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 <[email protected]>
---
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
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