[PULL,1/2] virtio-net: Fix num_buffers for version 1

Commit Message

Michael S. Tsirkin April 3, 2025, 9:17 p.m. UTC

From: Akihiko Odaki <[e-mail]>

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

Fixes: df91055db5c9 ("virtio-net: enable virtio 1.0")
Signed-off-by: Akihiko Odaki <[e-mail]>
Message-Id: <[e-mail]>
Reviewed-by: Michael S. Tsirkin <[e-mail]>
Signed-off-by: Michael S. Tsirkin <[e-mail]>
Tested-by: Lei Yang <[e-mail]>
Reviewed-by: Michael S. Tsirkin <[e-mail]>
Signed-off-by: Michael S. Tsirkin <[e-mail]>
---
 hw/net/virtio-net.c | 2 ++
 1 file changed, 2 insertions(+)

Patch

diff --git a/hw/net/virtio-net.c b/hw/net/virtio-net.c
index de87cfadff..340c6b6422 100644
--- a/hw/net/virtio-net.c
+++ b/hw/net/virtio-net.c
@@ -1999,6 +1999,8 @@  static ssize_t virtio_net_receive_rcu(NetClientState *nc, const uint8_t *buf,
                                     offsetof(typeof(hdr),
                                              virtio_net.hdr.num_buffers),
                                     sizeof(hdr.virtio_net.hdr.num_buffers));
+            } else {
+                hdr.virtio_net.hdr.num_buffers = cpu_to_le16(1);
             }
 
             guest_offset = n->has_vnet_hdr ?