[PATCH v3 6/7] iommu/mediatek: Gather iova in iommu_unmap to achieve tlb sync once

[Robin Murphy]

On 2021-01-18 16:58, Will Deacon wrote:
> On Mon, Jan 18, 2021 at 04:35:22PM +0000, Robin Murphy wrote:
>> On 2020-12-16 10:36, Yong Wu wrote:
>>> In current iommu_unmap, this code is:
>>>
>>> 	iommu_iotlb_gather_init(&iotlb_gather);
>>> 	ret = __iommu_unmap(domain, iova, size, &iotlb_gather);
>>> 	iommu_iotlb_sync(domain, &iotlb_gather);
>>>
>>> We could gather the whole iova range in __iommu_unmap, and then do tlb
>>> synchronization in the iommu_iotlb_sync.
>>>
>>> This patch implement this, Gather the range in mtk_iommu_unmap.
>>> then iommu_iotlb_sync call tlb synchronization for the gathered iova range.
>>> we don't call iommu_iotlb_gather_add_page since our tlb synchronization
>>> could be regardless of granule size.
>>>
>>> In this way, gather->start is impossible ULONG_MAX, remove the checking.
>>>
>>> This patch aims to do tlb synchronization *once* in the iommu_unmap.
>>
>> Assuming the update to patch #4 simply results in "unsigned long end = iova
>> + size - 1;" here,
>>
>> Reviewed-by: Robin Murphy <robin.murphy at arm.com>
> 
> There's a v4 here:
> 
> https://lore.kernel.org/r/20210107122909.16317-1-yong.wu@mediatek.com

Ha, so there is! Apparently I missed that in my post-holiday sweep last 
week and leant too heavily on the inbox-in-date-order assumption. Lemme 
just go catch up...

Thanks,
Robin.