[RFC PATCH 2/7] vhost: support for hash report virtio-net feature

[Yuri Benditovich <yuri.benditovich@daynix.com>]

According to the virtio specification if VIRTIO_NET_F_HASH_REPORT
feature acked the virtio-net header is extended to hold the hash
value and hash report type.

Signed-off-by: Yuri Benditovich <yuri.benditovich@daynix.com>
---
 drivers/vhost/net.c | 37 +++++++++++++++++++++++++++++--------
 1 file changed, 29 insertions(+), 8 deletions(-)

diff --git a/drivers/vhost/net.c b/drivers/vhost/net.c
index 531a00d703cd..31a894b9a992 100644
--- a/drivers/vhost/net.c
+++ b/drivers/vhost/net.c
@@ -73,7 +73,8 @@ enum {
 	VHOST_NET_FEATURES = VHOST_FEATURES |
 			 (1ULL << VHOST_NET_F_VIRTIO_NET_HDR) |
 			 (1ULL << VIRTIO_NET_F_MRG_RXBUF) |
-			 (1ULL << VIRTIO_F_ACCESS_PLATFORM)
+			 (1ULL << VIRTIO_F_ACCESS_PLATFORM) |
+			 (1ULL << VIRTIO_NET_F_HASH_REPORT)
 };
 
 enum {
@@ -1108,14 +1109,16 @@ static void handle_rx(struct vhost_net *net)
 		.msg_controllen = 0,
 		.msg_flags = MSG_DONTWAIT,
 	};
-	struct virtio_net_hdr hdr = {
-		.flags = 0,
-		.gso_type = VIRTIO_NET_HDR_GSO_NONE
+	struct virtio_net_hdr_v1_hash hdrv1 = {
+		{
+			.flags = 0,
+			.gso_type = VIRTIO_NET_HDR_GSO_NONE
+		}
 	};
 	size_t total_len = 0;
 	int err, mergeable;
 	s16 headcount;
-	size_t vhost_hlen, sock_hlen;
+	size_t vhost_hlen, sock_hlen, extra_hlen;
 	size_t vhost_len, sock_len;
 	bool busyloop_intr = false;
 	struct socket *sock;
@@ -1137,9 +1140,12 @@ static void handle_rx(struct vhost_net *net)
 	vhost_hlen = nvq->vhost_hlen;
 	sock_hlen = nvq->sock_hlen;
 
+
 	vq_log = unlikely(vhost_has_feature(vq, VHOST_F_LOG_ALL)) ?
 		vq->log : NULL;
 	mergeable = vhost_has_feature(vq, VIRTIO_NET_F_MRG_RXBUF);
+	extra_hlen = vhost_has_feature(vq, VIRTIO_NET_F_HASH_REPORT) ?
+		sizeof(hdrv1) - sizeof(hdrv1.hdr) : 0;
 
 	do {
 		sock_len = vhost_net_rx_peek_head_len(net, sock->sk,
@@ -1201,8 +1207,8 @@ static void handle_rx(struct vhost_net *net)
 		}
 		/* Supply virtio_net_hdr if VHOST_NET_F_VIRTIO_NET_HDR */
 		if (unlikely(vhost_hlen)) {
-			if (copy_to_iter(&hdr, sizeof(hdr),
-					 &fixup) != sizeof(hdr)) {
+			if (copy_to_iter(&hdrv1, sizeof(struct virtio_net_hdr),
+					 &fixup) != sizeof(struct virtio_net_hdr)) {
 				vq_err(vq, "Unable to write vnet_hdr "
 				       "at addr %p\n", vq->iov->iov_base);
 				goto out;
@@ -1211,7 +1217,7 @@ static void handle_rx(struct vhost_net *net)
 			/* Header came from socket; we'll need to patch
 			 * ->num_buffers over if VIRTIO_NET_F_MRG_RXBUF
 			 */
-			iov_iter_advance(&fixup, sizeof(hdr));
+			iov_iter_advance(&fixup, sizeof(struct virtio_net_hdr));
 		}
 		/* TODO: Should check and handle checksum. */
 
@@ -1223,6 +1229,18 @@ static void handle_rx(struct vhost_net *net)
 			vhost_discard_vq_desc(vq, headcount);
 			goto out;
 		}
+		if (unlikely(extra_hlen)) {
+			if (unlikely(vhost_hlen)) {
+				if (copy_to_iter(&hdrv1.hash_value, extra_hlen,
+						&fixup) != extra_hlen) {
+					vq_err(vq, "Unable to write extra_hdr "
+					"at addr %p\n", vq->iov->iov_base);
+					goto out;
+				}
+			} else {
+				iov_iter_advance(&fixup, extra_hlen);
+			}
+		}
 		nvq->done_idx += headcount;
 		if (nvq->done_idx > VHOST_NET_BATCH)
 			vhost_net_signal_used(nvq);
@@ -1624,6 +1642,9 @@ static int vhost_net_set_features(struct vhost_net *n, u64 features)
 			       (1ULL << VIRTIO_F_VERSION_1))) ?
 			sizeof(struct virtio_net_hdr_mrg_rxbuf) :
 			sizeof(struct virtio_net_hdr);
+	if (features & (1ULL << VIRTIO_NET_F_HASH_REPORT)) {
+		hdr_len = sizeof(struct virtio_net_hdr_v1_hash);
+	}
 	if (features & (1 << VHOST_NET_F_VIRTIO_NET_HDR)) {
 		/* vhost provides vnet_hdr */
 		vhost_hlen = hdr_len;
-- 
2.17.1