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([2001:ee0:4f0e:fb30:76aa:9d32:607:b042]) by smtp.gmail.com with ESMTPSA id d9443c01a7336-235069fa2c7sm3485485ad.0.2025.05.28.20.42.29 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Wed, 28 May 2025 20:42:35 -0700 (PDT) Message-ID: Date: Thu, 29 May 2025 10:42:27 +0700 Precedence: bulk X-Mailing-List: netdev@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [RFC PATCH net-next v2 1/2] virtio-net: support zerocopy multi buffer XDP in mergeable To: ALOK TIWARI , netdev@vger.kernel.org Cc: "Michael S. Tsirkin" , Jason Wang , Xuan Zhuo , =?UTF-8?Q?Eugenio_P=C3=A9rez?= , Andrew Lunn , "David S. Miller" , Eric Dumazet , Jakub Kicinski , Paolo Abeni , Alexei Starovoitov , Daniel Borkmann , Jesper Dangaard Brouer , John Fastabend , virtualization@lists.linux.dev, linux-kernel@vger.kernel.org, bpf@vger.kernel.org References: <20250527161904.75259-1-minhquangbui99@gmail.com> <20250527161904.75259-2-minhquangbui99@gmail.com> Content-Language: en-US From: Bui Quang Minh In-Reply-To: Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 8bit On 5/28/25 23:44, ALOK TIWARI wrote: > > > On 27-05-2025 21:49, Bui Quang Minh wrote: >> Currently, in zerocopy mode with mergeable receive buffer, virtio-net >> does not support multi buffer but a single buffer only. This commit adds >> support for multi mergeable receive buffer in the zerocopy XDP path by >> utilizing XDP buffer with frags. >> >> Signed-off-by: Bui Quang Minh >> --- >>   drivers/net/virtio_net.c | 123 +++++++++++++++++++++------------------ >>   1 file changed, 66 insertions(+), 57 deletions(-) >> >> diff --git a/drivers/net/virtio_net.c b/drivers/net/virtio_net.c >> index e53ba600605a..a9558650f205 100644 >> --- a/drivers/net/virtio_net.c >> +++ b/drivers/net/virtio_net.c >> @@ -45,6 +45,8 @@ module_param(napi_tx, bool, 0644); >>   #define VIRTIO_XDP_TX        BIT(0) >>   #define VIRTIO_XDP_REDIR    BIT(1) >>   +#define VIRTNET_MAX_ZC_SEGS    8 >> + >>   /* RX packet size EWMA. The average packet size is used to >> determine the packet >>    * buffer size when refilling RX rings. As the entire RX ring may >> be refilled >>    * at once, the weight is chosen so that the EWMA will be >> insensitive to short- >> @@ -1232,65 +1234,53 @@ static void xsk_drop_follow_bufs(struct >> net_device *dev, >>       } >>   } >>   -static int xsk_append_merge_buffer(struct virtnet_info *vi, >> -                   struct receive_queue *rq, >> -                   struct sk_buff *head_skb, >> -                   u32 num_buf, >> -                   struct virtio_net_hdr_mrg_rxbuf *hdr, >> -                   struct virtnet_rq_stats *stats) >> +static int virtnet_build_xsk_buff_mrg(struct virtnet_info *vi, >> +                      struct receive_queue *rq, >> +                      u32 num_buf, >> +                      struct xdp_buff *xdp, >> +                      struct virtnet_rq_stats *stats) >>   { >> -    struct sk_buff *curr_skb; >> -    struct xdp_buff *xdp; >> -    u32 len, truesize; >> -    struct page *page; >> +    unsigned int len; >>       void *buf; >>   -    curr_skb = head_skb; >> +    if (num_buf < 2) >> +        return 0; >> + >> +    while (num_buf > 1) { >> +        struct xdp_buff *new_xdp; >>   -    while (--num_buf) { >>           buf = virtqueue_get_buf(rq->vq, &len); >> -        if (unlikely(!buf)) { >> -            pr_debug("%s: rx error: %d buffers out of %d missing\n", >> -                 vi->dev->name, num_buf, >> -                 virtio16_to_cpu(vi->vdev, >> -                         hdr->num_buffers)); >> +        if (!unlikely(buf)) { > > if (unlikely(!buf)) { ? Thanks, I'll fix this in the next version. > >> +            pr_debug("%s: rx error: %d buffers missing\n", >> +                 vi->dev->name, num_buf); >>               DEV_STATS_INC(vi->dev, rx_length_errors); > > Thanks, > Alok