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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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        maxime.coquelin@redhat.com, stefanha@redhat.com,
        sgarzare@redhat.com
References: <20200924032125.18619-1-jasowang@redhat.com>
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 <70af3ff0-74ed-e519-56f5-d61e6a48767f@redhat.com>
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 <b1ac150b-0845-874f-75d0-7440133a1d41@redhat.com>
 <20201012081725.GB42327@mtl-vdi-166.wap.labs.mlnx>
From:   Jason Wang <jasowang@redhat.com>
Message-ID: <3e4a8bea-f187-3843-c1d1-75d0b86a137b@redhat.com>
Date:   Tue, 13 Oct 2020 13:40:44 +0800
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On 2020/10/12 下午4:17, Eli Cohen wrote:
> On Mon, Oct 12, 2020 at 03:45:10PM +0800, Jason Wang wrote:
>>> So in theory we can have several asid's (for different virtqueues), each
>>> one should be followed by a specific set_map call. If this is so, how do
>>> I know if I met all the conditions run my driver? Maybe we need another
>>> callback to let the driver know it should not expect more set_maps().
>>
>> This should work similarly as in the past. Two parts of the work is expected
>> to be done by the driver:
>>
>> 1) store the mapping somewhere (e.g hardware) during set_map()
>> 2) associating mapping with a specific virtqueue
>>
>> The only difference is that more than one mapping is used now.
> ok, so like today, I will always get DRIVER_OK after I got all the
> set_maps(), right?


Yes.

Thanks


>
>> For the issue of more set_maps(), driver should be always ready for the new
>> set_maps() call instead of not expecting new set_maps() since guest memory
>> topology could be changed due to several reasons.
>>
>> Qemu or vhost-vDPA will try their best to avoid the frequency of set_maps()
>> for better performance (e.g through batched IOTLB updating). E.g there
>> should be at most one set_map() during one time of guest booting.
>>
>>