On Thu, Jun 01, 2023 at 12:18:43AM +0200, Jann Horn wrote: > 3. We have to *serialize* with page table walks performed by the > IOMMU. We're doing an RCU barrier to synchronize against page table > walks from the MMU, but without an appropriate mmu_notifier call, we > have nothing to ensure that we aren't yanking a page table out from > under an IOMMU page table walker while it's in the middle of its walk. > Sure, this isn't very likely in practice, the IOMMU page table walker > is probably pretty fast, but still we need some kind of explicit > synchronization to make this robust, I think. There is another thread talking about this.. Broadly we are saying that we need to call mmu ops invalidate_range at any time the normal CPU TLB would be invalidated. invalidate_range will not return until the iommu HW is coherent with the current state of the page table. Jason
