Messages in this thread | | | Date | Tue, 18 Feb 2014 11:38:32 +0100 | From | Paolo Bonzini <> | Subject | Re: [PATCH 4/4] kvm/vfio: Support for DMA coherent IOMMUs |
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Il 17/02/2014 21:24, Alex Williamson ha scritto: > VFIO now has support for using the IOMMU_CACHE flag and a mechanism > for an external user to test the current operating mode of the IOMMU. > Add support for this to the kvm-vfio pseudo device so that we only > register noncoherent DMA when necessary. > > Signed-off-by: Alex Williamson <alex.williamson@redhat.com> > Cc: Gleb Natapov <gleb@kernel.org> > Cc: Paolo Bonzini <pbonzini@redhat.com> > --- > virt/kvm/vfio.c | 27 ++++++++++++++++++++------- > 1 file changed, 20 insertions(+), 7 deletions(-) > > diff --git a/virt/kvm/vfio.c b/virt/kvm/vfio.c > index b4f9507..ba1a93f 100644 > --- a/virt/kvm/vfio.c > +++ b/virt/kvm/vfio.c > @@ -59,6 +59,22 @@ static void kvm_vfio_group_put_external_user(struct vfio_group *vfio_group) > symbol_put(vfio_group_put_external_user); > } > > +static bool kvm_vfio_group_is_coherent(struct vfio_group *vfio_group) > +{ > + long (*fn)(struct vfio_group *, unsigned long); > + long ret; > + > + fn = symbol_get(vfio_external_check_extension); > + if (!fn) > + return false; > + > + ret = fn(vfio_group, VFIO_DMA_CC_IOMMU); > + > + symbol_put(vfio_external_check_extension); > + > + return ret > 0; > +} > + > /* > * Groups can use the same or different IOMMU domains. If the same then > * adding a new group may change the coherency of groups we've previously > @@ -75,13 +91,10 @@ static void kvm_vfio_update_coherency(struct kvm_device *dev) > mutex_lock(&kv->lock); > > list_for_each_entry(kvg, &kv->group_list, node) { > - /* > - * TODO: We need an interface to check the coherency of > - * the IOMMU domain this group is using. For now, assume > - * it's always noncoherent. > - */ > - noncoherent = true; > - break; > + if (!kvm_vfio_group_is_coherent(kvg->vfio_group)) { > + noncoherent = true; > + break; > + } > } > > if (noncoherent != kv->noncoherent) { >
Acked-by: Paolo Bonzini <pbonzini@redhat.com>
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