On Wed, 2017-01-04 at 11:11 +0100, Thomas Monjalon wrote: > 2017-01-03 22:50, Walker, Benjamin: > > 1) Physical addresses cannot be exposed to unprivileged users due to > > security > > concerns (the fallout of rowhammer). Therefore, systems without an IOMMU can > > only support privileged users. I think this is probably fine. > > 2) The IOCTL from vfio to pin the memory is tied to specifying the DMA > > address > > and programming the IOMMU. This is unfortunate - systems without an IOMMU > > still > > want to do the pinning, but they need to be given the physical address > > instead > > of specifying a DMA address. > > 3) Not all device types, particularly in virtualization environments, > > support > > vfio today. These devices have no way to explicitly pin memory. > > In VM we can use VFIO-noiommu. Is it helping for mapping?
There does not appear to be a vfio IOCTL that pins memory without also programming the IOMMU, so vfio-noiommu is broken in the same way that uio is for drivers that require physical memory.
