Re: [PATCH 2/2] vhost: re-introducing metadata acceleration through kernel virtual address

Jason Wang
2019-09-09T07:24:09Z

On 2019/9/9 下午12:45, Michael S. Tsirkin wrote:
>>> Since idx can be speculated, I guess we need array_index_nospec here?
>> So we have
>>
>> ACQUIRE(mmu_lock)
>>
>> get idx
>>
>> RELEASE(mmu_lock)
>>
>> ACQUIRE(mmu_lock)
>>
>> read array[idx]
>>
>> RELEASE(mmu_lock)
>>
>> Then I think idx can't be speculated consider we've passed RELEASE +
>> ACQUIRE?
> I don't think memory barriers have anything to do with speculation,
> they are architectural.
>

Oh right. Let me add array_index_nospec() in next version.

Thanks