6.11-stable review patch. If anyone has any objections, please let me know.
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From: Wenbo Li liwenbo.martin@bytedance.com
[ Upstream commit c11a49d58ad229a1be1ebe08a2b68fedf83db6c8 ]
Currently, the virtio-net driver will perform a pre-dma-mapping for small or mergeable RX buffer. But for small packets, a mismatched address without VIRTNET_RX_PAD and xdp_headroom is used for unmapping.
That will result in unsynchronized buffers when SWIOTLB is enabled, for example, when running as a TDX guest.
This patch unifies the address passed to the virtio core as the address of the virtnet header and fixes the mismatched buffer address.
Changes from v2: unify the buf that passed to the virtio core in small and merge mode. Changes from v1: Use ctx to get xdp_headroom.
Fixes: 295525e29a5b ("virtio_net: merge dma operations when filling mergeable buffers") Signed-off-by: Wenbo Li liwenbo.martin@bytedance.com Signed-off-by: Jiahui Cen cenjiahui@bytedance.com Signed-off-by: Ying Fang fangying.tommy@bytedance.com Reviewed-by: Xuan Zhuo xuanzhuo@linux.alibaba.com Link: https://patch.msgid.link/20240919081351.51772-1-liwenbo.martin@bytedance.com Signed-off-by: Paolo Abeni pabeni@redhat.com Signed-off-by: Sasha Levin sashal@kernel.org --- drivers/net/virtio_net.c | 10 ++++++++-- 1 file changed, 8 insertions(+), 2 deletions(-)
diff --git a/drivers/net/virtio_net.c b/drivers/net/virtio_net.c index 6f4781ec2b369..f8131f92a3928 100644 --- a/drivers/net/virtio_net.c +++ b/drivers/net/virtio_net.c @@ -1807,6 +1807,11 @@ static struct sk_buff *receive_small(struct net_device *dev, struct page *page = virt_to_head_page(buf); struct sk_buff *skb;
+ /* We passed the address of virtnet header to virtio-core, + * so truncate the padding. + */ + buf -= VIRTNET_RX_PAD + xdp_headroom; + len -= vi->hdr_len; u64_stats_add(&stats->bytes, len);
@@ -2422,8 +2427,9 @@ static int add_recvbuf_small(struct virtnet_info *vi, struct receive_queue *rq, if (unlikely(!buf)) return -ENOMEM;
- virtnet_rq_init_one_sg(rq, buf + VIRTNET_RX_PAD + xdp_headroom, - vi->hdr_len + GOOD_PACKET_LEN); + buf += VIRTNET_RX_PAD + xdp_headroom; + + virtnet_rq_init_one_sg(rq, buf, vi->hdr_len + GOOD_PACKET_LEN);
err = virtqueue_add_inbuf_ctx(rq->vq, rq->sg, 1, buf, ctx, gfp); if (err < 0) {