Re: [PATCH net V2 4/4] vhost: log dirty page correctly

Jason Wang
2018-12-14T02:43:03Z

On 2018/12/13 下午10:31, Michael S. Tsirkin wrote:
>> Just to make sure I understand this. It looks to me we should:
>>
>> - allow passing GIOVA->GPA through UAPI
>>
>> - cache GIOVA->GPA somewhere but still use GIOVA->HVA in device IOTLB for
>> performance
>>
>> Is this what you suggest?
>>
>> Thanks
> Not really. We already have GPA->HVA, so I suggested a flag to pass
> GIOVA->GPA in the IOTLB.
>
> This has advantages for security since a single table needs
> then to be validated to ensure guest does not corrupt
> QEMU memory.
>

I wonder how much we can gain through this. Currently, qemu IOMMU gives
GIOVA->GPA mapping, and qemu vhost code will translate GPA to HVA then
pass GIOVA->HVA to vhost. It looks no difference to me.

Thanks