On Mon, 2017-10-16 at 22:11 +1100, Alexey Kardashevskiy wrote: > On 16/10/17 19:38, Benjamin Herrenschmidt wrote: > > On Mon, 2017-10-16 at 18:36 +1100, Alexey Kardashevskiy wrote: > > > > > > 1. Allow msix mapping to the userspace (to address non-64k-aligned msix bar) > > > > > > 2. Allow write combining in vfio for the userspace (kvm guest is kinda > > > special and may simply ignore mapping flags in some configs but PPC radix > > > guests still rely on this) > > > > Why ? The "G" bit is entirely under control of the guest afaik. > > Yes, for hash guests. I am not sure sure about radix, Paul pointed me to > the code in KVM which uses the VFIO's mapping VMA. With radix, the HW will honor the G bit set in the guest page tables. > > > This > > would only affect qemu itself. It's still useful for things like dpdk > > using vfio. > > Correct, this is useful regardless KVM. > > > > 3. what callback and where needs to be added to inform HV/PR KVM about VFIO > > > group, like IOMMUMR::add_vfio_group() proposal or something. > > > > Can you elaborate a bit ? I haven't followed this. > > David knows :) > > >
