Commit 64c99d2d authored by Arseniy Krasnov's avatar Arseniy Krasnov Committed by Paolo Abeni
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vsock/virtio: support to send non-linear skb 



For non-linear skb use its pages from fragment array as buffers in
virtio tx queue. These pages are already pinned by 'get_user_pages()'
during such skb creation.

Signed-off-by: default avatarArseniy Krasnov <avkrasnov@salutedevices.com>
Reviewed-by: default avatarStefano Garzarella <sgarzare@redhat.com>
Acked-by: default avatarMichael S. Tsirkin <mst@redhat.com>
Signed-off-by: default avatarPaolo Abeni <pabeni@redhat.com>
parent 0df7cd3c

net/vmw_vsock/virtio_transport.c

+53 −7
Original line number Diff line number Diff line
@@ -63,6 +63,17 @@ struct virtio_vsock { 


	u32 guest_cid;

	bool seqpacket_allow;



	/* These fields are used only in tx path in function

	 * 'virtio_transport_send_pkt_work()', so to save

	 * stack space in it, place both of them here. Each

	 * pointer from 'out_sgs' points to the corresponding

	 * element in 'out_bufs' - this is initialized in

	 * 'virtio_vsock_probe()'. Both fields are protected

	 * by 'tx_lock'. +1 is needed for packet header.

	 */

	struct scatterlist *out_sgs[MAX_SKB_FRAGS + 1];

	struct scatterlist out_bufs[MAX_SKB_FRAGS + 1];

};



static u32 virtio_transport_get_local_cid(void)
@@ -100,8 +111,8 @@ virtio_transport_send_pkt_work(struct work_struct *work) 
	vq = vsock->vqs[VSOCK_VQ_TX];



	for (;;) {

		struct scatterlist hdr, buf, *sgs[2];

		int ret, in_sg = 0, out_sg = 0;

		struct scatterlist **sgs;

		struct sk_buff *skb;

		bool reply;
@@ -111,12 +122,43 @@ virtio_transport_send_pkt_work(struct work_struct *work) 


		virtio_transport_deliver_tap_pkt(skb);

		reply = virtio_vsock_skb_reply(skb);

		sgs = vsock->out_sgs;

		sg_init_one(sgs[out_sg], virtio_vsock_hdr(skb),

			    sizeof(*virtio_vsock_hdr(skb)));

		out_sg++;



		sg_init_one(&hdr, virtio_vsock_hdr(skb), sizeof(*virtio_vsock_hdr(skb)));

		sgs[out_sg++] = &hdr;

		if (!skb_is_nonlinear(skb)) {

			if (skb->len > 0) {

			sg_init_one(&buf, skb->data, skb->len);

			sgs[out_sg++] = &buf;

				sg_init_one(sgs[out_sg], skb->data, skb->len);

				out_sg++;

			}

		} else {

			struct skb_shared_info *si;

			int i;



			/* If skb is nonlinear, then its buffer must contain

			 * only header and nothing more. Data is stored in

			 * the fragged part.

			 */

			WARN_ON_ONCE(skb_headroom(skb) != sizeof(*virtio_vsock_hdr(skb)));



			si = skb_shinfo(skb);



			for (i = 0; i < si->nr_frags; i++) {

				skb_frag_t *skb_frag = &si->frags[i];

				void *va;



				/* We will use 'page_to_virt()' for the userspace page

				 * here, because virtio or dma-mapping layers will call

				 * 'virt_to_phys()' later to fill the buffer descriptor.

				 * We don't touch memory at "virtual" address of this page.

				 */

				va = page_to_virt(skb_frag->bv_page);

				sg_init_one(sgs[out_sg],

					    va + skb_frag->bv_offset,

					    skb_frag->bv_len);

				out_sg++;

			}

		}



		ret = virtqueue_add_sgs(vq, sgs, out_sg, in_sg, skb, GFP_KERNEL);
@@ -621,6 +663,7 @@ static int virtio_vsock_probe(struct virtio_device *vdev) 
{

	struct virtio_vsock *vsock = NULL;

	int ret;

	int i;



	ret = mutex_lock_interruptible(&the_virtio_vsock_mutex);

	if (ret)
@@ -663,6 +706,9 @@ static int virtio_vsock_probe(struct virtio_device *vdev) 
	if (ret < 0)

		goto out;



	for (i = 0; i < ARRAY_SIZE(vsock->out_sgs); i++)

		vsock->out_sgs[i] = &vsock->out_bufs[i];



	rcu_assign_pointer(the_virtio_vsock, vsock);



	mutex_unlock(&the_virtio_vsock_mutex);