From e0f0bbc527f6e9c0261f1d16b2a0b47612b7f235 Mon Sep 17 00:00:00 2001 From: Alex Williamson Date: Wed, 30 Oct 2013 11:02:30 -0600 Subject: kvm: Create non-coherent DMA registeration We currently use some ad-hoc arch variables tied to legacy KVM device assignment to manage emulation of instructions that depend on whether non-coherent DMA is present. Create an interface for this, adapting legacy KVM device assignment and adding VFIO via the KVM-VFIO device. For now we assume that non-coherent DMA is possible any time we have a VFIO group. Eventually an interface can be developed as part of the VFIO external user interface to query the coherency of a group. Signed-off-by: Alex Williamson Signed-off-by: Paolo Bonzini --- virt/kvm/vfio.c | 44 ++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 44 insertions(+) (limited to 'virt/kvm/vfio.c') diff --git a/virt/kvm/vfio.c b/virt/kvm/vfio.c index 597c258245e..ca4260e3503 100644 --- a/virt/kvm/vfio.c +++ b/virt/kvm/vfio.c @@ -27,6 +27,7 @@ struct kvm_vfio_group { struct kvm_vfio { struct list_head group_list; struct mutex lock; + bool noncoherent; }; static struct vfio_group *kvm_vfio_group_get_external_user(struct file *filep) @@ -58,6 +59,43 @@ static void kvm_vfio_group_put_external_user(struct vfio_group *vfio_group) symbol_put(vfio_group_put_external_user); } +/* + * 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 + * been told about. We don't want to care about any of that so we retest + * each group and bail as soon as we find one that's noncoherent. This + * means we only ever [un]register_noncoherent_dma once for the whole device. + */ +static void kvm_vfio_update_coherency(struct kvm_device *dev) +{ + struct kvm_vfio *kv = dev->private; + bool noncoherent = false; + struct kvm_vfio_group *kvg; + + 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 (noncoherent != kv->noncoherent) { + kv->noncoherent = noncoherent; + + if (kv->noncoherent) + kvm_arch_register_noncoherent_dma(dev->kvm); + else + kvm_arch_unregister_noncoherent_dma(dev->kvm); + } + + mutex_unlock(&kv->lock); +} + static int kvm_vfio_set_group(struct kvm_device *dev, long attr, u64 arg) { struct kvm_vfio *kv = dev->private; @@ -105,6 +143,8 @@ static int kvm_vfio_set_group(struct kvm_device *dev, long attr, u64 arg) mutex_unlock(&kv->lock); + kvm_vfio_update_coherency(dev); + return 0; case KVM_DEV_VFIO_GROUP_DEL: @@ -140,6 +180,8 @@ static int kvm_vfio_set_group(struct kvm_device *dev, long attr, u64 arg) kvm_vfio_group_put_external_user(vfio_group); + kvm_vfio_update_coherency(dev); + return ret; } @@ -185,6 +227,8 @@ static void kvm_vfio_destroy(struct kvm_device *dev) kfree(kvg); } + kvm_vfio_update_coherency(dev); + kfree(kv); kfree(dev); /* alloc by kvm_ioctl_create_device, free by .destroy */ } -- cgit v1.2.3-70-g09d2