netdev - Re: [PATCH net v2 5/6] virtio-net: fix the vq coalescing setting for vq resize

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Message-ID: <960e16021a529bc9df217b3c2546e0dc7532ce7b.camel@redhat.com>
Date: Tue, 03 Oct 2023 12:41:03 +0200
From: Paolo Abeni <pabeni@...hat.com>
To: Heng Qi <hengqi@...ux.alibaba.com>, netdev@...r.kernel.org, 
	virtualization@...ts.linux-foundation.org
Cc: Jason Wang <jasowang@...hat.com>, "Michael S . Tsirkin"
 <mst@...hat.com>,  "David S . Miller" <davem@...emloft.net>, Eric Dumazet
 <edumazet@...gle.com>, Jakub Kicinski <kuba@...nel.org>, Alexei Starovoitov
 <ast@...nel.org>, Daniel Borkmann <daniel@...earbox.net>, Jesper Dangaard
 Brouer <hawk@...nel.org>, John Fastabend <john.fastabend@...il.com>, Xuan
 Zhuo <xuanzhuo@...ux.alibaba.com>, Gavin Li <gavinl@...dia.com>
Subject: Re: [PATCH net v2 5/6] virtio-net: fix the vq coalescing setting
 for vq resize

On Mon, 2023-09-25 at 15:53 +0800, Heng Qi wrote:
> According to the definition of virtqueue coalescing spec[1]:
> 
>   Upon disabling and re-enabling a transmit virtqueue, the device MUST set
>   the coalescing parameters of the virtqueue to those configured through the
>   VIRTIO_NET_CTRL_NOTF_COAL_TX_SET command, or, if the driver did not set
>   any TX coalescing parameters, to 0.
> 
>   Upon disabling and re-enabling a receive virtqueue, the device MUST set
>   the coalescing parameters of the virtqueue to those configured through the
>   VIRTIO_NET_CTRL_NOTF_COAL_RX_SET command, or, if the driver did not set
>   any RX coalescing parameters, to 0.
> 
> We need to add this setting for vq resize (ethtool -G) where vq_reset happens.
> 
> [1] https://lists.oasis-open.org/archives/virtio-dev/202303/msg00415.html
> 
> Fixes: 394bd87764b6 ("virtio_net: support per queue interrupt coalesce command")
> Cc: Gavin Li <gavinl@...dia.com>
> Signed-off-by: Heng Qi <hengqi@...ux.alibaba.com>

@Jason, since you commented on v1, waiting for your ack.

> ---
>  drivers/net/virtio_net.c | 27 +++++++++++++++++++++++++++
>  1 file changed, 27 insertions(+)
> 
> diff --git a/drivers/net/virtio_net.c b/drivers/net/virtio_net.c
> index 12ec3ae19b60..cb19b224419b 100644
> --- a/drivers/net/virtio_net.c
> +++ b/drivers/net/virtio_net.c
> @@ -2855,6 +2855,9 @@ static void virtnet_get_ringparam(struct net_device *dev,
>  	ring->tx_pending = virtqueue_get_vring_size(vi->sq[0].vq);
>  }
>  
> +static int virtnet_send_ctrl_coal_vq_cmd(struct virtnet_info *vi,
> +					 u16 vqn, u32 max_usecs, u32 max_packets);
> +
>  static int virtnet_set_ringparam(struct net_device *dev,
>  				 struct ethtool_ringparam *ring,
>  				 struct kernel_ethtool_ringparam *kernel_ring,
> @@ -2890,12 +2893,36 @@ static int virtnet_set_ringparam(struct net_device *dev,
>  			err = virtnet_tx_resize(vi, sq, ring->tx_pending);
>  			if (err)
>  				return err;
> +
> +			/* Upon disabling and re-enabling a transmit virtqueue, the device must
> +			 * set the coalescing parameters of the virtqueue to those configured
> +			 * through the VIRTIO_NET_CTRL_NOTF_COAL_TX_SET command, or, if the driver
> +			 * did not set any TX coalescing parameters, to 0.
> +			 */
> +			err = virtnet_send_ctrl_coal_vq_cmd(vi, txq2vq(i),
> +							    vi->intr_coal_tx.max_usecs,
> +							    vi->intr_coal_tx.max_packets);
> +			if (err)
> +				return err;
> +			/* Save parameters */

As a very minor nit, I guess the comment could be dropped here (similar
to patch 4/6). @Heng Qi: please don't repost just for this, let's wait
for Jason' comments.

Cheers,

Paolo