virtio-net: put virtio net header inline with data (e7428e95) · Commits · 戴 / test

drivers/net/virtio_net.c

+34 −8

Original line number	Diff line number	Diff line
		@@ -106,6 +106,9 @@ struct virtnet_info {
		/* Has control virtqueue */
		bool has_cvq;

		/* Host can handle any s/g split between our header and packet data */
		bool any_header_sg;

		/* enable config space updates */
		bool config_enable;

		@@ -669,12 +672,28 @@ 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 = skb_vnet_hdr(skb);
		struct skb_vnet_hdr *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;
		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)) &&
		!skb_header_cloned(skb) && skb_headroom(skb) >= hdr_len;
		/* 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);
		else
		hdr = skb_vnet_hdr(skb);

		if (skb->ip_summed == CHECKSUM_PARTIAL) {
		hdr->hdr.flags = VIRTIO_NET_HDR_F_NEEDS_CSUM;
		@@ -703,15 +722,18 @@ static int xmit_skb(struct send_queue sq, struct sk_buff skb)
		hdr->hdr.gso_size = hdr->hdr.hdr_len = 0;
		}

		hdr->mhdr.num_buffers = 0;

		/* Encode metadata header at front. */
		if (vi->mergeable_rx_bufs)
		sg_set_buf(sq->sg, &hdr->mhdr, sizeof hdr->mhdr);
		else
		sg_set_buf(sq->sg, &hdr->hdr, sizeof hdr->hdr);
		hdr->mhdr.num_buffers = 0;

		if (can_push) {
		__skb_push(skb, hdr_len);
		num_sg = skb_to_sgvec(skb, sq->sg, 0, skb->len);
		/* Pull header back to avoid skew in tx bytes calculations. */
		__skb_pull(skb, hdr_len);
		} else {
		sg_set_buf(sq->sg, hdr, hdr_len);
		num_sg = skb_to_sgvec(skb, sq->sg + 1, 0, skb->len) + 1;
		}
		return virtqueue_add_outbuf(sq->vq, sq->sg, num_sg, skb, GFP_ATOMIC);
		}

		@@ -1552,6 +1574,9 @@ 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_F_ANY_LAYOUT))
		vi->any_header_sg = true;

		if (virtio_has_feature(vdev, VIRTIO_NET_F_CTRL_VQ))
		vi->has_cvq = true;

		@@ -1727,6 +1752,7 @@ static unsigned int features[] = {
		VIRTIO_NET_F_CTRL_RX, VIRTIO_NET_F_CTRL_VLAN,
		VIRTIO_NET_F_GUEST_ANNOUNCE, VIRTIO_NET_F_MQ,
		VIRTIO_NET_F_CTRL_MAC_ADDR,
		VIRTIO_F_ANY_LAYOUT,
		};

		static struct virtio_driver virtio_net_driver = {

include/uapi/linux/virtio_net.h

+3 −1

Original line number	Diff line number	Diff line
		@@ -70,7 +70,9 @@ struct virtio_net_config {
		__u16 max_virtqueue_pairs;
		} __attribute__((packed));

		/* This is the first element of the scatter-gather list. If you don't
		/* This header comes first in the scatter-gather list.
		* If VIRTIO_F_ANY_LAYOUT is not negotiated, it must
		* be the first element of the scatter-gather list. If you don't
		* specify GSO or CSUM features, you can simply ignore the header. */
		struct virtio_net_hdr {
		#define VIRTIO_NET_HDR_F_NEEDS_CSUM 1 // Use csum_start, csum_offset

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