On Fri, Aug 01, 2025 at 10:30:35AM +0100, Suzuki K Poulose wrote: > > Is there a reason not to just dump that into the T=0 SMMU using 1G > > huge pages and never touch it again? The GPT provides protection? > > That is possible, once we get guest_memfd mmap support merged upstream. > GPT does provide protection. The only caveat is, does the guest_memfd > support this at all ? i.e., shared->private transitions with a shared > mapping in place (Though this is in SMMU only, not the Host CPU > pagetables) I don't know, we haven't got to the guestmemfd/IOMMU integration yet, which is why I ask the questions. I think AMD and ARM would both be interested in guestmemfd <-> iommu working this way, at least. > I think we can go ahead with VMM pre-populating the entire DRAM > and keeping it pinned for DA. Rather than doing this from the > vfio kernel, it could be done by the VMM as it has better knowledge > of the populated contents and map the rest as "unmeasured" 0s. Yes, if done it should be done by the VMM and run through guestmemfd/kvm however that is agreed to. Jason
