[PATCH] vhost/net: Set num_buffers for virtio 1.0

[Akihiko Odaki]

The specification says the device MUST set num_buffers to 1 if
VIRTIO_NET_F_MRG_RXBUF has not been negotiated.

Fixes: 41e3e42108bc ("vhost/net: enable virtio 1.0")
Signed-off-by: Akihiko Odaki <akihiko.odaki@xxxxxxxxxx>
---
 drivers/vhost/net.c | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/drivers/vhost/net.c b/drivers/vhost/net.c
index f16279351db5..d4d97fa9cc8f 100644
--- a/drivers/vhost/net.c
+++ b/drivers/vhost/net.c
@@ -1107,6 +1107,7 @@ static void handle_rx(struct vhost_net *net)
 	size_t vhost_hlen, sock_hlen;
 	size_t vhost_len, sock_len;
 	bool busyloop_intr = false;
+	bool set_num_buffers;
 	struct socket *sock;
 	struct iov_iter fixup;
 	__virtio16 num_buffers;
@@ -1129,6 +1130,8 @@ static void handle_rx(struct vhost_net *net)
 	vq_log = unlikely(vhost_has_feature(vq, VHOST_F_LOG_ALL)) ?
 		vq->log : NULL;
 	mergeable = vhost_has_feature(vq, VIRTIO_NET_F_MRG_RXBUF);
+	set_num_buffers = mergeable ||
+			  vhost_has_feature(vq, VIRTIO_F_VERSION_1);
 
 	do {
 		sock_len = vhost_net_rx_peek_head_len(net, sock->sk,
@@ -1205,7 +1208,7 @@ static void handle_rx(struct vhost_net *net)
 		/* TODO: Should check and handle checksum. */
 
 		num_buffers = cpu_to_vhost16(vq, headcount);
-		if (likely(mergeable) &&
+		if (likely(set_num_buffers) &&
 		    copy_to_iter(&num_buffers, sizeof num_buffers,
 				 &fixup) != sizeof num_buffers) {
 			vq_err(vq, "Failed num_buffers write");

---
base-commit: 46a0057a5853cbdb58211c19e89ba7777dc6fd50
change-id: 20240908-v1-90fc83ff8b09

Best regards,
-- 
Akihiko Odaki <akihiko.odaki@xxxxxxxxxx>