On 16/10/17 19:01, David Gibson wrote: > 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. Any luck with these? Ben, ping. -- Alexey
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