From c3838262b824c71c145cd3668722e99a69bc9cd9 Mon Sep 17 00:00:00 2001 From: "Michael S. Tsirkin" Date: Fri, 31 Oct 2025 14:05:51 +0800 Subject: virtio_net: fix alignment for virtio_net_hdr_v1_hash Changing alignment of header would mean it's no longer safe to cast a 2 byte aligned pointer between formats. Use two 16 bit fields to make it 2 byte aligned as previously. This fixes the performance regression since commit ("virtio_net: enable gso over UDP tunnel support.") as it uses virtio_net_hdr_v1_hash_tunnel which embeds virtio_net_hdr_v1_hash. Pktgen in guest + XDP_DROP on TAP + vhost_net shows the TX PPS is recovered from 2.4Mpps to 4.45Mpps. Fixes: 56a06bd40fab ("virtio_net: enable gso over UDP tunnel support.") Cc: stable@vger.kernel.org Signed-off-by: Michael S. Tsirkin Signed-off-by: Jason Wang Tested-by: Lei Yang Link: https://patch.msgid.link/20251031060551.126-1-jasowang@redhat.com Signed-off-by: Jakub Kicinski --- include/uapi/linux/virtio_net.h | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) (limited to 'include/uapi') diff --git a/include/uapi/linux/virtio_net.h b/include/uapi/linux/virtio_net.h index 8bf27ab8bcb4..1db45b01532b 100644 --- a/include/uapi/linux/virtio_net.h +++ b/include/uapi/linux/virtio_net.h @@ -193,7 +193,8 @@ struct virtio_net_hdr_v1 { struct virtio_net_hdr_v1_hash { struct virtio_net_hdr_v1 hdr; - __le32 hash_value; + __le16 hash_value_lo; + __le16 hash_value_hi; #define VIRTIO_NET_HASH_REPORT_NONE 0 #define VIRTIO_NET_HASH_REPORT_IPv4 1 #define VIRTIO_NET_HASH_REPORT_TCPv4 2 -- cgit v1.2.3