On Fri, Feb 27, 2015 at 12:12:32AM +0000, Mario Smarduch wrote: > I noticed kernel tlbflush.h use tlbi va*, vaa* variants instead of > val, vaal ones. Reading the manual D.5.7.2 it appears that > va*, vaa* versions invalidate intermediate caching of > translation structures. > > With stage2 enabled that may result in 20+ memory lookups > for a 4 level page table walk. That's assuming that intermediate > caching structures cache mappings from stage1 table entry to > host page.
Yeah, Catalin and I discussed improving the kernel support for this, but it requires some changes to the generic mmu_gather code so that we can distinguish the leaf cases. I'd also like to see that done in a way that takes into account different granule sizes (we currently iterate over huge pages in 4k chunks). Last time I touched that, I entered a world of pain and don't plan to return there immediately :) Catalin -- feeling brave? FWIW: the new IOMMU page-table stuff I just got merged *does* make use of leaf-invalidation for the SMMU. Will _______________________________________________ kvmarm mailing list kvmarm@lists.cs.columbia.edu https://lists.cs.columbia.edu/mailman/listinfo/kvmarm
