Re: [dpdk-dev] [PATCH v2 3/3] virtio-user: set status on virtio-user reconnect

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

Hi Yinan,

On 10/22/20 6:01 AM, Wang, Yinan wrote:
> Hi Maxime/ Adrian，
> 
> Thanks for the patch.  we can launch vhost-user with client mode with this fix patch.
> But still fail to get throughput with basic vhost/virtio-user server mode loopback test. This is another problem which introduced by 57912824615fd7787a48a7b18e40661466.
> Bugzilla: https://bugs.dpdk.org/show_bug.cgi?id=541

Thanks for reporting the issue, I will look at it this morning.

BTW, this virtio-user server mode is broken by design, we should really
fix it.

For example, it assumes features to be supported by the backend before
the negotiation took place:
https://git.dpdk.org/dpdk/tree/drivers/net/virtio/virtio_user/virtio_user_dev.c#n513

As part of my rework, I suggest we implement the same behaviour as QEMU
does, which will be reliable and consistent with QEMU. It means that if
server mode is enabled in device command-line, the driver waits until
the socket is ready.

Chenbo, Adrian, what do you think?

Thanks,
Maxime

> BR,
> Yinan
>> -----Original Message-----
>> From: Maxime Coquelin <maxime.coquelin@redhat.com>
>> Sent: 2020年10月21日 0:43
>> To: Adrian Moreno <amorenoz@redhat.com>; dev@dpdk.org
>> Cc: Wang, Yinan <yinan.wang@intel.com>; Fu, Patrick <patrick.fu@intel.com>;
>> stable@dpdk.org; Xia, Chenbo <chenbo.xia@intel.com>; Wang, Zhihong
>> <zhihong.wang@intel.com>
>> Subject: Re: [PATCH v2 3/3] virtio-user: set status on virtio-user reconnect
>>
>>
>>
>> On 10/20/20 5:20 PM, Adrian Moreno wrote:
>>> Newer vhost-user backends will rely on SET_STATUS to start the device
>>> so this required to support them.
>>>
>>> Fixes: 57912824615f ("net/virtio-user: support vhost status setting")
>>> Cc: maxime.coquelin@redhat.com
>>> Cc: stable@dpdk.org
>>>
>>> Signed-off-by: Adrian Moreno <amorenoz@redhat.com>
>>> ---
>>>  drivers/net/virtio/virtio_user_ethdev.c | 14 ++++++++++++--
>>>  1 file changed, 12 insertions(+), 2 deletions(-)
>>>
>>> diff --git a/drivers/net/virtio/virtio_user_ethdev.c
>> b/drivers/net/virtio/virtio_user_ethdev.c
>>> index e870fb2ff..d8bea4537 100644
>>> --- a/drivers/net/virtio/virtio_user_ethdev.c
>>> +++ b/drivers/net/virtio/virtio_user_ethdev.c
>>> @@ -78,6 +78,13 @@ virtio_user_server_reconnect(struct virtio_user_dev
>> *dev)
>>>  		return -1;
>>>
>>>  	dev->vhostfd = connectfd;
>>> +
>>> +	vtpci_reset(hw);
>>> +
>>> +	vtpci_set_status(hw, VIRTIO_CONFIG_STATUS_ACK);
>>> +
>>> +	vtpci_set_status(hw, VIRTIO_CONFIG_STATUS_DRIVER);
>>> +
>>>  	if (dev->ops->send_request(dev, VHOST_USER_GET_FEATURES,
>>>  				   &dev->device_features) < 0) {
>>>  		PMD_INIT_LOG(ERR, "get_features failed: %s",
>>> @@ -111,6 +118,8 @@ virtio_user_server_reconnect(struct virtio_user_dev
>> *dev)
>>>
>>>  	dev->features &= dev->device_features;
>>>
>>> +	vtpci_set_status(hw, VIRTIO_CONFIG_STATUS_FEATURES_OK);
>>> +
>>>  	/* For packed ring, resetting queues is required in reconnection. */
>>>  	if (vtpci_packed_queue(hw) &&
>>>  	   (vtpci_get_status(hw) & VIRTIO_CONFIG_STATUS_DRIVER_OK)) {
>>> @@ -119,8 +128,9 @@ virtio_user_server_reconnect(struct virtio_user_dev
>> *dev)
>>>  		virtio_user_reset_queues_packed(eth_dev);
>>>  	}
>>>
>>> -	ret = virtio_user_start_device(dev);
>>> -	if (ret < 0)
>>> +	/*  Start the device */
>>> +	vtpci_set_status(hw, VIRTIO_CONFIG_STATUS_DRIVER_OK);
>>> +	if (!dev->started)
>>>  		return -1;
>>>
>>>  	if (dev->queue_pairs > 1) {
>>>
>>
>> Reviewed-by: Maxime Coquelin <maxime.coquelin@redhat.com>
>>
>> Thanks,
>> Maxime
>