On Thu, Aug 11, 2016 at 03:19:57PM +0200, Cornelia Huck wrote: > On Thu, 11 Aug 2016 14:57:24 +0200 > Paolo Bonzini <[email protected]> wrote: > > > On 26/08/2015 20:54, Paul Mackerras wrote: > > > On Wed, Aug 26, 2015 at 11:34:26AM +0200, Alexander Graf wrote: > > >> On 13.08.15 03:15, David Gibson wrote: > > >>> ec53500f "kvm: Add VFIO device" added a special KVM pseudo-device which > > >>> is > > >>> used to handle any necessary interactions between KVM and VFIO. > > >>> > > >>> Currently that device is built on x86 and ARM, but not powerpc, although > > >>> powerpc does support both KVM and VFIO. This makes things awkward in > > >>> userspace > > >>> > > >>> Currently qemu prints an alarming error message if you attempt to use > > >>> VFIO > > >>> and it can't initialize the KVM VFIO device. We don't want to remove > > >>> the > > >>> warning, because lack of the KVM VFIO device could mean coherency > > >>> problems > > >>> on x86. On powerpc, however, the error is harmless but looks > > >>> disturbing, > > >>> and a test based on host architecture in qemu would be ugly, and break > > >>> if > > >>> we do need the KVM VFIO device for something important in future. > > >>> > > >>> There's nothing preventing the KVM VFIO device from being built for > > >>> powerpc, so this patch turns it on. It won't actually do anything, > > >>> since > > >>> we don't define any of the arch_*() hooks, but it will make qemu happy > > >>> and > > >>> we can extend it in future if we need to. > > >>> > > >>> Signed-off-by: David Gibson <[email protected]> > > >>> Reviewed-by: Eric Auger <[email protected]> > > > > This patch (commit 178a787502123) did not select CONFIG_KVM_VFIO, so the > > patch did nothing---except causing build failures which I fixed in > > commit 0af574be32cdd ("KVM: PPC: do not compile in vfio.o > > unconditionally", 2016-03-21) by making the patch a total no-op. > > > > Is KVM_VFIO really needed, and if so can this patch be fixed? > > FWIW, we enabled building vfio.o on s390 in 14b0b4a ("KVM: s390: Enable > the KVM-VFIO device") with the rationale "while we don't need it, be > like everybody else". > > Should powerpc (and every other architecture supporting kvm and vfio) > select KVM_VFIO so that really everybody does the same thing?
Yes, I think it should. That was my intention when I sent that patch
- I just messed it up.
--
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
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