Re: [dpdk-dev] [PATCH] vhost: fix silent queue enabling with legacy guests

[Maxime Coquelin <maxime.coquelin@redhat.com>]

On 4/12/19 3:09 PM, Ilya Maximets wrote:
> vhost should notify the application in case of all vring state changes.
> 
> In general, application should not care about negotiation of
> VHOST_USER_F_PROTOCOL_FEATURES. Protocol details like this should
> be hidden by the vhost library.
> 
> With this patch applications like OVS will be able to assume that
> all vrings disabled by default and only process 'vring_state_changed'
> events.
> 
> Fixes: 321203a54ba7 ("vhost: enable rings at the right time")
> Cc: stable@dpdk.org
> 
> Signed-off-by: Ilya Maximets <i.maximets@samsung.com>
> ---
>   lib/librte_vhost/vhost_user.c | 6 +++++-
>   1 file changed, 5 insertions(+), 1 deletion(-)
> 
> diff --git a/lib/librte_vhost/vhost_user.c b/lib/librte_vhost/vhost_user.c
> index 23beed97d..c9e29ece8 100644
> --- a/lib/librte_vhost/vhost_user.c
> +++ b/lib/librte_vhost/vhost_user.c
> @@ -1231,8 +1231,12 @@ vhost_user_set_vring_kick(struct virtio_net **pdev, struct VhostUserMsg *msg,
>   	 * the ring starts already enabled. Otherwise, it is enabled via
>   	 * the SET_VRING_ENABLE message.
>   	 */
> -	if (!(dev->features & (1ULL << VHOST_USER_F_PROTOCOL_FEATURES)))
> +	if (!(dev->features & (1ULL << VHOST_USER_F_PROTOCOL_FEATURES))) {
>   		vq->enabled = 1;
> +		if (dev->notify_ops->vring_state_changed)
> +			dev->notify_ops->vring_state_changed(
> +				dev->vid, file.index, 1);
> +	}
>   
>   	if (vq->kickfd >= 0)
>   		close(vq->kickfd);
> 

Nice, this is indeed the right thing to do:

Reviewed-by: Maxime Coquelin <maxime.coquelin@redhat.com>

Thanks,
Maxime