Re: [RFC PATCH 3/4] drivers/net/virtio_net: Added basic RSS support.

From: Willem de Bruijn
Date: Sun Oct 31 2021 - 11:33:55 EST

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In reply to: Andrew Melnychenko: "[RFC PATCH 3/4] drivers/net/virtio_net: Added basic RSS support."
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On Sun, Oct 31, 2021 at 1:00 AM Andrew Melnychenko <andrew@xxxxxxxxxx> wrote:
>
> Added features for RSS and RSS hash report.
> Added initialization, RXHASH feature and ethtool ops.
> By default RSS/RXHASH is disabled.
> Added ethtools ops to set key and indirection table.
>
> Signed-off-by: Andrew Melnychenko <andrew@xxxxxxxxxx>
> ---
> drivers/net/virtio_net.c | 232 +++++++++++++++++++++++++++++++++++++--
> 1 file changed, 223 insertions(+), 9 deletions(-)
>
> diff --git a/drivers/net/virtio_net.c b/drivers/net/virtio_net.c
> index abca2e93355d..cff7340f40bb 100644
> --- a/drivers/net/virtio_net.c
> +++ b/drivers/net/virtio_net.c
> @@ -167,6 +167,28 @@ struct receive_queue {
> struct xdp_rxq_info xdp_rxq;
> };
>
> +/* This structure can contain rss message with maximum settings for indirection table and keysize
> + * Note, that default structure that describes RSS configuration virtio_net_rss_config
> + * contains same info but can't handle table values.
> + * In any case, structure would be passed to virtio hw through sg_buf split by parts
> + * because table sizes may be differ according to the device configuration.
> + */
> +#define VIRTIO_NET_RSS_MAX_KEY_SIZE 40

Unless there is a technical reason, this probably should be no shorter
than TOEPLITZ_KEY_LEN

> +#define VIRTIO_NET_RSS_MAX_TABLE_LEN 128
> +struct virtio_net_ctrl_rss {
> + struct {
> + __le32 hash_types;
> + __le16 indirection_table_mask;
> + __le16 unclassified_queue;

Is this explicit variable needed?

> + } __packed table_info;
> + u16 indirection_table[VIRTIO_NET_RSS_MAX_TABLE_LEN];
> + struct {
> + u16 max_tx_vq; /* queues */
> + u8 hash_key_length;
> + } __packed key_info;
> + u8 key[VIRTIO_NET_RSS_MAX_KEY_SIZE];
> +};
> +
> /* Control VQ buffers: protected by the rtnl lock */
> struct control_buf {
> struct virtio_net_ctrl_hdr hdr;
> @@ -176,6 +198,7 @@ struct control_buf {
> u8 allmulti;
> __virtio16 vid;
> __virtio64 offloads;
> + struct virtio_net_ctrl_rss rss;
> };
>
> struct virtnet_info {
> @@ -204,6 +227,12 @@ struct virtnet_info {
> /* Host will merge rx buffers for big packets (shake it! shake it!) */
> bool mergeable_rx_bufs;
>
> + /* Host supports rss and/or hash report */
> + bool has_rss;

Superfluous, can be derived form non-zero rss_key_size?

> + bool has_rss_hash_report;
> + u8 rss_key_size;
> + u16 rss_indir_table_size;
> +
> /* Has control virtqueue */
> bool has_cvq;
>
> @@ -1119,6 +1148,8 @@ static void receive_buf(struct virtnet_info *vi, struct receive_queue *rq,
> struct net_device *dev = vi->dev;
> struct sk_buff *skb;
> struct virtio_net_hdr_mrg_rxbuf *hdr;
> + struct virtio_net_hdr_v1_hash *hdr_hash;
> + enum pkt_hash_types rss_hash_type;
>
> if (unlikely(len < vi->hdr_len + ETH_HLEN)) {
> pr_debug("%s: short packet %i\n", dev->name, len);
> @@ -1145,6 +1176,29 @@ static void receive_buf(struct virtnet_info *vi, struct receive_queue *rq,
> return;
>
> hdr = skb_vnet_hdr(skb);
> + if (vi->has_rss_hash_report && (dev->features & NETIF_F_RXHASH)) {

Only the second test is needed? It should be impossible to configure
the feature unless the device advertises has_rss_hash_report

> + hdr_hash = (struct virtio_net_hdr_v1_hash *)(hdr);
> +
> + switch (hdr_hash->hash_report) {
> + case VIRTIO_NET_HASH_REPORT_TCPv4:
> + case VIRTIO_NET_HASH_REPORT_UDPv4:
> + case VIRTIO_NET_HASH_REPORT_TCPv6:
> + case VIRTIO_NET_HASH_REPORT_UDPv6:
> + case VIRTIO_NET_HASH_REPORT_TCPv6_EX:
> + case VIRTIO_NET_HASH_REPORT_UDPv6_EX:
> + rss_hash_type = PKT_HASH_TYPE_L4;
> + break;
> + case VIRTIO_NET_HASH_REPORT_IPv4:
> + case VIRTIO_NET_HASH_REPORT_IPv6:
> + case VIRTIO_NET_HASH_REPORT_IPv6_EX:
> + rss_hash_type = PKT_HASH_TYPE_L3;
> + break;
> + case VIRTIO_NET_HASH_REPORT_NONE:
> + default:
> + rss_hash_type = PKT_HASH_TYPE_NONE;
> + }

Is this detailed protocol typing necessary? Most devices only pass a bit is_l4.

> + skb_set_hash(skb, hdr_hash->hash_value, rss_hash_type);
> + }
>
> if (hdr->hdr.flags & VIRTIO_NET_HDR_F_DATA_VALID)
> skb->ip_summed = CHECKSUM_UNNECESSARY;
> @@ -2167,6 +2221,57 @@ static void virtnet_get_ringparam(struct net_device *dev,
> ring->tx_pending = ring->tx_max_pending;
> }
>
> +static bool virtnet_commit_rss_command(struct virtnet_info *vi)
> +{
> + struct net_device *dev = vi->dev;
> + struct scatterlist sgs[4];
> + unsigned int sg_buf_size;
> +
> + /* prepare sgs */
> + sg_init_table(sgs, 4);
> +
> + sg_buf_size = sizeof(vi->ctrl->rss.table_info);
> + sg_set_buf(&sgs[0], &vi->ctrl->rss.table_info, sg_buf_size);
> +
> + sg_buf_size = sizeof(uint16_t) * vi->rss_indir_table_size;
> + sg_set_buf(&sgs[1], vi->ctrl->rss.indirection_table, sg_buf_size);
> +
> + sg_buf_size = sizeof(vi->ctrl->rss.key_info);
> + sg_set_buf(&sgs[2], &vi->ctrl->rss.key_info, sg_buf_size);
> +
> + sg_buf_size = vi->rss_key_size;
> + sg_set_buf(&sgs[3], vi->ctrl->rss.key, sg_buf_size);
> +
> + if (!virtnet_send_command(vi, VIRTIO_NET_CTRL_MQ,
> + vi->has_rss ? VIRTIO_NET_CTRL_MQ_RSS_CONFIG
> + : VIRTIO_NET_CTRL_MQ_HASH_CONFIG, sgs)) {
> + dev_warn(&dev->dev, "VIRTIONET issue with committing RSS sgs\n");
> + return false;
> + }
> + return true;
> +}
> +
> +static void virtnet_init_default_rss(struct virtnet_info *vi)
> +{
> + u32 indir_val = 0;
> + int i = 0;
> +
> + vi->ctrl->rss.table_info.hash_types = vi->rss_hash_types_supported;

Similar to above, and related to the next patch: is this very detailed
specification of supported hash types needed? When is this useful? It
is not customary to specify RSS to that degree.

> + vi->rss_hash_types_saved = vi->rss_hash_types_supported;
> + vi->ctrl->rss.table_info.indirection_table_mask = vi->rss_indir_table_size - 1;
> + vi->ctrl->rss.table_info.unclassified_queue = 0;
> +
> + for (; i < vi->rss_indir_table_size; ++i) {
> + indir_val = ethtool_rxfh_indir_default(i, vi->max_queue_pairs);
> + vi->ctrl->rss.indirection_table[i] = indir_val;
> + }
> +
> + vi->ctrl->rss.key_info.max_tx_vq = vi->curr_queue_pairs;
> + vi->ctrl->rss.key_info.hash_key_length = vi->rss_key_size;
> +
> + netdev_rss_key_fill(vi->ctrl->rss.key, vi->rss_key_size);
> +}
> +
>
> static void virtnet_get_drvinfo(struct net_device *dev,
> struct ethtool_drvinfo *info)
> @@ -2395,6 +2500,71 @@ static void virtnet_update_settings(struct virtnet_info *vi)
> vi->duplex = duplex;
> }
>
> +static u32 virtnet_get_rxfh_key_size(struct net_device *dev)
> +{
> + return ((struct virtnet_info *)netdev_priv(dev))->rss_key_size;
> +}
> +
> +static u32 virtnet_get_rxfh_indir_size(struct net_device *dev)
> +{
> + return ((struct virtnet_info *)netdev_priv(dev))->rss_indir_table_size;
> +}
> +
> +static int virtnet_get_rxfh(struct net_device *dev, u32 *indir, u8 *key, u8 *hfunc)
> +{
> + struct virtnet_info *vi = netdev_priv(dev);
> + int i;
> +
> + if (indir) {
> + for (i = 0; i < vi->rss_indir_table_size; ++i)
> + indir[i] = vi->ctrl->rss.indirection_table[i];
> + }
> +
> + if (key)
> + memcpy(key, vi->ctrl->rss.key, vi->rss_key_size);
> +
> + if (hfunc)
> + *hfunc = ETH_RSS_HASH_TOP;
> +
> + return 0;
> +}
> +
> +static int virtnet_set_rxfh(struct net_device *dev, const u32 *indir, const u8 *key, const u8 hfunc)
> +{
> + struct virtnet_info *vi = netdev_priv(dev);
> + int i;
> +
> + if (hfunc != ETH_RSS_HASH_NO_CHANGE && hfunc != ETH_RSS_HASH_TOP)
> + return -EOPNOTSUPP;
> +
> + if (indir) {
> + for (i = 0; i < vi->rss_indir_table_size; ++i)
> + vi->ctrl->rss.indirection_table[i] = indir[i];
> + }
> + if (key)
> + memcpy(vi->ctrl->rss.key, key, vi->rss_key_size);
> +
> + virtnet_commit_rss_command(vi);
> +
> + return 0;
> +}
> +
> +static int virtnet_get_rxnfc(struct net_device *dev, struct ethtool_rxnfc *info, u32 *rule_locs)
> +{
> + struct virtnet_info *vi = netdev_priv(dev);
> + int rc = 0;
> +
> + switch (info->cmd) {
> + case ETHTOOL_GRXRINGS:
> + info->data = vi->curr_queue_pairs;
> + break;
> + default:
> + rc = -EOPNOTSUPP;
> + }
> +
> + return rc;
> +}
> +
> static const struct ethtool_ops virtnet_ethtool_ops = {
> .supported_coalesce_params = ETHTOOL_COALESCE_MAX_FRAMES,
> .get_drvinfo = virtnet_get_drvinfo,
> @@ -2410,6 +2580,11 @@ static const struct ethtool_ops virtnet_ethtool_ops = {
> .set_link_ksettings = virtnet_set_link_ksettings,
> .set_coalesce = virtnet_set_coalesce,
> .get_coalesce = virtnet_get_coalesce,
> + .get_rxfh_key_size = virtnet_get_rxfh_key_size,
> + .get_rxfh_indir_size = virtnet_get_rxfh_indir_size,
> + .get_rxfh = virtnet_get_rxfh,
> + .set_rxfh = virtnet_set_rxfh,
> + .get_rxnfc = virtnet_get_rxnfc,
> };
>
> static void virtnet_freeze_down(struct virtio_device *vdev)
> @@ -3040,7 +3215,10 @@ static bool virtnet_validate_features(struct virtio_device *vdev)
> "VIRTIO_NET_F_CTRL_VQ") ||
> VIRTNET_FAIL_ON(vdev, VIRTIO_NET_F_MQ, "VIRTIO_NET_F_CTRL_VQ") ||
> VIRTNET_FAIL_ON(vdev, VIRTIO_NET_F_CTRL_MAC_ADDR,
> - "VIRTIO_NET_F_CTRL_VQ"))) {
> + "VIRTIO_NET_F_CTRL_VQ") ||
> + VIRTNET_FAIL_ON(vdev, VIRTIO_NET_F_RSS, "VIRTIO_NET_F_RSS") ||
> + VIRTNET_FAIL_ON(vdev, VIRTIO_NET_F_HASH_REPORT,
> + "VIRTIO_NET_F_HASH_REPORT"))) {
> return false;
> }
>
> @@ -3080,13 +3258,14 @@ static int virtnet_probe(struct virtio_device *vdev)
> u16 max_queue_pairs;
> int mtu;
>
> - /* Find if host supports multiqueue virtio_net device */
> - err = virtio_cread_feature(vdev, VIRTIO_NET_F_MQ,
> - struct virtio_net_config,
> - max_virtqueue_pairs, &max_queue_pairs);
> + /* Find if host supports multiqueue/rss virtio_net device */
> + max_queue_pairs = 0;
> + if (virtio_has_feature(vdev, VIRTIO_NET_F_MQ) || virtio_has_feature(vdev, VIRTIO_NET_F_RSS))

Is VIRTIO_NET_F_RSS implied by VIRTIO_NET_F_MQ?

> + max_queue_pairs =
> + virtio_cread16(vdev, offsetof(struct virtio_net_config, max_virtqueue_pairs));
>
> /* We need at least 2 queue's */
> - if (err || max_queue_pairs < VIRTIO_NET_CTRL_MQ_VQ_PAIRS_MIN ||
> + if (max_queue_pairs < VIRTIO_NET_CTRL_MQ_VQ_PAIRS_MIN ||
> max_queue_pairs > VIRTIO_NET_CTRL_MQ_VQ_PAIRS_MAX ||
> !virtio_has_feature(vdev, VIRTIO_NET_F_CTRL_VQ))
> max_queue_pairs = 1;
> @@ -3170,8 +3349,36 @@ 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(vdev, VIRTIO_NET_F_MRG_RXBUF) ||
> - virtio_has_feature(vdev, VIRTIO_F_VERSION_1))
> + if (virtio_has_feature(vdev, VIRTIO_NET_F_HASH_REPORT)) {
> + vi->has_rss_hash_report = true;
> + vi->rss_indir_table_size = 1;
> + vi->rss_key_size = VIRTIO_NET_RSS_MAX_KEY_SIZE;
> + }
> +
> + if (virtio_has_feature(vdev, VIRTIO_NET_F_RSS)) {
> + vi->has_rss = true;
> + vi->rss_indir_table_size =
> + virtio_cread16(vdev, offsetof(struct virtio_net_config,
> + rss_max_indirection_table_length));
> + vi->rss_key_size =
> + virtio_cread8(vdev, offsetof(struct virtio_net_config, rss_max_key_size));
> + }

Please split adding the two features, hash report and rss, into two
separate patches.

Next message: Joe Perches: "Re: [PATCH] drivers: tty: replace snprintf in show functions with sysfs_emit"
Previous message: Rihab Manyang: "Hi"
In reply to: Andrew Melnychenko: "[RFC PATCH 3/4] drivers/net/virtio_net: Added basic RSS support."
Next in thread: Willem de Bruijn: "Re: [RFC PATCH 3/4] drivers/net/virtio_net: Added basic RSS support."
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