| Message ID | b3060caf-df19-f1df-6d27-4e58f894c417@sberdevices.ru (mailing list archive) |
|---|---|
| State | RFC |
| Headers | show |
| Series | vsock: MSG_ZEROCOPY flag support | expand |
On Mon, Feb 06, 2023 at 06:58:24AM +0000, Arseniy Krasnov wrote: >Use pages of non-linear skb as buffers in virtio tx queue. > >Signed-off-by: Arseniy Krasnov <AVKrasnov@sberdevices.ru> >--- > net/vmw_vsock/virtio_transport.c | 31 +++++++++++++++++++++++++------ > 1 file changed, 25 insertions(+), 6 deletions(-) > >diff --git a/net/vmw_vsock/virtio_transport.c b/net/vmw_vsock/virtio_transport.c >index 28b5a8e8e094..b8a7d6dc9f46 100644 >--- a/net/vmw_vsock/virtio_transport.c >+++ b/net/vmw_vsock/virtio_transport.c >@@ -100,7 +100,8 @@ virtio_transport_send_pkt_work(struct work_struct *work) > vq = vsock->vqs[VSOCK_VQ_TX]; > > for (;;) { >- struct scatterlist hdr, buf, *sgs[2]; >+ struct scatterlist *sgs[MAX_SKB_FRAGS + 1]; >+ struct scatterlist bufs[MAX_SKB_FRAGS + 1]; + 1 is for the header, right? I'd add a comment just to be clear ;-) > int ret, in_sg = 0, out_sg = 0; > struct sk_buff *skb; > bool reply; >@@ -111,12 +112,30 @@ 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[0], virtio_vsock_hdr(skb), sizeof(*virtio_vsock_hdr(skb))); >+ sgs[out_sg++] = &bufs[0]; >+ >+ if (skb_is_nonlinear(skb)) { >+ int i; >+ >+ for (i = 0; i < skb_shinfo(skb)->nr_frags; i++) { >+ struct page *data_page = skb_shinfo(skb)->frags[i].bv_page; >+ >+ /* 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. >+ */ IIUC data_page is a user page, so since we are exposing it to the host, I think we should pin it. Is data_page always a user page, or can it be a kernel page when skb is nonlinear? Thanks, Stefano >+ sg_init_one(&bufs[i + 1], >+ page_to_virt(data_page), PAGE_SIZE); >+ sgs[out_sg++] = &bufs[i + 1]; >+ } >+ } else { >+ if (skb->len > 0) { >+ sg_init_one(&bufs[1], skb->data, skb->len); >+ sgs[out_sg++] = &bufs[1]; >+ } > >- 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; > } > > ret = virtqueue_add_sgs(vq, sgs, out_sg, in_sg, skb, GFP_KERNEL); >-- >2.25.1
On 16.02.2023 17:18, Stefano Garzarella wrote: > On Mon, Feb 06, 2023 at 06:58:24AM +0000, Arseniy Krasnov wrote: >> Use pages of non-linear skb as buffers in virtio tx queue. >> >> Signed-off-by: Arseniy Krasnov <AVKrasnov@sberdevices.ru> >> --- >> net/vmw_vsock/virtio_transport.c | 31 +++++++++++++++++++++++++------ >> 1 file changed, 25 insertions(+), 6 deletions(-) >> >> diff --git a/net/vmw_vsock/virtio_transport.c b/net/vmw_vsock/virtio_transport.c >> index 28b5a8e8e094..b8a7d6dc9f46 100644 >> --- a/net/vmw_vsock/virtio_transport.c >> +++ b/net/vmw_vsock/virtio_transport.c >> @@ -100,7 +100,8 @@ virtio_transport_send_pkt_work(struct work_struct *work) >> vq = vsock->vqs[VSOCK_VQ_TX]; >> >> for (;;) { >> - struct scatterlist hdr, buf, *sgs[2]; >> + struct scatterlist *sgs[MAX_SKB_FRAGS + 1]; >> + struct scatterlist bufs[MAX_SKB_FRAGS + 1]; > > + 1 is for the header, right? > I'd add a comment just to be clear ;-) > >> int ret, in_sg = 0, out_sg = 0; >> struct sk_buff *skb; >> bool reply; >> @@ -111,12 +112,30 @@ 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[0], virtio_vsock_hdr(skb), sizeof(*virtio_vsock_hdr(skb))); >> + sgs[out_sg++] = &bufs[0]; >> + >> + if (skb_is_nonlinear(skb)) { >> + int i; >> + >> + for (i = 0; i < skb_shinfo(skb)->nr_frags; i++) { >> + struct page *data_page = skb_shinfo(skb)->frags[i].bv_page; >> + >> + /* 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. >> + */ > > IIUC data_page is a user page, so since we are exposing it to the host, > I think we should pin it. > > Is data_page always a user page, or can it be a kernel page when skb is nonlinear? By default it is user page, but...may be it is possible to send page of mapped file with MAP_SHARED flags(i think it this case it will be page from page cache) > > Thanks, > Stefano > >> + sg_init_one(&bufs[i + 1], >> + page_to_virt(data_page), PAGE_SIZE); >> + sgs[out_sg++] = &bufs[i + 1]; >> + } >> + } else { >> + if (skb->len > 0) { >> + sg_init_one(&bufs[1], skb->data, skb->len); >> + sgs[out_sg++] = &bufs[1]; >> + } >> >> - 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; >> } >> >> 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 28b5a8e8e094..b8a7d6dc9f46 100644 --- a/net/vmw_vsock/virtio_transport.c +++ b/net/vmw_vsock/virtio_transport.c @@ -100,7 +100,8 @@ virtio_transport_send_pkt_work(struct work_struct *work) vq = vsock->vqs[VSOCK_VQ_TX]; for (;;) { - struct scatterlist hdr, buf, *sgs[2]; + 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 +112,30 @@ 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[0], virtio_vsock_hdr(skb), sizeof(*virtio_vsock_hdr(skb))); + sgs[out_sg++] = &bufs[0]; + + if (skb_is_nonlinear(skb)) { + int i; + + for (i = 0; i < skb_shinfo(skb)->nr_frags; i++) { + struct page *data_page = skb_shinfo(skb)->frags[i].bv_page; + + /* 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[i + 1], + page_to_virt(data_page), PAGE_SIZE); + sgs[out_sg++] = &bufs[i + 1]; + } + } else { + if (skb->len > 0) { + sg_init_one(&bufs[1], skb->data, skb->len); + sgs[out_sg++] = &bufs[1]; + } - 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; } ret = virtqueue_add_sgs(vq, sgs, out_sg, in_sg, skb, GFP_KERNEL);
Use pages of non-linear skb as buffers in virtio tx queue. Signed-off-by: Arseniy Krasnov <AVKrasnov@sberdevices.ru> --- net/vmw_vsock/virtio_transport.c | 31 +++++++++++++++++++++++++------ 1 file changed, 25 insertions(+), 6 deletions(-)