On Wed, Oct 11, 2023 at 01:03:09PM -0400, Michael S. Tsirkin wrote: > On Wed, Oct 11, 2023 at 09:18:49AM -0300, Jason Gunthorpe wrote: > > The simple way to be sure is to never touch the PCI function that has > > DMA assigned to a VM from the hypervisor, except through config space. > > What makes config space different that it's safe though? Hypervisor fully mediates it and it is not accessible to P2P attacks. > Isn't this more of a "we can't avoid touching config space" than > that it's safe? The line doesn't look that bright to me - > if there's e.g. a memory area designed explicitly for > hypervisor to poke at, that seems fine. It is not. Jason
