virtio_net: get rid of virtio_net_hdr/skb_vnet_hdr

virtio 1.0 doesn't use virtio_net_hdr anymore, and in fact, it's not
really useful since virtio_net_hdr_mrg_rxbuf includes that as the first
field anyway.

Let's drop it, precalculate header len and store within vi instead.

This way we can also remove struct skb_vnet_hdr.

Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
Reviewed-by: Cornelia Huck <cornelia.huck@de.ibm.com>
Reviewed-by: Jason Wang <jasowang@redhat.com>

diff --git a/drivers/net/virtio_net.c b/drivers/net/virtio_net.c
index 1630c21..516f2cb 100644 (file)
--- a/drivers/net/virtio_net.c
+++ b/drivers/net/virtio_net.c
@@ -123,6 +123,9 @@ struct virtnet_info {
        /* Host can handle any s/g split between our header and packet data */
        bool any_header_sg;
 
+       /* Packet virtio header size */
+       u8 hdr_len;
+
        /* Active statistics */
        struct virtnet_stats __percpu *stats;
 
@@ -139,21 +142,14 @@ struct virtnet_info {
        struct notifier_block nb;
 };
 
-struct skb_vnet_hdr {
-       union {
-               struct virtio_net_hdr hdr;
-               struct virtio_net_hdr_mrg_rxbuf mhdr;
-       };
-};
-
 struct padded_vnet_hdr {
-       struct virtio_net_hdr hdr;
+       struct virtio_net_hdr_mrg_rxbuf hdr;
        /*
-        * virtio_net_hdr should be in a separated sg buffer because of a
-        * QEMU bug, and data sg buffer shares same page with this header sg.
-        * This padding makes next sg 16 byte aligned after virtio_net_hdr.
+        * hdr is in a separate sg buffer, and data sg buffer shares same page
+        * with this header sg. This padding makes next sg 16 byte aligned
+        * after the header.
         */
-       char padding[6];
+       char padding[4];
 };
 
 /* Converting between virtqueue no. and kernel tx/rx queue no.
@@ -179,9 +175,9 @@ static int rxq2vq(int rxq)
        return rxq * 2;
 }
 
-static inline struct skb_vnet_hdr *skb_vnet_hdr(struct sk_buff *skb)
+static inline struct virtio_net_hdr_mrg_rxbuf *skb_vnet_hdr(struct sk_buff *skb)
 {
-       return (struct skb_vnet_hdr *)skb->cb;
+       return (struct virtio_net_hdr_mrg_rxbuf *)skb->cb;
 }
 
 /*
@@ -247,7 +243,7 @@ static struct sk_buff *page_to_skb(struct virtnet_info *vi,
                                   unsigned int len, unsigned int truesize)
 {
        struct sk_buff *skb;
-       struct skb_vnet_hdr *hdr;
+       struct virtio_net_hdr_mrg_rxbuf *hdr;
        unsigned int copy, hdr_len, hdr_padded_len;
        char *p;
 
@@ -260,13 +256,11 @@ static struct sk_buff *page_to_skb(struct virtnet_info *vi,
 
        hdr = skb_vnet_hdr(skb);
 
-       if (vi->mergeable_rx_bufs) {
-               hdr_len = sizeof hdr->mhdr;
-               hdr_padded_len = sizeof hdr->mhdr;
-       } else {
-               hdr_len = sizeof hdr->hdr;
+       hdr_len = vi->hdr_len;
+       if (vi->mergeable_rx_bufs)
+               hdr_padded_len = sizeof *hdr;
+       else
                hdr_padded_len = sizeof(struct padded_vnet_hdr);
-       }
 
        memcpy(hdr, p, hdr_len);
 
@@ -317,11 +311,11 @@ static struct sk_buff *page_to_skb(struct virtnet_info *vi,
        return skb;
 }
 
-static struct sk_buff *receive_small(void *buf, unsigned int len)
+static struct sk_buff *receive_small(struct virtnet_info *vi, void *buf, unsigned int len)
 {
        struct sk_buff * skb = buf;
 
-       len -= sizeof(struct virtio_net_hdr);
+       len -= vi->hdr_len;
        skb_trim(skb, len);
 
        return skb;
@@ -354,8 +348,8 @@ static struct sk_buff *receive_mergeable(struct net_device *dev,
                                         unsigned int len)
 {
        void *buf = mergeable_ctx_to_buf_address(ctx);
-       struct skb_vnet_hdr *hdr = buf;
-       u16 num_buf = virtio16_to_cpu(rq->vq->vdev, hdr->mhdr.num_buffers);
+       struct virtio_net_hdr_mrg_rxbuf *hdr = buf;
+       u16 num_buf = virtio16_to_cpu(vi->vdev, hdr->num_buffers);
        struct page *page = virt_to_head_page(buf);
        int offset = buf - page_address(page);
        unsigned int truesize = max(len, mergeable_ctx_to_buf_truesize(ctx));
@@ -373,8 +367,8 @@ static struct sk_buff *receive_mergeable(struct net_device *dev,
                if (unlikely(!ctx)) {
                        pr_debug("%s: rx error: %d buffers out of %d missing\n",
                                 dev->name, num_buf,
-                                virtio16_to_cpu(rq->vq->vdev,
-                                                hdr->mhdr.num_buffers));
+                                virtio16_to_cpu(vi->vdev,
+                                                hdr->num_buffers));
                        dev->stats.rx_length_errors++;
                        goto err_buf;
                }
@@ -441,7 +435,7 @@ static void receive_buf(struct virtnet_info *vi, struct receive_queue *rq,
        struct net_device *dev = vi->dev;
        struct virtnet_stats *stats = this_cpu_ptr(vi->stats);
        struct sk_buff *skb;
-       struct skb_vnet_hdr *hdr;
+       struct virtio_net_hdr_mrg_rxbuf *hdr;
 
        if (unlikely(len < sizeof(struct virtio_net_hdr) + ETH_HLEN)) {
                pr_debug("%s: short packet %i\n", dev->name, len);
@@ -463,7 +457,7 @@ static void receive_buf(struct virtnet_info *vi, struct receive_queue *rq,
        else if (vi->big_packets)
                skb = receive_big(dev, vi, rq, buf, len);
        else
-               skb = receive_small(buf, len);
+               skb = receive_small(vi, buf, len);
 
        if (unlikely(!skb))
                return;
@@ -545,7 +539,7 @@ static int add_recvbuf_small(struct virtnet_info *vi, struct receive_queue *rq,
                             gfp_t gfp)
 {
        struct sk_buff *skb;
-       struct skb_vnet_hdr *hdr;
+       struct virtio_net_hdr_mrg_rxbuf *hdr;
        int err;
 
        skb = __netdev_alloc_skb_ip_align(vi->dev, GOOD_PACKET_LEN, gfp);
@@ -556,7 +550,7 @@ static int add_recvbuf_small(struct virtnet_info *vi, struct receive_queue *rq,
 
        hdr = skb_vnet_hdr(skb);
        sg_init_table(rq->sg, MAX_SKB_FRAGS + 2);
-       sg_set_buf(rq->sg, &hdr->hdr, sizeof hdr->hdr);
+       sg_set_buf(rq->sg, hdr, vi->hdr_len);
        skb_to_sgvec(skb, rq->sg + 1, 0, skb->len);
 
        err = virtqueue_add_inbuf(rq->vq, rq->sg, 2, skb, gfp);
@@ -566,7 +560,8 @@ static int add_recvbuf_small(struct virtnet_info *vi, struct receive_queue *rq,
        return err;
 }
 
-static int add_recvbuf_big(struct receive_queue *rq, gfp_t gfp)
+static int add_recvbuf_big(struct virtnet_info *vi, struct receive_queue *rq,
+                          gfp_t gfp)
 {
        struct page *first, *list = NULL;
        char *p;
@@ -597,8 +592,8 @@ static int add_recvbuf_big(struct receive_queue *rq, gfp_t gfp)
        p = page_address(first);
 
        /* rq->sg[0], rq->sg[1] share the same page */
-       /* a separated rq->sg[0] for virtio_net_hdr only due to QEMU bug */
-       sg_set_buf(&rq->sg[0], p, sizeof(struct virtio_net_hdr));
+       /* a separated rq->sg[0] for header - required in case !any_header_sg */
+       sg_set_buf(&rq->sg[0], p, vi->hdr_len);
 
        /* rq->sg[1] for data packet, from offset */
        offset = sizeof(struct padded_vnet_hdr);
@@ -677,7 +672,7 @@ static bool try_fill_recv(struct virtnet_info *vi, struct receive_queue *rq,
                if (vi->mergeable_rx_bufs)
                        err = add_recvbuf_mergeable(rq, gfp);
                else if (vi->big_packets)
-                       err = add_recvbuf_big(rq, gfp);
+                       err = add_recvbuf_big(vi, rq, gfp);
                else
                        err = add_recvbuf_small(vi, rq, gfp);
 
@@ -857,18 +852,14 @@ static void free_old_xmit_skbs(struct send_queue *sq)
 
 static int xmit_skb(struct send_queue *sq, struct sk_buff *skb)
 {
-       struct skb_vnet_hdr *hdr;
+       struct virtio_net_hdr_mrg_rxbuf *hdr;
        const unsigned char *dest = ((struct ethhdr *)skb->data)->h_dest;
        struct virtnet_info *vi = sq->vq->vdev->priv;
        unsigned num_sg;
-       unsigned hdr_len;
+       unsigned hdr_len = vi->hdr_len;
        bool can_push;
 
        pr_debug("%s: xmit %p %pM\n", vi->dev->name, skb, dest);
-       if (vi->mergeable_rx_bufs)
-               hdr_len = sizeof hdr->mhdr;
-       else
-               hdr_len = sizeof hdr->hdr;
 
        can_push = vi->any_header_sg &&
                !((unsigned long)skb->data & (__alignof__(*hdr) - 1)) &&
@@ -876,7 +867,7 @@ static int xmit_skb(struct send_queue *sq, struct sk_buff *skb)
        /* Even if we can, don't push here yet as this would skew
         * csum_start offset below. */
        if (can_push)
-               hdr = (struct skb_vnet_hdr *)(skb->data - hdr_len);
+               hdr = (struct virtio_net_hdr_mrg_rxbuf *)(skb->data - hdr_len);
        else
                hdr = skb_vnet_hdr(skb);
 
@@ -909,7 +900,7 @@ static int xmit_skb(struct send_queue *sq, struct sk_buff *skb)
        }
 
        if (vi->mergeable_rx_bufs)
-               hdr->mhdr.num_buffers = 0;
+               hdr->num_buffers = 0;
 
        sg_init_table(sq->sg, MAX_SKB_FRAGS + 2);
        if (can_push) {
@@ -1814,18 +1805,19 @@ static int virtnet_probe(struct virtio_device *vdev)
        if (virtio_has_feature(vdev, VIRTIO_NET_F_MRG_RXBUF))
                vi->mergeable_rx_bufs = true;
 
+       if (virtio_has_feature(vdev, VIRTIO_NET_F_MRG_RXBUF))
+               vi->hdr_len = sizeof(struct virtio_net_hdr_mrg_rxbuf);
+       else
+               vi->hdr_len = sizeof(struct virtio_net_hdr);
+
        if (virtio_has_feature(vdev, VIRTIO_F_ANY_LAYOUT))
                vi->any_header_sg = true;
 
        if (virtio_has_feature(vdev, VIRTIO_NET_F_CTRL_VQ))
                vi->has_cvq = true;
 
-       if (vi->any_header_sg) {
-               if (vi->mergeable_rx_bufs)
-                       dev->needed_headroom = sizeof(struct virtio_net_hdr_mrg_rxbuf);
-               else
-                       dev->needed_headroom = sizeof(struct virtio_net_hdr);
-       }
+       if (vi->any_header_sg)
+               dev->needed_headroom = vi->hdr_len;
 
        /* Use single tx/rx queue pair as default */
        vi->curr_queue_pairs = 1;