a697a334b3
Based on a patch from Mark McLoughlin, this patch introduces a new bottom half packet transmitter that avoids the latency imposed by the tx_timer approach. Rather than scheduling a timer when a TX packet comes in, schedule a bottom half to be run from the iothread. The bottom half handler first attempts to flush the queue with notification disabled (this is where we could race with a guest without txburst). If we flush a full burst, reschedule immediately. If we send short of a full burst, try to re-enable notification. To avoid a race with TXs that may have occurred, we must then flush again. If we find some packets to send, the guest it probably active, so we can reschedule again. tx_timer and tx_bh are mutually exclusive, so we can re-use the tx_waiting flag to indicate one or the other needs to be setup. This allows us to seamlessly migrate between timer and bh TX handling. The bottom half handler becomes the new default and we add a new tx= option to virtio-net-pci. Usage: -device virtio-net-pci,tx=timer # select timer mitigation vs "bh" Signed-off-by: Alex Williamson <alex.williamson@redhat.com> Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
190 lines
7.4 KiB
C
190 lines
7.4 KiB
C
/*
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* Virtio Network Device
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*
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* Copyright IBM, Corp. 2007
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*
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* Authors:
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* Anthony Liguori <aliguori@us.ibm.com>
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*
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* This work is licensed under the terms of the GNU GPL, version 2. See
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* the COPYING file in the top-level directory.
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*
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*/
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#ifndef _QEMU_VIRTIO_NET_H
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#define _QEMU_VIRTIO_NET_H
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#include "virtio.h"
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#include "net.h"
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#include "pci.h"
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#define ETH_ALEN 6
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/* from Linux's virtio_net.h */
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/* The ID for virtio_net */
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#define VIRTIO_ID_NET 1
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/* The feature bitmap for virtio net */
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#define VIRTIO_NET_F_CSUM 0 /* Host handles pkts w/ partial csum */
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#define VIRTIO_NET_F_GUEST_CSUM 1 /* Guest handles pkts w/ partial csum */
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#define VIRTIO_NET_F_MAC 5 /* Host has given MAC address. */
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#define VIRTIO_NET_F_GSO 6 /* Host handles pkts w/ any GSO type */
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#define VIRTIO_NET_F_GUEST_TSO4 7 /* Guest can handle TSOv4 in. */
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#define VIRTIO_NET_F_GUEST_TSO6 8 /* Guest can handle TSOv6 in. */
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#define VIRTIO_NET_F_GUEST_ECN 9 /* Guest can handle TSO[6] w/ ECN in. */
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#define VIRTIO_NET_F_GUEST_UFO 10 /* Guest can handle UFO in. */
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#define VIRTIO_NET_F_HOST_TSO4 11 /* Host can handle TSOv4 in. */
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#define VIRTIO_NET_F_HOST_TSO6 12 /* Host can handle TSOv6 in. */
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#define VIRTIO_NET_F_HOST_ECN 13 /* Host can handle TSO[6] w/ ECN in. */
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#define VIRTIO_NET_F_HOST_UFO 14 /* Host can handle UFO in. */
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#define VIRTIO_NET_F_MRG_RXBUF 15 /* Host can merge receive buffers. */
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#define VIRTIO_NET_F_STATUS 16 /* virtio_net_config.status available */
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#define VIRTIO_NET_F_CTRL_VQ 17 /* Control channel available */
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#define VIRTIO_NET_F_CTRL_RX 18 /* Control channel RX mode support */
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#define VIRTIO_NET_F_CTRL_VLAN 19 /* Control channel VLAN filtering */
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#define VIRTIO_NET_F_CTRL_RX_EXTRA 20 /* Extra RX mode control support */
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#define VIRTIO_NET_S_LINK_UP 1 /* Link is up */
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#define TX_TIMER_INTERVAL 150000 /* 150 us */
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/* Limit the number of packets that can be sent via a single flush
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* of the TX queue. This gives us a guaranteed exit condition and
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* ensures fairness in the io path. 256 conveniently matches the
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* length of the TX queue and shows a good balance of performance
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* and latency. */
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#define TX_BURST 256
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typedef struct virtio_net_conf
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{
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uint32_t txtimer;
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int32_t txburst;
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char *tx;
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} virtio_net_conf;
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/* Maximum packet size we can receive from tap device: header + 64k */
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#define VIRTIO_NET_MAX_BUFSIZE (sizeof(struct virtio_net_hdr) + (64 << 10))
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struct virtio_net_config
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{
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/* The config defining mac address ($ETH_ALEN bytes) */
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uint8_t mac[ETH_ALEN];
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/* See VIRTIO_NET_F_STATUS and VIRTIO_NET_S_* above */
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uint16_t status;
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} __attribute__((packed));
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/* This is the first element of the scatter-gather list. If you don't
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* specify GSO or CSUM features, you can simply ignore the header. */
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struct virtio_net_hdr
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{
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#define VIRTIO_NET_HDR_F_NEEDS_CSUM 1 // Use csum_start, csum_offset
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uint8_t flags;
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#define VIRTIO_NET_HDR_GSO_NONE 0 // Not a GSO frame
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#define VIRTIO_NET_HDR_GSO_TCPV4 1 // GSO frame, IPv4 TCP (TSO)
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#define VIRTIO_NET_HDR_GSO_UDP 3 // GSO frame, IPv4 UDP (UFO)
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#define VIRTIO_NET_HDR_GSO_TCPV6 4 // GSO frame, IPv6 TCP
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#define VIRTIO_NET_HDR_GSO_ECN 0x80 // TCP has ECN set
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uint8_t gso_type;
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uint16_t hdr_len;
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uint16_t gso_size;
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uint16_t csum_start;
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uint16_t csum_offset;
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};
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/* This is the version of the header to use when the MRG_RXBUF
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* feature has been negotiated. */
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struct virtio_net_hdr_mrg_rxbuf
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{
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struct virtio_net_hdr hdr;
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uint16_t num_buffers; /* Number of merged rx buffers */
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};
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/*
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* Control virtqueue data structures
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*
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* The control virtqueue expects a header in the first sg entry
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* and an ack/status response in the last entry. Data for the
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* command goes in between.
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*/
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struct virtio_net_ctrl_hdr {
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uint8_t class;
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uint8_t cmd;
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};
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typedef uint8_t virtio_net_ctrl_ack;
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#define VIRTIO_NET_OK 0
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#define VIRTIO_NET_ERR 1
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/*
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* Control the RX mode, ie. promisucous, allmulti, etc...
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* All commands require an "out" sg entry containing a 1 byte
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* state value, zero = disable, non-zero = enable. Commands
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* 0 and 1 are supported with the VIRTIO_NET_F_CTRL_RX feature.
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* Commands 2-5 are added with VIRTIO_NET_F_CTRL_RX_EXTRA.
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*/
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#define VIRTIO_NET_CTRL_RX_MODE 0
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#define VIRTIO_NET_CTRL_RX_MODE_PROMISC 0
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#define VIRTIO_NET_CTRL_RX_MODE_ALLMULTI 1
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#define VIRTIO_NET_CTRL_RX_MODE_ALLUNI 2
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#define VIRTIO_NET_CTRL_RX_MODE_NOMULTI 3
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#define VIRTIO_NET_CTRL_RX_MODE_NOUNI 4
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#define VIRTIO_NET_CTRL_RX_MODE_NOBCAST 5
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/*
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* Control the MAC filter table.
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*
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* The MAC filter table is managed by the hypervisor, the guest should
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* assume the size is infinite. Filtering should be considered
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* non-perfect, ie. based on hypervisor resources, the guest may
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* received packets from sources not specified in the filter list.
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*
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* In addition to the class/cmd header, the TABLE_SET command requires
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* two out scatterlists. Each contains a 4 byte count of entries followed
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* by a concatenated byte stream of the ETH_ALEN MAC addresses. The
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* first sg list contains unicast addresses, the second is for multicast.
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* This functionality is present if the VIRTIO_NET_F_CTRL_RX feature
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* is available.
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*/
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struct virtio_net_ctrl_mac {
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uint32_t entries;
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uint8_t macs[][ETH_ALEN];
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};
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#define VIRTIO_NET_CTRL_MAC 1
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#define VIRTIO_NET_CTRL_MAC_TABLE_SET 0
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/*
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* Control VLAN filtering
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*
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* The VLAN filter table is controlled via a simple ADD/DEL interface.
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* VLAN IDs not added may be filterd by the hypervisor. Del is the
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* opposite of add. Both commands expect an out entry containing a 2
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* byte VLAN ID. VLAN filterting is available with the
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* VIRTIO_NET_F_CTRL_VLAN feature bit.
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*/
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#define VIRTIO_NET_CTRL_VLAN 2
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#define VIRTIO_NET_CTRL_VLAN_ADD 0
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#define VIRTIO_NET_CTRL_VLAN_DEL 1
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#define DEFINE_VIRTIO_NET_FEATURES(_state, _field) \
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DEFINE_VIRTIO_COMMON_FEATURES(_state, _field), \
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DEFINE_PROP_BIT("csum", _state, _field, VIRTIO_NET_F_CSUM, true), \
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DEFINE_PROP_BIT("guest_csum", _state, _field, VIRTIO_NET_F_GUEST_CSUM, true), \
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DEFINE_PROP_BIT("gso", _state, _field, VIRTIO_NET_F_GSO, true), \
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DEFINE_PROP_BIT("guest_tso4", _state, _field, VIRTIO_NET_F_GUEST_TSO4, true), \
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DEFINE_PROP_BIT("guest_tso6", _state, _field, VIRTIO_NET_F_GUEST_TSO6, true), \
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DEFINE_PROP_BIT("guest_ecn", _state, _field, VIRTIO_NET_F_GUEST_ECN, true), \
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DEFINE_PROP_BIT("guest_ufo", _state, _field, VIRTIO_NET_F_GUEST_UFO, true), \
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DEFINE_PROP_BIT("host_tso4", _state, _field, VIRTIO_NET_F_HOST_TSO4, true), \
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DEFINE_PROP_BIT("host_tso6", _state, _field, VIRTIO_NET_F_HOST_TSO6, true), \
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DEFINE_PROP_BIT("host_ecn", _state, _field, VIRTIO_NET_F_HOST_ECN, true), \
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DEFINE_PROP_BIT("host_ufo", _state, _field, VIRTIO_NET_F_HOST_UFO, true), \
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DEFINE_PROP_BIT("mrg_rxbuf", _state, _field, VIRTIO_NET_F_MRG_RXBUF, true), \
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DEFINE_PROP_BIT("status", _state, _field, VIRTIO_NET_F_STATUS, true), \
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DEFINE_PROP_BIT("ctrl_vq", _state, _field, VIRTIO_NET_F_CTRL_VQ, true), \
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DEFINE_PROP_BIT("ctrl_rx", _state, _field, VIRTIO_NET_F_CTRL_RX, true), \
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DEFINE_PROP_BIT("ctrl_vlan", _state, _field, VIRTIO_NET_F_CTRL_VLAN, true), \
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DEFINE_PROP_BIT("ctrl_rx_extra", _state, _field, VIRTIO_NET_F_CTRL_RX_EXTRA, true)
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#endif
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