Re: [RFC PATCH 01/10] vdpa: add get_config_size callback in vdpa_config_ops

[Stefano Garzarella <sgarzare@redhat.com>]

On Thu, Mar 04, 2021 at 04:34:52PM +0800, Jason Wang wrote:
>
>On 2021/3/2 10:15 下午, Stefano Garzarella wrote:
>>On Tue, Mar 02, 2021 at 12:14:13PM +0800, Jason Wang wrote:
>>>
>>>On 2021/2/16 5:44 下午, Stefano Garzarella wrote:
>>>>This new callback is used to get the size of the configuration space
>>>>of vDPA devices.
>>>>
>>>>Signed-off-by: Stefano Garzarella <sgarzare@redhat.com>
>>>>---
>>>> include/linux/vdpa.h              | 4 ++++
>>>> drivers/vdpa/ifcvf/ifcvf_main.c   | 6 ++++++
>>>> drivers/vdpa/mlx5/net/mlx5_vnet.c | 6 ++++++
>>>> drivers/vdpa/vdpa_sim/vdpa_sim.c  | 9 +++++++++
>>>> 4 files changed, 25 insertions(+)
>>>>
>>>>diff --git a/include/linux/vdpa.h b/include/linux/vdpa.h
>>>>index 4ab5494503a8..fddf42b17573 100644
>>>>--- a/include/linux/vdpa.h
>>>>+++ b/include/linux/vdpa.h
>>>>@@ -150,6 +150,9 @@ struct vdpa_iova_range {
>>>>  * @set_status:            Set the device status
>>>>  *                @vdev: vdpa device
>>>>  *                @status: virtio device status
>>>>+ * @get_config_size:        Get the size of the configuration space
>>>>+ *                @vdev: vdpa device
>>>>+ *                Returns size_t: configuration size
>>>
>>>
>>>Rethink about this, how much we could gain by introducing a 
>>>dedicated ops here? E.g would it be simpler if we simply introduce 
>>>a max_config_size to vdpa device?
>>
>>Mainly because in this way we don't have to add new parameters to 
>>the vdpa_alloc_device() function.
>>
>>We do the same for example for 'get_device_id', 'get_vendor_id', 
>>'get_vq_num_max'. All of these are usually static, but we have ops.
>>I think because it's easier to extend.
>>
>>I don't know if it's worth adding a new structure for these static 
>>values at this point, like 'struct vdpa_config_params'.
>
>
>Yes, that's the point. I think for any static values, it should be set 
>during device allocation.

Yeah, I see.

>
>I'm fine with both.
>

@Michael any thoughts?

Thanks,
Stefano

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