Re: [dpdk-dev] [PATCH v1] net/virtio-user: fix packed ring server mode

["Ding, Xuan" <xuan.ding@intel.com>]

> -----Original Message-----
> From: Liu, Yong <yong.liu@intel.com>
> Sent: Monday, December 9, 2019 4:52 PM
> To: Ding, Xuan <xuan.ding@intel.com>; maintainer@dpdk.org
> Cc: dev@dpdk.org; maxime.coquelin@redhat.com; Bie, Tiwei
> <tiwei.bie@intel.com>; Wang, Zhihong <zhihong.wang@intel.com>; Ding, Xuan
> <xuan.ding@intel.com>; stable@dpdk.org
> Subject: RE: [dpdk-dev] [PATCH v1] net/virtio-user: fix packed ring server mode
> 
> 
> 
> > -----Original Message-----
> > From: dev <dev-bounces@dpdk.org> On Behalf Of Xuan Ding
> > Sent: Tuesday, December 10, 2019 12:50 AM
> > To: maintainer@dpdk.org
> > Cc: dev@dpdk.org; maxime.coquelin@redhat.com; Bie, Tiwei
> > <tiwei.bie@intel.com>; Wang, Zhihong <zhihong.wang@intel.com>; Ding,
> > Xuan <xuan.ding@intel.com>; stable@dpdk.org
> > Subject: [dpdk-dev] [PATCH v1] net/virtio-user: fix packed ring server
> > mode
> >
> > This patch fixes the situation where datapath does not work properly
> > when vhost reconnects to virtio in server mode with packed ring.
> >
> > Currently, virtio and vhost share memory of vring. For split ring,
> > vhost can read the status of discriptors directly from the available
> > ring and the used ring during reconnection. Therefore, the datapath can
> continue.
> >
> > But for packed ring, when reconnecting to virtio, vhost cannot get the
> > status of discriptors only through the descriptor ring. By resetting
> > Tx and Rx queues, the datapath can restart from the beginning.
> >
> > Fixes: 4c3f5822eb214 ("net/virtio: add packed virtqueue defines")
> > Cc: stable@dpdk.org
> >
> > Signed-off-by: Xuan Ding <xuan.ding@intel.com>
> > ---
> >  drivers/net/virtio/virtio_ethdev.c      | 112 +++++++++++++++++++++++-
> >  drivers/net/virtio/virtio_ethdev.h      |   3 +
> >  drivers/net/virtio/virtio_user_ethdev.c |   8 ++
> >  3 files changed, 121 insertions(+), 2 deletions(-)
> >
> > diff --git a/drivers/net/virtio/virtio_ethdev.c
> > b/drivers/net/virtio/virtio_ethdev.c
> > index 044eb10a7..c0cb0f23c 100644
> > --- a/drivers/net/virtio/virtio_ethdev.c
> > +++ b/drivers/net/virtio/virtio_ethdev.c
> > @@ -433,6 +433,94 @@ virtio_init_vring(struct virtqueue *vq)
> >  	virtqueue_disable_intr(vq);
> >  }
> >
> > +static int
> > +virtio_user_reset_rx_queues(struct rte_eth_dev *dev, uint16_t
> > +queue_idx) {
> 
> Hi Xuan,
> This function named as virtio_user_reset, but look like it has no relationship with
> virtio_user.
> Maybe rename this function to virtqueue_reset and move it to virtqueue.c will
> be more suitable.
> Please also add suffix _packed as this function only workable for packed ring.
> 
> Thanks,
> Marvin
> 

Hi Marvin, this function only works for virtqueue, so move it to virtqueue.c is better.
Two functions' name will be changed to virtqueue_rxvq_reset_packed and virtqueue_txvq_reset_packed, respectively.

Thank you for your suggestion.
Xuan

> > +	uint16_t vtpci_queue_idx = 2 * queue_idx + VTNET_SQ_RQ_QUEUE_IDX;
> > +	struct virtio_hw *hw = dev->data->dev_private;
> > +	struct virtqueue *vq = hw->vqs[vtpci_queue_idx];
> > +	struct virtnet_rx *rxvq;
> > +	struct vq_desc_extra *dxp;
> > +	unsigned int vq_size;
> > +	uint16_t desc_idx, i;
> > +
> > +	vq_size = VTPCI_OPS(hw)->get_queue_num(hw, vtpci_queue_idx);
> > +
> Virtqueue size has been set to vq_nentries in virtqueue structure. Do we need to
> re-catch it?
> 

Virtqueue size doesn't need to be re-catched, so vq->vq_nentries will be used instead.

> > +	vq->vq_packed.used_wrap_counter = 1;
> > +	vq->vq_packed.cached_flags = VRING_PACKED_DESC_F_AVAIL;
> > +	vq->vq_packed.event_flags_shadow = 0;
> > +	vq->vq_packed.cached_flags |= VRING_DESC_F_WRITE;
> > +
> > +	rxvq = &vq->rxq;
> > +	memset(rxvq->mz->addr, 0, rxvq->mz->len);
> > +
> > +	for (desc_idx = 0; desc_idx < vq_size; desc_idx++) {
> > +		dxp = &vq->vq_descx[desc_idx];
> > +		if (dxp->cookie != NULL) {
> > +			rte_pktmbuf_free(dxp->cookie);
> > +			dxp->cookie = NULL;
> > +		}
> > +	}
> > +
> > +	virtio_init_vring(vq);
> > +
> > +	for (i = 0; i < hw->max_queue_pairs; i++)
> > +		if (rxvq->mpool != NULL)
> > +			virtio_dev_rx_queue_setup_finish(dev, i);
> > +
> 
> Please add parentheses for multiple lines loop content.

Thank you for your notice.

> 
> > +	return 0;
> > +}
> > +
> > +static int
> > +virtio_user_reset_tx_queues(struct rte_eth_dev *dev, uint16_t
> > +queue_idx) {
> > +	uint8_t vtpci_queue_idx = 2 * queue_idx + VTNET_SQ_TQ_QUEUE_IDX;
> > +	struct virtio_hw *hw = dev->data->dev_private;
> > +	struct virtqueue *vq = hw->vqs[vtpci_queue_idx];
> > +	struct virtnet_tx *txvq;
> > +	struct vq_desc_extra *dxp;
> > +	unsigned int vq_size;
> > +	uint16_t desc_idx;
> > +
> > +	vq_size = VTPCI_OPS(hw)->get_queue_num(hw, vtpci_queue_idx);
> > +
> > +	vq->vq_packed.used_wrap_counter = 1;
> > +	vq->vq_packed.cached_flags = VRING_PACKED_DESC_F_AVAIL;
> > +	vq->vq_packed.event_flags_shadow = 0;
> > +
> > +	txvq = &vq->txq;
> > +	memset(txvq->mz->addr, 0, txvq->mz->len);
> > +	memset(txvq->virtio_net_hdr_mz->addr, 0,
> > +		txvq->virtio_net_hdr_mz->len);
> > +
> > +	for (desc_idx = 0; desc_idx < vq_size; desc_idx++) {
> > +		dxp = &vq->vq_descx[desc_idx];
> > +		if (dxp->cookie != NULL) {
> > +			rte_pktmbuf_free(dxp->cookie);
> > +			dxp->cookie = NULL;
> > +		}
> > +	}
> > +
> > +	virtio_init_vring(vq);
> > +
> > +	return 0;
> > +}
> > +
> > +static int
> > +virtio_user_reset_queues(struct rte_eth_dev *eth_dev) {
> > +	uint16_t i;
> > +
> > +	/* Vring reset for each Tx queue and Rx queue. */
> > +	for (i = 0; i < eth_dev->data->nb_rx_queues; i++)
> > +		virtio_user_reset_rx_queues(eth_dev, i);
> > +
> > +	for (i = 0; i < eth_dev->data->nb_rx_queues; i++)
> > +		virtio_user_reset_tx_queues(eth_dev, i);
> > +
> > +	return 0;
> > +}
> > +
> >  static int
> >  virtio_init_queue(struct rte_eth_dev *dev, uint16_t vtpci_queue_idx)
> > { @@ -1913,6 +2001,8 @@ eth_virtio_dev_init(struct rte_eth_dev
> > *eth_dev)
> >  			goto err_vtpci_init;
> >  	}
> >
> > +	rte_spinlock_init(&hw->state_lock);
> > +
> >  	/* reset device and negotiate default features */
> >  	ret = virtio_init_device(eth_dev,
> > VIRTIO_PMD_DEFAULT_GUEST_FEATURES);
> >  	if (ret < 0)
> > @@ -2155,8 +2245,6 @@ virtio_dev_configure(struct rte_eth_dev *dev)
> >  			return -EBUSY;
> >  		}
> >
> > -	rte_spinlock_init(&hw->state_lock);
> > -
> >  	hw->use_simple_rx = 1;
> >
> >  	if (vtpci_with_feature(hw, VIRTIO_F_IN_ORDER)) { @@ -2421,6
> +2509,26
> > @@ virtio_dev_vlan_offload_set(struct rte_eth_dev *dev, int mask)
> >  	return 0;
> >  }
> >
> > +int
> > +virtio_user_reset_device(struct rte_eth_dev *eth_dev, struct
> > +virtio_hw
> > *hw)
> > +{
> > +	/* Add lock to avoid queue contention. */
> > +	rte_spinlock_lock(&hw->state_lock);
> > +	hw->started = 0;
> > +	/*
> > +	 * Waitting for datapath to complete before resetting queues.
> > +	 * 1 ms should be enough for the ongoing Tx/Rx function to finish.
> > +	 */
> > +	rte_delay_ms(1);
> > +
> > +	virtio_user_reset_queues(eth_dev);
> > +
> > +	hw->started = 1;
> > +	rte_spinlock_unlock(&hw->state_lock);
> > +
> > +	return 0;
> > +}
> > +
> >  static int
> >  virtio_dev_info_get(struct rte_eth_dev *dev, struct rte_eth_dev_info
> > *dev_info)
> >  {
> > diff --git a/drivers/net/virtio/virtio_ethdev.h
> > b/drivers/net/virtio/virtio_ethdev.h
> > index a10111758..72e9e3ff8 100644
> > --- a/drivers/net/virtio/virtio_ethdev.h
> > +++ b/drivers/net/virtio/virtio_ethdev.h
> > @@ -49,6 +49,9 @@
> >
> >  extern const struct eth_dev_ops virtio_user_secondary_eth_dev_ops;
> >
> > +int virtio_user_reset_device(struct rte_eth_dev *eth_dev,
> > +		struct virtio_hw *hw);
> > +
> >  /*
> >   * CQ function prototype
> >   */
> > diff --git a/drivers/net/virtio/virtio_user_ethdev.c
> > b/drivers/net/virtio/virtio_user_ethdev.c
> > index 3fc172573..49068a578 100644
> > --- a/drivers/net/virtio/virtio_user_ethdev.c
> > +++ b/drivers/net/virtio/virtio_user_ethdev.c
> > @@ -31,6 +31,7 @@ virtio_user_server_reconnect(struct virtio_user_dev
> > *dev)
> >  	int ret;
> >  	int connectfd;
> >  	struct rte_eth_dev *eth_dev = &rte_eth_devices[dev->port_id];
> > +	struct virtio_hw *hw = eth_dev->data->dev_private;
> >
> >  	connectfd = accept(dev->listenfd, NULL, NULL);
> >  	if (connectfd < 0)
> > @@ -51,6 +52,13 @@ virtio_user_server_reconnect(struct virtio_user_dev
> > *dev)
> >
> >  	dev->features &= dev->device_features;
> >
> > +	/*
> > +	 * * For packed ring, resetting queues
> > +	 * is required in reconnection.
> > +	 */
> > +	if (vtpci_packed_queue(hw))
> > +		virtio_user_reset_device(eth_dev, hw);
> > +
> >  	ret = virtio_user_start_device(dev);
> >  	if (ret < 0)
> >  		return -1;
> > --
> > 2.17.1