When calling buf_to_xdp, the len argument is the frame data's length without virtio header's length (vi->hdr_len). We check that len with

xsk_pool_get_rx_frame_size() + vi->hdr_len

to ensure the provided len does not larger than the allocated chunk size. The additional vi->hdr_len is because in virtnet_add_recvbuf_xsk, we use part of XDP_PACKET_HEADROOM for virtio header and ask the vhost to start placing data from

hard_start + XDP_PACKET_HEADROOM - vi->hdr_len not hard_start + XDP_PACKET_HEADROOM

But the first buffer has virtio_header, so the maximum frame's length in the first buffer can only be

xsk_pool_get_rx_frame_size() not xsk_pool_get_rx_frame_size() + vi->hdr_len

like in the current check.

This commit adds an additional argument to buf_to_xdp differentiate between the first buffer and other ones to correctly calculate the maximum frame's length.

Cc: stable@vger.kernel.org Reviewed-by: Xuan Zhuo xuanzhuo@linux.alibaba.com Fixes: a4e7ba702701 ("virtio_net: xsk: rx: support recv small mode") Signed-off-by: Bui Quang Minh minhquangbui99@gmail.com --- drivers/net/virtio_net.c | 22 ++++++++++++++++++---- 1 file changed, 18 insertions(+), 4 deletions(-)

diff --git a/drivers/net/virtio_net.c b/drivers/net/virtio_net.c index e53ba600605a..1eb237cd5d0b 100644 --- a/drivers/net/virtio_net.c +++ b/drivers/net/virtio_net.c @@ -1127,15 +1127,29 @@ static void check_sq_full_and_disable(struct virtnet_info *vi, } }

+/* Note that @len is the length of received data without virtio header */ static struct xdp_buff *buf_to_xdp(struct virtnet_info *vi, - struct receive_queue *rq, void *buf, u32 len) + struct receive_queue *rq, void *buf, + u32 len, bool first_buf) { struct xdp_buff *xdp; u32 bufsize;

xdp = (struct xdp_buff *)buf;

- bufsize = xsk_pool_get_rx_frame_size(rq->xsk_pool) + vi->hdr_len; + /* In virtnet_add_recvbuf_xsk, we use part of XDP_PACKET_HEADROOM for + * virtio header and ask the vhost to fill data from + * hard_start + XDP_PACKET_HEADROOM - vi->hdr_len + * The first buffer has virtio header so the remaining region for frame + * data is + * xsk_pool_get_rx_frame_size() + * While other buffers than the first one do not have virtio header, so + * the maximum frame data's length can be + * xsk_pool_get_rx_frame_size() + vi->hdr_len + */ + bufsize = xsk_pool_get_rx_frame_size(rq->xsk_pool); + if (!first_buf) + bufsize += vi->hdr_len;

if (unlikely(len > bufsize)) { pr_debug("%s: rx error: len %u exceeds truesize %u\n", @@ -1260,7 +1274,7 @@ static int xsk_append_merge_buffer(struct virtnet_info *vi,

u64_stats_add(&stats->bytes, len);

- xdp = buf_to_xdp(vi, rq, buf, len); + xdp = buf_to_xdp(vi, rq, buf, len, false); if (!xdp) goto err;

@@ -1358,7 +1372,7 @@ static void virtnet_receive_xsk_buf(struct virtnet_info *vi, struct receive_queu

u64_stats_add(&stats->bytes, len);

- xdp = buf_to_xdp(vi, rq, buf, len); + xdp = buf_to_xdp(vi, rq, buf, len, true); if (!xdp) return;