Re: [PATCH v12 2/5] iommu: Enhance IOMMU default DMA mode build options

[John Garry]

On 12/06/2021 02:21, Lu Baolu wrote:
> On 2021/6/11 20:20, John Garry wrote:
> > +config IOMMU_DEFAULT_LAZY
> > +    bool "lazy"
> > +    help
> > +      Support lazy mode, where for every IOMMU DMA unmap operation, the
> > +      flush operation of IOTLB and the free operation of IOVA are 
> > deferred.
> > +      They are only guaranteed to be done before the related IOVA 
> > will be
> > +      reused.
> > +
> > +      The isolation provided in this mode is not as secure as STRICT 
> > mode,
> > +      such that a vulnerable time window may be created between the DMA
> > +      unmap and the mapping finally being torn down in the IOMMU, 
> > where the
> > +      device can still access the system memory. However this mode may
>
> " ... and the mappings cached in the IOMMU IOTLB or device TLB finally
> being invalidated, where the device probably can still access the memory
> which has already been unmapped by the device driver."

ok, I can try to incorporate some of this wording.

As for this:

On 12/06/2021 03:12, Lu Baolu wrote:
> On 2021/6/11 20:20, John Garry wrote:
>> +choice
>> +    prompt "IOMMU default DMA mode"
>
> This is not explicit.
>
> How about
>
> "IOMMU DMA default cache invalidation policy"
>
> ?
>

OK, but I'd rather use IOTLB, as that better matches the relevant 
iommu.c API name (iommu_ops.flush_iotlb_all).

Thanks,
john