Virtualization - Mar 2021 - [PATCH V3 1/6] vDPA/ifcvf: get_vendor_id returns a device specific vendor id

On 2021/3/10 5:00 ??, Zhu Lingshan wrote:
> In this commit, ifcvf_get_vendor_id() will return
> a device specific vendor id of the probed pci device
> than a hard code.
>
> Signed-off-by: Zhu Lingshan <lingshan.zhu at intel.com>
> ---
>   drivers/vdpa/ifcvf/ifcvf_main.c | 5 ++++-
>   1 file changed, 4 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/vdpa/ifcvf/ifcvf_main.c
b/drivers/vdpa/ifcvf/ifcvf_main.c
> index fa1af301cf55..e501ee07de17 100644
> --- a/drivers/vdpa/ifcvf/ifcvf_main.c
> +++ b/drivers/vdpa/ifcvf/ifcvf_main.c
> @@ -324,7 +324,10 @@ static u32 ifcvf_vdpa_get_device_id(struct vdpa_device
*vdpa_dev)
>   
>   static u32 ifcvf_vdpa_get_vendor_id(struct vdpa_device *vdpa_dev)
>   {
> -	return IFCVF_SUBSYS_VENDOR_ID;
> +	struct ifcvf_adapter *adapter = vdpa_to_adapter(vdpa_dev);
> +	struct pci_dev *pdev = adapter->pdev;
> +
> +	return pdev->subsystem_vendor;
>   }

While at this, I wonder if we can do something similar in 
get_device_id() if it could be simple deduced from some simple math from 
the pci device id?

Thanks

>   
>   static u32 ifcvf_vdpa_get_vq_align(struct vdpa_device *vdpa_dev)

On 3/11/2021 11:23 AM, Jason Wang wrote:
>
> On 2021/3/10 5:00 ??, Zhu Lingshan wrote:
>> In this commit, ifcvf_get_vendor_id() will return
>> a device specific vendor id of the probed pci device
>> than a hard code.
>>
>> Signed-off-by: Zhu Lingshan <lingshan.zhu at intel.com>
>> ---
>> ? drivers/vdpa/ifcvf/ifcvf_main.c | 5 ++++-
>> ? 1 file changed, 4 insertions(+), 1 deletion(-)
>>
>> diff --git a/drivers/vdpa/ifcvf/ifcvf_main.c 
>> b/drivers/vdpa/ifcvf/ifcvf_main.c
>> index fa1af301cf55..e501ee07de17 100644
>> --- a/drivers/vdpa/ifcvf/ifcvf_main.c
>> +++ b/drivers/vdpa/ifcvf/ifcvf_main.c
>> @@ -324,7 +324,10 @@ static u32 ifcvf_vdpa_get_device_id(struct 
>> vdpa_device *vdpa_dev)
>> ? ? static u32 ifcvf_vdpa_get_vendor_id(struct vdpa_device *vdpa_dev)
>> ? {
>> -??? return IFCVF_SUBSYS_VENDOR_ID;
>> +??? struct ifcvf_adapter *adapter = vdpa_to_adapter(vdpa_dev);
>> +??? struct pci_dev *pdev = adapter->pdev;
>> +
>> +??? return pdev->subsystem_vendor;
>> ? }
>
>
> While at this, I wonder if we can do something similar in 
> get_device_id() if it could be simple deduced from some simple math 
> from the pci device id?
>
> Thanks
Hi Jason,

IMHO, this implementation is just some memory read ops, I think other 
implementations may not save many cpu cycles, an if cost at least three 
cpu cycles.

Thanks!
>
>
>> ? ? static u32 ifcvf_vdpa_get_vq_align(struct vdpa_device *vdpa_dev)
>