Subject: Re: [net-next PATCH v4 1/6] net: virtio dynamically disable/enable LRO

From: John Fastabend <[email-masked]>
Date: Sun, 4 Dec 2016 10:59:12 -0800

On 16-12-03 09:36 PM, Michael S. Tsirkin wrote:
> On Fri, Dec 02, 2016 at 12:49:45PM -0800, John Fastabend wrote:
>> This adds support for dynamically setting the LRO feature flag. The
>> message to control guest features in the backend uses the
>> CTRL_GUEST_OFFLOADS msg type.
>>
>> Signed-off-by: John Fastabend <[email-masked]>
>> ---
>>  drivers/net/virtio_net.c |   45 ++++++++++++++++++++++++++++++++++++++++++++-
>>  1 file changed, 44 insertions(+), 1 deletion(-)
>>
>> diff --git a/drivers/net/virtio_net.c b/drivers/net/virtio_net.c
>> index a21d93a..d814e7cb 100644
>> --- a/drivers/net/virtio_net.c
>> +++ b/drivers/net/virtio_net.c
>> @@ -1419,6 +1419,41 @@ static void virtnet_init_settings(struct net_device *dev)
>>  	.set_settings = virtnet_set_settings,
>>  };
>>  
>> +static int virtnet_set_features(struct net_device *netdev,
>> +				netdev_features_t features)
>> +{
>> +	struct virtnet_info *vi = netdev_priv(netdev);
>> +	struct virtio_device *vdev = vi->vdev;
>> +	struct scatterlist sg;
>> +	u64 offloads = 0;
>> +
>> +	if (features & NETIF_F_LRO)
>> +		offloads |= (1 << VIRTIO_NET_F_GUEST_TSO4) |
>> +			    (1 << VIRTIO_NET_F_GUEST_TSO6);
>> +
>> +	if (features & NETIF_F_RXCSUM)
>> +		offloads |= (1 << VIRTIO_NET_F_GUEST_CSUM);
>> +
>> +	if (virtio_has_feature(vdev, VIRTIO_NET_F_CTRL_GUEST_OFFLOADS)) {
>> +		sg_init_one(&sg, &offloads, sizeof(uint64_t));
>> +		if (!virtnet_send_command(vi,
>> +					  VIRTIO_NET_CTRL_GUEST_OFFLOADS,
>> +					  VIRTIO_NET_CTRL_GUEST_OFFLOADS_SET,
>> +					  &sg)) {
>> +			dev_warn(&netdev->dev,
>> +				 "Failed to set guest offloads by virtnet command.\n");
>> +			return -EINVAL;
>> +		}
>> +	} else if (virtio_has_feature(vdev, VIRTIO_NET_F_CTRL_GUEST_OFFLOADS) &&
>> +		   !virtio_has_feature(vdev, VIRTIO_F_VERSION_1)) {
> 
> No need for VIRTIO_F_VERSION_1 here.
> 

Yep Dave pointed it out as well. Also I found a bug on driver unload
path where XDP tx queues are not cleaned up correctly so will need a v5
for that.

Thanks,
John