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	net: virtio_net: notifications coalescing support
New VirtIO network feature: VIRTIO_NET_F_NOTF_COAL.
Control a Virtio network device notifications coalescing parameters
using the control virtqueue.
A device that supports this fetature can receive
VIRTIO_NET_CTRL_NOTF_COAL control commands.
- VIRTIO_NET_CTRL_NOTF_COAL_TX_SET:
  Ask the network device to change the following parameters:
  - tx_usecs: Maximum number of usecs to delay a TX notification.
  - tx_max_packets: Maximum number of packets to send before a
    TX notification.
- VIRTIO_NET_CTRL_NOTF_COAL_RX_SET:
  Ask the network device to change the following parameters:
  - rx_usecs: Maximum number of usecs to delay a RX notification.
  - rx_max_packets: Maximum number of packets to receive before a
    RX notification.
VirtIO spec. patch:
https://lists.oasis-open.org/archives/virtio-comment/202206/msg00100.html
Signed-off-by: Alvaro Karsz <alvaro.karsz@solid-run.com>
Message-Id: <20220718091102.498774-1-alvaro.karsz@solid-run.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
Reviewed-by: Jakub Kicinski <kuba@kernel.org>
Acked-by: Jason Wang <jasowang@redhat.com>
			
			
This commit is contained in:
		
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					 2 changed files with 129 additions and 16 deletions
				
			
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			@ -270,6 +270,12 @@ struct virtnet_info {
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	u8 duplex;
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	u32 speed;
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	/* Interrupt coalescing settings */
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	u32 tx_usecs;
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	u32 rx_usecs;
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	u32 tx_max_packets;
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	u32 rx_max_packets;
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	unsigned long guest_offloads;
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	unsigned long guest_offloads_capable;
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			@ -2737,27 +2743,89 @@ static int virtnet_get_link_ksettings(struct net_device *dev,
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	return 0;
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}
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static int virtnet_send_notf_coal_cmds(struct virtnet_info *vi,
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				       struct ethtool_coalesce *ec)
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{
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	struct scatterlist sgs_tx, sgs_rx;
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	struct virtio_net_ctrl_coal_tx coal_tx;
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	struct virtio_net_ctrl_coal_rx coal_rx;
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	coal_tx.tx_usecs = cpu_to_le32(ec->tx_coalesce_usecs);
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	coal_tx.tx_max_packets = cpu_to_le32(ec->tx_max_coalesced_frames);
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	sg_init_one(&sgs_tx, &coal_tx, sizeof(coal_tx));
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	if (!virtnet_send_command(vi, VIRTIO_NET_CTRL_NOTF_COAL,
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				  VIRTIO_NET_CTRL_NOTF_COAL_TX_SET,
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				  &sgs_tx))
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		return -EINVAL;
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	/* Save parameters */
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	vi->tx_usecs = ec->tx_coalesce_usecs;
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	vi->tx_max_packets = ec->tx_max_coalesced_frames;
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	coal_rx.rx_usecs = cpu_to_le32(ec->rx_coalesce_usecs);
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	coal_rx.rx_max_packets = cpu_to_le32(ec->rx_max_coalesced_frames);
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	sg_init_one(&sgs_rx, &coal_rx, sizeof(coal_rx));
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	if (!virtnet_send_command(vi, VIRTIO_NET_CTRL_NOTF_COAL,
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				  VIRTIO_NET_CTRL_NOTF_COAL_RX_SET,
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				  &sgs_rx))
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		return -EINVAL;
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	/* Save parameters */
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	vi->rx_usecs = ec->rx_coalesce_usecs;
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	vi->rx_max_packets = ec->rx_max_coalesced_frames;
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	return 0;
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}
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static int virtnet_coal_params_supported(struct ethtool_coalesce *ec)
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{
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	/* usecs coalescing is supported only if VIRTIO_NET_F_NOTF_COAL
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	 * feature is negotiated.
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	 */
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	if (ec->rx_coalesce_usecs || ec->tx_coalesce_usecs)
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		return -EOPNOTSUPP;
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	if (ec->tx_max_coalesced_frames > 1 ||
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	    ec->rx_max_coalesced_frames != 1)
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		return -EINVAL;
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	return 0;
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}
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static int virtnet_set_coalesce(struct net_device *dev,
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				struct ethtool_coalesce *ec,
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				struct kernel_ethtool_coalesce *kernel_coal,
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				struct netlink_ext_ack *extack)
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{
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	struct virtnet_info *vi = netdev_priv(dev);
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	int i, napi_weight;
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	if (ec->tx_max_coalesced_frames > 1 ||
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	    ec->rx_max_coalesced_frames != 1)
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		return -EINVAL;
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	int ret, i, napi_weight;
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	bool update_napi = false;
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	/* Can't change NAPI weight if the link is up */
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	napi_weight = ec->tx_max_coalesced_frames ? NAPI_POLL_WEIGHT : 0;
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	if (napi_weight ^ vi->sq[0].napi.weight) {
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		if (dev->flags & IFF_UP)
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			return -EBUSY;
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		else
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			update_napi = true;
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	}
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	if (virtio_has_feature(vi->vdev, VIRTIO_NET_F_NOTF_COAL))
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		ret = virtnet_send_notf_coal_cmds(vi, ec);
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	else
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		ret = virtnet_coal_params_supported(ec);
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	if (ret)
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		return ret;
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	if (update_napi) {
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		for (i = 0; i < vi->max_queue_pairs; i++)
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			vi->sq[i].napi.weight = napi_weight;
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	}
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	return 0;
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	return ret;
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}
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static int virtnet_get_coalesce(struct net_device *dev,
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			@ -2765,16 +2833,19 @@ static int virtnet_get_coalesce(struct net_device *dev,
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				struct kernel_ethtool_coalesce *kernel_coal,
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				struct netlink_ext_ack *extack)
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{
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	struct ethtool_coalesce ec_default = {
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		.cmd = ETHTOOL_GCOALESCE,
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		.rx_max_coalesced_frames = 1,
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	};
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	struct virtnet_info *vi = netdev_priv(dev);
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	memcpy(ec, &ec_default, sizeof(ec_default));
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	if (virtio_has_feature(vi->vdev, VIRTIO_NET_F_NOTF_COAL)) {
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		ec->rx_coalesce_usecs = vi->rx_usecs;
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		ec->tx_coalesce_usecs = vi->tx_usecs;
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		ec->tx_max_coalesced_frames = vi->tx_max_packets;
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		ec->rx_max_coalesced_frames = vi->rx_max_packets;
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	} else {
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		ec->rx_max_coalesced_frames = 1;
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		if (vi->sq[0].napi.weight)
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			ec->tx_max_coalesced_frames = 1;
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	}
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	return 0;
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}
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			@ -2893,7 +2964,8 @@ static int virtnet_set_rxnfc(struct net_device *dev, struct ethtool_rxnfc *info)
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}
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static const struct ethtool_ops virtnet_ethtool_ops = {
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	.supported_coalesce_params = ETHTOOL_COALESCE_MAX_FRAMES,
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	.supported_coalesce_params = ETHTOOL_COALESCE_MAX_FRAMES |
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		ETHTOOL_COALESCE_USECS,
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	.get_drvinfo = virtnet_get_drvinfo,
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	.get_link = ethtool_op_get_link,
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	.get_ringparam = virtnet_get_ringparam,
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			@ -3606,6 +3678,8 @@ static bool virtnet_validate_features(struct virtio_device *vdev)
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	     VIRTNET_FAIL_ON(vdev, VIRTIO_NET_F_RSS,
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			     "VIRTIO_NET_F_CTRL_VQ") ||
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	     VIRTNET_FAIL_ON(vdev, VIRTIO_NET_F_HASH_REPORT,
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			     "VIRTIO_NET_F_CTRL_VQ") ||
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	     VIRTNET_FAIL_ON(vdev, VIRTIO_NET_F_NOTF_COAL,
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			     "VIRTIO_NET_F_CTRL_VQ"))) {
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		return false;
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	}
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			@ -3742,6 +3816,13 @@ static int virtnet_probe(struct virtio_device *vdev)
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	if (virtio_has_feature(vdev, VIRTIO_NET_F_MRG_RXBUF))
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		vi->mergeable_rx_bufs = true;
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	if (virtio_has_feature(vi->vdev, VIRTIO_NET_F_NOTF_COAL)) {
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		vi->rx_usecs = 0;
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		vi->tx_usecs = 0;
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		vi->tx_max_packets = 0;
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		vi->rx_max_packets = 0;
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	}
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	if (virtio_has_feature(vdev, VIRTIO_NET_F_HASH_REPORT))
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		vi->has_rss_hash_report = true;
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			@ -3977,7 +4058,7 @@ static struct virtio_device_id id_table[] = {
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	VIRTIO_NET_F_CTRL_MAC_ADDR, \
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	VIRTIO_NET_F_MTU, VIRTIO_NET_F_CTRL_GUEST_OFFLOADS, \
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	VIRTIO_NET_F_SPEED_DUPLEX, VIRTIO_NET_F_STANDBY, \
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	VIRTIO_NET_F_RSS, VIRTIO_NET_F_HASH_REPORT
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	VIRTIO_NET_F_RSS, VIRTIO_NET_F_HASH_REPORT, VIRTIO_NET_F_NOTF_COAL
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static unsigned int features[] = {
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	VIRTNET_FEATURES,
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			@ -56,7 +56,7 @@
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#define VIRTIO_NET_F_MQ	22	/* Device supports Receive Flow
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					 * Steering */
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#define VIRTIO_NET_F_CTRL_MAC_ADDR 23	/* Set MAC address */
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#define VIRTIO_NET_F_NOTF_COAL	53	/* Guest can handle notifications coalescing */
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#define VIRTIO_NET_F_HASH_REPORT  57	/* Supports hash report */
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#define VIRTIO_NET_F_RSS	  60	/* Supports RSS RX steering */
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#define VIRTIO_NET_F_RSC_EXT	  61	/* extended coalescing info */
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			@ -355,4 +355,36 @@ struct virtio_net_hash_config {
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#define VIRTIO_NET_CTRL_GUEST_OFFLOADS   5
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#define VIRTIO_NET_CTRL_GUEST_OFFLOADS_SET        0
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/*
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 * Control notifications coalescing.
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 *
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 * Request the device to change the notifications coalescing parameters.
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 *
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 * Available with the VIRTIO_NET_F_NOTF_COAL feature bit.
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 */
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#define VIRTIO_NET_CTRL_NOTF_COAL		6
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/*
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 * Set the tx-usecs/tx-max-packets patameters.
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 * tx-usecs - Maximum number of usecs to delay a TX notification.
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 * tx-max-packets - Maximum number of packets to send before a TX notification.
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 */
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struct virtio_net_ctrl_coal_tx {
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	__le32 tx_max_packets;
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	__le32 tx_usecs;
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};
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#define VIRTIO_NET_CTRL_NOTF_COAL_TX_SET		0
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/*
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 * Set the rx-usecs/rx-max-packets patameters.
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 * rx-usecs - Maximum number of usecs to delay a RX notification.
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 * rx-max-frames - Maximum number of packets to receive before a RX notification.
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 */
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struct virtio_net_ctrl_coal_rx {
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	__le32 rx_max_packets;
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	__le32 rx_usecs;
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};
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#define VIRTIO_NET_CTRL_NOTF_COAL_RX_SET		1
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#endif /* _UAPI_LINUX_VIRTIO_NET_H */
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