1. 根目录:
2. include
3. uapi
4. linux
5. virtio_net.h

#ifndef _LINUX_VIRTIO_NET_H
#define _LINUX_VIRTIO_NET_H
/* This header is BSD licensed so anyone can use the definitions to implement
 * compatible drivers/servers.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 * 3. Neither the name of IBM nor the names of its contributors
 *    may be used to endorse or promote products derived from this software
 *    without specific prior written permission.
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS ``AS IS'' AND
 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED.  IN NO EVENT SHALL IBM OR CONTRIBUTORS BE LIABLE
 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE. */
#include <linux/types.h>
#include <linux/virtio_ids.h>
#include <linux/virtio_config.h>
#include <linux/if_ether.h>

/* The feature bitmap for virtio net */
#define VIRTIO_NET_F_CSUM	0	/* Host handles pkts w/ partial csum */
#define VIRTIO_NET_F_GUEST_CSUM	1	/* Guest handles pkts w/ partial csum */
#define VIRTIO_NET_F_MAC	5	/* Host has given MAC address. */
#define VIRTIO_NET_F_GSO	6	/* Host handles pkts w/ any GSO type */
#define VIRTIO_NET_F_GUEST_TSO4	7	/* Guest can handle TSOv4 in. */
#define VIRTIO_NET_F_GUEST_TSO6	8	/* Guest can handle TSOv6 in. */
#define VIRTIO_NET_F_GUEST_ECN	9	/* Guest can handle TSO[6] w/ ECN in. */
#define VIRTIO_NET_F_GUEST_UFO	10	/* Guest can handle UFO in. */
#define VIRTIO_NET_F_HOST_TSO4	11	/* Host can handle TSOv4 in. */
#define VIRTIO_NET_F_HOST_TSO6	12	/* Host can handle TSOv6 in. */
#define VIRTIO_NET_F_HOST_ECN	13	/* Host can handle TSO[6] w/ ECN in. */
#define VIRTIO_NET_F_HOST_UFO	14	/* Host can handle UFO in. */
#define VIRTIO_NET_F_MRG_RXBUF	15	/* Host can merge receive buffers. */
#define VIRTIO_NET_F_STATUS	16	/* virtio_net_config.status available */
#define VIRTIO_NET_F_CTRL_VQ	17	/* Control channel available */
#define VIRTIO_NET_F_CTRL_RX	18	/* Control channel RX mode support */
#define VIRTIO_NET_F_CTRL_VLAN	19	/* Control channel VLAN filtering */
#define VIRTIO_NET_F_CTRL_RX_EXTRA 20	/* Extra RX mode control support */
#define VIRTIO_NET_F_GUEST_ANNOUNCE 21	/* Guest can announce device on the
					 * network */
#define VIRTIO_NET_F_MQ	22	/* Device supports Receive Flow
					 * Steering */
#define VIRTIO_NET_F_CTRL_MAC_ADDR 23	/* Set MAC address */

#define VIRTIO_NET_S_LINK_UP	1	/* Link is up */
#define VIRTIO_NET_S_ANNOUNCE	2	/* Announcement is needed */

struct virtio_net_config {
	/* The config defining mac address (if VIRTIO_NET_F_MAC) */
	__u8 mac[6];
	/* See VIRTIO_NET_F_STATUS and VIRTIO_NET_S_* above */
	__u16 status;
	/* Maximum number of each of transmit and receive queues;
	 * see VIRTIO_NET_F_MQ and VIRTIO_NET_CTRL_MQ.
	 * Legal values are between 1 and 0x8000
	 */
	__u16 max_virtqueue_pairs;
} __attribute__((packed));

/* This is the first element of the scatter-gather list.  If you don't
 * specify GSO or CSUM features, you can simply ignore the header. */
struct virtio_net_hdr {
#define VIRTIO_NET_HDR_F_NEEDS_CSUM	1	// Use csum_start, csum_offset
#define VIRTIO_NET_HDR_F_DATA_VALID	2	// Csum is valid
	__u8 flags;
#define VIRTIO_NET_HDR_GSO_NONE		0	// Not a GSO frame
#define VIRTIO_NET_HDR_GSO_TCPV4	1	// GSO frame, IPv4 TCP (TSO)
#define VIRTIO_NET_HDR_GSO_UDP		3	// GSO frame, IPv4 UDP (UFO)
#define VIRTIO_NET_HDR_GSO_TCPV6	4	// GSO frame, IPv6 TCP
#define VIRTIO_NET_HDR_GSO_ECN		0x80	// TCP has ECN set
	__u8 gso_type;
	__u16 hdr_len;		/* Ethernet + IP + tcp/udp hdrs */
	__u16 gso_size;		/* Bytes to append to hdr_len per frame */
	__u16 csum_start;	/* Position to start checksumming from */
	__u16 csum_offset;	/* Offset after that to place checksum */
};

/* This is the version of the header to use when the MRG_RXBUF
 * feature has been negotiated. */
struct virtio_net_hdr_mrg_rxbuf {
	struct virtio_net_hdr hdr;
	__u16 num_buffers;	/* Number of merged rx buffers */
};

/*
 * Control virtqueue data structures
 *
 * The control virtqueue expects a header in the first sg entry
 * and an ack/status response in the last entry.  Data for the
 * command goes in between.
 */
struct virtio_net_ctrl_hdr {
	__u8 class;
	__u8 cmd;
} __attribute__((packed));

typedef __u8 virtio_net_ctrl_ack;

#define VIRTIO_NET_OK     0
#define VIRTIO_NET_ERR    1

/*
 * Control the RX mode, ie. promisucous, allmulti, etc...
 * All commands require an "out" sg entry containing a 1 byte
 * state value, zero = disable, non-zero = enable.  Commands
 * 0 and 1 are supported with the VIRTIO_NET_F_CTRL_RX feature.
 * Commands 2-5 are added with VIRTIO_NET_F_CTRL_RX_EXTRA.
 */
#define VIRTIO_NET_CTRL_RX    0
 #define VIRTIO_NET_CTRL_RX_PROMISC      0
 #define VIRTIO_NET_CTRL_RX_ALLMULTI     1
 #define VIRTIO_NET_CTRL_RX_ALLUNI       2
 #define VIRTIO_NET_CTRL_RX_NOMULTI      3
 #define VIRTIO_NET_CTRL_RX_NOUNI        4
 #define VIRTIO_NET_CTRL_RX_NOBCAST      5

/*
 * Control the MAC
 *
 * The MAC filter table is managed by the hypervisor, the guest should
 * assume the size is infinite.  Filtering should be considered
 * non-perfect, ie. based on hypervisor resources, the guest may
 * received packets from sources not specified in the filter list.
 *
 * In addition to the class/cmd header, the TABLE_SET command requires
 * two out scatterlists.  Each contains a 4 byte count of entries followed
 * by a concatenated byte stream of the ETH_ALEN MAC addresses.  The
 * first sg list contains unicast addresses, the second is for multicast.
 * This functionality is present if the VIRTIO_NET_F_CTRL_RX feature
 * is available.
 *
 * The ADDR_SET command requests one out scatterlist, it contains a
 * 6 bytes MAC address. This functionality is present if the
 * VIRTIO_NET_F_CTRL_MAC_ADDR feature is available.
 */
struct virtio_net_ctrl_mac {
	__u32 entries;
	__u8 macs[][ETH_ALEN];
} __attribute__((packed));

#define VIRTIO_NET_CTRL_MAC    1
 #define VIRTIO_NET_CTRL_MAC_TABLE_SET        0
 #define VIRTIO_NET_CTRL_MAC_ADDR_SET         1

/*
 * Control VLAN filtering
 *
 * The VLAN filter table is controlled via a simple ADD/DEL interface.
 * VLAN IDs not added may be filterd by the hypervisor.  Del is the
 * opposite of add.  Both commands expect an out entry containing a 2
 * byte VLAN ID.  VLAN filterting is available with the
 * VIRTIO_NET_F_CTRL_VLAN feature bit.
 */
#define VIRTIO_NET_CTRL_VLAN       2
 #define VIRTIO_NET_CTRL_VLAN_ADD             0
 #define VIRTIO_NET_CTRL_VLAN_DEL             1

/*
 * Control link announce acknowledgement
 *
 * The command VIRTIO_NET_CTRL_ANNOUNCE_ACK is used to indicate that
 * driver has recevied the notification; device would clear the
 * VIRTIO_NET_S_ANNOUNCE bit in the status field after it receives
 * this command.
 */
#define VIRTIO_NET_CTRL_ANNOUNCE       3
 #define VIRTIO_NET_CTRL_ANNOUNCE_ACK         0

/*
 * Control Receive Flow Steering
 *
 * The command VIRTIO_NET_CTRL_MQ_VQ_PAIRS_SET
 * enables Receive Flow Steering, specifying the number of the transmit and
 * receive queues that will be used. After the command is consumed and acked by
 * the device, the device will not steer new packets on receive virtqueues
 * other than specified nor read from transmit virtqueues other than specified.
 * Accordingly, driver should not transmit new packets  on virtqueues other than
 * specified.
 */
struct virtio_net_ctrl_mq {
	__u16 virtqueue_pairs;
};

#define VIRTIO_NET_CTRL_MQ   4
 #define VIRTIO_NET_CTRL_MQ_VQ_PAIRS_SET        0
 #define VIRTIO_NET_CTRL_MQ_VQ_PAIRS_MIN        1
 #define VIRTIO_NET_CTRL_MQ_VQ_PAIRS_MAX        0x8000

#endif /* _LINUX_VIRTIO_NET_H */