[RFC PATCH 1/9] virtio_net: disable the hole mechanism for xdp

Heng Qi
2022-11-22T07:43:58Z

XDP core assumes that the frame_size of xdp_buff and the length of
the frag are PAGE_SIZE. But before xdp is set, the length of the prefilled
buffer may exceed PAGE_SIZE, which may cause the processing of xdp to fail,
so we disable the hole mechanism when xdp is loaded.

Signed-off-by: Heng Qi <hengqi@linux.alibaba.com>
Reviewed-by: Xuan Zhuo <xuanzhuo@linux.alibaba.com>
---
drivers/net/virtio_net.c | 5 ++++-
1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/drivers/net/virtio_net.c b/drivers/net/virtio_net.c
index 9cce7dec7366..c5046d21b281 100644
--- a/drivers/net/virtio_net.c
+++ b/drivers/net/virtio_net.c
@@ -1419,8 +1419,11 @@ static int add_recvbuf_mergeable(struct virtnet_info *vi,
/* To avoid internal fragmentation, if there is very likely not
* enough space for another buffer, add the remaining space to
* the current buffer.
+ * XDP core assumes that frame_size of xdp_buff and the length
+ * of the frag are PAGE_SIZE, so we disable the hole mechanism.
*/
- len += hole;
+ if (!vi->xdp_enabled)
+ len += hole;
alloc_frag->offset += hole;
}

--
2.19.1.6.gb485710b