Re: [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@xxxxxxx>
>
> There's a v4 here:
>
> https://lore.kernel.org/r/20210107122909.16317-1-yong.wu@xxxxxxxxxxxx

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.