6.6-stable review patch. If anyone has any objections, please let me know.
------------------
From: Wenbo Li <liwenbo.martin@xxxxxxxxxxxxx>
[ 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@xxxxxxxxxxxxx>
Signed-off-by: Jiahui Cen <cenjiahui@xxxxxxxxxxxxx>
Signed-off-by: Ying Fang <fangying.tommy@xxxxxxxxxxxxx>
Reviewed-by: Xuan Zhuo <xuanzhuo@xxxxxxxxxxxxxxxxx>
Link: https://patch.msgid.link/20240919081351.51772-1-liwenbo.martin@xxxxxxxxxxxxx
Signed-off-by: Paolo Abeni <pabeni@xxxxxxxxxx>
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
---
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 bc01f2dafa948..2da3be3fb9423 100644
--- a/drivers/net/virtio_net.c
+++ b/drivers/net/virtio_net.c
@@ -1269,6 +1269,11 @@ 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);
@@ -1859,8 +1864,9 @@ 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) {
--
2.43.0
