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vsock/virtio: support to send non-linear skb

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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@salutedevices.com>
Reviewed-by: Stefano Garzarella <sgarzare@redhat.com>
Acked-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Paolo Abeni <pabeni@redhat.com>
This commit is contained in:
Arseniy Krasnov 2023-09-16 16:09:16 +03:00 committed by Paolo Abeni
parent 0df7cd3c13
commit 64c99d2d6a
1 changed files with 52 additions and 6 deletions
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58
net/vmw_vsock/virtio_transport.c
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@ -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);
sgs = vsock->out_sgs;
sg_init_one(sgs[out_sg], virtio_vsock_hdr(skb),
sizeof(*virtio_vsock_hdr(skb)));
out_sg++;
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;
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);