Subject: [PATCH net-next V3 3/4] virtio_net: support per queue interrupt coalesce command

From: Gavin Li <[email-masked]>
Date: Mon, 24 Jul 2023 06:40:47 +0300

Add interrupt_coalesce config in send_queue and receive_queue to cache user
config.

Send per virtqueue interrupt moderation config to underline device in order
to have more efficient interrupt moderation and cpu utilization of guest
VM.

Signed-off-by: Gavin Li <[email-masked]>
Reviewed-by: Dragos Tatulea <[email-masked]>
Reviewed-by: Jiri Pirko <[email-masked]>
Acked-by: Michael S. Tsirkin <[email-masked]>
---
 drivers/net/virtio_net.c        | 120 ++++++++++++++++++++++++++++----
 include/uapi/linux/virtio_net.h |  14 ++++
 2 files changed, 122 insertions(+), 12 deletions(-)

diff --git a/drivers/net/virtio_net.c b/drivers/net/virtio_net.c
index 802ed21453f5..0c3ee1e26ece 100644
--- a/drivers/net/virtio_net.c
+++ b/drivers/net/virtio_net.c
@@ -144,6 +144,8 @@ struct send_queue {
 
 	struct virtnet_sq_stats stats;
 
+	struct virtnet_interrupt_coalesce intr_coal;
+
 	struct napi_struct napi;
 
 	/* Record whether sq is in reset state. */
@@ -161,6 +163,8 @@ struct receive_queue {
 
 	struct virtnet_rq_stats stats;
 
+	struct virtnet_interrupt_coalesce intr_coal;
+
 	/* Chain pages by the private ptr. */
 	struct page *pages;
 
@@ -212,6 +216,7 @@ struct control_buf {
 	struct virtio_net_ctrl_rss rss;
 	struct virtio_net_ctrl_coal_tx coal_tx;
 	struct virtio_net_ctrl_coal_rx coal_rx;
+	struct virtio_net_ctrl_coal_vq coal_vq;
 };
 
 struct virtnet_info {
@@ -3078,6 +3083,55 @@ static int virtnet_send_notf_coal_cmds(struct virtnet_info *vi,
 	return 0;
 }
 
+static int virtnet_send_ctrl_coal_vq_cmd(struct virtnet_info *vi,
+					 u16 vqn, u32 max_usecs, u32 max_packets)
+{
+	struct scatterlist sgs;
+
+	vi->ctrl->coal_vq.vqn = cpu_to_le16(vqn);
+	vi->ctrl->coal_vq.coal.max_usecs = cpu_to_le32(max_usecs);
+	vi->ctrl->coal_vq.coal.max_packets = cpu_to_le32(max_packets);
+	sg_init_one(&sgs, &vi->ctrl->coal_vq, sizeof(vi->ctrl->coal_vq));
+
+	if (!virtnet_send_command(vi, VIRTIO_NET_CTRL_NOTF_COAL,
+				  VIRTIO_NET_CTRL_NOTF_COAL_VQ_SET,
+				  &sgs))
+		return -EINVAL;
+
+	return 0;
+}
+
+static int virtnet_send_notf_coal_vq_cmds(struct virtnet_info *vi,
+					  struct ethtool_coalesce *ec,
+					  u16 queue)
+{
+	int err;
+
+	if (ec->rx_coalesce_usecs || ec->rx_max_coalesced_frames) {
+		err = virtnet_send_ctrl_coal_vq_cmd(vi, rxq2vq(queue),
+						    ec->rx_coalesce_usecs,
+						    ec->rx_max_coalesced_frames);
+		if (err)
+			return err;
+		/* Save parameters */
+		vi->rq[queue].intr_coal.max_usecs = ec->rx_coalesce_usecs;
+		vi->rq[queue].intr_coal.max_packets = ec->rx_max_coalesced_frames;
+	}
+
+	if (ec->tx_coalesce_usecs || ec->tx_max_coalesced_frames) {
+		err = virtnet_send_ctrl_coal_vq_cmd(vi, txq2vq(queue),
+						    ec->tx_coalesce_usecs,
+						    ec->tx_max_coalesced_frames);
+		if (err)
+			return err;
+		/* Save parameters */
+		vi->sq[queue].intr_coal.max_usecs = ec->tx_coalesce_usecs;
+		vi->sq[queue].intr_coal.max_packets = ec->tx_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
@@ -3094,23 +3148,39 @@ static int virtnet_coal_params_supported(struct ethtool_coalesce *ec)
 }
 
 static int virtnet_set_coalesce_one(struct net_device *dev,
-				    struct ethtool_coalesce *ec)
+				    struct ethtool_coalesce *ec,
+				    bool per_queue,
+				    u32 queue)
 {
 	struct virtnet_info *vi = netdev_priv(dev);
-	int ret, i, napi_weight;
+	int queue_count = per_queue ? 1 : vi->max_queue_pairs;
+	int queue_number = per_queue ? queue : 0;
 	bool update_napi = false;
+	int ret, i, napi_weight;
+
+	if (queue >= vi->max_queue_pairs)
+		return -EINVAL;
 
 	/* 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
+	for (i = queue_number; i < queue_count; i++) {
+		if (napi_weight ^ vi->sq[i].napi.weight) {
+			if (dev->flags & IFF_UP)
+				return -EBUSY;
+
 			update_napi = true;
+			/* All queues that belong to [queue_number, queue_count] will be
+			 * updated for the sake of simplicity, which might not be necessary
+			 */
+			queue_number = i;
+			break;
+		}
 	}
 
-	if (virtio_has_feature(vi->vdev, VIRTIO_NET_F_NOTF_COAL))
+	if (!per_queue && virtio_has_feature(vi->vdev, VIRTIO_NET_F_NOTF_COAL))
 		ret = virtnet_send_notf_coal_cmds(vi, ec);
+	else if (per_queue && virtio_has_feature(vi->vdev, VIRTIO_NET_F_VQ_NOTF_COAL))
+		ret = virtnet_send_notf_coal_vq_cmds(vi, ec, queue);
 	else
 		ret = virtnet_coal_params_supported(ec);
 
@@ -3118,7 +3188,7 @@ static int virtnet_set_coalesce_one(struct net_device *dev,
 		return ret;
 
 	if (update_napi) {
-		for (i = 0; i < vi->max_queue_pairs; i++)
+		for (i = queue_number; i < queue_count; i++)
 			vi->sq[i].napi.weight = napi_weight;
 	}
 
@@ -3130,19 +3200,29 @@ static int virtnet_set_coalesce(struct net_device *dev,
 				struct kernel_ethtool_coalesce *kernel_coal,
 				struct netlink_ext_ack *extack)
 {
-	return virtnet_set_coalesce_one(dev, ec);
+	return virtnet_set_coalesce_one(dev, ec, false, 0);
 }
 
 static int virtnet_get_coalesce_one(struct net_device *dev,
-				    struct ethtool_coalesce *ec)
+				    struct ethtool_coalesce *ec,
+				    bool per_queue,
+				    u32 queue)
 {
 	struct virtnet_info *vi = netdev_priv(dev);
 
-	if (virtio_has_feature(vi->vdev, VIRTIO_NET_F_NOTF_COAL)) {
+	if (queue >= vi->max_queue_pairs)
+		return -EINVAL;
+
+	if (!per_queue && virtio_has_feature(vi->vdev, VIRTIO_NET_F_NOTF_COAL)) {
 		ec->rx_coalesce_usecs = vi->intr_coal_rx.max_usecs;
 		ec->tx_coalesce_usecs = vi->intr_coal_tx.max_usecs;
 		ec->tx_max_coalesced_frames = vi->intr_coal_tx.max_packets;
 		ec->rx_max_coalesced_frames = vi->intr_coal_rx.max_packets;
+	} else if (per_queue && virtio_has_feature(vi->vdev, VIRTIO_NET_F_VQ_NOTF_COAL)) {
+		ec->rx_coalesce_usecs = vi->rq[queue].intr_coal.max_usecs;
+		ec->tx_coalesce_usecs = vi->sq[queue].intr_coal.max_usecs;
+		ec->tx_max_coalesced_frames = vi->sq[queue].intr_coal.max_packets;
+		ec->rx_max_coalesced_frames = vi->rq[queue].intr_coal.max_packets;
 	} else {
 		ec->rx_max_coalesced_frames = 1;
 
@@ -3158,7 +3238,21 @@ static int virtnet_get_coalesce(struct net_device *dev,
 				struct kernel_ethtool_coalesce *kernel_coal,
 				struct netlink_ext_ack *extack)
 {
-	return virtnet_get_coalesce_one(dev, ec);
+	return virtnet_get_coalesce_one(dev, ec, false, 0);
+}
+
+static int virtnet_set_per_queue_coalesce(struct net_device *dev,
+					  u32 queue,
+					  struct ethtool_coalesce *ec)
+{
+	return virtnet_set_coalesce_one(dev, ec, true, queue);
+}
+
+static int virtnet_get_per_queue_coalesce(struct net_device *dev,
+					  u32 queue,
+					  struct ethtool_coalesce *ec)
+{
+	return virtnet_get_coalesce_one(dev, ec, true, queue);
 }
 
 static void virtnet_init_settings(struct net_device *dev)
@@ -3291,6 +3385,8 @@ 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,
+	.set_per_queue_coalesce = virtnet_set_per_queue_coalesce,
+	.get_per_queue_coalesce = virtnet_get_per_queue_coalesce,
 	.get_rxfh_key_size = virtnet_get_rxfh_key_size,
 	.get_rxfh_indir_size = virtnet_get_rxfh_indir_size,
 	.get_rxfh = virtnet_get_rxfh,
diff --git a/include/uapi/linux/virtio_net.h b/include/uapi/linux/virtio_net.h
index 12c1c9699935..cc65ef0f3c3e 100644
--- a/include/uapi/linux/virtio_net.h
+++ b/include/uapi/linux/virtio_net.h
@@ -56,6 +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_VQ_NOTF_COAL 52	/* Device supports virtqueue notification coalescing */
 #define VIRTIO_NET_F_NOTF_COAL	53	/* Device supports notifications coalescing */
 #define VIRTIO_NET_F_GUEST_USO4	54	/* Guest can handle USOv4 in. */
 #define VIRTIO_NET_F_GUEST_USO6	55	/* Guest can handle USOv6 in. */
@@ -391,5 +392,18 @@ struct virtio_net_ctrl_coal_rx {
 };
 
 #define VIRTIO_NET_CTRL_NOTF_COAL_RX_SET		1
+#define VIRTIO_NET_CTRL_NOTF_COAL_VQ_SET		2
+#define VIRTIO_NET_CTRL_NOTF_COAL_VQ_GET		3
+
+struct virtio_net_ctrl_coal {
+	__le32 max_packets;
+	__le32 max_usecs;
+};
+
+struct  virtio_net_ctrl_coal_vq {
+	__le16 vqn;
+	__le16 reserved;
+	struct virtio_net_ctrl_coal coal;
+};
 
 #endif /* _UAPI_LINUX_VIRTIO_NET_H */
-- 
2.39.1