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/* SPDX-License-Identifier: MIT */
/******************************************************************************
* xen_netif.h
*
* Unified network-device I/O interface for Xen guest OSes.
*
* Copyright (c) 2003-2004, Keir Fraser
*/
#ifndef __XEN_PUBLIC_IO_XEN_NETIF_H__
#define __XEN_PUBLIC_IO_XEN_NETIF_H__
#include "ring.h"
#include "../grant_table.h"
/*
* Older implementation of Xen network frontend / backend has an
* implicit dependency on the MAX_SKB_FRAGS as the maximum number of
* ring slots a skb can use. Netfront / netback may not work as
* expected when frontend and backend have different MAX_SKB_FRAGS.
*
* A better approach is to add mechanism for netfront / netback to
* negotiate this value. However we cannot fix all possible
* frontends, so we need to define a value which states the minimum
* slots backend must support.
*
* The minimum value derives from older Linux kernel's MAX_SKB_FRAGS
* (18), which is proved to work with most frontends. Any new backend
* which doesn't negotiate with frontend should expect frontend to
* send a valid packet using slots up to this value.
*/
#define XEN_NETIF_NR_SLOTS_MIN 18
/*
* Notifications after enqueuing any type of message should be conditional on
* the appropriate req_event or rsp_event field in the shared ring.
* If the client sends notification for rx requests then it should specify
* feature 'feature-rx-notify' via xenbus. Otherwise the backend will assume
* that it cannot safely queue packets (as it may not be kicked to send them).
*/
/*
* "feature-split-event-channels" is introduced to separate guest TX
* and RX notification. Backend either doesn't support this feature or
* advertises it via xenstore as 0 (disabled) or 1 (enabled).
*
* To make use of this feature, frontend should allocate two event
* channels for TX and RX, advertise them to backend as
* "event-channel-tx" and "event-channel-rx" respectively. If frontend
* doesn't want to use this feature, it just writes "event-channel"
* node as before.
*/
/*
* Multiple transmit and receive queues:
* If supported, the backend will write the key "multi-queue-max-queues" to
* the directory for that vif, and set its value to the maximum supported
* number of queues.
* Frontends that are aware of this feature and wish to use it can write the
* key "multi-queue-num-queues", set to the number they wish to use, which
* must be greater than zero, and no more than the value reported by the backend
* in "multi-queue-max-queues".
*
* Queues replicate the shared rings and event channels.
* "feature-split-event-channels" may optionally be used when using
* multiple queues, but is not mandatory.
*
* Each queue consists of one shared ring pair, i.e. there must be the same
* number of tx and rx rings.
*
* For frontends requesting just one queue, the usual event-channel and
* ring-ref keys are written as before, simplifying the backend processing
* to avoid distinguishing between a frontend that doesn't understand the
* multi-queue feature, and one that does, but requested only one queue.
*
* Frontends requesting two or more queues must not write the toplevel
* event-channel (or event-channel-{tx,rx}) and {tx,rx}-ring-ref keys,
* instead writing those keys under sub-keys having the name "queue-N" where
* N is the integer ID of the queue for which those keys belong. Queues
* are indexed from zero. For example, a frontend with two queues and split
* event channels must write the following set of queue-related keys:
*
* /local/domain/1/device/vif/0/multi-queue-num-queues = "2"
* /local/domain/1/device/vif/0/queue-0 = ""
* /local/domain/1/device/vif/0/queue-0/tx-ring-ref = "<ring-ref-tx0>"
* /local/domain/1/device/vif/0/queue-0/rx-ring-ref = "<ring-ref-rx0>"
* /local/domain/1/device/vif/0/queue-0/event-channel-tx = "<evtchn-tx0>"
* /local/domain/1/device/vif/0/queue-0/event-channel-rx = "<evtchn-rx0>"
* /local/domain/1/device/vif/0/queue-1 = ""
* /local/domain/1/device/vif/0/queue-1/tx-ring-ref = "<ring-ref-tx1>"
* /local/domain/1/device/vif/0/queue-1/rx-ring-ref = "<ring-ref-rx1"
* /local/domain/1/device/vif/0/queue-1/event-channel-tx = "<evtchn-tx1>"
* /local/domain/1/device/vif/0/queue-1/event-channel-rx = "<evtchn-rx1>"
*
* If there is any inconsistency in the XenStore data, the backend may
* choose not to connect any queues, instead treating the request as an
* error. This includes scenarios where more (or fewer) queues were
* requested than the frontend provided details for.
*
* Mapping of packets to queues is considered to be a function of the
* transmitting system (backend or frontend) and is not negotiated
* between the two. Guests are free to transmit packets on any queue
* they choose, provided it has been set up correctly. Guests must be
* prepared to receive packets on any queue they have requested be set up.
*/
/*
* "feature-no-csum-offload" should be used to turn IPv4 TCP/UDP checksum
* offload off or on. If it is missing then the feature is assumed to be on.
* "feature-ipv6-csum-offload" should be used to turn IPv6 TCP/UDP checksum
* offload on or off. If it is missing then the feature is assumed to be off.
*/
/*
* "feature-gso-tcpv4" and "feature-gso-tcpv6" advertise the capability to
* handle large TCP packets (in IPv4 or IPv6 form respectively). Neither
* frontends nor backends are assumed to be capable unless the flags are
* present.
*/
/*
* "feature-multicast-control" and "feature-dynamic-multicast-control"
* advertise the capability to filter ethernet multicast packets in the
* backend. If the frontend wishes to take advantage of this feature then
* it may set "request-multicast-control". If the backend only advertises
* "feature-multicast-control" then "request-multicast-control" must be set
* before the frontend moves into the connected state. The backend will
* sample the value on this state transition and any subsequent change in
* value will have no effect. However, if the backend also advertises
* "feature-dynamic-multicast-control" then "request-multicast-control"
* may be set by the frontend at any time. In this case, the backend will
* watch the value and re-sample on watch events.
*
* If the sampled value of "request-multicast-control" is set then the
* backend transmit side should no longer flood multicast packets to the
* frontend, it should instead drop any multicast packet that does not
* match in a filter list.
* The list is amended by the frontend by sending dummy transmit requests
* containing XEN_NETIF_EXTRA_TYPE_MCAST_{ADD,DEL} extra-info fragments as
* specified below.
* Note that the filter list may be amended even if the sampled value of
* "request-multicast-control" is not set, however the filter should only
* be applied if it is set.
*/
/*
* "xdp-headroom" is used to request that extra space is added
* for XDP processing. The value is measured in bytes and passed by
* the frontend to be consistent between both ends.
* If the value is greater than zero that means that
* an RX response is going to be passed to an XDP program for processing.
* XEN_NETIF_MAX_XDP_HEADROOM defines the maximum headroom offset in bytes
*
* "feature-xdp-headroom" is set to "1" by the netback side like other features
* so a guest can check if an XDP program can be processed.
*/
#define XEN_NETIF_MAX_XDP_HEADROOM 0x7FFF
/*
* Control ring
* ============
*
* Some features, such as hashing (detailed below), require a
* significant amount of out-of-band data to be passed from frontend to
* backend. Use of xenstore is not suitable for large quantities of data
* because of quota limitations and so a dedicated 'control ring' is used.
* The ability of the backend to use a control ring is advertised by
* setting:
*
* /local/domain/X/backend/<domid>/<vif>/feature-ctrl-ring = "1"
*
* The frontend provides a control ring to the backend by setting:
*
* /local/domain/<domid>/device/vif/<vif>/ctrl-ring-ref = <gref>
* /local/domain/<domid>/device/vif/<vif>/event-channel-ctrl = <port>
*
* where <gref> is the grant reference of the shared page used to
* implement the control ring and <port> is an event channel to be used
* as a mailbox interrupt. These keys must be set before the frontend
* moves into the connected state.
*
* The control ring uses a fixed request/response message size and is
* balanced (i.e. one request to one response), so operationally it is much
* the same as a transmit or receive ring.
* Note that there is no requirement that responses are issued in the same
* order as requests.
*/
/*
* Hash types
* ==========
*
* For the purposes of the definitions below, 'Packet[]' is an array of
* octets containing an IP packet without options, 'Array[X..Y]' means a
* sub-array of 'Array' containing bytes X thru Y inclusive, and '+' is
* used to indicate concatenation of arrays.
*/
/*
* A hash calculated over an IP version 4 header as follows:
*
* Buffer[0..8] = Packet[12..15] (source address) +
* Packet[16..19] (destination address)
*
* Result = Hash(Buffer, 8)
*/
#define _XEN_NETIF_CTRL_HASH_TYPE_IPV4 0
#define XEN_NETIF_CTRL_HASH_TYPE_IPV4 \
(1 << _XEN_NETIF_CTRL_HASH_TYPE_IPV4)
/*
* A hash calculated over an IP version 4 header and TCP header as
* follows:
*
* Buffer[0..12] = Packet[12..15] (source address) +
* Packet[16..19] (destination address) +
* Packet[20..21] (source port) +
* Packet[22..23] (destination port)
*
* Result = Hash(Buffer, 12)
*/
#define _XEN_NETIF_CTRL_HASH_TYPE_IPV4_TCP 1
#define XEN_NETIF_CTRL_HASH_TYPE_IPV4_TCP \
(1 << _XEN_NETIF_CTRL_HASH_TYPE_IPV4_TCP)
/*
* A hash calculated over an IP version 6 header as follows:
*
* Buffer[0..32] = Packet[8..23] (source address ) +
* Packet[24..39] (destination address)
*
* Result = Hash(Buffer, 32)
*/
#define _XEN_NETIF_CTRL_HASH_TYPE_IPV6 2
#define XEN_NETIF_CTRL_HASH_TYPE_IPV6 \
(1 << _XEN_NETIF_CTRL_HASH_TYPE_IPV6)
/*
* A hash calculated over an IP version 6 header and TCP header as
* follows:
*
* Buffer[0..36] = Packet[8..23] (source address) +
* Packet[24..39] (destination address) +
* Packet[40..41] (source port) +
* Packet[42..43] (destination port)
*
* Result = Hash(Buffer, 36)
*/
#define _XEN_NETIF_CTRL_HASH_TYPE_IPV6_TCP 3
#define XEN_NETIF_CTRL_HASH_TYPE_IPV6_TCP \
(1 << _XEN_NETIF_CTRL_HASH_TYPE_IPV6_TCP)
/*
* Hash algorithms
* ===============
*/
#define XEN_NETIF_CTRL_HASH_ALGORITHM_NONE 0
/*
* Toeplitz hash:
*/
#define XEN_NETIF_CTRL_HASH_ALGORITHM_TOEPLITZ 1
/*
* This algorithm uses a 'key' as well as the data buffer itself.
* (Buffer[] and Key[] are treated as shift-registers where the MSB of
* Buffer/Key[0] is considered 'left-most' and the LSB of Buffer/Key[N-1]
* is the 'right-most').
*
* Value = 0
* For number of bits in Buffer[]
* If (left-most bit of Buffer[] is 1)
* Value ^= left-most 32 bits of Key[]
* Key[] << 1
* Buffer[] << 1
*
* The code below is provided for convenience where an operating system
* does not already provide an implementation.
*/
#ifdef XEN_NETIF_DEFINE_TOEPLITZ
static uint32_t xen_netif_toeplitz_hash(const uint8_t *key,
unsigned int keylen,
const uint8_t *buf, unsigned int buflen)
{
unsigned int keyi, bufi;
uint64_t prefix = 0;
uint64_t hash = 0;
/* Pre-load prefix with the first 8 bytes of the key */
for (keyi = 0; keyi < 8; keyi++) {
prefix <<= 8;
prefix |= (keyi < keylen) ? key[keyi] : 0;
}
for (bufi = 0; bufi < buflen; bufi++) {
uint8_t byte = buf[bufi];
unsigned int bit;
for (bit = 0; bit < 8; bit++) {
if (byte & 0x80)
hash ^= prefix;
prefix <<= 1;
byte <<= 1;
}
/*
* 'prefix' has now been left-shifted by 8, so
* OR in the next byte.
*/
prefix |= (keyi < keylen) ? key[keyi] : 0;
keyi++;
}
/* The valid part of the hash is in the upper 32 bits. */
return hash >> 32;
}
#endif /* XEN_NETIF_DEFINE_TOEPLITZ */
/*
* Control requests (struct xen_netif_ctrl_request)
* ================================================
*
* All requests have the following format:
*
* 0 1 2 3 4 5 6 7 octet
* +-----+-----+-----+-----+-----+-----+-----+-----+
* | id | type | data[0] |
* +-----+-----+-----+-----+-----+-----+-----+-----+
* | data[1] | data[2] |
* +-----+-----+-----+-----+-----------------------+
*
* id: the request identifier, echoed in response.
* type: the type of request (see below)
* data[]: any data associated with the request (determined by type)
*/
struct xen_netif_ctrl_request {
uint16_t id;
uint16_t type;
#define XEN_NETIF_CTRL_TYPE_INVALID 0
#define XEN_NETIF_CTRL_TYPE_GET_HASH_FLAGS 1
#define XEN_NETIF_CTRL_TYPE_SET_HASH_FLAGS 2
#define XEN_NETIF_CTRL_TYPE_SET_HASH_KEY 3
#define XEN_NETIF_CTRL_TYPE_GET_HASH_MAPPING_SIZE 4
#define XEN_NETIF_CTRL_TYPE_SET_HASH_MAPPING_SIZE 5
#define XEN_NETIF_CTRL_TYPE_SET_HASH_MAPPING 6
#define XEN_NETIF_CTRL_TYPE_SET_HASH_ALGORITHM 7
uint32_t data[3];
};
/*
* Control responses (struct xen_netif_ctrl_response)
* ==================================================
*
* All responses have the following format:
*
* 0 1 2 3 4 5 6 7 octet
* +-----+-----+-----+-----+-----+-----+-----+-----+
* | id | type | status |
* +-----+-----+-----+-----+-----+-----+-----+-----+
* | data |
* +-----+-----+-----+-----+
*
* id: the corresponding request identifier
* type: the type of the corresponding request
* status: the status of request processing
* data: any data associated with the response (determined by type and
* status)
*/
struct xen_netif_ctrl_response {
uint16_t id;
uint16_t type;
uint32_t status;
#define XEN_NETIF_CTRL_STATUS_SUCCESS 0
#define XEN_NETIF_CTRL_STATUS_NOT_SUPPORTED 1
#define XEN_NETIF_CTRL_STATUS_INVALID_PARAMETER 2
#define XEN_NETIF_CTRL_STATUS_BUFFER_OVERFLOW 3
uint32_t data;
};
/*
* Control messages
* ================
*
* XEN_NETIF_CTRL_TYPE_SET_HASH_ALGORITHM
* --------------------------------------
*
* This is sent by the frontend to set the desired hash algorithm.
*
* Request:
*
* type = XEN_NETIF_CTRL_TYPE_SET_HASH_ALGORITHM
* data[0] = a XEN_NETIF_CTRL_HASH_ALGORITHM_* value
* data[1] = 0
* data[2] = 0
*
* Response:
*
* status = XEN_NETIF_CTRL_STATUS_NOT_SUPPORTED - Operation not
* supported
* XEN_NETIF_CTRL_STATUS_INVALID_PARAMETER - The algorithm is not
* supported
* XEN_NETIF_CTRL_STATUS_SUCCESS - Operation successful
*
* NOTE: Setting data[0] to XEN_NETIF_CTRL_HASH_ALGORITHM_NONE disables
* hashing and the backend is free to choose how it steers packets
* to queues (which is the default behaviour).
*
* XEN_NETIF_CTRL_TYPE_GET_HASH_FLAGS
* ----------------------------------
*
* This is sent by the frontend to query the types of hash supported by
* the backend.
*
* Request:
*
* type = XEN_NETIF_CTRL_TYPE_GET_HASH_FLAGS
* data[0] = 0
* data[1] = 0
* data[2] = 0
*
* Response:
*
* status = XEN_NETIF_CTRL_STATUS_NOT_SUPPORTED - Operation not supported
* XEN_NETIF_CTRL_STATUS_SUCCESS - Operation successful
* data = supported hash types (if operation was successful)
*
* NOTE: A valid hash algorithm must be selected before this operation can
* succeed.
*
* XEN_NETIF_CTRL_TYPE_SET_HASH_FLAGS
* ----------------------------------
*
* This is sent by the frontend to set the types of hash that the backend
* should calculate. (See above for hash type definitions).
* Note that the 'maximal' type of hash should always be chosen. For
* example, if the frontend sets both IPV4 and IPV4_TCP hash types then
* the latter hash type should be calculated for any TCP packet and the
* former only calculated for non-TCP packets.
*
* Request:
*
* type = XEN_NETIF_CTRL_TYPE_SET_HASH_FLAGS
* data[0] = bitwise OR of XEN_NETIF_CTRL_HASH_TYPE_* values
* data[1] = 0
* data[2] = 0
*
* Response:
*
* status = XEN_NETIF_CTRL_STATUS_NOT_SUPPORTED - Operation not
* supported
* XEN_NETIF_CTRL_STATUS_INVALID_PARAMETER - One or more flag
* value is invalid or
* unsupported
* XEN_NETIF_CTRL_STATUS_SUCCESS - Operation successful
* data = 0
*
* NOTE: A valid hash algorithm must be selected before this operation can
* succeed.
* Also, setting data[0] to zero disables hashing and the backend
* is free to choose how it steers packets to queues.
*
* XEN_NETIF_CTRL_TYPE_SET_HASH_KEY
* --------------------------------
*
* This is sent by the frontend to set the key of the hash if the algorithm
* requires it. (See hash algorithms above).
*
* Request:
*
* type = XEN_NETIF_CTRL_TYPE_SET_HASH_KEY
* data[0] = grant reference of page containing the key (assumed to
* start at beginning of grant)
* data[1] = size of key in octets
* data[2] = 0
*
* Response:
*
* status = XEN_NETIF_CTRL_STATUS_NOT_SUPPORTED - Operation not
* supported
* XEN_NETIF_CTRL_STATUS_INVALID_PARAMETER - Key size is invalid
* XEN_NETIF_CTRL_STATUS_BUFFER_OVERFLOW - Key size is larger
* than the backend
* supports
* XEN_NETIF_CTRL_STATUS_SUCCESS - Operation successful
* data = 0
*
* NOTE: Any key octets not specified are assumed to be zero (the key
* is assumed to be empty by default) and specifying a new key
* invalidates any previous key, hence specifying a key size of
* zero will clear the key (which ensures that the calculated hash
* will always be zero).
* The maximum size of key is algorithm and backend specific, but
* is also limited by the single grant reference.
* The grant reference may be read-only and must remain valid until
* the response has been processed.
*
* XEN_NETIF_CTRL_TYPE_GET_HASH_MAPPING_SIZE
* -----------------------------------------
*
* This is sent by the frontend to query the maximum size of mapping
* table supported by the backend. The size is specified in terms of
* table entries.
*
* Request:
*
* type = XEN_NETIF_CTRL_TYPE_GET_HASH_MAPPING_SIZE
* data[0] = 0
* data[1] = 0
* data[2] = 0
*
* Response:
*
* status = XEN_NETIF_CTRL_STATUS_NOT_SUPPORTED - Operation not supported
* XEN_NETIF_CTRL_STATUS_SUCCESS - Operation successful
* data = maximum number of entries allowed in the mapping table
* (if operation was successful) or zero if a mapping table is
* not supported (i.e. hash mapping is done only by modular
* arithmetic).
*
* XEN_NETIF_CTRL_TYPE_SET_HASH_MAPPING_SIZE
* -------------------------------------
*
* This is sent by the frontend to set the actual size of the mapping
* table to be used by the backend. The size is specified in terms of
* table entries.
* Any previous table is invalidated by this message and any new table
* is assumed to be zero filled.
*
* Request:
*
* type = XEN_NETIF_CTRL_TYPE_SET_HASH_MAPPING_SIZE
* data[0] = number of entries in mapping table
* data[1] = 0
* data[2] = 0
*
* Response:
*
* status = XEN_NETIF_CTRL_STATUS_NOT_SUPPORTED - Operation not
* supported
* XEN_NETIF_CTRL_STATUS_INVALID_PARAMETER - Table size is invalid
* XEN_NETIF_CTRL_STATUS_SUCCESS - Operation successful
* data = 0
*
* NOTE: Setting data[0] to 0 means that hash mapping should be done
* using modular arithmetic.
*
* XEN_NETIF_CTRL_TYPE_SET_HASH_MAPPING
* ------------------------------------
*
* This is sent by the frontend to set the content of the table mapping
* hash value to queue number. The backend should calculate the hash from
* the packet header, use it as an index into the table (modulo the size
* of the table) and then steer the packet to the queue number found at
* that index.
*
* Request:
*
* type = XEN_NETIF_CTRL_TYPE_SET_HASH_MAPPING
* data[0] = grant reference of page containing the mapping (sub-)table
* (assumed to start at beginning of grant)
* data[1] = size of (sub-)table in entries
* data[2] = offset, in entries, of sub-table within overall table
*
* Response:
*
* status = XEN_NETIF_CTRL_STATUS_NOT_SUPPORTED - Operation not
* supported
* XEN_NETIF_CTRL_STATUS_INVALID_PARAMETER - Table size or content
* is invalid
* XEN_NETIF_CTRL_STATUS_BUFFER_OVERFLOW - Table size is larger
* than the backend
* supports
* XEN_NETIF_CTRL_STATUS_SUCCESS - Operation successful
* data = 0
*
* NOTE: The overall table has the following format:
*
* 0 1 2 3 4 5 6 7 octet
* +-----+-----+-----+-----+-----+-----+-----+-----+
* | mapping[0] | mapping[1] |
* +-----+-----+-----+-----+-----+-----+-----+-----+
* | . |
* | . |
* | . |
* +-----+-----+-----+-----+-----+-----+-----+-----+
* | mapping[N-2] | mapping[N-1] |
* +-----+-----+-----+-----+-----+-----+-----+-----+
*
* where N is specified by a XEN_NETIF_CTRL_TYPE_SET_HASH_MAPPING_SIZE
* message and each mapping must specifies a queue between 0 and
* "multi-queue-num-queues" (see above).
* The backend may support a mapping table larger than can be
* mapped by a single grant reference. Thus sub-tables within a
* larger table can be individually set by sending multiple messages
* with differing offset values. Specifying a new sub-table does not
* invalidate any table data outside that range.
* The grant reference may be read-only and must remain valid until
* the response has been processed.
*/
DEFINE_RING_TYPES(xen_netif_ctrl,
struct xen_netif_ctrl_request,
struct xen_netif_ctrl_response);
/*
* Guest transmit
* ==============
*
* This is the 'wire' format for transmit (frontend -> backend) packets:
*
* Fragment 1: xen_netif_tx_request_t - flags = XEN_NETTXF_*
* size = total packet size
* [Extra 1: xen_netif_extra_info_t] - (only if fragment 1 flags include
* XEN_NETTXF_extra_info)
* ...
* [Extra N: xen_netif_extra_info_t] - (only if extra N-1 flags include
* XEN_NETIF_EXTRA_MORE)
* ...
* Fragment N: xen_netif_tx_request_t - (only if fragment N-1 flags include
* XEN_NETTXF_more_data - flags on preceding
* extras are not relevant here)
* flags = 0
* size = fragment size
*
* NOTE:
*
* This format slightly is different from that used for receive
* (backend -> frontend) packets. Specifically, in a multi-fragment
* packet the actual size of fragment 1 can only be determined by
* subtracting the sizes of fragments 2..N from the total packet size.
*
* Ring slot size is 12 octets, however not all request/response
* structs use the full size.
*
* tx request data (xen_netif_tx_request_t)
* ------------------------------------
*
* 0 1 2 3 4 5 6 7 octet
* +-----+-----+-----+-----+-----+-----+-----+-----+
* | grant ref | offset | flags |
* +-----+-----+-----+-----+-----+-----+-----+-----+
* | id | size |
* +-----+-----+-----+-----+
*
* grant ref: Reference to buffer page.
* offset: Offset within buffer page.
* flags: XEN_NETTXF_*.
* id: request identifier, echoed in response.
* size: packet size in bytes.
*
* tx response (xen_netif_tx_response_t)
* ---------------------------------
*
* 0 1 2 3 4 5 6 7 octet
* +-----+-----+-----+-----+-----+-----+-----+-----+
* | id | status | unused |
* +-----+-----+-----+-----+-----+-----+-----+-----+
* | unused |
* +-----+-----+-----+-----+
*
* id: reflects id in transmit request
* status: XEN_NETIF_RSP_*
*
* Guest receive
* =============
*
* This is the 'wire' format for receive (backend -> frontend) packets:
*
* Fragment 1: xen_netif_rx_request_t - flags = XEN_NETRXF_*
* size = fragment size
* [Extra 1: xen_netif_extra_info_t] - (only if fragment 1 flags include
* XEN_NETRXF_extra_info)
* ...
* [Extra N: xen_netif_extra_info_t] - (only if extra N-1 flags include
* XEN_NETIF_EXTRA_MORE)
* ...
* Fragment N: xen_netif_rx_request_t - (only if fragment N-1 flags include
* XEN_NETRXF_more_data - flags on preceding
* extras are not relevant here)
* flags = 0
* size = fragment size
*
* NOTE:
*
* This format slightly is different from that used for transmit
* (frontend -> backend) packets. Specifically, in a multi-fragment
* packet the size of the packet can only be determined by summing the
* sizes of fragments 1..N.
*
* Ring slot size is 8 octets.
*
* rx request (xen_netif_rx_request_t)
* -------------------------------
*
* 0 1 2 3 4 5 6 7 octet
* +-----+-----+-----+-----+-----+-----+-----+-----+
* | id | pad | gref |
* +-----+-----+-----+-----+-----+-----+-----+-----+
*
* id: request identifier, echoed in response.
* gref: reference to incoming granted frame.
*
* rx response (xen_netif_rx_response_t)
* ---------------------------------
*
* 0 1 2 3 4 5 6 7 octet
* +-----+-----+-----+-----+-----+-----+-----+-----+
* | id | offset | flags | status |
* +-----+-----+-----+-----+-----+-----+-----+-----+
*
* id: reflects id in receive request
* offset: offset in page of start of received packet
* flags: XEN_NETRXF_*
* status: -ve: XEN_NETIF_RSP_*; +ve: Rx'ed pkt size.
*
* NOTE: Historically, to support GSO on the frontend receive side, Linux
* netfront does not make use of the rx response id (because, as
* described below, extra info structures overlay the id field).
* Instead it assumes that responses always appear in the same ring
* slot as their corresponding request. Thus, to maintain
* compatibility, backends must make sure this is the case.
*
* Extra Info
* ==========
*
* Can be present if initial request or response has NET{T,R}XF_extra_info,
* or previous extra request has XEN_NETIF_EXTRA_MORE.
*
* The struct therefore needs to fit into either a tx or rx slot and
* is therefore limited to 8 octets.
*
* NOTE: Because extra info data overlays the usual request/response
* structures, there is no id information in the opposite direction.
* So, if an extra info overlays an rx response the frontend can
* assume that it is in the same ring slot as the request that was
* consumed to make the slot available, and the backend must ensure
* this assumption is true.
*
* extra info (xen_netif_extra_info_t)
* -------------------------------
*
* General format:
*
* 0 1 2 3 4 5 6 7 octet
* +-----+-----+-----+-----+-----+-----+-----+-----+
* |type |flags| type specific data |
* +-----+-----+-----+-----+-----+-----+-----+-----+
* | padding for tx |
* +-----+-----+-----+-----+
*
* type: XEN_NETIF_EXTRA_TYPE_*
* flags: XEN_NETIF_EXTRA_FLAG_*
* padding for tx: present only in the tx case due to 8 octet limit
* from rx case. Not shown in type specific entries
* below.
*
* XEN_NETIF_EXTRA_TYPE_GSO:
*
* 0 1 2 3 4 5 6 7 octet
* +-----+-----+-----+-----+-----+-----+-----+-----+
* |type |flags| size |type | pad | features |
* +-----+-----+-----+-----+-----+-----+-----+-----+
*
* type: Must be XEN_NETIF_EXTRA_TYPE_GSO
* flags: XEN_NETIF_EXTRA_FLAG_*
* size: Maximum payload size of each segment. For example,
* for TCP this is just the path MSS.
* type: XEN_NETIF_GSO_TYPE_*: This determines the protocol of
* the packet and any extra features required to segment the
* packet properly.
* features: EN_XEN_NETIF_GSO_FEAT_*: This specifies any extra GSO
* features required to process this packet, such as ECN
* support for TCPv4.
*
* XEN_NETIF_EXTRA_TYPE_MCAST_{ADD,DEL}:
*
* 0 1 2 3 4 5 6 7 octet
* +-----+-----+-----+-----+-----+-----+-----+-----+
* |type |flags| addr |
* +-----+-----+-----+-----+-----+-----+-----+-----+
*
* type: Must be XEN_NETIF_EXTRA_TYPE_MCAST_{ADD,DEL}
* flags: XEN_NETIF_EXTRA_FLAG_*
* addr: address to add/remove
*
* XEN_NETIF_EXTRA_TYPE_HASH:
*
* A backend that supports teoplitz hashing is assumed to accept
* this type of extra info in transmit packets.
* A frontend that enables hashing is assumed to accept
* this type of extra info in receive packets.
*
* 0 1 2 3 4 5 6 7 octet
* +-----+-----+-----+-----+-----+-----+-----+-----+
* |type |flags|htype| alg |LSB ---- value ---- MSB|
* +-----+-----+-----+-----+-----+-----+-----+-----+
*
* type: Must be XEN_NETIF_EXTRA_TYPE_HASH
* flags: XEN_NETIF_EXTRA_FLAG_*
* htype: Hash type (one of _XEN_NETIF_CTRL_HASH_TYPE_* - see above)
* alg: The algorithm used to calculate the hash (one of
* XEN_NETIF_CTRL_HASH_TYPE_ALGORITHM_* - see above)
* value: Hash value
*/
/* Protocol checksum field is blank in the packet (hardware offload)? */
#define _XEN_NETTXF_csum_blank (0)
#define XEN_NETTXF_csum_blank (1U<<_XEN_NETTXF_csum_blank)
/* Packet data has been validated against protocol checksum. */
#define _XEN_NETTXF_data_validated (1)
#define XEN_NETTXF_data_validated (1U<<_XEN_NETTXF_data_validated)
/* Packet continues in the next request descriptor. */
#define _XEN_NETTXF_more_data (2)
#define XEN_NETTXF_more_data (1U<<_XEN_NETTXF_more_data)
/* Packet to be followed by extra descriptor(s). */
#define _XEN_NETTXF_extra_info (3)
#define XEN_NETTXF_extra_info (1U<<_XEN_NETTXF_extra_info)
#define XEN_NETIF_MAX_TX_SIZE 0xFFFF
struct xen_netif_tx_request {
grant_ref_t gref;
uint16_t offset;
uint16_t flags;
uint16_t id;
uint16_t size;
};
/* Types of xen_netif_extra_info descriptors. */
#define XEN_NETIF_EXTRA_TYPE_NONE (0) /* Never used - invalid */
#define XEN_NETIF_EXTRA_TYPE_GSO (1) /* u.gso */
#define XEN_NETIF_EXTRA_TYPE_MCAST_ADD (2) /* u.mcast */
#define XEN_NETIF_EXTRA_TYPE_MCAST_DEL (3) /* u.mcast */
#define XEN_NETIF_EXTRA_TYPE_HASH (4) /* u.hash */
#define XEN_NETIF_EXTRA_TYPE_XDP (5) /* u.xdp */
#define XEN_NETIF_EXTRA_TYPE_MAX (6)
/* xen_netif_extra_info_t flags. */
#define _XEN_NETIF_EXTRA_FLAG_MORE (0)
#define XEN_NETIF_EXTRA_FLAG_MORE (1U<<_XEN_NETIF_EXTRA_FLAG_MORE)
/* GSO types */
#define XEN_NETIF_GSO_TYPE_NONE (0)
#define XEN_NETIF_GSO_TYPE_TCPV4 (1)
#define XEN_NETIF_GSO_TYPE_TCPV6 (2)
/*
* This structure needs to fit within both xen_netif_tx_request_t and
* xen_netif_rx_response_t for compatibility.
*/
struct xen_netif_extra_info {
uint8_t type;
uint8_t flags;
union {
struct {
uint16_t size;
uint8_t type;
uint8_t pad;
uint16_t features;
} gso;
struct {
uint8_t addr[6];
} mcast;
struct {
uint8_t type;
uint8_t algorithm;
uint8_t value[4];
} hash;
struct {
uint16_t headroom;
uint16_t pad[2];
} xdp;
uint16_t pad[3];
} u;
};
struct xen_netif_tx_response {
uint16_t id;
int16_t status;
};
struct xen_netif_rx_request {
uint16_t id; /* Echoed in response message. */
uint16_t pad;
grant_ref_t gref;
};
/* Packet data has been validated against protocol checksum. */
#define _XEN_NETRXF_data_validated (0)
#define XEN_NETRXF_data_validated (1U<<_XEN_NETRXF_data_validated)
/* Protocol checksum field is blank in the packet (hardware offload)? */
#define _XEN_NETRXF_csum_blank (1)
#define XEN_NETRXF_csum_blank (1U<<_XEN_NETRXF_csum_blank)
/* Packet continues in the next request descriptor. */
#define _XEN_NETRXF_more_data (2)
#define XEN_NETRXF_more_data (1U<<_XEN_NETRXF_more_data)
/* Packet to be followed by extra descriptor(s). */
#define _XEN_NETRXF_extra_info (3)
#define XEN_NETRXF_extra_info (1U<<_XEN_NETRXF_extra_info)
/* Packet has GSO prefix. Deprecated but included for compatibility */
#define _XEN_NETRXF_gso_prefix (4)
#define XEN_NETRXF_gso_prefix (1U<<_XEN_NETRXF_gso_prefix)
struct xen_netif_rx_response {
uint16_t id;
uint16_t offset;
uint16_t flags;
int16_t status;
};
/*
* Generate xen_netif ring structures and types.
*/
DEFINE_RING_TYPES(xen_netif_tx, struct xen_netif_tx_request,
struct xen_netif_tx_response);
DEFINE_RING_TYPES(xen_netif_rx, struct xen_netif_rx_request,
struct xen_netif_rx_response);
#define XEN_NETIF_RSP_DROPPED -2
#define XEN_NETIF_RSP_ERROR -1
#define XEN_NETIF_RSP_OKAY 0
/* No response: used for auxiliary requests (e.g., xen_netif_extra_info_t). */
#define XEN_NETIF_RSP_NULL 1
#endif