[dpdk-dev] [PATCH] vhost: dequeue zero copy should restore mbuf before return to pool

[Junjie Chen]

dequeue zero copy change buf_addr and buf_iova of mbuf, and return
to mbuf pool without restore them, it breaks vm memory if others allocate
mbuf from same pool since mbuf reset doesn't reset buf_addr and buf_iova.

Signed-off-by: Junjie Chen <junjie.j.chen at intel.com>
---
 lib/librte_vhost/virtio_net.c | 21 +++++++++++++++++++++
 1 file changed, 21 insertions(+)

diff --git a/lib/librte_vhost/virtio_net.c b/lib/librte_vhost/virtio_net.c
index 568ad0e..e9aaf6d 100644
--- a/lib/librte_vhost/virtio_net.c
+++ b/lib/librte_vhost/virtio_net.c
@@ -1158,6 +1158,26 @@ mbuf_is_consumed(struct rte_mbuf *m)
 	return true;
 }
 
+
+static __rte_always_inline void
+restore_mbuf(struct rte_mbuf *m)
+{
+	uint32_t mbuf_size, priv_size;
+
+	while (m) {
+		priv_size = rte_pktmbuf_priv_size(m->pool);
+		mbuf_size = sizeof(struct rte_mbuf) + priv_size;
+		/* start of buffer is after mbuf structure and priv data */
+		m->priv_size = priv_size;
+
+		m->buf_addr = (char *)m + mbuf_size;
+		m->buf_iova = rte_mempool_virt2iova(m) + mbuf_size;
+		m->data_off = RTE_MIN(RTE_PKTMBUF_HEADROOM,
+			(uint16_t)m->buf_len);
+		m = m->next;
+	}
+}
+
 uint16_t
 rte_vhost_dequeue_burst(int vid, uint16_t queue_id,
 	struct rte_mempool *mbuf_pool, struct rte_mbuf **pkts, uint16_t count)
@@ -1209,6 +1229,7 @@ rte_vhost_dequeue_burst(int vid, uint16_t queue_id,
 				nr_updated += 1;
 
 				TAILQ_REMOVE(&vq->zmbuf_list, zmbuf, next);
+				restore_mbuf(zmbuf->mbuf);
 				rte_pktmbuf_free(zmbuf->mbuf);
 				put_zmbuf(zmbuf);
 				vq->nr_zmbuf -= 1;
-- 
2.0.1