_RSP_ERROR -1
177 #define XEN_NETIF_RSP_OKAY 0
178 /* No response: used for auxiliary requests (e.g., xen_netif_extra_info). */
179 #define XEN_NETIF_RSP_NULL 1