From 64c99d2d6adac80cb17669736e32bdb331d68193 Mon Sep 17 00:00:00 2001 From: Arseniy Krasnov Date: Sat, 16 Sep 2023 16:09:16 +0300 Subject: 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 Reviewed-by: Stefano Garzarella Acked-by: Michael S. Tsirkin Signed-off-by: Paolo Abeni --- net/vmw_vsock/virtio_transport.c | 60 +++++++++++++++++++++++++++++++++++----- 1 file changed, 53 insertions(+), 7 deletions(-) (limited to 'net') diff --git a/net/vmw_vsock/virtio_transport.c b/net/vmw_vsock/virtio_transport.c index e95df847176b..73d730156349 100644 --- a/net/vmw_vsock/virtio_transport.c +++ b/net/vmw_vsock/virtio_transport.c @@ -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); - - sg_init_one(&hdr, virtio_vsock_hdr(skb), sizeof(*virtio_vsock_hdr(skb))); - sgs[out_sg++] = &hdr; - if (skb->len > 0) { - sg_init_one(&buf, skb->data, skb->len); - sgs[out_sg++] = &buf; + sgs = vsock->out_sgs; + sg_init_one(sgs[out_sg], virtio_vsock_hdr(skb), + sizeof(*virtio_vsock_hdr(skb))); + out_sg++; + + if (!skb_is_nonlinear(skb)) { + if (skb->len > 0) { + 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); -- cgit v1.2.3