On Mon, Oct 16, 2017 at 06:36:29PM +1100, Alexey Kardashevskiy wrote: > On 16/10/17 17:00, David Gibson wrote: > > On Mon, Oct 16, 2017 at 04:54:08PM +1100, Alexey Kardashevskiy wrote: > >> On 12/10/17 02:35, Benjamin Herrenschmidt wrote: > >>> On Wed, 2017-10-11 at 13:56 +1100, Alexey Kardashevskiy wrote: > >>>> Oopsie. This is because I overlooked it. Others do not use it. So I do need > >>>> a file. But in the current scheme where all BARs share one fd - it won't > >>>> work - I simply cannot allow WC on non-prefetchable BARs :-/ > >>> > >>> This is an oversight in the design of VFIO-PCI, it should have a way to > >>> specify write combine, either implicitely via such an arch hook, or > >>> explicitely via an ioctl prior to mapping the BARs for example. > >>> > >>> Alex, what do you reckon is the best approach here ? > >> > >> /me wonders if it is yet another issue for the dead issues bucket, just > >> like the msix mapping one :) > > > > Maybe. Alexey, maybe you can make up a list of things that we (me, > > you, BenH) need to discuss with Alex W at KVM Forum? > > "you" - you meant me? I am not coming over there :( Oh.. I thought you were. > The list is: > > 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) > > 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. Thanks. -- David Gibson | I'll have my music baroque, and my code david AT gibson.dropbear.id.au | minimalist, thank you. NOT _the_ _other_ | _way_ _around_! http://www.ozlabs.org/~dgibson
Attachment:
signature.asc
Description: PGP signature
