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

[Alex Bennée]

"Michael S. Tsirkin" <mst@redhat.com> writes:

> On Wed, Sep 21, 2022 at 07:23:12PM +0100, Alex Bennée wrote:
>> 
>> chenh <chenh@yusur.tech> writes:
>> 
>> > 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;
>> 
>> <snip>
>> 
>> NACK from me. The supports_config flag is there for a reason.
>
>
> Alex please, do not send NACKs. If you feel compelled to stress
> your point, provide extra justification instead. Thanks!

OK I was objecting to ripping out the common vhost-user code which was
implemented as a fix for behaviour found while attempting to upstream:

  Subject: [PATCH  v4 for 7.2 00/22] virtio-gpio and various virtio cleanups
  Date: Tue,  2 Aug 2022 10:49:48 +0100
  Message-Id: <20220802095010.3330793-1-alex.bennee@linaro.org>

I vhost-user-blk wants to suppress its use of vhost-user config messages
I guess that should be a control option but it sounds like a buggy
back-end.

>
>> >  
>> > 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);
>> 
>> 
>> -- 
>> Alex Bennée


-- 
Alex Bennée