netdev - Re: [PATCH V3 2/2] vDPA/ifcvf: implement doorbell mapping for ifcvf

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Message-ID: <68a31c70-cc9f-346a-14a0-cbc05905c287@intel.com>
Date:   Tue, 1 Jun 2021 16:58:52 +0800
From:   "Zhu, Lingshan" <lingshan.zhu@...el.com>
To:     Jason Wang <jasowang@...hat.com>, mst@...hat.com
Cc:     virtualization@...ts.linux-foundation.org, netdev@...r.kernel.org,
        kvm@...r.kernel.org
Subject: Re: [PATCH V3 2/2] vDPA/ifcvf: implement doorbell mapping for ifcvf



On 6/1/2021 4:57 PM, Jason Wang wrote:
>
> 在 2021/6/1 下午4:56, Zhu, Lingshan 写道:
>>
>>
>> On 6/1/2021 4:50 PM, Jason Wang wrote:
>>>
>>> 在 2021/6/1 下午2:28, Zhu Lingshan 写道:
>>>> This commit implements doorbell mapping feature for ifcvf.
>>>> This feature maps the notify page to userspace, to eliminate
>>>> vmexit when kick a vq.
>>>>
>>>> Signed-off-by: Zhu Lingshan <lingshan.zhu@...el.com>
>>>> ---
>>>>   drivers/vdpa/ifcvf/ifcvf_main.c | 21 +++++++++++++++++++++
>>>>   1 file changed, 21 insertions(+)
>>>>
>>>> diff --git a/drivers/vdpa/ifcvf/ifcvf_main.c 
>>>> b/drivers/vdpa/ifcvf/ifcvf_main.c
>>>> index ab0ab5cf0f6e..d41db042612c 100644
>>>> --- a/drivers/vdpa/ifcvf/ifcvf_main.c
>>>> +++ b/drivers/vdpa/ifcvf/ifcvf_main.c
>>>> @@ -413,6 +413,26 @@ static int ifcvf_vdpa_get_vq_irq(struct 
>>>> vdpa_device *vdpa_dev,
>>>>       return vf->vring[qid].irq;
>>>>   }
>>>>   +static struct vdpa_notification_area 
>>>> ifcvf_get_vq_notification(struct vdpa_device *vdpa_dev,
>>>> +                                   u16 idx)
>>>> +{
>>>> +    struct ifcvf_adapter *adapter = vdpa_to_adapter(vdpa_dev);
>>>> +    struct ifcvf_hw *vf = vdpa_to_vf(vdpa_dev);
>>>> +    struct pci_dev *pdev = adapter->pdev;
>>>> +    struct vdpa_notification_area area;
>>>> +
>>>> +    area.addr = vf->vring[idx].notify_pa;
>>>> +    if (!vf->notify_off_multiplier)
>>>> +        area.size = PAGE_SIZE;
>>>> +    else
>>>> +        area.size = vf->notify_off_multiplier;
>>>> +
>>>> +    if (area.addr % PAGE_SIZE)
>>>> +        IFCVF_DBG(pdev, "vq %u doorbell address is not PAGE_SIZE 
>>>> aligned\n", idx);
>>>
>>>
>>> I don't see the reason to keep this, or get_notification is not the 
>>> proper place to do this kind of warning.
>>>
>>> Thanks
>> some customers have ever complained have troubles to enable such 
>> features with their IP,
>> I think this can help them debug.
>
>
> If you want to do this, the ifcvf_init_hw() is the proper place.
>
> Note that this function is called by userspace.
>
> Thanks
OK, will move to there.

Thanks!
>
>
>>
>> Thanks
>>>
>>>
>>>> +
>>>> +    return area;
>>>> +}
>>>> +
>>>>   /*
>>>>    * IFCVF currently does't have on-chip IOMMU, so not
>>>>    * implemented set_map()/dma_map()/dma_unmap()
>>>> @@ -440,6 +460,7 @@ static const struct vdpa_config_ops 
>>>> ifc_vdpa_ops = {
>>>>       .get_config    = ifcvf_vdpa_get_config,
>>>>       .set_config    = ifcvf_vdpa_set_config,
>>>>       .set_config_cb  = ifcvf_vdpa_set_config_cb,
>>>> +    .get_vq_notification = ifcvf_get_vq_notification,
>>>>   };
>>>>     static int ifcvf_probe(struct pci_dev *pdev, const struct 
>>>> pci_device_id *id)
>>>
>>
>