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

[Michael S. Tsirkin]

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.


> >
> >
> >
> > 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
> >
> > >
> >
> >