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net: virtio_net: notifications coalescing support
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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>
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@Alvaro-Karsz @mstsirkin
Alvaro-Karsz authored and mstsirkin committed Aug 11, 2022
1 parent 95bf979 commit 699b045
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Showing 2 changed files with 129 additions and 16 deletions.
111 changes: 96 additions & 15 deletions drivers/net/virtio_net.c
View file
Expand Up @@ -270,6 +270,12 @@ struct virtnet_info {
u8 duplex;
u32 speed;

/* Interrupt coalescing settings */
u32 tx_usecs;
u32 rx_usecs;
u32 tx_max_packets;
u32 rx_max_packets;

unsigned long guest_offloads;
unsigned long guest_offloads_capable;

Expand Down Expand Up @@ -2737,44 +2743,109 @@ static int virtnet_get_link_ksettings(struct net_device *dev,
return 0;
}

static int virtnet_send_notf_coal_cmds(struct virtnet_info *vi,
struct ethtool_coalesce *ec)
{
struct scatterlist sgs_tx, sgs_rx;
struct virtio_net_ctrl_coal_tx coal_tx;
struct virtio_net_ctrl_coal_rx coal_rx;

coal_tx.tx_usecs = cpu_to_le32(ec->tx_coalesce_usecs);
coal_tx.tx_max_packets = cpu_to_le32(ec->tx_max_coalesced_frames);
sg_init_one(&sgs_tx, &coal_tx, sizeof(coal_tx));

if (!virtnet_send_command(vi, VIRTIO_NET_CTRL_NOTF_COAL,
VIRTIO_NET_CTRL_NOTF_COAL_TX_SET,
&sgs_tx))
return -EINVAL;

/* Save parameters */
vi->tx_usecs = ec->tx_coalesce_usecs;
vi->tx_max_packets = ec->tx_max_coalesced_frames;

coal_rx.rx_usecs = cpu_to_le32(ec->rx_coalesce_usecs);
coal_rx.rx_max_packets = cpu_to_le32(ec->rx_max_coalesced_frames);
sg_init_one(&sgs_rx, &coal_rx, sizeof(coal_rx));

if (!virtnet_send_command(vi, VIRTIO_NET_CTRL_NOTF_COAL,
VIRTIO_NET_CTRL_NOTF_COAL_RX_SET,
&sgs_rx))
return -EINVAL;

/* Save parameters */
vi->rx_usecs = ec->rx_coalesce_usecs;
vi->rx_max_packets = ec->rx_max_coalesced_frames;

return 0;
}

static int virtnet_coal_params_supported(struct ethtool_coalesce *ec)
{
/* usecs coalescing is supported only if VIRTIO_NET_F_NOTF_COAL
* feature is negotiated.
*/
if (ec->rx_coalesce_usecs || ec->tx_coalesce_usecs)
return -EOPNOTSUPP;

if (ec->tx_max_coalesced_frames > 1 ||
ec->rx_max_coalesced_frames != 1)
return -EINVAL;

return 0;
}

static int virtnet_set_coalesce(struct net_device *dev,
struct ethtool_coalesce *ec,
struct kernel_ethtool_coalesce *kernel_coal,
struct netlink_ext_ack *extack)
{
struct virtnet_info *vi = netdev_priv(dev);
int i, napi_weight;

if (ec->tx_max_coalesced_frames > 1 ||
ec->rx_max_coalesced_frames != 1)
return -EINVAL;
int ret, i, napi_weight;
bool update_napi = false;

/* Can't change NAPI weight if the link is up */
napi_weight = ec->tx_max_coalesced_frames ? NAPI_POLL_WEIGHT : 0;
if (napi_weight ^ vi->sq[0].napi.weight) {
if (dev->flags & IFF_UP)
return -EBUSY;
else
update_napi = true;
}

if (virtio_has_feature(vi->vdev, VIRTIO_NET_F_NOTF_COAL))
ret = virtnet_send_notf_coal_cmds(vi, ec);
else
ret = virtnet_coal_params_supported(ec);

if (ret)
return ret;

if (update_napi) {
for (i = 0; i < vi->max_queue_pairs; i++)
vi->sq[i].napi.weight = napi_weight;
}

return 0;
return ret;
}

static int virtnet_get_coalesce(struct net_device *dev,
struct ethtool_coalesce *ec,
struct kernel_ethtool_coalesce *kernel_coal,
struct netlink_ext_ack *extack)
{
struct ethtool_coalesce ec_default = {
.cmd = ETHTOOL_GCOALESCE,
.rx_max_coalesced_frames = 1,
};
struct virtnet_info *vi = netdev_priv(dev);

memcpy(ec, &ec_default, sizeof(ec_default));
if (virtio_has_feature(vi->vdev, VIRTIO_NET_F_NOTF_COAL)) {
ec->rx_coalesce_usecs = vi->rx_usecs;
ec->tx_coalesce_usecs = vi->tx_usecs;
ec->tx_max_coalesced_frames = vi->tx_max_packets;
ec->rx_max_coalesced_frames = vi->rx_max_packets;
} else {
ec->rx_max_coalesced_frames = 1;

if (vi->sq[0].napi.weight)
ec->tx_max_coalesced_frames = 1;
if (vi->sq[0].napi.weight)
ec->tx_max_coalesced_frames = 1;
}

return 0;
}
Expand Down Expand Up @@ -2893,7 +2964,8 @@ static int virtnet_set_rxnfc(struct net_device *dev, struct ethtool_rxnfc *info)
}

static const struct ethtool_ops virtnet_ethtool_ops = {
.supported_coalesce_params = ETHTOOL_COALESCE_MAX_FRAMES,
.supported_coalesce_params = ETHTOOL_COALESCE_MAX_FRAMES |
ETHTOOL_COALESCE_USECS,
.get_drvinfo = virtnet_get_drvinfo,
.get_link = ethtool_op_get_link,
.get_ringparam = virtnet_get_ringparam,
Expand Down Expand Up @@ -3606,6 +3678,8 @@ static bool virtnet_validate_features(struct virtio_device *vdev)
VIRTNET_FAIL_ON(vdev, VIRTIO_NET_F_RSS,
"VIRTIO_NET_F_CTRL_VQ") ||
VIRTNET_FAIL_ON(vdev, VIRTIO_NET_F_HASH_REPORT,
"VIRTIO_NET_F_CTRL_VQ") ||
VIRTNET_FAIL_ON(vdev, VIRTIO_NET_F_NOTF_COAL,
"VIRTIO_NET_F_CTRL_VQ"))) {
return false;
}
Expand Down Expand Up @@ -3742,6 +3816,13 @@ static int virtnet_probe(struct virtio_device *vdev)
if (virtio_has_feature(vdev, VIRTIO_NET_F_MRG_RXBUF))
vi->mergeable_rx_bufs = true;

if (virtio_has_feature(vi->vdev, VIRTIO_NET_F_NOTF_COAL)) {
vi->rx_usecs = 0;
vi->tx_usecs = 0;
vi->tx_max_packets = 0;
vi->rx_max_packets = 0;
}

if (virtio_has_feature(vdev, VIRTIO_NET_F_HASH_REPORT))
vi->has_rss_hash_report = true;

Expand Down Expand Up @@ -3977,7 +4058,7 @@ static struct virtio_device_id id_table[] = {
VIRTIO_NET_F_CTRL_MAC_ADDR, \
VIRTIO_NET_F_MTU, VIRTIO_NET_F_CTRL_GUEST_OFFLOADS, \
VIRTIO_NET_F_SPEED_DUPLEX, VIRTIO_NET_F_STANDBY, \
VIRTIO_NET_F_RSS, VIRTIO_NET_F_HASH_REPORT
VIRTIO_NET_F_RSS, VIRTIO_NET_F_HASH_REPORT, VIRTIO_NET_F_NOTF_COAL

static unsigned int features[] = {
VIRTNET_FEATURES,
Expand Down
34 changes: 33 additions & 1 deletion include/uapi/linux/virtio_net.h
View file
Expand Up @@ -56,7 +56,7 @@
#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_F_NOTF_COAL 53 /* Guest can handle notifications coalescing */
#define VIRTIO_NET_F_HASH_REPORT 57 /* Supports hash report */
#define VIRTIO_NET_F_RSS 60 /* Supports RSS RX steering */
#define VIRTIO_NET_F_RSC_EXT 61 /* extended coalescing info */
Expand Down Expand Up @@ -355,4 +355,36 @@ struct virtio_net_hash_config {
#define VIRTIO_NET_CTRL_GUEST_OFFLOADS 5
#define VIRTIO_NET_CTRL_GUEST_OFFLOADS_SET 0

/*
* Control notifications coalescing.
*
* Request the device to change the notifications coalescing parameters.
*
* Available with the VIRTIO_NET_F_NOTF_COAL feature bit.
*/
#define VIRTIO_NET_CTRL_NOTF_COAL 6
/*
* Set the tx-usecs/tx-max-packets patameters.
* tx-usecs - Maximum number of usecs to delay a TX notification.
* tx-max-packets - Maximum number of packets to send before a TX notification.
*/
struct virtio_net_ctrl_coal_tx {
__le32 tx_max_packets;
__le32 tx_usecs;
};

#define VIRTIO_NET_CTRL_NOTF_COAL_TX_SET 0

/*
* Set the rx-usecs/rx-max-packets patameters.
* rx-usecs - Maximum number of usecs to delay a RX notification.
* rx-max-frames - Maximum number of packets to receive before a RX notification.
*/
struct virtio_net_ctrl_coal_rx {
__le32 rx_max_packets;
__le32 rx_usecs;
};

#define VIRTIO_NET_CTRL_NOTF_COAL_RX_SET 1

#endif /* _UAPI_LINUX_VIRTIO_NET_H */

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