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authorAlex Williamson <alex.williamson@redhat.com>2014-02-26 11:38:40 -0700
committerAlex Williamson <alex.williamson@redhat.com>2014-02-26 11:38:40 -0700
commit9d830d47c7a756da6f0b55fa25d51eec0739eb02 (patch)
tree3f40dbe93c1b0120246eab829f33490a127e336c /virt
parent88d7ab8949427f492c39f6daf0ac67f0242a88bc (diff)
downloadkernel-9d830d47c7a756da6f0b55fa25d51eec0739eb02.tar.gz
kvm/vfio: Support for DMA coherent IOMMUs
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> Acked-by: Paolo Bonzini <pbonzini@redhat.com>
Diffstat (limited to 'virt')
-rw-r--r--virt/kvm/vfio.c27
1 files changed, 20 insertions, 7 deletions
diff --git a/virt/kvm/vfio.c b/virt/kvm/vfio.c
index b4f9507ae650..ba1a93f935c7 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) {