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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: Arseniy Krasnov <avkrasnov@salutedevices.com> Reviewed-by: Stefano Garzarella <sgarzare@redhat.com> Acked-by: Michael S. Tsirkin <mst@redhat.com> Signed-off-by: Paolo Abeni <pabeni@redhat.com>
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@ -63,6 +63,17 @@ struct virtio_vsock {
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u32 guest_cid;
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bool seqpacket_allow;
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/* These fields are used only in tx path in function
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* 'virtio_transport_send_pkt_work()', so to save
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* stack space in it, place both of them here. Each
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* pointer from 'out_sgs' points to the corresponding
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* element in 'out_bufs' - this is initialized in
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* 'virtio_vsock_probe()'. Both fields are protected
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* by 'tx_lock'. +1 is needed for packet header.
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*/
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struct scatterlist *out_sgs[MAX_SKB_FRAGS + 1];
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struct scatterlist out_bufs[MAX_SKB_FRAGS + 1];
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};
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static u32 virtio_transport_get_local_cid(void)
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@ -100,8 +111,8 @@ virtio_transport_send_pkt_work(struct work_struct *work)
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vq = vsock->vqs[VSOCK_VQ_TX];
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for (;;) {
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struct scatterlist hdr, buf, *sgs[2];
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int ret, in_sg = 0, out_sg = 0;
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struct scatterlist **sgs;
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struct sk_buff *skb;
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bool reply;
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@ -111,12 +122,43 @@ virtio_transport_send_pkt_work(struct work_struct *work)
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virtio_transport_deliver_tap_pkt(skb);
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reply = virtio_vsock_skb_reply(skb);
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sgs = vsock->out_sgs;
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sg_init_one(sgs[out_sg], virtio_vsock_hdr(skb),
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sizeof(*virtio_vsock_hdr(skb)));
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out_sg++;
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sg_init_one(&hdr, virtio_vsock_hdr(skb), sizeof(*virtio_vsock_hdr(skb)));
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sgs[out_sg++] = &hdr;
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if (skb->len > 0) {
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sg_init_one(&buf, skb->data, skb->len);
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sgs[out_sg++] = &buf;
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if (!skb_is_nonlinear(skb)) {
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if (skb->len > 0) {
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sg_init_one(sgs[out_sg], skb->data, skb->len);
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out_sg++;
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}
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} else {
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struct skb_shared_info *si;
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int i;
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/* If skb is nonlinear, then its buffer must contain
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* only header and nothing more. Data is stored in
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* the fragged part.
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*/
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WARN_ON_ONCE(skb_headroom(skb) != sizeof(*virtio_vsock_hdr(skb)));
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si = skb_shinfo(skb);
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for (i = 0; i < si->nr_frags; i++) {
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skb_frag_t *skb_frag = &si->frags[i];
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void *va;
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/* We will use 'page_to_virt()' for the userspace page
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* here, because virtio or dma-mapping layers will call
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* 'virt_to_phys()' later to fill the buffer descriptor.
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* We don't touch memory at "virtual" address of this page.
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*/
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va = page_to_virt(skb_frag->bv_page);
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sg_init_one(sgs[out_sg],
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va + skb_frag->bv_offset,
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skb_frag->bv_len);
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out_sg++;
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}
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}
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ret = virtqueue_add_sgs(vq, sgs, out_sg, in_sg, skb, GFP_KERNEL);
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@ -621,6 +663,7 @@ static int virtio_vsock_probe(struct virtio_device *vdev)
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{
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struct virtio_vsock *vsock = NULL;
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int ret;
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int i;
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ret = mutex_lock_interruptible(&the_virtio_vsock_mutex);
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if (ret)
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@ -663,6 +706,9 @@ static int virtio_vsock_probe(struct virtio_device *vdev)
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if (ret < 0)
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goto out;
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for (i = 0; i < ARRAY_SIZE(vsock->out_sgs); i++)
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vsock->out_sgs[i] = &vsock->out_bufs[i];
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rcu_assign_pointer(the_virtio_vsock, vsock);
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mutex_unlock(&the_virtio_vsock_mutex);
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