[dpdk-dev] [PATCH 3/5] net/virtio-user: support to report net status

Tan, Jianfeng jianfeng.tan at intel.com
Wed Mar 29 09:48:04 CEST 2017



On 3/29/2017 3:14 PM, Yuanhan Liu wrote:
> On Wed, Mar 29, 2017 at 03:07:28PM +0800, Tan, Jianfeng wrote:
>>
>> On 3/29/2017 2:33 PM, Yuanhan Liu wrote:
>>> On Mon, Mar 27, 2017 at 07:46:32AM +0000, Tan, Jianfeng wrote:
>>>>>> diff --git a/drivers/net/virtio/virtio_user/virtio_user_dev.c
>>>>> b/drivers/net/virtio/virtio_user/virtio_user_dev.c
>>>>>> index 9777d6b..cc6f557 100644
>>>>>> --- a/drivers/net/virtio/virtio_user/virtio_user_dev.c
>>>>>> +++ b/drivers/net/virtio/virtio_user/virtio_user_dev.c
>>>>>> @@ -176,6 +176,7 @@ virtio_user_start_device(struct virtio_user_dev
>>>>> *dev, uint8_t portid)
>>>>>>   	features &= ~(1ull << VIRTIO_NET_F_MAC);
>>>>>>   	/* Strip VIRTIO_NET_F_CTRL_VQ, as devices do not really need to
>>>>> know */
>>>>>>   	features &= ~(1ull << VIRTIO_NET_F_CTRL_VQ);
>>>>>> +	features &= ~(1ull << VIRTIO_NET_F_STATUS);
>>>>>>   	ret = dev->ops->send_request(dev, VHOST_USER_SET_FEATURES,
>>>>> &features);
>>>>>>   	if (ret < 0)
>>>>>>   		goto error;
>>>>>> diff --git a/drivers/net/virtio/virtio_user_ethdev.c
>>>>> b/drivers/net/virtio/virtio_user_ethdev.c
>>>>>> index fa79419..fbdd0a8 100644
>>>>>> --- a/drivers/net/virtio/virtio_user_ethdev.c
>>>>>> +++ b/drivers/net/virtio/virtio_user_ethdev.c
>>>>>> @@ -121,7 +121,8 @@ virtio_user_get_features(struct virtio_hw *hw)
>>>>>>   	struct virtio_user_dev *dev = virtio_user_get_dev(hw);
>>>>>>
>>>>>>   	/* unmask feature bits defined in vhost user protocol */
>>>>>> -	return dev->device_features &
>>>>> VIRTIO_PMD_SUPPORTED_GUEST_FEATURES;
>>>>>> +	return (dev->device_features | (1 << VIRTIO_NET_F_STATUS))
>>>>>> +		& VIRTIO_PMD_SUPPORTED_GUEST_FEATURES;
>>>>> Why not handle the features at virtio_user_dev_init()?
>>>> You mean add VIRTIO_NET_F_STATUS when get_features from device? Yes, we could do that there. But we originally add device_features to only record features supported by device.
>>>>
>>> Aren't you adding the F_STATUS features to this device?
>>>
>> For virtio driver, yes, we are adding F_STATUS feature so the it sees a
>> device supporting LSC.
> That means you are adding a device feature (F_STATUS) and reporting it to
> the driver that this feature is always on, no matter whether the device
> actually supports it or not? This looks wrong to me.

Why? IMO, device is not necessary to know this feature. For vhost-user, 
except explicitly cutting down the unix connection, I don't see a 
message of vhost-user protocol to report that.

>
>> But for backend driver, we need hide this feature, it
>> happens when we set_features to the backend driver.
> The feature negotion of virtio-user seems broken to me.
>
>
Why? vhost does not claim to support this feature, VHOST_SUPPORTED_FEATURES.

Thanks,
Jianfeng


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