> > I doubt you can handle pci memory bars like regular ram when it comes to > > dma and iommu support. There is a reason we have p2pdma in the first > > place ... > > The thing is that such bars would be actually backed by regular host > RAM. Do we really need the complexity of real PCI bar handling for > that? Well, taking shortcuts because of virtualization-specific assumptions already caused problems in the past. See the messy iommu handling we have in virtio-pci for example. So I don't feel like going the "we know it's just normal pages, so lets simplify things" route. Beside that hostmap isn't important for secure buffers, we wouldn't allow the guest mapping them anyway ;) cheers, Gerd
