diff options
Diffstat (limited to 'drivers/net/virtio_net.c')
| -rw-r--r-- | drivers/net/virtio_net.c | 75 |
1 files changed, 74 insertions, 1 deletions
diff --git a/drivers/net/virtio_net.c b/drivers/net/virtio_net.c index ca3d2e2350c6..08327e005ccc 100644 --- a/drivers/net/virtio_net.c +++ b/drivers/net/virtio_net.c @@ -471,6 +471,64 @@ xdp_xmit: return NULL; } +/* The conditions to enable XDP should preclude the underlying device from + * sending packets across multiple buffers (num_buf > 1). However per spec + * it does not appear to be illegal to do so but rather just against convention. + * So in order to avoid making a system unresponsive the packets are pushed + * into a page and the XDP program is run. This will be extremely slow and we + * push a warning to the user to fix this as soon as possible. Fixing this may + * require resolving the underlying hardware to determine why multiple buffers + * are being received or simply loading the XDP program in the ingress stack + * after the skb is built because there is no advantage to running it here + * anymore. + */ +static struct page *xdp_linearize_page(struct receive_queue *rq, + u16 num_buf, + struct page *p, + int offset, + unsigned int *len) +{ + struct page *page = alloc_page(GFP_ATOMIC); + unsigned int page_off = 0; + + if (!page) + return NULL; + + memcpy(page_address(page) + page_off, page_address(p) + offset, *len); + page_off += *len; + + while (--num_buf) { + unsigned int buflen; + unsigned long ctx; + void *buf; + int off; + + ctx = (unsigned long)virtqueue_get_buf(rq->vq, &buflen); + if (unlikely(!ctx)) + goto err_buf; + + /* guard against a misconfigured or uncooperative backend that + * is sending packet larger than the MTU. + */ + if ((page_off + buflen) > PAGE_SIZE) + goto err_buf; + + buf = mergeable_ctx_to_buf_address(ctx); + p = virt_to_head_page(buf); + off = buf - page_address(p); + + memcpy(page_address(page) + page_off, + page_address(p) + off, buflen); + page_off += buflen; + } + + *len = page_off; + return page; +err_buf: + __free_pages(page, 0); + return NULL; +} + static struct sk_buff *receive_mergeable(struct net_device *dev, struct virtnet_info *vi, struct receive_queue *rq, @@ -491,6 +549,7 @@ static struct sk_buff *receive_mergeable(struct net_device *dev, rcu_read_lock(); xdp_prog = rcu_dereference(rq->xdp_prog); if (xdp_prog) { + struct page *xdp_page; u32 act; /* No known backend devices should send packets with @@ -500,7 +559,15 @@ static struct sk_buff *receive_mergeable(struct net_device *dev, */ if (unlikely(num_buf > 1)) { bpf_warn_invalid_xdp_buffer(); - goto err_xdp; + + /* linearize data for XDP */ + xdp_page = xdp_linearize_page(rq, num_buf, + page, offset, &len); + if (!xdp_page) + goto err_xdp; + offset = 0; + } else { + xdp_page = page; } /* Transient failure which in theory could occur if @@ -514,12 +581,18 @@ static struct sk_buff *receive_mergeable(struct net_device *dev, act = do_xdp_prog(vi, rq, xdp_prog, page, offset, len); switch (act) { case XDP_PASS: + if (unlikely(xdp_page != page)) + __free_pages(xdp_page, 0); break; case XDP_TX: + if (unlikely(xdp_page != page)) + goto err_xdp; rcu_read_unlock(); goto xdp_xmit; case XDP_DROP: default: + if (unlikely(xdp_page != page)) + __free_pages(xdp_page, 0); goto err_xdp; } } |