[net-next,v10,10/10] vhost/net: Support VIRTIO_NET_F_HASH_REPORT

Commit Message

Akihiko Odaki March 13, 2025, 7:01 a.m. UTC

VIRTIO_NET_F_HASH_REPORT allows to report hash values calculated on the
host. When VHOST_NET_F_VIRTIO_NET_HDR is employed, it will report no
hash values (i.e., the hash_report member is always set to
VIRTIO_NET_HASH_REPORT_NONE). Otherwise, the values reported by the
underlying socket will be reported.

VIRTIO_NET_F_HASH_REPORT requires VIRTIO_F_VERSION_1.

Signed-off-by: Akihiko Odaki <[e-mail]>
Tested-by: Lei Yang <[e-mail]>
---
 drivers/vhost/net.c | 68 +++++++++++++++++++++++++++--------------------------
 1 file changed, 35 insertions(+), 33 deletions(-)

Patch

diff --git a/drivers/vhost/net.c b/drivers/vhost/net.c
index b9b9e9d40951..fc5b43e43a06 100644
--- a/drivers/vhost/net.c
+++ b/drivers/vhost/net.c
@@ -73,6 +73,7 @@  enum {
 	VHOST_NET_FEATURES = VHOST_FEATURES |
 			 (1ULL << VHOST_NET_F_VIRTIO_NET_HDR) |
 			 (1ULL << VIRTIO_NET_F_MRG_RXBUF) |
+			 (1ULL << VIRTIO_NET_F_HASH_REPORT) |
 			 (1ULL << VIRTIO_F_ACCESS_PLATFORM) |
 			 (1ULL << VIRTIO_F_RING_RESET)
 };
@@ -1097,10 +1098,6 @@  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
-	};
 	size_t total_len = 0;
 	int err, mergeable;
 	s16 headcount;
@@ -1174,11 +1171,15 @@  static void handle_rx(struct vhost_net *net)
 		/* We don't need to be notified again. */
 		iov_iter_init(&msg.msg_iter, ITER_DEST, vq->iov, in, vhost_len);
 		fixup = msg.msg_iter;
-		if (unlikely((vhost_hlen))) {
-			/* We will supply the header ourselves
-			 * TODO: support TSO.
-			 */
-			iov_iter_advance(&msg.msg_iter, vhost_hlen);
+		/*
+		 * Supply virtio_net_hdr if VHOST_NET_F_VIRTIO_NET_HDR
+		 * TODO: support TSO.
+		 */
+		if (unlikely(vhost_hlen) &&
+		    iov_iter_zero(vhost_hlen, &msg.msg_iter) != vhost_hlen) {
+			vq_err(vq, "Unable to write vnet_hdr at addr %p\n",
+			       vq->iov->iov_base);
+			goto out;
 		}
 		err = sock->ops->recvmsg(sock, &msg,
 					 sock_len, MSG_DONTWAIT | MSG_TRUNC);
@@ -1191,30 +1192,24 @@  static void handle_rx(struct vhost_net *net)
 			vhost_discard_vq_desc(vq, headcount);
 			continue;
 		}
-		/* 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)) {
-				vq_err(vq, "Unable to write vnet_hdr "
-				       "at addr %p\n", vq->iov->iov_base);
-				goto out;
-			}
-		} else {
-			/* Header came from socket; we'll need to patch
-			 * ->num_buffers over if VIRTIO_NET_F_MRG_RXBUF
-			 */
-			iov_iter_advance(&fixup, sizeof(hdr));
-		}
 		/* TODO: Should check and handle checksum. */
 
+		/*
+		 * We'll need to patch ->num_buffers over if
+		 * VIRTIO_NET_F_MRG_RXBUF or VIRTIO_F_VERSION_1
+		 */
 		num_buffers = cpu_to_vhost16(vq, headcount);
-		if (likely(set_num_buffers) &&
-		    copy_to_iter(&num_buffers, sizeof num_buffers,
-				 &fixup) != sizeof num_buffers) {
-			vq_err(vq, "Failed num_buffers write");
-			vhost_discard_vq_desc(vq, headcount);
-			goto out;
+		if (likely(set_num_buffers)) {
+			iov_iter_advance(&fixup, offsetof(struct virtio_net_hdr_v1, num_buffers));
+
+			if (copy_to_iter(&num_buffers, sizeof(num_buffers),
+					 &fixup) != sizeof(num_buffers)) {
+				vq_err(vq, "Failed num_buffers write");
+				vhost_discard_vq_desc(vq, headcount);
+				goto out;
+			}
 		}
+
 		nvq->done_idx += headcount;
 		if (nvq->done_idx > VHOST_NET_BATCH)
 			vhost_net_signal_used(nvq);
@@ -1607,10 +1602,13 @@  static int vhost_net_set_features(struct vhost_net *n, u64 features)
 	size_t vhost_hlen, sock_hlen, hdr_len;
 	int i;
 
-	hdr_len = (features & ((1ULL << VIRTIO_NET_F_MRG_RXBUF) |
-			       (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);
+	else if (features & ((1ULL << VIRTIO_NET_F_MRG_RXBUF) |
+			     (1ULL << VIRTIO_F_VERSION_1)))
+		hdr_len = sizeof(struct virtio_net_hdr_mrg_rxbuf);
+	else
+		hdr_len = sizeof(struct virtio_net_hdr);
 	if (features & (1 << VHOST_NET_F_VIRTIO_NET_HDR)) {
 		/* vhost provides vnet_hdr */
 		vhost_hlen = hdr_len;
@@ -1691,6 +1689,10 @@  static long vhost_net_ioctl(struct file *f, unsigned int ioctl,
 			return -EFAULT;
 		if (features & ~VHOST_NET_FEATURES)
 			return -EOPNOTSUPP;
+		if ((features & ((1ULL << VIRTIO_F_VERSION_1) |
+				 (1ULL << VIRTIO_NET_F_HASH_REPORT))) ==
+		    (1ULL << VIRTIO_NET_F_HASH_REPORT))
+			return -EINVAL;
 		return vhost_net_set_features(n, features);
 	case VHOST_GET_BACKEND_FEATURES:
 		features = VHOST_NET_BACKEND_FEATURES;