Re: [PATCH V2 RESEND 2/6] vDPA: only report driver features if FEATURES_OK is set

From: "Zhu, Lingshan" <lingshan.zhu@intel.com>
To: Jason Wang <jasowang@redhat.com>
Cc: mst@redhat.com, virtualization@lists.linux-foundation.org,
	netdev@vger.kernel.org, kvm@vger.kernel.org
Subject: Re: [PATCH V2 RESEND 2/6] vDPA: only report driver features if FEATURES_OK is set
Date: Tue, 27 Sep 2022 18:02:53 +0800	[thread overview]
Message-ID: <750e006b-7ec8-873e-8df0-b6979f6890b3@intel.com> (raw)
In-Reply-To: <CACGkMEsioquc=hVe0D87UjZkaZ1m3B-g1hXAAyq6bHD=Fc0uFQ@mail.gmail.com>


On 9/27/2022 12:37 PM, Jason Wang wrote:
> On Tue, Sep 27, 2022 at 11:09 AM Zhu Lingshan <lingshan.zhu@intel.com> wrote:
>> This commit reports driver features to user space
>> only after FEATURES_OK is features negotiation is done.
>>
>> Signed-off-by: Zhu Lingshan <lingshan.zhu@intel.com>
>> ---
>>   drivers/vdpa/vdpa.c | 22 ++++++++++++++++------
>>   1 file changed, 16 insertions(+), 6 deletions(-)
>>
>> diff --git a/drivers/vdpa/vdpa.c b/drivers/vdpa/vdpa.c
>> index 2035700d6fc8..e7765953307f 100644
>> --- a/drivers/vdpa/vdpa.c
>> +++ b/drivers/vdpa/vdpa.c
>> @@ -816,7 +816,7 @@ static int vdpa_dev_net_mq_config_fill(struct vdpa_device *vdev,
>>   static int vdpa_dev_net_config_fill(struct vdpa_device *vdev, struct sk_buff *msg)
>>   {
>>          struct virtio_net_config config = {};
>> -       u64 features_device, features_driver;
>> +       u64 features_device;
>>          u16 val_u16;
>>
>>          vdev->config->get_config(vdev, 0, &config, sizeof(config));
>> @@ -833,11 +833,6 @@ static int vdpa_dev_net_config_fill(struct vdpa_device *vdev, struct sk_buff *ms
>>          if (nla_put_u16(msg, VDPA_ATTR_DEV_NET_CFG_MTU, val_u16))
>>                  return -EMSGSIZE;
>>
>> -       features_driver = vdev->config->get_driver_features(vdev);
>> -       if (nla_put_u64_64bit(msg, VDPA_ATTR_DEV_NEGOTIATED_FEATURES, features_driver,
>> -                             VDPA_ATTR_PAD))
>> -               return -EMSGSIZE;
>> -
>>          features_device = vdev->config->get_device_features(vdev);
>>
>>          if (nla_put_u64_64bit(msg, VDPA_ATTR_VDPA_DEV_SUPPORTED_FEATURES, features_device,
>> @@ -851,6 +846,8 @@ static int
>>   vdpa_dev_config_fill(struct vdpa_device *vdev, struct sk_buff *msg, u32 portid, u32 seq,
>>                       int flags, struct netlink_ext_ack *extack)
>>   {
>> +       u64 features_driver;
>> +       u8 status = 0;
>>          u32 device_id;
>>          void *hdr;
>>          int err;
>> @@ -874,6 +871,19 @@ vdpa_dev_config_fill(struct vdpa_device *vdev, struct sk_buff *msg, u32 portid,
>>                  goto msg_err;
>>          }
>>
>> +       /* only read driver features after the feature negotiation is done */
>> +       if (vdev->config->get_status)
>> +               status = vdev->config->get_status(vdev);
> get_status is mandatory, so I think we can remove this check.
>
> Or if you want a strict check on the config operations, we need to do
> that in __vdpa_alloc_device().
I will remove it

Thanks!
>
> Thanks
>
>> +
>> +       if (status & VIRTIO_CONFIG_S_FEATURES_OK) {
>> +               features_driver = vdev->config->get_driver_features(vdev);
>> +               if (nla_put_u64_64bit(msg, VDPA_ATTR_DEV_NEGOTIATED_FEATURES, features_driver,
>> +                                     VDPA_ATTR_PAD)) {
>> +                       err = -EMSGSIZE;
>> +                       goto msg_err;
>> +               }
>> +       }
>> +
>>          switch (device_id) {
>>          case VIRTIO_ID_NET:
>>                  err = vdpa_dev_net_config_fill(vdev, msg);
>> --
>> 2.31.1
>>