Re: [PATCH kernel 12/15] KVM: PPC: Enable IOMMU_API for KVM_BOOK3S_64 permanently
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From: David Gibson <hidden>
Date: 2016-08-12 04:48:53
On Wed, Aug 03, 2016 at 06:40:53PM +1000, Alexey Kardashevskiy wrote:
quoted hunk ↗ jump to hunk
It does not make much sense to have KVM in book3s-64 and not to have IOMMU bits for PCI pass through support as it costs little and allows VFIO to function on book3s KVM. Having IOMMU_API always enabled makes it unnecessary to have a lot of "#ifdef IOMMU_API" in arch/powerpc/kvm/book3s_64_vio*. With those ifdef's we could have only user space emulated devices accelerated (but not VFIO) which do not seem to be very useful. Signed-off-by: Alexey Kardashevskiy <redacted> --- arch/powerpc/kvm/Kconfig | 1 + 1 file changed, 1 insertion(+)diff --git a/arch/powerpc/kvm/Kconfig b/arch/powerpc/kvm/Kconfig index b7c494b..63b60a8 100644 --- a/arch/powerpc/kvm/Kconfig +++ b/arch/powerpc/kvm/Kconfig@@ -65,6 +65,7 @@ config KVM_BOOK3S_64 select KVM select KVM_BOOK3S_PR_POSSIBLE if !KVM_BOOK3S_HV_POSSIBLE select KVM_VFIO if VFIO + select SPAPR_TCE_IOMMU if IOMMU_SUPPORT ---help--- Support running unmodified book3s_64 and book3s_32 guest kernels in virtual machines on book3s_64 host processors.
I don't quite see how this change accomplishes the stated goal. AFAICT even with this change you can still turn off IOMMU_SUPPORT, which will break the IOMMU for VFIO passthrough, but not IOMMU acceleration for emulated devices (since that requires no interaction with the hardware IOMMU). -- 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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