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It can be an S1 > domain or an S2 nesting parent domain, depending on whether the VM is built > with a vSMMU or not. > > Given that the IOAS for this gPA mapping is the same across SMMU instances, > this domain can be shared across devices even if they sit behind different > SMMUs, so long as the underlying page table is compatible between the SMMU > instances. > > There is no direct information about the page table from the master device, > but a comparison can be done between the physical SMMU that the domain was > allocated for and the physical SMMU that the device is behind. I would very much prefer this works by inspecting the cfg from the iopgtable.. You can get it by doing struct io_pgtable_cfg *pgtbl_cfg = &io_pgtable_ops_to_pgtable(domain->pgtbl_ops)->cfg; I think it is important that the domain->smmu pointer be removed as well Jason