Signed-off-by: Shirley Ma <x...@us.ibm.com>
-------------

diff --git a/drivers/net/virtio_net.c b/drivers/net/virtio_net.c
index 100b4b9..dde8060 100644
--- a/drivers/net/virtio_net.c
+++ b/drivers/net/virtio_net.c
@@ -203,6 +203,73 @@ static struct sk_buff *skb_goodcopy(struct virtnet_info 
*vi, struct page **page,
        return skb;
 }
 
+static struct sk_buff *receive_big(struct virtnet_info *vi, struct page *page,
+                                  unsigned int len)
+{
+       struct sk_buff *skb;
+
+       skb = skb_goodcopy(vi, &page, &len);
+       if (unlikely(!skb))
+               return NULL;
+
+       while (len > 0) {
+               len = skb_set_frag(skb, page, 0, len);
+               page = (struct page *)page->private;
+       }
+
+       if (page)
+               give_pages(vi, page);
+
+       return skb;
+}
+
+static struct sk_buff *receive_mergeable(struct virtnet_info *vi,
+                                        struct page *page, unsigned int len)
+{
+       struct sk_buff *skb;
+       struct skb_vnet_hdr *hdr;
+       int num_buf, i;
+
+       if (len > PAGE_SIZE)
+               len = PAGE_SIZE;
+
+       skb = skb_goodcopy(vi, &page, &len);
+
+       if (unlikely(!skb))
+               return NULL;
+
+       hdr = skb_vnet_hdr(skb);
+       num_buf = hdr->mhdr.num_buffers;
+       while (--num_buf) {
+               struct page *page;
+
+               i = skb_shinfo(skb)->nr_frags;
+               if (i >= MAX_SKB_FRAGS) {
+                       pr_debug("%s: packet too long %d\n", skb->dev->name,
+                                len);
+                       skb->dev->stats.rx_length_errors++;
+                       return skb;
+               }
+
+               page = vi->rvq->vq_ops->get_buf(vi->rvq, &len);
+               if (!page) {
+                       pr_debug("%s: rx error: %d buffers missing\n",
+                                skb->dev->name, hdr->mhdr.num_buffers);
+                       skb->dev->stats.rx_length_errors++;
+                       return skb;
+               }
+
+               if (len > PAGE_SIZE)
+                       len = PAGE_SIZE;
+
+               skb_set_frag(skb, page, 0, len);
+
+               vi->num--;
+       }
+
+       return skb;
+}
+
 static void receive_skb(struct net_device *dev, struct sk_buff *skb,
                        unsigned len)
 {
@@ -356,6 +423,103 @@ drop:
        dev_kfree_skb(skb);
 }
 
+static int add_recvbuf_small(struct virtnet_info *vi, gfp_t gfp, bool *oom)
+{
+       struct sk_buff *skb;
+       struct skb_vnet_hdr *hdr;
+       struct scatterlist sg[2];
+       int err = 0;
+
+       skb = netdev_alloc_skb(vi->dev, MAX_PACKET_LEN + NET_IP_ALIGN);
+       if (unlikely(!skb)) {
+               *oom = true;
+               return err;
+       }
+
+       skb_reserve(skb, NET_IP_ALIGN);
+       skb_put(skb, MAX_PACKET_LEN);
+
+       hdr = skb_vnet_hdr(skb);
+       sg_set_buf(sg, &hdr->hdr, sizeof(hdr->hdr));
+
+       skb_to_sgvec(skb, sg+1, 0, skb->len);
+
+       err = vi->rvq->vq_ops->add_buf(vi->rvq, sg, 0, 2, skb);
+       if (err < 0)
+               kfree_skb(skb);
+       else
+               skb_queue_head(&vi->recv, skb);
+
+       return err;
+}
+
+static int add_recvbuf_big(struct virtnet_info *vi, gfp_t gfp, bool *oom)
+{
+       struct scatterlist sg[2 + MAX_SKB_FRAGS];
+       int total = MAX_SKB_FRAGS + 2;
+       char *p;
+       int err = 0;
+       int i, offset;
+       struct page *first = NULL;
+       struct page *page;
+       /* share one page between virtio_net header and data */
+       struct padded_vnet_hdr {
+               struct virtio_net_hdr hdr;
+               /* This padding makes our data 16 byte aligned */
+               char padding[6];
+       };
+
+       offset = sizeof(struct padded_vnet_hdr);
+
+       for (i = total - 1; i > 0; i--) {
+               page = get_a_page(vi, gfp);
+               if (!page) {
+                       if (first)
+                               give_pages(vi, first);
+                       *oom = true;
+                       break;
+               }
+
+               p = page_address(page);
+               page->private = (unsigned long)first;
+               first = page;
+
+               /* allocate MAX_SKB_FRAGS + 1 pages for big packets */
+               if (i == 1) {
+                       sg_set_buf(&sg[i-1], p, sizeof(struct virtio_net_hdr));
+                       sg_set_buf(&sg[i], p + offset, PAGE_SIZE - offset);
+                       err = vi->rvq->vq_ops->add_buf(vi->rvq, sg, 0, total,
+                                                      first);
+                       if (err < 0)
+                               give_pages(vi, first);
+               } else
+                       sg_set_buf(&sg[i], p, PAGE_SIZE);
+       }
+
+       return err;
+}
+
+static int add_recvbuf_mergeable(struct virtnet_info *vi, gfp_t gfp, bool *oom)
+{
+       struct page *page;
+       struct scatterlist sg;
+       int err = 0;
+
+       page = get_a_page(vi, gfp);
+       if (!page) {
+               *oom = true;
+               return err;
+       }
+
+       sg_init_one(&sg, page_address(page), PAGE_SIZE);
+
+       err = vi->rvq->vq_ops->add_buf(vi->rvq, &sg, 0, 1, page);
+       if (err < 0)
+               give_pages(vi, page);
+
+       return err;
+}
+
 static bool try_fill_recv_maxbufs(struct virtnet_info *vi, gfp_t gfp)
 {
        struct sk_buff *skb;


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