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Date: Tue, 2 Jul 2019 14:15:55 +0900
From: Yuya Kusakabe <yuya.kusakabe@...il.com>
To: Jason Wang <jasowang@...hat.com>
Cc: ast@...nel.org, daniel@...earbox.net, davem@...emloft.net,
hawk@...nel.org, jakub.kicinski@...ronome.com,
john.fastabend@...il.com, kafai@...com, mst@...hat.com,
netdev@...r.kernel.org, songliubraving@...com, yhs@...com
Subject: Re: [PATCH bpf-next v2] virtio_net: add XDP meta data support
On 7/2/19 12:59 PM, Jason Wang wrote:
>
> On 2019/7/2 上午11:15, Yuya Kusakabe wrote:
>> This adds XDP meta data support to both receive_small() and
>> receive_mergeable().
>>
>> Fixes: de8f3a83b0a0 ("bpf: add meta pointer for direct access")
>> Signed-off-by: Yuya Kusakabe <yuya.kusakabe@...il.com>
>> ---
>> v2:
>> - keep copy untouched in page_to_skb().
>> - preserve the vnet header in receive_small().
>> - fix indentation.
>> ---
>> drivers/net/virtio_net.c | 39 +++++++++++++++++++++++++++------------
>> 1 file changed, 27 insertions(+), 12 deletions(-)
>>
>> diff --git a/drivers/net/virtio_net.c b/drivers/net/virtio_net.c
>> index 4f3de0ac8b0b..2ebabb08b824 100644
>> --- a/drivers/net/virtio_net.c
>> +++ b/drivers/net/virtio_net.c
>> @@ -371,7 +371,7 @@ static struct sk_buff *page_to_skb(struct virtnet_info *vi,
>> struct receive_queue *rq,
>> struct page *page, unsigned int offset,
>> unsigned int len, unsigned int truesize,
>> - bool hdr_valid)
>> + bool hdr_valid, unsigned int metasize)
>> {
>> struct sk_buff *skb;
>> struct virtio_net_hdr_mrg_rxbuf *hdr;
>> @@ -393,7 +393,7 @@ static struct sk_buff *page_to_skb(struct virtnet_info *vi,
>> else
>> hdr_padded_len = sizeof(struct padded_vnet_hdr);
>> - if (hdr_valid)
>> + if (hdr_valid && !metasize)
>> memcpy(hdr, p, hdr_len);
>> len -= hdr_len;
>> @@ -405,6 +405,11 @@ static struct sk_buff *page_to_skb(struct virtnet_info *vi,
>> copy = skb_tailroom(skb);
>> skb_put_data(skb, p, copy);
>> + if (metasize) {
>> + __skb_pull(skb, metasize);
>> + skb_metadata_set(skb, metasize);
>> + }
>> +
>> len -= copy;
>> offset += copy;
>> @@ -644,6 +649,7 @@ static struct sk_buff *receive_small(struct net_device *dev,
>> unsigned int delta = 0;
>> struct page *xdp_page;
>> int err;
>> + unsigned int metasize = 0;
>> len -= vi->hdr_len;
>> stats->bytes += len;
>> @@ -683,8 +689,8 @@ static struct sk_buff *receive_small(struct net_device *dev,
>> xdp.data_hard_start = buf + VIRTNET_RX_PAD + vi->hdr_len;
>> xdp.data = xdp.data_hard_start + xdp_headroom;
>> - xdp_set_data_meta_invalid(&xdp);
>> xdp.data_end = xdp.data + len;
>> + xdp.data_meta = xdp.data;
>> xdp.rxq = &rq->xdp_rxq;
>> orig_data = xdp.data;
>> act = bpf_prog_run_xdp(xdp_prog, &xdp);
>> @@ -695,9 +701,11 @@ static struct sk_buff *receive_small(struct net_device *dev,
>> /* Recalculate length in case bpf program changed it */
>> delta = orig_data - xdp.data;
>> len = xdp.data_end - xdp.data;
>> + metasize = xdp.data - xdp.data_meta;
>> break;
>> case XDP_TX:
>> stats->xdp_tx++;
>> + xdp.data_meta = xdp.data;
>> xdpf = convert_to_xdp_frame(&xdp);
>> if (unlikely(!xdpf))
>> goto err_xdp;
>> @@ -740,6 +748,9 @@ static struct sk_buff *receive_small(struct net_device *dev,
>> memcpy(skb_vnet_hdr(skb), buf, vi->hdr_len);
>> } /* keep zeroed vnet hdr since packet was changed by bpf */
>
>
> I wonder whether or not it's as simple as this. Consider bpf may adjust meta, it looks to me that the vnet header will be overwrite here? If yes, we probably need to have a device specific value then bpf can move the device metadata like vnet header for us?>
> Thanks
Yes, the vnet header is overwrite by xdp metadata. I'll fix it.
Thanks.
>
>
>> + if (metasize)
>> + skb_metadata_set(skb, metasize);
>> +
>> err:
>> return skb;
>> @@ -760,8 +771,8 @@ static struct sk_buff *receive_big(struct net_device *dev,
>> struct virtnet_rq_stats *stats)
>> {
>> struct page *page = buf;
>> - struct sk_buff *skb = page_to_skb(vi, rq, page, 0, len,
>> - PAGE_SIZE, true);
>> + struct sk_buff *skb =
>> + page_to_skb(vi, rq, page, 0, len, PAGE_SIZE, true, 0);
>> stats->bytes += len - vi->hdr_len;
>> if (unlikely(!skb))
>> @@ -793,6 +804,7 @@ static struct sk_buff *receive_mergeable(struct net_device *dev,
>> unsigned int truesize;
>> unsigned int headroom = mergeable_ctx_to_headroom(ctx);
>> int err;
>> + unsigned int metasize = 0;
>> head_skb = NULL;
>> stats->bytes += len - vi->hdr_len;
>> @@ -839,8 +851,8 @@ static struct sk_buff *receive_mergeable(struct net_device *dev,
>> data = page_address(xdp_page) + offset;
>> xdp.data_hard_start = data - VIRTIO_XDP_HEADROOM + vi->hdr_len;
>> xdp.data = data + vi->hdr_len;
>> - xdp_set_data_meta_invalid(&xdp);
>> xdp.data_end = xdp.data + (len - vi->hdr_len);
>> + xdp.data_meta = xdp.data;
>> xdp.rxq = &rq->xdp_rxq;
>> act = bpf_prog_run_xdp(xdp_prog, &xdp);
>> @@ -852,8 +864,9 @@ static struct sk_buff *receive_mergeable(struct net_device *dev,
>> * adjustments. Note other cases do not build an
>> * skb and avoid using offset
>> */
>> - offset = xdp.data -
>> - page_address(xdp_page) - vi->hdr_len;
>> + metasize = xdp.data - xdp.data_meta;
>> + offset = xdp.data - page_address(xdp_page) -
>> + vi->hdr_len - metasize;
>> /* recalculate len if xdp.data or xdp.data_end were
>> * adjusted
>> @@ -863,14 +876,15 @@ static struct sk_buff *receive_mergeable(struct net_device *dev,
>> if (unlikely(xdp_page != page)) {
>> rcu_read_unlock();
>> put_page(page);
>> - head_skb = page_to_skb(vi, rq, xdp_page,
>> - offset, len,
>> - PAGE_SIZE, false);
>> + head_skb = page_to_skb(vi, rq, xdp_page, offset,
>> + len, PAGE_SIZE, false,
>> + metasize);
>> return head_skb;
>> }
>> break;
>> case XDP_TX:
>> stats->xdp_tx++;
>> + xdp.data_meta = xdp.data;
>> xdpf = convert_to_xdp_frame(&xdp);
>> if (unlikely(!xdpf))
>> goto err_xdp;
>> @@ -921,7 +935,8 @@ static struct sk_buff *receive_mergeable(struct net_device *dev,
>> goto err_skb;
>> }
>> - head_skb = page_to_skb(vi, rq, page, offset, len, truesize, !xdp_prog);
>> + head_skb = page_to_skb(vi, rq, page, offset, len, truesize, !xdp_prog,
>> + metasize);
>> curr_skb = head_skb;
>> if (unlikely(!curr_skb))
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