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Groups > linux.kernel > #1460515
| From | Cornelia Huck <cornelia.huck@de.ibm.com> |
|---|---|
| Newsgroups | linux.kernel |
| Subject | Re: [PATCH] vfio: Enable VFIO device for powerpc |
| Date | 2016-08-11 15:30 +0200 |
| Message-ID | <s4Ydz-4ms-9@gated-at.bofh.it> (permalink) |
| References | <pWPlv-4Vr-1@gated-at.bofh.it> <q1Flw-1N4-13@gated-at.bofh.it> <q1O5s-5Pg-13@gated-at.bofh.it> <s4XKx-3Wr-7@gated-at.bofh.it> |
| Organization | IBM Deutschland Research & Development GmbH Vorsitzende des Aufsichtsrats: Martina Koederitz Geschäftsführung: Dirk Wittkopp Sitz der Gesellschaft: Böblingen Registergericht: Amtsgericht Stuttgart, HRB 243294 |
On Thu, 11 Aug 2016 14:57:24 +0200
Paolo Bonzini <pbonzini@redhat.com> 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 <david@gibson.dropbear.id.au>
> >>> Reviewed-by: Eric Auger <eric.auger@linaro.org>
>
> 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?
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Re: [PATCH] vfio: Enable VFIO device for powerpc Paolo Bonzini <pbonzini@redhat.com> - 2016-08-11 15:00 +0200
Re: [PATCH] vfio: Enable VFIO device for powerpc Cornelia Huck <cornelia.huck@de.ibm.com> - 2016-08-11 15:30 +0200
Re: [PATCH] vfio: Enable VFIO device for powerpc Alexey Kardashevskiy <aik@ozlabs.ru> - 2016-08-11 16:10 +0200
Re: [PATCH] vfio: Enable VFIO device for powerpc David Gibson <david@gibson.dropbear.id.au> - 2016-08-12 09:00 +0200
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