linux-kernel - Re: [RFC 2/2] vhost: IFC VF vdpa layer

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Message-ID: <6588d9f4-f357-ec78-16a4-ccaf0e3768e7@intel.com>
Date:   Wed, 23 Oct 2019 14:19:13 +0800
From:   "Zhu, Lingshan" <lingshan.zhu@...el.com>
To:     Jason Wang <jasowang@...hat.com>,
        Zhu Lingshan <lingshan.zhu@...ux.intel.com>, mst@...hat.com,
        alex.williamson@...hat.com
Cc:     linux-kernel@...r.kernel.org,
        virtualization@...ts.linux-foundation.org, kvm@...r.kernel.org,
        netdev@...r.kernel.org, dan.daly@...el.com,
        cunming.liang@...el.com, tiwei.bie@...el.com, jason.zeng@...el.com,
        zhiyuan.lv@...el.com
Subject: Re: [RFC 2/2] vhost: IFC VF vdpa layer


On 10/22/2019 9:05 PM, Jason Wang wrote:
>
> On 2019/10/22 下午2:53, Zhu Lingshan wrote:
>>
>> On 10/21/2019 6:19 PM, Jason Wang wrote:
>>>
>>> On 2019/10/21 下午5:53, Zhu, Lingshan wrote:
>>>>
>>>> On 10/16/2019 6:19 PM, Jason Wang wrote:
>>>>>
>>>>> On 2019/10/16 上午9:30, 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@...el.com>
>>>>>> ---
>
>
> [...]
>
>
>>>
>>>
>>>>
>>>>>
>>>>>
>>>>>> +}
>>>>>> +
>>>>>> +static int ifcvf_mdev_set_features(struct mdev_device *mdev, u64 
>>>>>> features)
>>>>>> +{
>>>>>> +    struct ifcvf_adapter *adapter = mdev_get_drvdata(mdev);
>>>>>> +    struct ifcvf_hw *vf = IFC_PRIVATE_TO_VF(adapter);
>>>>>> +
>>>>>> +    vf->req_features = features;
>>>>>> +
>>>>>> +    return 0;
>>>>>> +}
>>>>>> +
>>>>>> +static u64 ifcvf_mdev_get_vq_state(struct mdev_device *mdev, u16 
>>>>>> qid)
>>>>>> +{
>>>>>> +    struct ifcvf_adapter *adapter = mdev_get_drvdata(mdev);
>>>>>> +    struct ifcvf_hw *vf = IFC_PRIVATE_TO_VF(adapter);
>>>>>> +
>>>>>> +    return vf->vring[qid].last_avail_idx;
>>>>>
>>>>>
>>>>> Does this really work? I'd expect it should be fetched from hw 
>>>>> 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 
>>> between the hardware and last_avail_idx, so last_avail_idx should 
>>> not change.
>>>
>>> Btw, what did "LM" mean :) ?
>>
>> I can add bar IO operations here, LM = live migration, sorry for the 
>> abbreviation.
>
>
> Just make sure I understand here, I believe you mean reading 
> last_avail_idx through IO bar here?
>
> Thanks

Hi Jason,

Yes, I mean last_avail_idx. is that correct?

THanks

>
>