Re: [PATCH] vhost: call rte_vhost_enable_guest_notification only on enabled queues

["Tan, Jianfeng" <jianfeng.tan@intel.com>]

Hi,

On 4/7/2016 8:29 AM, Rich Lane wrote:
> If the vhost PMD were configured with more queues than the guest, the old
> code would segfault in rte_vhost_enable_guest_notification due to a NULL
> virtqueue pointer.
>
> Fixes: ee584e9710b9 ("vhost: add driver on top of the library")
> Signed-off-by: Rich Lane <rich.lane@bigswitch.com>
> ---
>   drivers/net/vhost/rte_eth_vhost.c | 5 +++--
>   1 file changed, 3 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/net/vhost/rte_eth_vhost.c b/drivers/net/vhost/rte_eth_vhost.c
> index b1eb082..310cbef 100644
> --- a/drivers/net/vhost/rte_eth_vhost.c
> +++ b/drivers/net/vhost/rte_eth_vhost.c
> @@ -265,7 +265,6 @@ new_device(struct virtio_net *dev)
>   		vq->device = dev;
>   		vq->internal = internal;
>   		vq->port = eth_dev->data->port_id;
> -		rte_vhost_enable_guest_notification(dev, vq->virtqueue_id, 0);
>   	}
>   	for (i = 0; i < eth_dev->data->nb_tx_queues; i++) {
>   		vq = eth_dev->data->tx_queues[i];
> @@ -274,9 +273,11 @@ new_device(struct virtio_net *dev)
>   		vq->device = dev;
>   		vq->internal = internal;
>   		vq->port = eth_dev->data->port_id;
> -		rte_vhost_enable_guest_notification(dev, vq->virtqueue_id, 0);
>   	}
>   
> +	for (i = 0; i < dev->virt_qp_nb * VIRTIO_QNUM; i++)
> +		rte_vhost_enable_guest_notification(dev, i, 0);
> +
>   	dev->flags |= VIRTIO_DEV_RUNNING;
>   	dev->priv = eth_dev;
>   	eth_dev->data->dev_link.link_status = ETH_LINK_UP;

Just one question, when qemu starts a vm, usually, only one queue is 
enabled, then only 1 tx and 1 rx are called 
rte_vhost_enable_guest_notification; but after system is up, we use 
"ethtool -K eth0 combined x" to enable multiqueues, there's no chance to 
call rte_vhost_enable_guest_notification for other queues, right?

Thanks,
Jianfeng