> On 05/10/2011 02:33 PM, Paul Brook wrote: > > There should be nothing special about virtio-pci. These devices should > > access memory in exactly the same way as any other PCI device. Bypassing > > the normal PCI iommu is IMO a serious bug. > > I suspect that the argument is that virtio is implemented on several > busses, and ignoring any bus-specific stuff means that there's less > need for any code differences.
It also has some horrifically bad implications. Not least of which is the inability to sanely handle nested virtualization. IMO the whole point of virtio-pci is that it avoids magical weirdness for virtio devices devices. If you're going to start adding nonstandard exceptions for virtio devices than there seem little point using PCI in the first place. It's likely to cause more problems than it solves for the guest drivers. Paul
