On Mon, Feb 06, 2023 at 06:57:16AM +0000, Arseniy Krasnov wrote:
This adds copying to guest's virtio buffers from non-linear skbs. Such
skbs are created by protocol layer when MSG_ZEROCOPY flags is used.
Signed-off-by: Arseniy Krasnov <[email protected]>
---
drivers/vhost/vsock.c | 56 ++++++++++++++++++++++++++++++++----
include/linux/virtio_vsock.h | 12 ++++++++
2 files changed, 63 insertions(+), 5 deletions(-)
diff --git a/drivers/vhost/vsock.c b/drivers/vhost/vsock.c
index 1f3b89c885cc..60b9cafa3e31 100644
--- a/drivers/vhost/vsock.c
+++ b/drivers/vhost/vsock.c
@@ -86,6 +86,44 @@ static struct vhost_vsock *vhost_vsock_get(u32 guest_cid)
return NULL;
}
+static int vhost_transport_copy_nonlinear_skb(struct sk_buff *skb,
+ struct iov_iter *iov_iter,
+ size_t len)
+{
+ size_t rest_len = len;
+
+ while (rest_len && virtio_vsock_skb_has_frags(skb)) {
+ struct bio_vec *curr_vec;
+ size_t curr_vec_end;
+ size_t to_copy;
+ int curr_frag;
+ int curr_offs;
+
+ curr_frag = VIRTIO_VSOCK_SKB_CB(skb)->curr_frag;
+ curr_offs = VIRTIO_VSOCK_SKB_CB(skb)->frag_off;
+ curr_vec = &skb_shinfo(skb)->frags[curr_frag];
+
+ curr_vec_end = curr_vec->bv_offset + curr_vec->bv_len;
+ to_copy = min(rest_len, (size_t)(curr_vec_end - curr_offs));
+
+ if (copy_page_to_iter(curr_vec->bv_page, curr_offs,
+ to_copy, iov_iter) != to_copy)
+ return -1;
+
+ rest_len -= to_copy;
+ VIRTIO_VSOCK_SKB_CB(skb)->frag_off += to_copy;
+
+ if (VIRTIO_VSOCK_SKB_CB(skb)->frag_off == (curr_vec_end)) {
+ VIRTIO_VSOCK_SKB_CB(skb)->curr_frag++;
+ VIRTIO_VSOCK_SKB_CB(skb)->frag_off = 0;
+ }
+ }
Can it happen that we exit this loop and rest_len is not 0?
In this case, is it correct to decrement data_len by len?
Thanks,
Stefano
+
+ skb->data_len -= len;
+
+ return 0;
+}
+
static void
vhost_transport_do_send_pkt(struct vhost_vsock *vsock,
struct vhost_virtqueue *vq)
@@ -197,11 +235,19 @@ vhost_transport_do_send_pkt(struct vhost_vsock *vsock,
break;
}
- nbytes = copy_to_iter(skb->data, payload_len, &iov_iter);
- if (nbytes != payload_len) {
- kfree_skb(skb);
- vq_err(vq, "Faulted on copying pkt buf\n");
- break;
+ if (skb_is_nonlinear(skb)) {
+ if (vhost_transport_copy_nonlinear_skb(skb, &iov_iter,
+ payload_len)) {
+ vq_err(vq, "Faulted on copying pkt buf from
page\n");
+ break;
+ }
+ } else {
+ nbytes = copy_to_iter(skb->data, payload_len,
&iov_iter);
+ if (nbytes != payload_len) {
+ kfree_skb(skb);
+ vq_err(vq, "Faulted on copying pkt buf\n");
+ break;
+ }
}
/* Deliver to monitoring devices all packets that we
diff --git a/include/linux/virtio_vsock.h b/include/linux/virtio_vsock.h
index 3f9c16611306..e7efdb78ce6e 100644
--- a/include/linux/virtio_vsock.h
+++ b/include/linux/virtio_vsock.h
@@ -12,6 +12,10 @@
struct virtio_vsock_skb_cb {
bool reply;
bool tap_delivered;
+ /* Current fragment in 'frags' of skb. */
+ u32 curr_frag;
+ /* Offset from 0 in current fragment. */
+ u32 frag_off;
};
#define VIRTIO_VSOCK_SKB_CB(skb) ((struct virtio_vsock_skb_cb *)((skb)->cb))
@@ -46,6 +50,14 @@ static inline void
virtio_vsock_skb_clear_tap_delivered(struct sk_buff *skb)
VIRTIO_VSOCK_SKB_CB(skb)->tap_delivered = false;
}
+static inline bool virtio_vsock_skb_has_frags(struct sk_buff *skb)
+{
+ if (!skb_is_nonlinear(skb))
+ return false;
+
+ return VIRTIO_VSOCK_SKB_CB(skb)->curr_frag != skb_shinfo(skb)->nr_frags;
+}
+
static inline void virtio_vsock_skb_rx_put(struct sk_buff *skb)
{
u32 len;
--
2.25.1
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