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Tsirkin" To: Xuan Zhuo Cc: netdev@vger.kernel.org, "David S. Miller" , Eric Dumazet , Jakub Kicinski , Paolo Abeni , Jason Wang , Alexei Starovoitov , Daniel Borkmann , Jesper Dangaard Brouer , John Fastabend , virtualization@lists.linux-foundation.org, bpf@vger.kernel.org Subject: Re: [PATCH net-next v2 12/21] virtio_net: xsk: tx: support tx Message-ID: <20231109030424-mutt-send-email-mst@kernel.org> References: <20231107031227.100015-1-xuanzhuo@linux.alibaba.com> <20231107031227.100015-13-xuanzhuo@linux.alibaba.com> Precedence: bulk X-Mailing-List: virtualization@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 In-Reply-To: <20231107031227.100015-13-xuanzhuo@linux.alibaba.com> X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Content-Type: text/plain; charset=us-ascii Content-Disposition: inline On Tue, Nov 07, 2023 at 11:12:18AM +0800, Xuan Zhuo wrote: > The driver's tx napi is very important for XSK. It is responsible for > obtaining data from the XSK queue and sending it out. > > At the beginning, we need to trigger tx napi. > > Signed-off-by: Xuan Zhuo > --- > drivers/net/virtio/main.c | 12 +++- > drivers/net/virtio/virtio_net.h | 3 +- > drivers/net/virtio/xsk.c | 110 ++++++++++++++++++++++++++++++++ > drivers/net/virtio/xsk.h | 13 ++++ > 4 files changed, 136 insertions(+), 2 deletions(-) > > diff --git a/drivers/net/virtio/main.c b/drivers/net/virtio/main.c > index 6c608b3ce27d..ff6bc764089d 100644 > --- a/drivers/net/virtio/main.c > +++ b/drivers/net/virtio/main.c > @@ -2074,6 +2074,7 @@ static int virtnet_poll_tx(struct napi_struct *napi, int budget) > struct virtnet_info *vi = sq->vq->vdev->priv; > unsigned int index = vq2txq(sq->vq); > struct netdev_queue *txq; > + int busy = 0; > int opaque; > bool done; > > @@ -2086,11 +2087,20 @@ static int virtnet_poll_tx(struct napi_struct *napi, int budget) > txq = netdev_get_tx_queue(vi->dev, index); > __netif_tx_lock(txq, raw_smp_processor_id()); > virtqueue_disable_cb(sq->vq); > - free_old_xmit(sq, true); > + > + if (sq->xsk.pool) > + busy |= virtnet_xsk_xmit(sq, sq->xsk.pool, budget); You use bitwise or on errno values? What's going on here? > + else > + free_old_xmit(sq, true); > > if (sq->vq->num_free >= 2 + MAX_SKB_FRAGS) > netif_tx_wake_queue(txq); > > + if (busy) { > + __netif_tx_unlock(txq); > + return budget; > + } > + > opaque = virtqueue_enable_cb_prepare(sq->vq); > > done = napi_complete_done(napi, 0); > diff --git a/drivers/net/virtio/virtio_net.h b/drivers/net/virtio/virtio_net.h > index 442af4673bf8..1c21af47e13c 100644 > --- a/drivers/net/virtio/virtio_net.h > +++ b/drivers/net/virtio/virtio_net.h > @@ -9,7 +9,8 @@ > #include > > #define VIRTIO_XDP_FLAG BIT(0) > -#define VIRTIO_XMIT_DATA_MASK (VIRTIO_XDP_FLAG) > +#define VIRTIO_XSK_FLAG BIT(1) > +#define VIRTIO_XMIT_DATA_MASK (VIRTIO_XDP_FLAG | VIRTIO_XSK_FLAG) > > /* 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 > diff --git a/drivers/net/virtio/xsk.c b/drivers/net/virtio/xsk.c > index 8b397787603f..caa448308232 100644 > --- a/drivers/net/virtio/xsk.c > +++ b/drivers/net/virtio/xsk.c > @@ -4,9 +4,119 @@ > */ > > #include "virtio_net.h" > +#include "xsk.h" > > static struct virtio_net_hdr_mrg_rxbuf xsk_hdr; > > +static void sg_fill_dma(struct scatterlist *sg, dma_addr_t addr, u32 len) > +{ > + sg->dma_address = addr; > + sg->length = len; > +} > + > +static void virtnet_xsk_check_queue(struct virtnet_sq *sq) > +{ > + struct virtnet_info *vi = sq->vq->vdev->priv; > + struct net_device *dev = vi->dev; > + int qnum = sq - vi->sq; > + > + /* If it is a raw buffer queue, it does not check whether the status > + * of the queue is stopped when sending. So there is no need to check > + * the situation of the raw buffer queue. > + */ > + if (virtnet_is_xdp_raw_buffer_queue(vi, qnum)) > + return; > + > + /* If this sq is not the exclusive queue of the current cpu, > + * then it may be called by start_xmit, so check it running out > + * of space. > + * > + * Stop the queue to avoid getting packets that we are > + * then unable to transmit. Then wait the tx interrupt. > + */ > + if (sq->vq->num_free < 2 + MAX_SKB_FRAGS) what does MAX_SKB_FRAGS have to do with it? And where's 2 coming from? > + netif_stop_subqueue(dev, qnum); > +} > + > +static int virtnet_xsk_xmit_one(struct virtnet_sq *sq, > + struct xsk_buff_pool *pool, > + struct xdp_desc *desc) > +{ > + struct virtnet_info *vi; > + dma_addr_t addr; > + > + vi = sq->vq->vdev->priv; > + > + addr = xsk_buff_raw_get_dma(pool, desc->addr); > + xsk_buff_raw_dma_sync_for_device(pool, addr, desc->len); > + > + sg_init_table(sq->sg, 2); > + > + sg_fill_dma(sq->sg, sq->xsk.hdr_dma_address, vi->hdr_len); > + sg_fill_dma(sq->sg + 1, addr, desc->len); > + > + return virtqueue_add_outbuf(sq->vq, sq->sg, 2, > + virtnet_xsk_to_ptr(desc->len), GFP_ATOMIC); > +} > + > +static int virtnet_xsk_xmit_batch(struct virtnet_sq *sq, > + struct xsk_buff_pool *pool, > + unsigned int budget, > + u64 *kicks) > +{ > + struct xdp_desc *descs = pool->tx_descs; > + u32 nb_pkts, max_pkts, i; > + bool kick = false; > + int err; > + > + /* Every xsk tx packet needs two desc(virtnet header and packet). So we > + * use sq->vq->num_free / 2 as the limitation. > + */ > + max_pkts = min_t(u32, budget, sq->vq->num_free / 2); > + > + nb_pkts = xsk_tx_peek_release_desc_batch(pool, max_pkts); > + if (!nb_pkts) > + return 0; > + > + for (i = 0; i < nb_pkts; i++) { > + err = virtnet_xsk_xmit_one(sq, pool, &descs[i]); > + if (unlikely(err)) > + break; > + > + kick = true; > + } > + > + if (kick && virtqueue_kick_prepare(sq->vq) && virtqueue_notify(sq->vq)) > + (*kicks)++; > + > + return i; > +} > + > +bool virtnet_xsk_xmit(struct virtnet_sq *sq, struct xsk_buff_pool *pool, > + int budget) > +{ > + u64 bytes = 0, packets = 0, kicks = 0; > + int sent; > + > + virtnet_free_old_xmit(sq, true, &bytes, &packets); > + > + sent = virtnet_xsk_xmit_batch(sq, pool, budget, &kicks); > + > + virtnet_xsk_check_queue(sq); > + > + u64_stats_update_begin(&sq->stats.syncp); > + u64_stats_add(&sq->stats.packets, packets); > + u64_stats_add(&sq->stats.bytes, bytes); > + u64_stats_add(&sq->stats.kicks, kicks); > + u64_stats_add(&sq->stats.xdp_tx, sent); > + u64_stats_update_end(&sq->stats.syncp); > + > + if (xsk_uses_need_wakeup(pool)) > + xsk_set_tx_need_wakeup(pool); > + > + return sent == budget; > +} > + > static int virtnet_rq_bind_xsk_pool(struct virtnet_info *vi, struct virtnet_rq *rq, > struct xsk_buff_pool *pool) > { > diff --git a/drivers/net/virtio/xsk.h b/drivers/net/virtio/xsk.h > index 1918285c310c..73ca8cd5308b 100644 > --- a/drivers/net/virtio/xsk.h > +++ b/drivers/net/virtio/xsk.h > @@ -3,5 +3,18 @@ > #ifndef __XSK_H__ > #define __XSK_H__ > > +#define VIRTIO_XSK_FLAG_OFFSET 4 > + > +static inline void *virtnet_xsk_to_ptr(u32 len) > +{ > + unsigned long p; > + > + p = len << VIRTIO_XSK_FLAG_OFFSET; > + > + return (void *)(p | VIRTIO_XSK_FLAG); > +} > + > int virtnet_xsk_pool_setup(struct net_device *dev, struct netdev_bpf *xdp); > +bool virtnet_xsk_xmit(struct virtnet_sq *sq, struct xsk_buff_pool *pool, > + int budget); > #endif > -- > 2.32.0.3.g01195cf9f