/******************************************************************************
* netif.h
*
* Unified network-device I/O interface for Xen guest OSes.
*
* Copyright (c) 2003-2004, Keir Fraser
*/
#ifndef __XEN_PUBLIC_IO_NETIF_H__
#define __XEN_PUBLIC_IO_NETIF_H__
#include <xen/interface/io/ring.h>
#include <xen/interface/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 notificaion. Backend either doesn't support this feature or
* advertise 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.
*/
/*
* This is the 'wire' format for packets:
* Request 1: xen_netif_tx_request -- XEN_NETTXF_* (any flags)
* [Request 2: xen_netif_extra_info] (only if request 1 has XEN_NETTXF_extra_info)
* [Request 3: xen_netif_extra_info] (only if request 2 has XEN_NETIF_EXTRA_MORE)
* Request 4: xen_netif_tx_request -- XEN_NETTXF_more_data
* Request 5: xen_netif_tx_request -- XEN_NETTXF_more_data
* ...
* Request N: xen_netif_tx_request -- 0
*/
/* 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; /* Reference to buffer page */
uint16_t offset; /* Offset within buffer page */
uint16_t flags; /* XEN_NETTXF_* */
uint16_t id; /* Echoed in response message. */
uint16_t size; /* Packet size in bytes. */
};
/* 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_MAX (2)
/* xen_netif_extra_info 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 netif_tx_request and
* netif_rx_response for compatibility.
*/
struct xen_netif_extra_info {
uint8_t type; /* XEN_NETIF_EXTRA_TYPE_* */
uint8_t flags; /* XEN_NETIF_EXTRA_FLAG_* */
union {
struct {
/*
* Maximum payload size of each segment. For
* example, for TCP this is just the path MSS.
*/
uint16_t size;
/*
* GSO type. This determines the protocol of
* the packet and any extra features required
* to segment the packet properly.
*/
uint8_t type; /* XEN_NETIF_GSO_TYPE_* */
/* Future expansion. */
uint8_t pad;
/*
* GSO features. This specifies any extra GSO
* features required to process this packet,
* such as ECN support for TCPv4.
*/
uint16_t features; /* XEN_NETIF_GSO_FEAT_* */
} gso;
uint16_t pad[3];
} u;
};
struct xen_netif_tx_response {
uint16_t id;
int16_t status; /* XEN_NETIF_RSP_* */
};
struct xen_netif_rx_request {
uint16_t id; /* Echoed in response message. */
grant_ref_t gref; /* Reference to incoming granted frame */
};
/* 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)
/* GSO Prefix descriptor. */
#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; /* Offset in page of start of received packet */
uint16_t flags; /* XEN_NETRXF_* */
int16_t status; /* -ve: BLKIF_RSP_* ; +ve: Rx'ed pkt size. */
};
/*
* Generate 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). */
#define XEN_NETIF_RSP_NULL 1
#endif