From: Jason Wang <jasowang@redhat.com>
Date: Wed, 19 Jul 2017 16:54:49 +0800
Subject: virtio-net: switch off offloads on demand if possible on XDP set
Patch-mainline: v4.14-rc1
Git-commit: 3f93522ffab2d46a36b57adf324a54e674fc9536
References: bsc#1109837

Current XDP implementation wants guest offloads feature to be disabled
on device. This is inconvenient and means guest can't benefit from
offloads if XDP is not used. This patch tries to address this
limitation by disabling the offloads on demand through control guest
offloads. Guest offloads will be disabled and enabled on demand on XDP
set.

Signed-off-by: Jason Wang <jasowang@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Acked-by: Thomas Bogendoerfer <tbogendoerfer@suse.de>
---
 drivers/net/virtio_net.c |   70 +++++++++++++++++++++++++++++++++++++++++++----
 1 file changed, 65 insertions(+), 5 deletions(-)

--- a/drivers/net/virtio_net.c
+++ b/drivers/net/virtio_net.c
@@ -57,6 +57,11 @@ DECLARE_EWMA(pkt_len, 0, 64)
 
 #define VIRTNET_DRIVER_VERSION "1.0.0"
 
+const unsigned long guest_offloads[] = { VIRTIO_NET_F_GUEST_TSO4,
+					 VIRTIO_NET_F_GUEST_TSO6,
+					 VIRTIO_NET_F_GUEST_ECN,
+					 VIRTIO_NET_F_GUEST_UFO };
+
 struct virtnet_stats {
 	struct u64_stats_sync tx_syncp;
 	struct u64_stats_sync rx_syncp;
@@ -164,10 +169,13 @@ struct virtnet_info {
 	u8 ctrl_promisc;
 	u8 ctrl_allmulti;
 	u16 ctrl_vid;
+	u64 ctrl_offloads;
 
 	/* Ethtool settings */
 	u8 duplex;
 	u32 speed;
+
+	unsigned long guest_offloads;
 };
 
 struct padded_vnet_hdr {
@@ -1897,6 +1905,47 @@ static int virtnet_restore_up(struct vir
 	return err;
 }
 
+static int virtnet_set_guest_offloads(struct virtnet_info *vi, u64 offloads)
+{
+	struct scatterlist sg;
+	vi->ctrl_offloads = cpu_to_virtio64(vi->vdev, offloads);
+
+	sg_init_one(&sg, &vi->ctrl_offloads, sizeof(vi->ctrl_offloads));
+
+	if (!virtnet_send_command(vi, VIRTIO_NET_CTRL_GUEST_OFFLOADS,
+				  VIRTIO_NET_CTRL_GUEST_OFFLOADS_SET, &sg)) {
+		dev_warn(&vi->dev->dev, "Fail to set guest offload. \n");
+		return -EINVAL;
+	}
+
+	return 0;
+}
+
+static int virtnet_clear_guest_offloads(struct virtnet_info *vi)
+{
+	u64 offloads = 0;
+
+	if (!vi->guest_offloads)
+		return 0;
+
+	if (virtio_has_feature(vi->vdev, VIRTIO_NET_F_GUEST_CSUM))
+		offloads = 1ULL << VIRTIO_NET_F_GUEST_CSUM;
+
+	return virtnet_set_guest_offloads(vi, offloads);
+}
+
+static int virtnet_restore_guest_offloads(struct virtnet_info *vi)
+{
+	u64 offloads = vi->guest_offloads;
+
+	if (!vi->guest_offloads)
+		return 0;
+	if (virtio_has_feature(vi->vdev, VIRTIO_NET_F_GUEST_CSUM))
+		offloads |= 1ULL << VIRTIO_NET_F_GUEST_CSUM;
+
+	return virtnet_set_guest_offloads(vi, offloads);
+}
+
 static int virtnet_xdp_set(struct net_device *dev, struct bpf_prog *prog,
 			   struct netlink_ext_ack *extack)
 {
@@ -1906,10 +1955,11 @@ static int virtnet_xdp_set(struct net_de
 	u16 xdp_qp = 0, curr_qp;
 	int i, err;
 
-	if (virtio_has_feature(vi->vdev, VIRTIO_NET_F_GUEST_TSO4) ||
-	    virtio_has_feature(vi->vdev, VIRTIO_NET_F_GUEST_TSO6) ||
-	    virtio_has_feature(vi->vdev, VIRTIO_NET_F_GUEST_ECN) ||
-	    virtio_has_feature(vi->vdev, VIRTIO_NET_F_GUEST_UFO)) {
+	if (!virtio_has_feature(vi->vdev, VIRTIO_NET_F_CTRL_GUEST_OFFLOADS)
+	    && (virtio_has_feature(vi->vdev, VIRTIO_NET_F_GUEST_TSO4) ||
+	        virtio_has_feature(vi->vdev, VIRTIO_NET_F_GUEST_TSO6) ||
+	        virtio_has_feature(vi->vdev, VIRTIO_NET_F_GUEST_ECN) ||
+		virtio_has_feature(vi->vdev, VIRTIO_NET_F_GUEST_UFO))) {
 		NL_SET_ERR_MSG_MOD(extack, "Can't set XDP while host is implementing LRO, disable LRO first");
 		return -EOPNOTSUPP;
 	}
@@ -1956,6 +2006,12 @@ static int virtnet_xdp_set(struct net_de
 	for (i = 0; i < vi->max_queue_pairs; i++) {
 		old_prog = rtnl_dereference(vi->rq[i].xdp_prog);
 		rcu_assign_pointer(vi->rq[i].xdp_prog, prog);
+		if (i == 0) {
+			if (!old_prog)
+				virtnet_clear_guest_offloads(vi);
+			if (!prog)
+				virtnet_restore_guest_offloads(vi);
+		}
 		if (old_prog)
 			bpf_prog_put(old_prog);
 		virtnet_napi_enable(vi->rq[i].vq, &vi->rq[i].napi);
@@ -2591,6 +2647,10 @@ static int virtnet_probe(struct virtio_d
 		netif_carrier_on(dev);
 	}
 
+	for (i = 0; i < ARRAY_SIZE(guest_offloads); i++)
+		if (virtio_has_feature(vi->vdev, guest_offloads[i]))
+			set_bit(guest_offloads[i], &vi->guest_offloads);
+
 	pr_debug("virtnet: registered device %s with %d RX and TX vq's\n",
 		 dev->name, max_queue_pairs);
 
@@ -2687,7 +2747,7 @@ static struct virtio_device_id id_table[
 	VIRTIO_NET_F_CTRL_RX, VIRTIO_NET_F_CTRL_VLAN, \
 	VIRTIO_NET_F_GUEST_ANNOUNCE, VIRTIO_NET_F_MQ, \
 	VIRTIO_NET_F_CTRL_MAC_ADDR, \
-	VIRTIO_NET_F_MTU
+	VIRTIO_NET_F_MTU, VIRTIO_NET_F_CTRL_GUEST_OFFLOADS
 
 static unsigned int features[] = {
 	VIRTNET_FEATURES,