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.
> 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.
--yliu
