| Message ID | 20230701063947.3422088-4-AVKrasnov@sberdevices.ru (mailing list archive) |
|---|---|
| State | RFC |
| Delegated to: | Netdev Maintainers |
| Headers | show |
| Series | vsock: MSG_ZEROCOPY flag support | expand |
On Sat, Jul 01, 2023 at 09:39:33AM +0300, Arseniy Krasnov wrote: >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@sberdevices.ru> >--- > Changelog: > v4 -> v5: > * Use 'out_sgs' variable to index 'bufs', not only 'sgs'. > * Move smaller branch above, see 'if (!skb_is_nonlinear(skb)'). > * Remove blank line. > * R-b from Bobby Eshleman removed due to patch update. > > net/vmw_vsock/virtio_transport.c | 40 +++++++++++++++++++++++++++----- > 1 file changed, 34 insertions(+), 6 deletions(-) Reviewed-by: Stefano Garzarella <sgarzare@redhat.com> > >diff --git a/net/vmw_vsock/virtio_transport.c b/net/vmw_vsock/virtio_transport.c >index e95df847176b..6cbb45bb12d2 100644 >--- a/net/vmw_vsock/virtio_transport.c >+++ b/net/vmw_vsock/virtio_transport.c >@@ -100,7 +100,9 @@ virtio_transport_send_pkt_work(struct work_struct *work) > vq = vsock->vqs[VSOCK_VQ_TX]; > > for (;;) { >- struct scatterlist hdr, buf, *sgs[2]; >+ /* +1 is for packet header. */ >+ struct scatterlist *sgs[MAX_SKB_FRAGS + 1]; >+ struct scatterlist bufs[MAX_SKB_FRAGS + 1]; > int ret, in_sg = 0, out_sg = 0; > struct sk_buff *skb; > bool reply; >@@ -111,12 +113,38 @@ virtio_transport_send_pkt_work(struct work_struct *work) > > virtio_transport_deliver_tap_pkt(skb); > reply = virtio_vsock_skb_reply(skb); >+ sg_init_one(&bufs[out_sg], virtio_vsock_hdr(skb), >+ sizeof(*virtio_vsock_hdr(skb))); >+ sgs[out_sg] = &bufs[out_sg]; >+ out_sg++; >+ >+ if (!skb_is_nonlinear(skb)) { >+ if (skb->len > 0) { >+ sg_init_one(&bufs[out_sg], skb->data, skb->len); >+ sgs[out_sg] = &bufs[out_sg]; >+ out_sg++; >+ } >+ } else { >+ struct skb_shared_info *si; >+ int i; >+ >+ si = skb_shinfo(skb); >+ >+ for (i = 0; i < si->nr_frags; i++) { >+ skb_frag_t *skb_frag = &si->frags[i]; >+ void *va = page_to_virt(skb_frag->bv_page); > >- 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; >+ /* We will use 'page_to_virt()' for userspace page here, >+ * because virtio layer will call 'virt_to_phys()' later >+ * to fill buffer descriptor. We don't touch memory at >+ * "virtual" address of this page. >+ */ >+ sg_init_one(&bufs[out_sg], >+ va + skb_frag->bv_offset, >+ skb_frag->bv_len); >+ sgs[out_sg] = &bufs[out_sg]; >+ out_sg++; >+ } > } > > ret = virtqueue_add_sgs(vq, sgs, out_sg, in_sg, skb, GFP_KERNEL); >-- >2.25.1 >
diff --git a/net/vmw_vsock/virtio_transport.c b/net/vmw_vsock/virtio_transport.c index e95df847176b..6cbb45bb12d2 100644 --- a/net/vmw_vsock/virtio_transport.c +++ b/net/vmw_vsock/virtio_transport.c @@ -100,7 +100,9 @@ virtio_transport_send_pkt_work(struct work_struct *work) vq = vsock->vqs[VSOCK_VQ_TX]; for (;;) { - struct scatterlist hdr, buf, *sgs[2]; + /* +1 is for packet header. */ + struct scatterlist *sgs[MAX_SKB_FRAGS + 1]; + struct scatterlist bufs[MAX_SKB_FRAGS + 1]; int ret, in_sg = 0, out_sg = 0; struct sk_buff *skb; bool reply; @@ -111,12 +113,38 @@ virtio_transport_send_pkt_work(struct work_struct *work) virtio_transport_deliver_tap_pkt(skb); reply = virtio_vsock_skb_reply(skb); + sg_init_one(&bufs[out_sg], virtio_vsock_hdr(skb), + sizeof(*virtio_vsock_hdr(skb))); + sgs[out_sg] = &bufs[out_sg]; + out_sg++; + + if (!skb_is_nonlinear(skb)) { + if (skb->len > 0) { + sg_init_one(&bufs[out_sg], skb->data, skb->len); + sgs[out_sg] = &bufs[out_sg]; + out_sg++; + } + } else { + struct skb_shared_info *si; + int i; + + si = skb_shinfo(skb); + + for (i = 0; i < si->nr_frags; i++) { + skb_frag_t *skb_frag = &si->frags[i]; + void *va = page_to_virt(skb_frag->bv_page); - 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; + /* We will use 'page_to_virt()' for userspace page here, + * because virtio layer will call 'virt_to_phys()' later + * to fill buffer descriptor. We don't touch memory at + * "virtual" address of this page. + */ + sg_init_one(&bufs[out_sg], + va + skb_frag->bv_offset, + skb_frag->bv_len); + sgs[out_sg] = &bufs[out_sg]; + out_sg++; + } } ret = virtqueue_add_sgs(vq, sgs, out_sg, in_sg, skb, GFP_KERNEL);
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@sberdevices.ru> --- Changelog: v4 -> v5: * Use 'out_sgs' variable to index 'bufs', not only 'sgs'. * Move smaller branch above, see 'if (!skb_is_nonlinear(skb)'). * Remove blank line. * R-b from Bobby Eshleman removed due to patch update. net/vmw_vsock/virtio_transport.c | 40 +++++++++++++++++++++++++++----- 1 file changed, 34 insertions(+), 6 deletions(-)