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

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