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Subject: Re: [RFC 2/2] vhost: IFC VF vdpa layer
To:     Zhu Lingshan <lingshan.zhu@linux.intel.com>,
        "Zhu, Lingshan" <lingshan.zhu@intel.com>, mst@redhat.com,
        alex.williamson@redhat.com
Cc:     linux-kernel@vger.kernel.org,
        virtualization@lists.linux-foundation.org, kvm@vger.kernel.org,
        netdev@vger.kernel.org, dan.daly@intel.com,
        cunming.liang@intel.com, tiwei.bie@intel.com, jason.zeng@intel.com,
        zhiyuan.lv@intel.com
References: <20191016013050.3918-1-lingshan.zhu@intel.com>
 <20191016013050.3918-3-lingshan.zhu@intel.com>
 <9495331d-3c65-6f49-dcd9-bfdb17054cf0@redhat.com>
 <f65358e9-6728-8260-74f7-176d7511e989@intel.com>
 <1cae60b6-938d-e2df-2dca-fbf545f06853@redhat.com>
 <ddf412c6-69e2-b3ca-d0c8-75de1db78ed9@linux.intel.com>
From:   Jason Wang <jasowang@redhat.com>
Message-ID: <b2adaab0-bbc3-b7f0-77da-e1e3cab93b76@redhat.com>
Date:   Tue, 22 Oct 2019 21:05:57 +0800
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On 2019/10/22 =E4=B8=8B=E5=8D=882:53, Zhu Lingshan wrote:
>
> On 10/21/2019 6:19 PM, Jason Wang wrote:
>>
>> On 2019/10/21 =E4=B8=8B=E5=8D=885:53, Zhu, Lingshan wrote:
>>>
>>> On 10/16/2019 6:19 PM, Jason Wang wrote:
>>>>
>>>> On 2019/10/16 =E4=B8=8A=E5=8D=889:30, Zhu Lingshan wrote:
>>>>> This commit introduced IFC VF operations for vdpa, which complys to
>>>>> vhost_mdev interfaces, handles IFC VF initialization,
>>>>> configuration and removal.
>>>>>
>>>>> Signed-off-by: Zhu Lingshan <lingshan.zhu@intel.com>
>>>>> ---


[...]


>>
>>
>>>
>>>>
>>>>
>>>>> +}
>>>>> +
>>>>> +static int ifcvf_mdev_set_features(struct mdev_device *mdev, u64=20
>>>>> features)
>>>>> +{
>>>>> +=C2=A0=C2=A0=C2=A0 struct ifcvf_adapter *adapter =3D mdev_get_drvdat=
a(mdev);
>>>>> +=C2=A0=C2=A0=C2=A0 struct ifcvf_hw *vf =3D IFC_PRIVATE_TO_VF(adapter=
);
>>>>> +
>>>>> +=C2=A0=C2=A0=C2=A0 vf->req_features =3D features;
>>>>> +
>>>>> +=C2=A0=C2=A0=C2=A0 return 0;
>>>>> +}
>>>>> +
>>>>> +static u64 ifcvf_mdev_get_vq_state(struct mdev_device *mdev, u16=20
>>>>> qid)
>>>>> +{
>>>>> +=C2=A0=C2=A0=C2=A0 struct ifcvf_adapter *adapter =3D mdev_get_drvdat=
a(mdev);
>>>>> +=C2=A0=C2=A0=C2=A0 struct ifcvf_hw *vf =3D IFC_PRIVATE_TO_VF(adapter=
);
>>>>> +
>>>>> +=C2=A0=C2=A0=C2=A0 return vf->vring[qid].last_avail_idx;
>>>>
>>>>
>>>> Does this really work? I'd expect it should be fetched from hw=20
>>>> since it's an internal state.
>>> for now, it's working, we intend to support LM in next version drivers.
>>
>>
>> I'm not sure I understand here, I don't see any synchronization=20
>> between the hardware and last_avail_idx, so last_avail_idx should not=20
>> change.
>>
>> Btw, what did "LM" mean :) ?
>
> I can add bar IO operations here, LM =3D live migration, sorry for the=20
> abbreviation.


Just make sure I understand here, I believe you mean reading=20
last_avail_idx through IO bar here?

Thanks