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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; > > OK. I will make it a detailed scan > > > I think it is important that the domain->smmu pointer be removed as > > well > > I will try that too. > > There are smmu_domain->smmu validations in two SVA functions, > which presumably might be replaced with this can_share() too. Those are because we replicate the mmu notifier for every instance. That can now be revised too, I think. Let's leave that for another series after this and leave the smmu pointer for now, but don't use it outside that SVA stuff. Jason