Re: [PATCH v2] hw/virtio/vhost-user: support obtain vdpa device's mac address automatically

[Jason Wang]

On Fri, Sep 23, 2022 at 11:33 AM 陈浩 <chenh@yusur.tech> wrote:
>
>
> On 2022/9/22 17:56, Michael S. Tsirkin wrote:
> > On Thu, Sep 22, 2022 at 09:34:41AM +0800, Jason Wang wrote:
> >> On Thu, Sep 22, 2022 at 1:58 AM Raphael Norwitz
> >> <raphael.norwitz@nutanix.com> wrote:
> >>> If I read your response on the other thread correctly, this change is 
> >>> intended
> >>>
> >>> to prioritize the MAC address exposed by DPDK over the one provided by the
> >>>
> >>> QEMU command line? Sounds reasonable in principle, but I would get 
> >>> confirmation
> >>>
> >>> from vDPA/vhost-net maintainers.
> >> I think the best way is to (and it seems easier)
> >>
> >> 1) have the management layer to make sure the mac came from cli
> >> matches the underlayer vDPA
> >> 2) having a sanity check and fail the device initialization if they don't 
> >> match
> >>
> >> Thanks
> > I think I agree, we should not overwrite user supplied arguments.
> > I think the case where we might want to get the mac from VDPA
> > and use it is when it's been assigned randomly as opposed to coming from 
> > cli.
> Yes, when the cli passes in a random mac address that is inconsistent
> with the vdpa device, qemu still starts the virtual machine as usual,
> but in this case, the qemu and vdpa environments do not work correctly.
> So I want to get mac address directly from vdpa device instead of cli.

Let's teach the management to do that. It has a lot of advantages, more below.

Not sure for the DPDK case, but kernel vDPA allows the mgmt to
provision the vDPA with a mac address which could be used in this
case.

>
> Having a sanity check and fail the device initialization if they don't
> match is a good idea, but it seems more convenient to directly overwrite
> the cli mac address.

This will confuse the management where it may do a lot of mac related setups.

Thanks

> >
> >
> >>>
> >>>
> >>> That said the way you’re hacking the vhost-user code breaks a valuable 
> >>> check for
> >>>
> >>> bad vhost-user-blk backends. I would suggest finding another 
> >>> implementation which
> >>>
> >>> does not regress functionality for other device types.
> >>>
> >>>
> >>>
> >>>
> >>>
> >>>> From: Hao Chen <chenh@yusur.tech>
> >>>> When use dpdk-vdpa tests vdpa device. You need to specify the mac 
> >>>> address to
> >>>> start the virtual machine through libvirt or qemu, but now, the libvirt 
> >>>> or
> >>>> qemu can call dpdk vdpa vendor driver's ops .get_config through 
> >>>> vhost_net_get_config
> >>>> to get the mac address of the vdpa hardware without manual configuration.
> >>>> v1->v2:
> >>>> Only copy ETH_ALEN data of netcfg for some vdpa device such as
> >>>> NVIDIA BLUEFIELD DPU(BF2)'s netcfg->status is not right.
> >>>> We only need the mac address and don't care about the status field.
> >>>> Signed-off-by: Hao Chen <chenh@yusur.tech>
> >>>> ---
> >>>> hw/block/vhost-user-blk.c |  1 -
> >>>> hw/net/virtio-net.c       |  7 +++++++
> >>>> hw/virtio/vhost-user.c    | 19 -------------------
> >>>> 3 files changed, 7 insertions(+), 20 deletions(-)
> >>>> diff --git a/hw/block/vhost-user-blk.c b/hw/block/vhost-user-blk.c
> >>>> index 9117222456..5dca4eab09 100644
> >>>> --- a/hw/block/vhost-user-blk.c
> >>>> +++ b/hw/block/vhost-user-blk.c
> >>>> @@ -337,7 +337,6 @@ static int vhost_user_blk_connect(DeviceState *dev, 
> >>>> Error **errp)
> >>>>      vhost_dev_set_config_notifier(&s->dev, &blk_ops);
> >>>> -    s->vhost_user.supports_config = true;
> >>>>      ret = vhost_dev_init(&s->dev, &s->vhost_user, 
> >>>> VHOST_BACKEND_TYPE_USER, 0,
> >>>>                           errp);
> >>>>      if (ret < 0) {
> >>>> diff --git a/hw/net/virtio-net.c b/hw/net/virtio-net.c
> >>>> index dd0d056fde..90405083b1 100644
> >>>> --- a/hw/net/virtio-net.c
> >>>> +++ b/hw/net/virtio-net.c
> >>>> @@ -166,6 +166,13 @@ static void virtio_net_get_config(VirtIODevice 
> >>>> *vdev, uint8_t *config)
> >>>>              }
> >>>>              memcpy(config, &netcfg, n->config_size);
> >>>>          }
> >>>> +    } else if (nc->peer && nc->peer->info->type == 
> >>>> NET_CLIENT_DRIVER_VHOST_USER) {
> >>>> +        ret = vhost_net_get_config(get_vhost_net(nc->peer), (uint8_t 
> >>>> *)&netcfg,
> >>>> +                                   n->config_size);
> >>>> +        if (ret != -1) {
> >>>> +               /* Automatically obtain the mac address of the vdpa 
> >>>> device
> >>>> +                * when using the dpdk vdpa */
> >>>> +                memcpy(config, &netcfg, ETH_ALEN);
> >>>>      }
> >>>> }
> >>>> diff --git a/hw/virtio/vhost-user.c b/hw/virtio/vhost-user.c
> >>>> index bd24741be8..8b01078249 100644
> >>>> --- a/hw/virtio/vhost-user.c
> >>>> +++ b/hw/virtio/vhost-user.c
> >>>> @@ -2013,8 +2013,6 @@ static int vhost_user_backend_init(struct 
> >>>> vhost_dev *dev, void *opaque,
> >>>>      }
> >>>>      if (virtio_has_feature(features, VHOST_USER_F_PROTOCOL_FEATURES)) {
> >>>> -        bool supports_f_config = vus->supports_config ||
> >>>> -            (dev->config_ops && 
> >>>> dev->config_ops->vhost_dev_config_notifier);
> >>>>          uint64_t protocol_features;
> >>>>          dev->backend_features |= 1ULL << VHOST_USER_F_PROTOCOL_FEATURES;
> >>>> @@ -2033,23 +2031,6 @@ static int vhost_user_backend_init(struct 
> >>>> vhost_dev *dev, void *opaque,
> >>>>           */
> >>>>          protocol_features &= VHOST_USER_PROTOCOL_FEATURE_MASK;
> >>>> -        if (supports_f_config) {
> >>>> -            if (!virtio_has_feature(protocol_features,
> >>>> -                                    VHOST_USER_PROTOCOL_F_CONFIG)) {
> >>>> -                error_setg(errp, "vhost-user device expecting "
> >>>> -                           "VHOST_USER_PROTOCOL_F_CONFIG but the 
> >>>> vhost-user backend does "
> >>>> -                           "not support it.");
> >>>> -                return -EPROTO;
> >>>> -            }
> >>>> -        } else {
> >>>> -            if (virtio_has_feature(protocol_features,
> >>>> -                                   VHOST_USER_PROTOCOL_F_CONFIG)) {
> >>>> -                warn_reportf_err(*errp, "vhost-user backend supports "
> >>>> -                                 "VHOST_USER_PROTOCOL_F_CONFIG but QEMU 
> >>>> does not.");
> >>>> -                protocol_features &= ~(1ULL << 
> >>>> VHOST_USER_PROTOCOL_F_CONFIG);
> >>>> -            }
> >>>> -        }
> >>>> -
> >>>>          /* final set of protocol features */
> >>>>          dev->protocol_features = protocol_features;
> >>>>          err = vhost_user_set_protocol_features(dev, 
> >>>> dev->protocol_features);
> >>>> --
> >>>> 2.27.0
> >>>
> >
>