vfio: Change vfio_external_check_extension() to vfio_file_enforced_coherent()

Instead of a general extension check change the function into a limited
test if the iommu_domain has enforced coherency, which is the only thing
kvm needs to query.

Make the new op self contained by properly refcounting the container
before touching it.

Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Jason Gunthorpe <jgg@nvidia.com>
Link: https://lore.kernel.org/r/5-v3-f7729924a7ea+25e33-vfio_kvm_no_group_jgg@nvidia.com
Signed-off-by: Alex Williamson <alex.williamson@redhat.com>

1 files changed, 8 insertions, 8 deletions

diff --git a/virt/kvm/vfio.c b/virt/kvm/vfio.c
index 0b84916c3f71..d44cb3efb0b9 100644
--- a/virt/kvm/vfio.c
+++ b/virt/kvm/vfio.c
@@ -75,20 +75,20 @@ static void kvm_vfio_group_set_kvm(struct vfio_group *group, struct kvm *kvm)
 	symbol_put(vfio_group_set_kvm);
 }
 
-static bool kvm_vfio_group_is_coherent(struct vfio_group *vfio_group)
+static bool kvm_vfio_file_enforced_coherent(struct file *file)
 {
-	long (*fn)(struct vfio_group *, unsigned long);
-	long ret;
+	bool (*fn)(struct file *file);
+	bool ret;
 
-	fn = symbol_get(vfio_external_check_extension);
+	fn = symbol_get(vfio_file_enforced_coherent);
 	if (!fn)
 		return false;
 
-	ret = fn(vfio_group, VFIO_DMA_CC_IOMMU);
+	ret = fn(file);
 
-	symbol_put(vfio_external_check_extension);
+	symbol_put(vfio_file_enforced_coherent);
 
-	return ret > 0;
+	return ret;
 }
 
 #ifdef CONFIG_SPAPR_TCE_IOMMU
@@ -136,7 +136,7 @@ static void kvm_vfio_update_coherency(struct kvm_device *dev)
 	mutex_lock(&kv->lock);
 
 	list_for_each_entry(kvg, &kv->group_list, node) {
-		if (!kvm_vfio_group_is_coherent(kvg->vfio_group)) {
+		if (!kvm_vfio_file_enforced_coherent(kvg->file)) {
 			noncoherent = true;
 			break;
 		}