path: root/virt
diff options
authorAlex Williamson <alex.williamson@redhat.com>2017-06-28 13:50:05 -0600
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>2017-07-27 15:06:07 -0700
commit3457c0459496d028a4f47167a8b8871671abdeda (patch)
treebe46c9476658460252f2f266d5fe5ab1de847d7e /virt
parentdb42944cc63a2db5de17b6cb572327c7ab8ab637 (diff)
vfio: New external user group/file match
commit 5d6dee80a1e94cc284d03e06d930e60e8d3ecf7d upstream. At the point where the kvm-vfio pseudo device wants to release its vfio group reference, we can't always acquire a new reference to make that happen. The group can be in a state where we wouldn't allow a new reference to be added. This new helper function allows a caller to match a file to a group to facilitate this. Given a file and group, report if they match. Thus the caller needs to already have a group reference to match to the file. This allows the deletion of a group without acquiring a new reference. Signed-off-by: Alex Williamson <alex.williamson@redhat.com> Reviewed-by: Eric Auger <eric.auger@redhat.com> Reviewed-by: Paolo Bonzini <pbonzini@redhat.com> Tested-by: Eric Auger <eric.auger@redhat.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'virt')
1 files changed, 19 insertions, 8 deletions
diff --git a/virt/kvm/vfio.c b/virt/kvm/vfio.c
index 1dd087da6f31..111e09c3f4bf 100644
--- a/virt/kvm/vfio.c
+++ b/virt/kvm/vfio.c
@@ -47,6 +47,22 @@ static struct vfio_group *kvm_vfio_group_get_external_user(struct file *filep)
return vfio_group;
+static bool kvm_vfio_external_group_match_file(struct vfio_group *group,
+ struct file *filep)
+ bool ret, (*fn)(struct vfio_group *, struct file *);
+ fn = symbol_get(vfio_external_group_match_file);
+ if (!fn)
+ return false;
+ ret = fn(group, filep);
+ symbol_put(vfio_external_group_match_file);
+ return ret;
static void kvm_vfio_group_put_external_user(struct vfio_group *vfio_group)
void (*fn)(struct vfio_group *);
@@ -171,18 +187,13 @@ static int kvm_vfio_set_group(struct kvm_device *dev, long attr, u64 arg)
if (!f.file)
return -EBADF;
- vfio_group = kvm_vfio_group_get_external_user(f.file);
- fdput(f);
- if (IS_ERR(vfio_group))
- return PTR_ERR(vfio_group);
ret = -ENOENT;
list_for_each_entry(kvg, &kv->group_list, node) {
- if (kvg->vfio_group != vfio_group)
+ if (!kvm_vfio_external_group_match_file(kvg->vfio_group,
+ f.file))
@@ -196,7 +207,7 @@ static int kvm_vfio_set_group(struct kvm_device *dev, long attr, u64 arg)
- kvm_vfio_group_put_external_user(vfio_group);
+ fdput(f);