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Message-ID: <20230814212720.3679058-3-AVKrasnov@sberdevices.ru>
Date: Tue, 15 Aug 2023 00:27:18 +0300
From: Arseniy Krasnov <AVKrasnov@...rdevices.ru>
To: Stefan Hajnoczi <stefanha@...hat.com>,
Stefano Garzarella <sgarzare@...hat.com>,
"David S. Miller" <davem@...emloft.net>,
Eric Dumazet <edumazet@...gle.com>,
Jakub Kicinski <kuba@...nel.org>,
Paolo Abeni <pabeni@...hat.com>,
"Michael S. Tsirkin" <mst@...hat.com>,
Jason Wang <jasowang@...hat.com>,
Bobby Eshleman <bobby.eshleman@...edance.com>
CC: <kvm@...r.kernel.org>, <virtualization@...ts.linux-foundation.org>,
<netdev@...r.kernel.org>, <linux-kernel@...r.kernel.org>,
<kernel@...rdevices.ru>, <oxffffaa@...il.com>,
<avkrasnov@...rdevices.ru>,
Arseniy Krasnov <AVKrasnov@...rdevices.ru>
Subject: [PATCH net-next v6 2/4] 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@...rdevices.ru>
Reviewed-by: Stefano Garzarella <sgarzare@...hat.com>
---
Changelog:
v2 -> v3:
* Comment about 'page_to_virt()' is updated. I don't remove R-b,
as this change is quiet small I guess.
net/vmw_vsock/virtio_transport.c | 41 +++++++++++++++++++++++++++-----
1 file changed, 35 insertions(+), 6 deletions(-)
diff --git a/net/vmw_vsock/virtio_transport.c b/net/vmw_vsock/virtio_transport.c
index e95df847176b..7bbcc8093e51 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 +113,39 @@ 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;
- 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 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(&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
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