Re: [PATCH] crypto: gcm - fix cacheline sharing

[Horia Geanta]

On 5/30/2019 4:26 PM, Herbert Xu wrote:
> On Thu, May 30, 2019 at 01:18:34PM +0000, Horia Geanta wrote:
>>
>> I guess there are only two options:
>> -either cache line sharing is avoided OR
>> -users need to be *aware* they are sharing the cache line and some rules /
>> assumptions are in place on how to safely work on the data
> 
> No there is a third option and it's very simple:
> 
I see this as the 2nd option.

> You must only access the virtual addresses given to you before DMA
> mapping or after DMA unmapping.
> 
Unless it's clearly defined *which* virtual addresses mustn't be accessed,
things won't work properly.
In theory, any two objects could share a cache line. We can't just stop all
memory accesses from CPU while a peripheral is busy.

Thanks,
Horia