Re: [PATCH v3 2/4] drivers/net/virtio_net: Added basic RSS support.

Added features for RSS.
Added initialization, RXHASH feature and ethtool ops.
By default RSS/RXHASH is disabled.
Virtio RSS "IPv6 extensions" hashes disabled.
Added ethtools ops to set key and indirection table.

Signed-off-by: Andrew Melnychenko <redacted>
---
 drivers/net/virtio_net.c | 191 +++++++++++++++++++++++++++++++++++++--
 1 file changed, 185 insertions(+), 6 deletions(-)

diff --git a/drivers/net/virtio_net.c b/drivers/net/virtio_net.c
index 1404e683a2fd..495aed524e33 100644
--- a/drivers/net/virtio_net.c
+++ b/drivers/net/virtio_net.c

@@ -169,6 +169,24 @@ 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

+       u16 indirection_table_mask;
+       u16 unclassified_queue;
+       u16 indirection_table[VIRTIO_NET_RSS_MAX_TABLE_LEN];
+       u16 max_tx_vq;
+       u8 hash_key_length;
+       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;

@@ -178,6 +196,7 @@ struct control_buf {
        u8 allmulti;
        __virtio16 vid;
        __virtio64 offloads;
+       struct virtio_net_ctrl_rss rss;
 };

 struct virtnet_info {

@@ -206,6 +225,12 @@ 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;
+       u8 rss_key_size;
+       u16 rss_indir_table_size;
+       u32 rss_hash_types_supported;
+
        /* Has control virtqueue */
        bool has_cvq;

@@ -2184,6 +2209,56 @@ 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 = offsetof(struct virtio_net_ctrl_rss, indirection_table);
+       sg_set_buf(&sgs[0], &vi->ctrl->rss, 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 = offsetof(struct virtio_net_ctrl_rss, key)
+                       - offsetof(struct virtio_net_ctrl_rss, max_tx_vq);
+       sg_set_buf(&sgs[2], &vi->ctrl->rss.max_tx_vq, 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,
+                                 VIRTIO_NET_CTRL_MQ_RSS_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.hash_types = vi->rss_hash_types_supported;
+       vi->ctrl->rss.indirection_table_mask = vi->rss_indir_table_size - 1;

+       vi->ctrl->rss.unclassified_queue = 0;
+
+       for (; i < vi->rss_indir_table_size; ++i) {
+               indir_val = ethtool_rxfh_indir_default(i, vi->curr_queue_pairs);
+               vi->ctrl->rss.indirection_table[i] = indir_val;
+       }
+
+       vi->ctrl->rss.max_tx_vq = vi->curr_queue_pairs;
+       vi->ctrl->rss.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)

@@ -2412,6 +2487,71 @@ 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,

@@ -2427,6 +2567,11 @@ 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)

@@ -2679,6 +2824,16 @@ static int virtnet_set_features(struct net_device *dev,
                vi->guest_offloads = offloads;
        }

+       if ((dev->features ^ features) & NETIF_F_RXHASH) {
+               if (features & NETIF_F_RXHASH)
+                       vi->ctrl->rss.hash_types = vi->rss_hash_types_supported;
+               else
+                       vi->ctrl->rss.hash_types = VIRTIO_NET_HASH_REPORT_NONE;
+
+               if (!virtnet_commit_rss_command(vi))
+                       return -EINVAL;
+       }
+
        return 0;
 }

@@ -3073,6 +3228,8 @@ 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") ||
+            VIRTNET_FAIL_ON(vdev, VIRTIO_NET_F_RSS,
                             "VIRTIO_NET_F_CTRL_VQ"))) {
                return false;
        }

@@ -3113,13 +3270,14 @@ 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 = 1;
+       if (virtio_has_feature(vdev, VIRTIO_NET_F_MQ) || virtio_has_feature(vdev, VIRTIO_NET_F_RSS))
+               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;

@@ -3207,6 +3365,23 @@ 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_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));
+
+               vi->rss_hash_types_supported =
+                   virtio_cread32(vdev, offsetof(struct virtio_net_config, supported_hash_types));
+               vi->rss_hash_types_supported &=
+                               ~(VIRTIO_NET_RSS_HASH_TYPE_IP_EX |
+                                 VIRTIO_NET_RSS_HASH_TYPE_TCP_EX |
+                                 VIRTIO_NET_RSS_HASH_TYPE_UDP_EX);
+
+               dev->hw_features |= NETIF_F_RXHASH;