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Subject: Re: [RFC PATCH 10/24] vdpa: introduce config operations for
 associating ASID to a virtqueue group
To:     Eli Cohen <elic@nvidia.com>
Cc:     mst@redhat.com, lulu@redhat.com, kvm@vger.kernel.org,
        virtualization@lists.linux-foundation.org, netdev@vger.kernel.org,
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        lingshan.zhu@intel.com, eperezma@redhat.com, hanand@xilinx.com,
        mhabets@solarflare.com, amorenoz@redhat.com,
        maxime.coquelin@redhat.com, stefanha@redhat.com,
        sgarzare@redhat.com
References: <20200924032125.18619-1-jasowang@redhat.com>
 <20200924032125.18619-11-jasowang@redhat.com>
 <20201001132927.GC32363@mtl-vdi-166.wap.labs.mlnx>
From:   Jason Wang <jasowang@redhat.com>
Message-ID: <70af3ff0-74ed-e519-56f5-d61e6a48767f@redhat.com>
Date:   Fri, 9 Oct 2020 11:56:45 +0800
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On 2020/10/1 下午9:29, Eli Cohen wrote:
> On Thu, Sep 24, 2020 at 11:21:11AM +0800, Jason Wang wrote:
>> This patch introduces a new bus operation to allow the vDPA bus driver
>> to associate an ASID to a virtqueue group.
>>
> So in case of virtio_net, I would expect that all the data virtqueues
> will be associated with the same address space identifier.


Right.

I will add the codes to do this in the next version. It should be more 
explicit than have this assumption by default.


> Moreover,
> this assignment should be provided before the set_map call that provides
> the iotlb for the address space, correct?


I think it's better not have this limitation, note that set_map() now 
takes a asid argument.

So for hardware if the associated as is changed, the driver needs to 
program the hardware to switch to the new mapping.

Does this work for mlx5?


>> Signed-off-by: Jason Wang <jasowang@redhat.com>
>> ---
>>   include/linux/vdpa.h | 10 ++++++++++
>>   1 file changed, 10 insertions(+)
>>
>> diff --git a/include/linux/vdpa.h b/include/linux/vdpa.h
>> index 1e1163daa352..e2394995a3cd 100644
>> --- a/include/linux/vdpa.h
>> +++ b/include/linux/vdpa.h
>> @@ -160,6 +160,12 @@ struct vdpa_device {
>>    * @get_generation:		Get device config generation (optional)
>>    *				@vdev: vdpa device
>>    *				Returns u32: device generation
>> + * @set_group_asid:		Set address space identifier for a
>> + *				virtqueue group
>> + *				@vdev: vdpa device
>> + *				@group: virtqueue group
>> + *				@asid: address space id for this group
>> + *				Returns integer: success (0) or error (< 0)
>>    * @set_map:			Set device memory mapping (optional)
>>    *				Needed for device that using device
>>    *				specific DMA translation (on-chip IOMMU)
>> @@ -237,6 +243,10 @@ struct vdpa_config_ops {
>>   		       u64 iova, u64 size, u64 pa, u32 perm);
>>   	int (*dma_unmap)(struct vdpa_device *vdev, unsigned int asid,
>>   			 u64 iova, u64 size);
>> +	int (*set_group_asid)(struct vdpa_device *vdev, unsigned int group,
>> +			      unsigned int asid);
>> +
>> +
> Extra space


Will fix.

Thanks


>>   
>>   	/* Free device resources */
>>   	void (*free)(struct vdpa_device *vdev);
>> -- 
>> 2.20.1
>>