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Subject: Re: [PATCH 1/3] vDPA/ifcvf: deduce VIRTIO device ID when probe
To:     Zhu Lingshan <lingshan.zhu@linux.intel.com>,
        Zhu Lingshan <lingshan.zhu@intel.com>, mst@redhat.com,
        lulu@redhat.com, leonro@nvidia.com
Cc:     virtualization@lists.linux-foundation.org, netdev@vger.kernel.org,
        kvm@vger.kernel.org, linux-kernel@vger.kernel.org
References: <20210414091832.5132-1-lingshan.zhu@intel.com>
 <20210414091832.5132-2-lingshan.zhu@intel.com>
 <85483ff1-cf98-ad05-0c53-74caa2464459@redhat.com>
 <ccf7001b-27f0-27ea-40d2-52ca3cc2386b@linux.intel.com>
From:   Jason Wang <jasowang@redhat.com>
Message-ID: <ffd2861d-2395-de51-a227-f1ef33f74322@redhat.com>
Date:   Thu, 15 Apr 2021 14:30:42 +0800
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在 2021/4/15 下午1:52, Zhu Lingshan 写道:
>
>
> On 4/15/2021 11:30 AM, Jason Wang wrote:
>>
>> 在 2021/4/14 下午5:18, Zhu Lingshan 写道:
>>> This commit deduces VIRTIO device ID as device type when probe,
>>> then ifcvf_vdpa_get_device_id() can simply return the ID.
>>> ifcvf_vdpa_get_features() and ifcvf_vdpa_get_config_size()
>>> can work properly based on the device ID.
>>>
>>> Signed-off-by: Zhu Lingshan <lingshan.zhu@intel.com>
>>> ---
>>>   drivers/vdpa/ifcvf/ifcvf_base.h |  1 +
>>>   drivers/vdpa/ifcvf/ifcvf_main.c | 22 ++++++++++------------
>>>   2 files changed, 11 insertions(+), 12 deletions(-)
>>>
>>> diff --git a/drivers/vdpa/ifcvf/ifcvf_base.h 
>>> b/drivers/vdpa/ifcvf/ifcvf_base.h
>>> index b2eeb16b9c2c..1c04cd256fa7 100644
>>> --- a/drivers/vdpa/ifcvf/ifcvf_base.h
>>> +++ b/drivers/vdpa/ifcvf/ifcvf_base.h
>>> @@ -84,6 +84,7 @@ struct ifcvf_hw {
>>>       u32 notify_off_multiplier;
>>>       u64 req_features;
>>>       u64 hw_features;
>>> +    u32 dev_type;
>>>       struct virtio_pci_common_cfg __iomem *common_cfg;
>>>       void __iomem *net_cfg;
>>>       struct vring_info vring[IFCVF_MAX_QUEUE_PAIRS * 2];
>>> diff --git a/drivers/vdpa/ifcvf/ifcvf_main.c 
>>> b/drivers/vdpa/ifcvf/ifcvf_main.c
>>> index 44d7586019da..99b0a6b4c227 100644
>>> --- a/drivers/vdpa/ifcvf/ifcvf_main.c
>>> +++ b/drivers/vdpa/ifcvf/ifcvf_main.c
>>> @@ -323,19 +323,9 @@ static u32 ifcvf_vdpa_get_generation(struct 
>>> vdpa_device *vdpa_dev)
>>>     static u32 ifcvf_vdpa_get_device_id(struct vdpa_device *vdpa_dev)
>>>   {
>>> -    struct ifcvf_adapter *adapter = vdpa_to_adapter(vdpa_dev);
>>> -    struct pci_dev *pdev = adapter->pdev;
>>> -    u32 ret = -ENODEV;
>>> -
>>> -    if (pdev->device < 0x1000 || pdev->device > 0x107f)
>>> -        return ret;
>>> -
>>> -    if (pdev->device < 0x1040)
>>> -        ret =  pdev->subsystem_device;
>>> -    else
>>> -        ret =  pdev->device -0x1040;
>>> +    struct ifcvf_hw *vf = vdpa_to_vf(vdpa_dev);
>>>   -    return ret;
>>> +    return vf->dev_type;
>>>   }
>>>     static u32 ifcvf_vdpa_get_vendor_id(struct vdpa_device *vdpa_dev)
>>> @@ -466,6 +456,14 @@ static int ifcvf_probe(struct pci_dev *pdev, 
>>> const struct pci_device_id *id)
>>>       pci_set_drvdata(pdev, adapter);
>>>         vf = &adapter->vf;
>>> +    if (pdev->device < 0x1000 || pdev->device > 0x107f)
>>> +        return -EOPNOTSUPP;
>>> +
>>> +    if (pdev->device < 0x1040)
>>> +        vf->dev_type =  pdev->subsystem_device;
>>> +    else
>>> +        vf->dev_type =  pdev->device - 0x1040;
>>
>>
>> So a question here, is the device a transtional device or modern one?
>>
>> If it's a transitonal one, can it swtich endianess automatically or not?
>>
>> Thanks
> Hi Jason,
>
> This driver should drive both modern and transitional devices as we 
> discussed before.
> If it's a transitional one, it will act as a modern device by default, 
> legacy mode is a fail-over path.


Note that legacy driver use native endian, support legacy driver 
requires the device to know native endian which I'm not sure your device 
can do that.

Thanks


> For vDPA, it has to support VIRTIO_1 and ACCESS_PLATFORM, so it must 
> in modern mode.
> I think we don't need to worry about endianess for legacy mode.
>
> Thanks
> Zhu Lingshan
>>
>>
>>> +
>>>       vf->base = pcim_iomap_table(pdev);
>>>         adapter->pdev = pdev;
>>
>